Radiation Safety Manual




The Radiation Safety Manual outlines the regulations and procedures governing the use of radioisotopes under the University of California, San Francisco (UCSF) Type A Broad Scope Radioactive Materials License (Broad License).  This document was submitted to the State of California, Radiologic Health Branch as part of the license renewal application and therefore it continues to be the legal document governing the use of radioactive material at UCSF.  (IT ALSO SUPERSEDES ALL PREVIOUS COMMITMENTS, DOCUMENTS AND PROCEDURES.)

Any future changes in this document will be approved by the Radiation Safety Committee (RSC), and/or the State of California, as appropriate, prior to implementation.  You will receive updated copies from the Radiation Safety Officer (RSO) when such changes have been made.


Table of Contents











     A.    GOALS





























     D.    BIOASSAYS






     J.    FORMS

     K.    GLOSSARY





Radiation sources are useful tools in clinical applications, as well as biomedical investigations.  On a health sciences campus, such as the University of California, San Francisco (UCSF), important research often depends upon the use of radiation sources or radioactive materials.  Such research includes studies of basic cellular mechanisms, disease processes from the molecular to the whole organism level, genetic processes, and interactions of radiation with biological entities.  At an even more immediate level, the routine diagnosis and treatment of diseases often depend upon the use of ionizing radiation.

Thus, this extremely useful tool needs to be incorporated into campus activities in such a manner that maximum benefit is achieved while potential hazard is reduced to the minimum achievable level.




The setting and execution of guidelines for radiation protection are based upon an underlying philosophy in which two factors are of prime importance.  First is the assumption that there is no radiation dose so small that it does not involve some degree of risk.  The second major factor to consider is that radiation, like many other developments of modern life, confers great benefit upon both the individual and the society in spite of its small risk to health.  Consideration of the extent of these benefits makes a certain degree of risk acceptable.  Thus, a balance must be struck in each contemplated radiation usage, in which the benefit to be gained is weighed against the anticipated risk.  If the benefit outweighs the risk, the radiation is utilized so that its maximum benefit will be realized while individual exposure will be reduced to the minimum consistent with deriving these benefits. The overall protection philosophy, then, is to maximize the advantages from the use of radiation while minimizing exposure by eliminating whenever possible all unnecessary exposure to radiation.

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Occupational exposure includes all the dose equivalents and intakes incurred by a worker during periods of work but excludes medical and natural radiation, unless the latter is enhanced as a result of a particular working environment.  The arrangements for restricting occupational exposure should be applied to the source of radiation and to the designed features of the work place so that the use of Personal Protective Equipment should, in general, be regarded as supplemental to these more fundamental provisions.  Access to controlled areas should be restricted and subject to local operating instructions.  External exposure may be restricted by the use of shielding, distance and limitation of time.  Contamination by radioactive material may be avoided by attention to safety precautions and good work habits, which should ensure substantial reduction in occupational exposure.  The State of California has set occupational exposure limits which should not be exceeded under normal operational conditions.  Even though current occupational exposure limits provide a very low risk of injury, it is prudent to maintain exposure to radiation below these limits.  The objective is thus to reduce exposure by means of good radiation protection planning, as well as by management commitment to policies that foster vigilance against departure from good, prudent practices.  This is the concept of As Low As is Reasonably Achievable (ALARA) occupational exposure to radiation.  This is only possible if each individual user of radioactive materials joins the Management’s efforts in implementation of these concepts. 


The purpose of this manual is to assist University research personnel in using ionizing radiation in accordance with the current standards of good practice, the provisions of the University license, and the laws of the State of California. The manual is designed primarily for laboratory personnel.  There is a Radiation Protection Handbook covering clinical uses of ionizing radiation.


Requests for exemption from procedures discussed in this manual must be submitted in writing to the Radiation Safety Committee (RSC). The RSC will forward its recommendation to the Director of Environment, Health & Safety (EH&S), or the Assistant Vice Chancellor, Research as appropriate for consideration.


The following State of California and Federal requirements are applicable to the use of radioactive material at the University of California, San Francisco (UCSF).

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1.    CAL/OSHA

8 CCR 3203(a)(1) Effective July 1, 1991, every employer shall inaugurate and  maintain an accident prevention program which shall include, but not be limited to a training program designed to instruct employees in general safety work practices and specific instructions with respect to hazards unique to the employee's job assignment.


17 CCR 30253 incorporates by reference the federal regulations specified in Title 10,Code of Federal Regulations (CFR), Part 20, “ Standards for Radiation Protection Against Radiation.”

17 CCR 30195 incorporates by reference the federal regulations specified in Title 10, Code of Federal Regulations (CFR), Part 35.“Medical Use of Radioisotopes.”

17 CCR 30255 requires that each user shall inform individuals working in or frequenting any portion of a controlled area as to the presence of sources of radiation; instruct such individuals in safety problems associated therewith and in precautions or procedures to minimize radiation exposure; and instruct such individuals in the provisions of department regulations and licenses applicable for the protection of personnel.





UCSF has a Type A Broad Scope Radioactive Materials License (Broad License) issued by the California Department of Public Health, Radiologic Health Branch.

Copies of the license are available for inspection at EH&S.  The license describes the campus possession limits for each radioisotope, the authorized addresses, and provides for internal authorization procedures.

Any requests for amendments to the campus Radioactive Materials License must be approved by the Radiation Safety Committee (RSC) and communicated to the State of California by Environment, Health & Safety (EH&S).


Authorization by the RSC is required before any individual may bring into, or remove radioisotopes in any form from the Medical Center.  All uses of radioisotopes involving humans must have prior approval of the RSC, the Radioactive Drug Research Committee (RDRC) (if applicable), and the Committee on Human Research (CHR)(research only).


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As a health sciences campus, the University of California, San Francisco (UCSF) has extensive teaching, research and clinical facilities in which sources of ionizing radiation are used.  The goal of the campus Radiation Safety Program is to provide adequate protective measures against exposure to these sources for patients, visitors, students, faculty and staff on campus, and for the community at large. These measures are required by the UCSF Radioactive Material License. Responsibility for maintaining this license is delegated appropriately within the campus.


The State of California Department of Public Health, Radiologic Health Branch has the responsibility of evaluating each proposed use of radioactive materials within its jurisdiction. The State of California Department of Public Health could accomplish this by requiring a direct, individual application for each proposed use of radiation.  Instead, it has delegated the responsibility of reviewing such uses on this campus to UCSF, through the issuance of a Type A Broad Scope Radioactive Material License (Broad License).

It is through the campus Radiation Safety Program that this internal, delegated responsibility is implemented. To obtain a Type A Broad Scope Radioactive Material License, UCSF has had to demonstrate:

a.    Considerable experience with a large and varied radioisotope program.

b.    A well-developed health physics group capable of evaluating and dealing with radiation safety problems.

c.    Detailed procedures for evaluating proposed uses of radioactive materials and for maintaining surveillance over approved users.

d.    Establishment of a program to assure technical review of individual users and their procedures and facilities before approval.

The internal review program must be coupled with an internal inspection program to ensure that all health and safety requirements are being met. These licensing and inspection functions are coordinated through EH&S. These operations are recorded to demonstrate compliance with the State of California Department of Public Health statewide programs.


The rules and procedures set forth in the Radiation Safety Manual have one single, straightforward purpose -- to protect UCSF patients, students, and employees against unnecessary and potentially harmful radiation exposure.


UCSF is authorized to procure and use radioactive materials in specified areas, including satellite programs, under a Broad License issued by the State of California Department of Public Health. This license is contingent upon the existence of a Radiation Safety Committee (RSC) and a Radiation Safety Officer (RSO).

a.    Responsibility

The UCSF RSC is appointed by the Executive Vice Chancellor for Research, in accordance with the conditions of the license.  This committee will:

i.      Establish policies and regulations governing the use of ionizing radiation at UCSF.

ii.     Consider technical and safety related aspects of the use of ionizing radiation within the jurisdiction of UCSF.

iii.    Advise the Chancellor on all matters related to radiation safety, and recommend such policies and procedures as it may deem appropriate to protect the safety of users, patients, students, employees and the public.

iv.   Promulgate a Radiation Safety Program that satisfies the conditions of the UCSF License.

v.    Committee meetings are scheduled to review the present Radiation Safety Program and to consider radiation safety problems.

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b.    Organization of the RSC

The RSC shall consist of a minimum of six members including at least one physician from the Department of Nuclear Medicine, one from the Department of Radiation Oncology, one from the Department of Radiology, one person from the research community, and one person representing the UCSF administration.  The RSO is a member of the committee.

Activities of the RSC are directed by its Chair who shall be a member of the Academic Senate. The Chair shall convene the RSC at least quarterly and at other times at the call of the Chair. A quorum shall consist of a majority of the members and the RSO (or a designated alternate in the RSO’s absence).

The Chair of the RSC may appoint subcommittees to examine and approve or disapprove of Radiation Use Authorization (RUA) applications and renewals, and such other duties, as directed by the Chair of the RSC and authorized in the license.

c.    Functions and Activities of the RSC

i.      Review the safety-related aspects of the use of all sources of ionizing radiation, including radiation producing machines and equipment.  When humans are to receive radiation in research, the RSC will forward a copy of its review to the Committee on Human Research (CHR).

ii.     Assure that any Principal Investigator (PI) using radioactive materials is qualified by training and experience, has the facilities to handle the materials safely, and proposes a plan that is safe to all concerned

iii.    Establish guidelines for and advise on the content of the UCSF Radiation Safety Program.  All new users must participate in a campus training program for the use of radioactive materials.  The extent of which will be determined by the RSO.  All exemptions must be approved by the RSC/RSO.

iv.   Assure observance of safety standards established by the Nuclear Regulatory Commission, State of California Department of Public Health, Federal and State Department of Transportation, National Council on Radiation Protection and Measurements, and other duly recognized regulatory and standard-setting bodies.

v.    Provide oversight of the campus Radiation Safety Program implemented by the RSO, including annually reviewing the operation of the Radiation Safety Office in receiving, auditing the use, and disposing of radioactive material at locations specified in the license.

vi.   Review infractions of use and safety rules referred by the RSO and responsible clinical or laboratory directors. Review investigations of accidents and incidents and prepare reports, when deemed necessary.

vii.  Recommend policy on patient and research activities that use ionizing radiation.

viii. Request technical advice from the RSO on matters regarding radiation safety.

ix.   Receive, review, and act on applications (requiring RSC approval) for the use of radioactive sources used by UCSF personnel. This includes the use of radioactive materials in human subjects


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a.    Responsibility

The purpose of the Radioactive Drug Research Committee (RDRC) is to guarantee subjects who take part in research protocols the greatest degree of both radiological and pharmacological safety.  Before approving such studies, it is this Committee’s responsibility to determine the intrinsic value of the research with a risk versus benefit analysis.  The RDRC is defined by Federal law, and its membership must be approved by the Food and Drug Administration

(FDA, 21 CFR, Part 361).

The RDRC is independent of the RSC and its services are available to all users of radioactive material and Department Chairs.  It shall complement the RSC activities already existing within the hospitals and medical research facilities.

b.    Organization

The RDRC Chair shall be a member of the RSC.  The RDRC members shall be appointed by the Assistant Vice Chancellor, Research. The RDRC shall consist of at least five members and include the RSO as a member who advises the committee and implements its decisions.

The activities of the RDRC are directed by its Chair. To conduct business, a quorum (including the RSO, or his designated alternate) is necessary.  Meetings of the RDRC shall be called by the Chair not less than four times a year, or on petition of any member of the RDRC.

c.    Approvals

Research involving radioactive drugs must be approved by the RDRC when they are administered to human subjects in a study intended to:

i.      Obtain basic information regarding the metabolism (including kinetics, distribution, and localization) of a drug.

ii.     Obtain basic information regarding human physiology, pathophysiology, or biochemistry.

The RDRC regulations, from the Food and Drug Administration, require review of study design and appropriateness of the research protocol; they also impose limits on radiation absorbed doses and the amount of the drug administered. The RDRC grants final approval to a study that falls under its purview after approval of the CHR and the RSC has been received.


a.    Organization

Environment, Health and Safety (EH&S) conducts the Radiation Safety Program.  This program includes surveillance of all users of radioisotopes, radiation-producing machines and equipment; monitoring of exposure levels, and investigation of incidents.  EH&S provides consultation, training in radiation safety, and radiation safety services. These services conform to the standards set forth in this Manual, the license conditions, State of California Regulations, Nuclear Regulatory Commission 10 CFR regulations, National Council on Radiation Protection Guidelines, as well as other standards as set by the RSC.

The Director of EH&S is responsible for informing the Chancellor of matters related to radiation safety.

The RSO is responsible for the operation of the Radiation Safety Program and for assuring that the use of ionizing radiation is in conformance with UCSF policies and applicable government regulations. The RSO is also responsible for referring to the RSC matters requiring its review and approval.

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b.    Functions of the Radiation Safety Program

i.      General surveillance of all health physics activities, including both personnel and environmental monitoring.

ii.     Provide consulting services to personnel at all levels of responsibility on all aspects of radiation protection.

iii.    Receive and inspect all radioisotopes that come to UCSF, and consult on all packages of radioisotopes shipped from UCSF.

iv.   Monitor all machines capable of producing ionizing radiation.  Evaluate the output of these machines on an annual basis or as requested.

v.    Distribute and process personnel monitoring equipment. Keep records of internal and external personnel exposure.  Notify individuals and their Laboratory Supervisor of exposures approaching or exceeding the maximum permissible levels and recommending appropriate remedial action.

vi.   Instruct personnel in proper procedures for the use of radioactive materials and conduct refresher classes.

vii.  Supervise and coordinate the waste disposal program, including the keeping of waste storage and disposal records.

viii. Perform leak tests on all sealed sources greater than 100 μCi.

ix.   Maintain a periodic inventory of all radioactive materials at UCSF.

x.    Supervise decontamination of any contaminations; investigate accidents.

xi.   Maintain a continuous program of environmental radiation hazard evaluation and hazard elimination.

xii.  Review all radiation use authorization applications and renewals.

xiii. Conduct the laboratory audit program designed to evaluate the conformance of the users with the safety requirements.

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Authorized laboratory workers handling radioactive materials are immediately responsible for their own safety and the safety of those around them.  These responsibilities include:

a.    Keep exposure to radiation as low as reasonably achievable, and specifically below the maximum permissible dose as listed in the following table:





Whole body

50 mSv (5 rem)

Lens of eyes

150 mSv (15 rem)

Extremities or skin

500 mSv (50 rem)

Any individual organ or tissue

500 mSv (50 rem)

Declared pregnant worker dose to fetus (over gestation period)

5 mSv (0.5 rem)


1 mSv (0.1 rem)

Dose in any unrestricted area cannot exceed 2 mrem in any hour or 100 mrem in a year


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b.    Maintain a laboratory environment free from airborne radioactive contamination. This is done through the maintenance and use of engineering controls such as fume hoods.

c.    When issued, wear the prescribed monitoring equipment, such as dosimetry badges and ring badges, when working with radioactive materials.

d.    Survey hands and body for radioactivity with a rate meter with a thin end-window or pancake probe (exception: 125I, use rate meter with a scintillation probe) and remove all loose contamination before leaving the laboratory for any reason.


Principal Investigators (PI) are responsible for ensuring that the laboratory environment of the individual users is kept safe. Further responsibilities are as follows:

a.    Adequate planning is required before an experiment is conducted.  The Laboratory Supervisor shall determine the types and amounts of radiation or radioactive material necessary for the procedure.  This will provide an indication of the necessary protection.  Before the procedure is conducted, it should be rehearsed to preclude any unexpected circumstances. In any situation where there may be a radiation hazard, the Departmental Safety Advisor (DSA) shall be consulted prior to conducting the experiment.

b.    Instruct their employees in the safe use of radionuclides used in their procedures, including appropriate use of Personal Protective Equipment (PPE)  All untrained personnel are required to read and to be tested on the Radiation Safety Training Manual that is available online in the laboratory; additional copies may be obtained from EH&S.  In addition, all authorized principal investigators, or their delegated alternative, must provide practical instruction in all aspects of radiation safety that are detailed in this manual.

c.    Inform the DSA when the individuals or activities under your RUA are changing.  This includes new individuals, changing laboratory locations or termination of activity on the campus.

d.    Follow correct procedures for the procurement of radioactive materials by purchase or transfer.

e.    Post areas where radionuclides are kept or used, or where radiation fields may exist.

f.     Record the receipt, transfer, use, and disposal of radioactive material used in your area. This includes sealed sources.  The PI must be prepared to submit a quarterly inventory upon request.

g.    Properly prepare all radioactive waste material for pickup by EH&S for disposal.

h.    Minimize the stock of stored radioisotopes within the laboratory area.

i.      When terminating an RUA, the PI must either transfer to an authorized user or return to EH&S all radioactive materials, including waste, assigned to him/her under the authorization. All dosimetry badges for staff must also be returned at this time.  A final laboratory survey must be performed by the PI to ensure that the area is free of contamination.  An exit survey will be conducted by the DSA before releasing the laboratory for general use.


Department Chairs have the following responsibilities. All may be delegated to a departmental safety representative:

a.    Assure that the applicant and all personnel listed on an application have training that will be commensurate with the proposed project.

b.    Assure that the project design and monitoring methods, as well as the resources available, meet the UCSF safety standards.

c.    Correct work errors and conditions that may result in personal injury.

In departments with electrical sources of ionizing radiation, the Department Chair may appoint a person or subcommittee to see that all practical efforts to reduce radiation exposure have been performed. This should be done prior to purchase, installation, and use of equipment.  The person or subcommittee should cooperate with the RSO to:

i.      Establish guidelines for qualifications of users of radiation sources.

ii.     Assure departmental compliance with UCSF radiation policies.

iii.    Review incident investigations.


Under the terms of the Broad License, from the State of California Department of Health Services to the Regents, the Chancellor has the ultimate responsibility for the safe handling of radiation on the UCSF campus. Acting for the Assistant Vice Chancellor, Research, administers the UCSF Radiation Safety Program through the RSC, the RDRC, and EH&S.  The Chancellor certifies that UCSF will implement the As Low As is Reasonably Achievable (ALARA) Program set forth in this manual.

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The review process is designed to ensure the safe handling and use of radioisotopes and other radiation sources.  Applications are reviewed on their merit as well as for their impact on the campus.



a.    Basic Research Authorization  (Non-Human)

Each Principal Investigator (PI) must apply for a Radiation Use Authorization (RUA) before using radioisotopes at the University of California, San Francisco (UCSF). The PI can access the online RUA application by using the RIO program located in MyAccess or the UCSF EH&S website. The RIO program provides step by step instructions for creating all RUAs, human or non-human.  Entry to the RIO program requires a username and password.  Contact the department DSA or RSO for more information on creating a new RUA application.  The Radiation Safety Program will review the proposed project and facilities which normally includes an interview with the applicant and a visit to the proposed use locations to evaluate the factors outlined below:

i.      The training and experience of all personnel who will be involved in the project.  PIs must have some training or practical experience in the following areas: characteristics of ionizing radiation, radiation dose quantities, radiation detection instrumentation, and the biological hazards of exposure to the types and forms of radiation to be used.

All personnel involved in the project must be familiar with the UCSF radiation safety requirements.  The PI is responsible for initial indoctrination and training of all persons working under his/her authorization. The DSA will assist if needed.

ii.     The radioisotopes (quantities, and chemical and physical forms of each of the radioisotopes) to be used will be reviewed.

iii.    A brief description of lab procedures to be utilized.

iv.   The adequacy of all locations for the proposed use with respect to: (See Appendix A for Criteria)

  •    Storage facilities.
  •    Hoods, glove boxes, and other special equipment.
  •    Housing and maintenance of experiment animals, if applicable.
  •    Impact of radiation use on surrounding areas.
  •    Housekeeping and hygiene.

v.    Radiation Control and Personnel Protection

  •    Inventory records (receipts, use, transfer, and disposal of radioisotopes). 
  •    Waste disposal procedures.
  •    Monitoring methods, frequency and record keeping.
  •    Survey instrumentation, calibration procedures and records.
  •    Contamination control procedures.
  •    Shielding and/or remote handling techniques.
  •    Provisions for controlling releases to the environment. 
  •    Personnel dosimetry and bioassay requirements.

vi.   Area posting and security

  •    Proper posting of work areas.
  •    Security measures to prevent unauthorized removal of   radioisotopes.

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b.    Human Use Authorizations

Projects involving human subjects must have the overall approval of the Committee for Human Research Committee (CHR) and the Radiation Safety Committee (RSC).  For some research projects, the approval of the Radioactive Drug Research Committee (RDRC) is also required. 

Requirements for human use are much more restrictive than those not involving human subjects.  Human Use Authorizations are renewable when approved by the DSA, RSO, RSC, and/or RDRC.  This authorization may be revoked at any time.  The review and approval process is similar to that of Basic Research Authorization.

Whenever humans are to be exposed to radiation in a research context, the Radiation Exposure to Subjects form must be completed and submitted to the RSC and/or RDRC, in addition to a Radioisotope Use Authorization, if necessary.  The CHR requires approval from the RSC on studies involving radiation exposure to human subjects before giving its final approval.

c.    Classroom Use of Radioisotopes

Application shall be submitted to the Radiation Safety Program at least four (4) weeks prior to the commencement of the class.  The following supplemental information will be required:

i.      Laboratory instructor (if other than applicant) in charge, and years of training and experience in the use of radioisotopes.

ii.     Names and years of experience of laboratory or teaching assistants involved in the course.

iii.    Number of laboratory sections.

iv.   Number of students per laboratory assistant.

v.    Number, type, and calibration data of monitoring instruments available in the laboratory.

vi.   Health and safety instructions for students.

vii.  Extent to which students will be handling radioisotopes.

viii. Safety measures and emergency procedures.

As a condition of approval, the RSC will require special safety measures, equipment and procedures.

The application will be reviewed by the RSO and will be submitted to the RSC for final approval.  A copy of the approved application will be returned to the applicant with the conditions of approval.

Allow approximately three weeks for processing of the RSC application. Radioisotopes may not be ordered before satisfying the conditions of the approval.  Violation of this requirement may result in denial or revocation of the authorization.


a.    A completed RUA application submitted in RIO (Research Information Online).

b.    Each user included in the RUA must have current radiation safety training, and be trained by the PI in safe handling practices for the isotopes specified. 

c.    Information must be complete and include necessary supplements.

d.    A Radiation Safety Office report on the facility, competency of PIs, and handling procedures must be satisfactory.

e.    Experimental design, technique, and safety must be adequate.

f.     Laboratory staff dosimetry history and compliance record during the previous interval must be acceptable.

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An authorized user found to be willfully or negligently violating any of the UCSF or State of California regulations regarding the safe use of ionizing radiation may have his RUA revoked.  Any radioactive materials in his possession may be removed for storage or disposal. 

RUAs will ordinarily be terminated upon:

a.    Completion of the research project.   

Upon completion of work with radioisotopes or cessation of the use of an approved facility, the DSA must be notified.  This will be followed by final monitoring, clearance, and proper disposal of the remaining radioisotopes by the PI.  An exit inspection should then be performed by the DSA before the PI leaves UCSF.

b.    Expiration of the authorization without renewal.


Upon an extended leave from campus, the PI shall appoint an "alternate," who will be responsible for laboratory activities and ensure that the laboratory complies with all of the UCSF radiation safety requirements. This appointment must be reviewed by the RSO and submitted to the RSC for approval.


All changes to the RUA must be approved by the RSC/RSO.  To modify an existing RUA, submit a modification in RIO and include an explanation of the changes in the Mod Justifications section.   

a.    Personnel

To add or delete a new user to the RUA, note the user change in the Mod Justifications section.  For new users, radiation safety training must be current before the modification can be approved.  If new users require dosimetry, submit a Dosimetry Request Form.  For deleted users who were receiving dosimetry, contact dosimetry.coordinator@ucsf.edu to discontinue dosimetry.

b.    Use Area

To add a new use area, note the room to be added in the Mod Justifications section and upload a map of the room in the documents section.  After a site visit the RSP staff will issue the appropriate approvals.

To delete a use area, note the room to be removed in the Mod Justifications section.  Remove all radioactive materials from the room, survey and decontaminate if necessary.  The DSA will conduct a site visit and spot check for contamination prior to approving the request.

c.    Changes in Possession Limits

Changes in possession limits of existing approved radionuclides must be listed in the Mod Justifications section.  Minor changes (few mCi) will be approved by the Radiation Safety Program.  Addition of substantial quantities (10's of mCi) will be sent to RSC for review and approval.

d.    Addition of New Radionuclides

Addition of new radionuclides must be listed in the Mod Justifications section.  Addition of low mCi quantities of radionuclides with similar hazards to those already permitted (e.g., 35S for 14C users) may be approved by the Radiation Safety Program.  All other requests will be forwarded to the RSC for review and approval.

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All persons using radioisotopes at UCSF must have radiation safety training documented in the UC Learning Management system and/or RIO.  Specific training experience may be requested by the RSC/RSO.  All exemptions must be approved by the RSC/RSO.



In order to maintain a working knowledge of safety, all staff will be required to undergo radiation safety retraining at least once every two years.  This schedule may be revised if the RSO believes that the skills of an individual warrant such a revision.


Copies of rules, regulations, and standards and the UCSF license to procure and use radioactive materials are available in the EH&S Radiation Safety Program for review by employees and staff.

A copy of the UCSF Radiation Safety Manual must be maintained in the office of each department that uses sources of ionizing radiation, or be readily available online.  It must be available for review by all employees.  It is highly recommended that these manuals be available in all laboratories using radioactive materials.  Personal copies of the manual are available from the DSA.

In addition, the Radiation Safety Program has a wide range of books, publications and audio-visual materials which are available to users.  Please contact your DSA for further information.


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a.    Posting of an Area

i.      Areas in which radioactive materials are used shall be conspicuously posted with a sign or signs displaying the conventional three bladed symbol in magenta or purple on a yellow background.  The sign shall bear the following words:


ii.     Areas in which the radiation exposure to individuals is at such levels that an individual could receive in any one hour a dose to the whole body in excess of 5 millirem, at 30 centimeters from the source shall have a conspicuously posted sign bearing the following words:


iii.    Areas in which the radiation exposure to individuals is at such levels that an individual could receive in any one hour a dose to the whole body in excess of 100 millirem shall have a conspicuously posted sign bearing the following words: 


When a High Radiation Area has been detected, the Radiation Safety Officer (RSO) must be notified immediately.  The area must also be posted for advice on safe working procedures or engineering controls.

b.    Exceptions from Posting

i.      Hospital rooms or hospital areas should be posted when there is a patient present containing therapeutic levels of radioactive material.  No diagnostic imaging rooms will be posted. These areas are not required to be posted if personnel, who will take the necessary precautions to prevent exposure of any individual to radiation in excess of the established limits, are in attendance.

ii.     Rooms or other areas containing radioactive materials for periods of less than 8 hours are not required to be posted with a “CAUTION RADIOACTIVE MATERIAL” sign - provided the materials are constantly attended by an individual who shall take necessary precautions to prevent the exposure of any individual to radiation or radioactive materials in excess of established limits.

iii.    Equipment rooms used for measurement of the activity of samples with quantities which are exempted under 10 CFR 20 Appendix C will not be posted.

c.    Labeling of Containers

i.      Each container in which radioactive material is transported, stored, or used shall bear a label with the caution symbol and the words:  CAUTION RADIOACTIVE MATERIAL

ii.     Whenever a container is removed from the working area or when containers are used for storage it must be labeled.  The labels shall also state the types and quantities of radioactive materials in the containers and the date of the measurement of the quantities.

d.    Other Posting

The University of California, San Francisco (UCSF) Type A Broad Scope Radioactive Materials License (Broad License) conditions and State of California Regulations require that specific informational materials be conspicuously posted in areas where radioactive materials are stored or used.  These are available on the UCSF EH&S website, Radiation Safety section, and include the following:

i.      Summary of UCSF Campus Radiation Safety Procedure Guide which includes information regarding the following:

  •    Procurement of Radioactive Materials
  •    Authorized Applicant Responsibility
  •    General Safety Precautions
  •    Administration to Animals
  •    Waste Disposal
  •    Emergency Procedures

ii.     RH-2364, Notice to Employees

  •    This form is to be posted.
  •    The form will indicate the location of the license. 

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Radioactive materials stored on the campus shall be secured against unauthorized removal.  The security methods are determined by the Principal Investigator (PI) with approval of the RSO.  This depends upon specific laboratory conditions.

An inventory log (containing the date, radioisotope, manufacturer's lot number, and amount) must be kept for all radioisotopes stored.  Log corrections must be updated through a routine physical inventory of storage items.  The RSO/ Radiation Safety Committee (RSC) will determine the frequency of updates.


a.    Within the University

Transfer of radioactive material from one department, laboratory, or project to another within UCSF requires a TRANSFER OF RADIOACTIVE MATERIAL FORM, which must be completed for each transfer.  (This form may be obtained at the Radiation Safety Program by calling 476-1771, and is also available online on the UCSF EH&S website, Radiation Safety section). Adherence to these procedures is crucial for compliance with the requirements of the Broad License granted to UCSF.

No radioactive materials may be transferred from one PI to another unless the recipient has a valid RUA number for the radioisotope and quantity to be transferred. The container and means of transportation must be adequate to ensure safety during transfer.  When a vehicle is involved in the transfer, specific approval of the packaging (in accordance with Department of Transportation (DOT)) is necessary from the Radiation Safety Program prior to the transfer.  All transfers of radioactive material must be documented in the files of the PI who transferred the material, the recipient of the radioisotope, and the Radiation Safety Program.

b.    Off-Campus (Non-UCSF Facilities)

Radioisotopes purchased under the UCSF license may not be used for research projects at locations not specified in the license.  Radioisotopes transferred off campus must be transferred in accordance with procedures described below.

i.      Radioactive material may not be transferred off campus unless the recipient is authorized by a specific license issued by an Agreement State or the U.S. Nuclear Regulatory Commission.

ii.     A completed TRANSFER OF RADIOACTIVE MATERIAL FORM must accompany each transfer.

iii.    Radioactive material must be packaged according to the DOT specifications, if shipped domestically. International shipments must comply with applicable international regulations (International Air Transport Association (IATA), International Civil Aviation Organization (ICAO)). 

iv.   The transfer must be approved in advance of shipment by the RSO of the receiving institution.

v.    UCSF shall assume no responsibility for possession, use, storage, or radiation safety after the radioisotope transfer.

vi.   In the event UCSF personnel are actively participating in the project, the RSO must be able to assure or verify that the RSP provided by the other licensee meets standards acceptable to UCSF.

vii.  Before the package is sealed, it shall be brought to the Radiation Safety Receiving Laboratory for a wipe test.  The Radiation Safety Program will provide necessary assistance for safe shipment of radioactive packages. Arrangements may be made by the PI transferring the radioactive material to have the common carrier pick-up of the package at the Radiation Safety Receiving Laboratory or to have the EH&S transport the material.

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Radioactive materials may only be purchased or brought to UCSF by individuals having a valid Radioactive Use Authorization (RUA).  All radioisotope orders must be initiated by the Purchasing Department.  When an individual orders radioisotopes, the following procurement information must be provided to the vendor:

  •    PI.
  •    Researcher responsible for the order.
  •    PI RUA number.
  •    Telephone and room number of laboratory.

The amount of any single vial order may not exceed the licensed maximum single vial purchase limit and the total quantity must be less than the laboratory's maximum possession limit. Vendors wishing a copy of the UCSF license should contact EH&S.

a.    Special Purchase Order

For a single order, submit a Purchase Requisition with the procurement information

b.    Miscellaneous Blanket Purchase Order

This type of blanket purchase order does not name a specific vendor. The PI is responsible for verifying that purchase amounts do not exceed the RUA authorization. Orders received at the Radiation Safety Receiving Laboratory in excess of the RUA authorization will not be released to the PI.

Provide the necessary procurement information on a Purchase Requisition including the expiration date and a "not-to-exceed" dollar amount for the blanket period.

c.    Specific Blanket Purchase Order

This blanket order is issued to a specific vendor for specific items to be delivered on a regular basis or as needed by the user.


All incoming radioisotopes are delivered to the areas designated as approved Radioisotope Receiving Laboratories.


Shipments are checked for damage, external or internal contamination as necessary, and appropriate authorization for the amount and type of radioisotope.

All radioactive material orders that exceed the PI's authorized amount, type, or form will be held for review.  After review these may be released if it is verified that the possession limits have been increased (e.g., RUA amendment) or inventory on hand reduced (e.g., waste disposal). These shipments may also be disposed of as radioactive waste or returned to the vendor, as appropriate.

The PI will be notified of contaminated shipments. Contaminated shipments will not be released unless the PI accepts responsibility for the contamination.  If the levels of contamination are unacceptable by UCSF standards, the Radiation Safety Program will take necessary actions as required by UCSF procedures and applicable regulations. 

Upon completion of the package surveillance, the Radiation Safety Program will deliver the package to the laboratory address on the invoice.  If shipping papers from the vendor do not contain the proper documentation (i.e., PI, RUA number, laboratory address, and phone number) additional time will be needed for the Receiving Technicians to identify the proper recipient.  EH&S WILL NOT BE RESPONSIBLE FOR SPOILAGE OF SUCH PACKAGES.  

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Safety is achieved when careful procedures are followed in the laboratory. The safety of each operation or manipulation must be considered separately and in relation to the overall experiment design. Periodic self-evaluation of the facility or procedures is suggested for all users of ionizing radiation. The following precautions should be followed regardless of the amount or type of radioisotope involved:

1.    Wear protective clothing whenever contamination is possible.  Do not wear such clothing outside of the laboratory area unless the clothing has been monitored appropriately.

2.    Use mechanical devices whenever their aid will assist in reducing exposure. 

3.    Use protective barriers and other shields whenever possible.

4.    Use pipette-filling devices. NEVER PIPETTE RADIOACTIVE SOLUTIONS BY MOUTH.

5.    Do not smoke, drink or eat in radionuclide laboratories. Eating may be permitted in a specified area of an office or laboratory that has been approved by the DSA.

6.    Maintain good personal hygiene.

7.    Use good laboratory work practices.

8.    Wash hands and arms thoroughly before handling any object which goes to the mouth, nose or eyes. 

9.    Check the immediate areas, (e.g., hoods, benches) in which radioactive materials are being used, at least once daily for contamination.  A record of routine surveys must be maintained at the frequency established in the RUA.  The survey results should include background results. Any contamination observed should be clearly marked, decontaminated, resurveyed, and the results recorded.

10.  The laboratory must be kept neat and clean.  The work area should be free from equipment and materials not required for the immediate procedure.  Keep or transport materials in such a manner as to prevent breakage or spillage (double container), and to ensure adequate shielding.  Wherever practical, keep work surfaces covered with absorbent material, preferably in a stainless steel tray or a pan, to limit and collect spillage in case of accident. 

11.  Label and isolate equipment, such as glassware, used in laboratories for radioactive materials.  Once used for radioactive substances, equipment should not be used for other work - unless the equipment is decontaminated.

12.  Request Radiation Safety Program supervision of any emergency repair of contaminated equipment in the laboratory by shop personnel or by commercial services contractor.

13.  Immediately report accidental inhalation, ingestion, or injury involving radioactive materials to the Laboratory Supervisor and the DSA, and carry out the recommended corrective measures.  All individuals shall cooperate in any and all attempts to evaluate their exposure.

14.  Carry out decontamination procedures when necessary, and take the necessary steps to prevent the spread of contamination to other areas.

15.  Comply with requests from the RSP for bioassays. See Appendix D, Bioassays, for specifications and methodology of bioassay procedures.

16.  Disposable gloves must be worn during all manipulations that could result in contamination. Gloves should be frequently changed during procedures.  Some procedures call for the use of double gloving with the outside pair being frequently changed.

17.  Refrigerators containing, or having contained, radioisotopes may not be used for the storage of food or drink.

18.  Unbreakable containers must be used whenever possible for storage of radioactive solutions.  If glass is used, secondary containers must be provided to contain any spilled material. 

19.  Absorbent material with an impervious backing is required for covering all work areas where radioactive material may be used.  Exemption may be made if sterility requirements dictate; in these cases the bench top must be impervious. The absorbent material must be routinely changed. 

20.  Radioactive material usage should be confined to small areas.  This will simplify containment, shielding, and clean-up in case of contamination.

21.  Fume hoods must be used if appreciable amounts of radioisotopes are being manipulated, or if there is potential for contamination, volatilization, or aerosol formation.

22.  Use of protective equipment (masks, coats, gloves, shoe covers, etc.) must never substitute for adequate hazard controls in the laboratory environment.

23.  Labeled, and if appropriate, shielded, waste storage containers shall be used.

24.  Work areas and clothing should be monitored daily for radioactive contamination when working with radioisotopes.

25.  All areas of radioactive material use or storage must be identified by the use of a sign or label with the radiation symbol.  

26.  All entrances to the laboratories using radioactive materials must be identified by the use of a sign with the radiation symbol.  

27.  All radioactive materials use areas must have posted a California Form RH 2364, Notice to Employees.

28.  Individuals who have been assigned dosimeters must wear them when they are working with radioactive materials or when they are present in radiation areas.

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Only personnel designated as authorized users under an RUA may use radioisotopes.  Such designation requires, as a minimum, having a valid training number issued by EH&S and appropriate isotope specific training and experience documented on the Training Experience Verification Form.  Copies of this form must be on file with the Radiation Safety Program, a duplicate should be placed in the laboratory files.

All facilities must be approved by the RSC and/or DSA prior to being used for radioisotope work.


Before an authorization is granted for use of radioisotopes in animals, the Radiation Safety Program will review procedures with the applicant.  The applicant must provide assurance that adequate animal care facilities are available and must make provision for collection and storage of animal carcasses and all associated waste.

Administration of radioactive materials into animals shall be done in a manner which will control and limit accidental spillage.  The animal should be placed on absorbent material with a backing that is impervious to liquid during administration of the radioisotope.  A laboratory coat and protective gloves shall be worn.


a.    Labeling and Control of Contamination

Cages in which animals containing radioisotopes are housed must be labeled by the PI with a placard with the radiation symbol.  The placard shall list the type and quantity of radioisotopes in each animal and the date of administration. If radioactive materials are excreted in the urine or feces, it is the responsibility of the PI to frequently change the bedding materials. All contaminated materials must be discarded as radioactive waste according to the established guidelines.  The PI is responsible for immediate decontamination of all contamination caused by the animals.  The PI is responsible for ensuring that cages to be washed at the cage-washing facility are surveyed and decontaminated prior to being released for final washing.  Documentation of the release survey must be maintained for inspection. 

b.    Segregation

The Radiation Safety Program may specify that animals containing radioactive materials be kept in cages apart from other animals.  The applicant must also inform the Laboratory Animal Resource Center (LARC) concerning the type and number of animals, the radioisotope used, and the room(s) where the animals will be housed.  The applicant shall inform the LARC through the use of the Animal Involvement Form, which includes posting information.


a.    Excreta

Animal excreta should be regarded as radioactive unless appropriate monitoring indicates that there is not any radioactive material present.  The PI is responsible for ensuring that such monitoring is done. Monitoring for soft beta emitters shall be done by taking swipes and using a liquid scintillation counting device. A portable survey meter is not appropriate.  Disposal of radioactive excreta shall be performed in the same manner as that for the animal carcasses.

b.    Carcasses

Animal carcasses containing radioactive materials must be properly packaged for disposal. The carcasses must be separately placed into double bags.  Each bag must be labeled with type and number of animals contained, the radioisotopes, the activity of each radioisotope, the date, and the name of the PI.  It is the responsibility of the PI to bring the carcasses to the Radiation Safety waste refrigerator/freezer area for disposal.  The areas are: Parnassus – Medical Sciences loading dock, Mt. Zion – Cancer Center Research basement S-071.  SFGH location is EH&S office in BLDG 1. Mission Bay – contact Genentech Hall Radioisotope receiving at 514-4107.


Adequate ventilation or air cleaning must be provided for animal rooms if there is a possibility of airborne radioactive contamination.  The PI is responsible for working with the DSA to assess this need.  If special ventilation needs are required, the PI shall work with the Chief Animal Care Technician. 

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PIs are responsible for assuring that Animal Care Technicians and Laboratory Custodians are aware of potential hazards.  They must be adequately trained and supervised in the observance of necessary precautions. If any assistance is needed in training Animal Care personnel to use radioactive materials in the project, or in the monitoring of the facilities, the PI should contact the Radiation Safety Program.


a.    The LARC Supervisor must be informed and advised when animals under his/her care contain radioisotopes.  This is the responsibility of the assigned PI.  To contact the LARC Area Supervisor for the particular location, call 476-2204 (San Francisco General Hospital (SFGH), call 502-8223).

b.    Cages or cage cards must be posted with an appropriate "Caution Radioactive Material" sign.

c.    Radiation surveys must be made around the cages to determine levels of radiation exposure.  These surveys must be conducted when the animals are initially placed into the cage room and then on a weekly basis.  If the PI cannot provide an adequate survey, he/she shall contact the DSA for assistance. The PI is responsible for conducting a contamination survey of cage facilities following use.

d.    Animals that have been irradiated by external beam radiation will not present a radiation hazard.

e.    If the radioisotopes will be excreted in the urine or feces, the PI must ensure that all excreta is collected.  All animal bedding must be changed periodically and disposed of as radioactive waste.

f.     Small animal cages may be washed in the laboratory sink if this procedure is approved by the Radiation Safety Program.  In centralized animal care facilities, Animal Care Laboratory Supervisors shall be fully apprised of the radioisotopes in use so that an animal husbandry procedure may be initiated as defined on the Animal Involvement Form.  Animal cages should not be taken to the cage wash facility until they have been surveyed with an appropriate survey meter and wipe tests have been taken.  Removable contamination may not exceed 3x background.

g.    Laboratory coats, appropriate eye protection, and disposable gloves must be worn during cage cleaning and when handling the animals containing radioactive materials.

h.    Personnel radiation dosimeters may be required in some animal care situations. Contact the DSA for advice concerning this service. 


Radioactive Waste is defined as any material that has come in contact with radioactivity and may be contaminated. The UCSF Radioactive Waste Management Program concentrates on source reduction and volume reduction. Source reduction can be achieved in the laboratory by using non-radioactive labeling methods whenever possible. Volume reduction can be achieved by both laboratory personnel before the waste is collected and EH&S personnel after the waste is collected.  Since disposal fees are directly related to the volume of waste disposed, volume reduction is an effective method of reducing costs. Laboratory personnel should implement the following volume reduction procedures:

  •    Limit the areas where radioactive materials are used to a minimum.  The larger the area the larger the volume of waste materials generated, such as absorbent paper.  Using smaller areas also limits the opportunity for cross contamination of other materials.
  •    Survey materials being disposed, such as absorbent paper or pipettes, with a proper radiation detector prior to disposal. If uncontaminated, dispose as non-radioactive waste.
  •    The use of a proper survey meter is paramount (e.g. 3H cannot be detected with a survey meter; the efficiency of most detectors for 14C or 35S is less than 5%).
  •    Reduce the volume of liquid used (e.g., from washes) to the minimum needed for proper conduct of the experiment.
  •    Try to maintain separate work areas for different radioisotopes.  

EH&S personnel use consolidation, compaction, and other techniques to further reduce the volume of waste.

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Radioactive waste must be segregated into the following general categories:

  •    Dry solid.
  •    Source vials and pigs
  •    Aqueous liquid.
  •    Liquid bulk organic solutions.
  •    Liquid scintillation vials.
  •    Biological materials.
  •    Clinical waste (from nuclear medicine and radiation oncology).
  •    Other miscellaneous categories, such as Bactec vials, Beta plates, Uranium compounds, contaminated equipment and articles, sealed sources.

NOTICE:  UCSF policy prohibits the disposal of radioactive material via the sanitary sewer.  The exceptions are:

  •    Excreta directly discharged into the sewer from patients who have been administered radioactive materials for diagnostic or therapeutic purposes.
  •    Radioactive material remaining in secondary washes or their equivalent.   
a.    Dry Solid Waste

Dry waste is defined as any solid waste, generally composed of paper, plastic, gloves, i.e., general lab trash, containing less than 0.5 percent by volume of free standing liquid.  Dry waste shall not contain any of the following:

  •    Sharps
  •    Biological material
  •    Scintillation vials
  •    Any liquids
  •    Any other waste category

Dry waste must be packaged in 4-mil yellow transparent plastic waste bags marked with the “Caution Radioactive Materials” and trefoil radioactive symbol. These bags may be purchased from a commercial vendor.  For more information contact your DSA.  Bags must be securely closed with tape and the UCSF Radioactive Waste Tag (See Documentation, Section 5) must be attached to each bag. 

  • Dry waste must also be segregated into one of three categories based on the radioisotope or half-life of the radioactive material:
  •    32P only
  •    < 90 day half-life (e.g. 35S,  51Cr, 125I, 131I)
  •    > 90 day half-life (e.g. 3H, 14C, 57Co)

Note: Cost reductions are made by proper segregation of waste. Every attempt should be made to segregate all categories of waste by INDIVIDUAL isotope. Large, dry waste items (e.g., equipment, trash cans) require special arrangements with EH&S for pick-up.  

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b.    Radioisotope Source Vial and Pig Disposal
   i.     Source Vials

Separate the source vials by:

  •    32P only
  •    <90 days half-life
  •    >90 days half-life

Place source vials separated by these categories in separate plastic bags.

You are not required to empty the source vials prior to pick-up for disposal.

Labeling Radioactive waste with radioactive waste tags and requesting a radioactive waste pickup in RIO:

 You do not need to account for radioactive decay.

 For the “empty” vials, record a value of 1% of the total original source vial activity.  Example: for a vial originally containing 1 millicurie of any isotope, 1 mCi x 0.01 mCi, record 0.01 millicurie on the waste form and tag.

For partially full vials, enter the value from the usage log.

For unused vials, record the total vial quantity.

   ii.    “Pigs”

Return the source vials shields (pigs, lead pigs, plastic pigs) to EH&S for disposal.  Separate the screw top from the pig body.  Do not accumulate the pigs.

c.    Aqueous Liquids

Aqueous radioactive liquids are those in which the solvent and solute are both water-based. Liquid waste must be contained in plastic transparent narrow-necked containers with secure screw tops. Containers should not be larger than one-gallon; glass and metal containers are not acceptable. One-gallon jugs which meet these criteria are available from a commercial vendor.

Aqueous liquid waste must also be segregated by the radioisotope or half-life of the radioactive material:

  •    32P only
  •    < 90 day half-life (e.g. 35S, 51Cr, 125I, 131I)
  •    > 90 day half-life (e.g. 3H, 14C, 57Co)

Every attempt should be made to segregate all categories of waste by INDIVIDUAL isotope.

The UCSF Radioactive Waste Tag must be attached to each container.  To avoid cross-contamination, the jugs should be clearly marked and reused only for the same isotope.  Containers must not be leaking and the outer surfaces must be free of contamination.  Leaking containers will not be picked-up.  The contents of the container should be limited to aqueous liquids; no foreign items such as pipette tips are allowed.


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d.    Liquid Bulk Organic

These liquid radioactive wastes that contains organic compounds such as xylene, toluene, acetone, phenol, or corrosives with a pH <2 or >10.  The waste must be packaged in one-gallon plastic or glass transparent containers with a screw top and narrow neck.  Clear or amber bottles which originally contained other chemicals may be used for this purpose if the original labels have been removed and the empty container triple-rinsed before being used to collect waste.  The container should be compatible with the waste being stored.

Liquid Bulk Organic solutions are considered for regulatory purposes as Mixed Waste.  That is, the waste not only exhibits the properties of radioactivity, but also other hazardous properties such as ignitability, corrosivity, toxicity or reactivity.  

The UCSF Radioactive Waste Tag must be attached to each container.  In addition, a hazardous waste tag must be attached to the container using the Online Tag Program for chemical waste.  Containers must not be leaking and the outer surfaces must be free of contamination.  Leaking or contaminated containers will not be picked-up.  The contents of the container should be limited to organic liquids; no foreign items such as pipette tips are allowed. 


e.    Liquid Scintillation Counting Vials

Liquid Scintillation vial waste consists of glass or plastic containers of less than 25 ml capacity that contain or have contained liquid scintillation media. Unused liquid scintillation vial or vials which have been used for other purposes must be handled as radioactive liquid scintillation vial waste. This latter requirement is due to the recognition by commercial waste handlers and regulatory personnel of these vials as normally containing radioactive material.

Liquid Scintillation vials are divided into two specific categories:

i.      Deminimus Vials – contain only 14C and/or 3H with total activity concentration not exceeding 0.05 microcuries/ml (1.85 KBq/ml).

ii.     Regulated Vials – contain 14C and/or 3H at concentrations exceeding 1.85 KBq per milliliter (0.05 microcuries/ml) or any other nuclide other than 14C or 3H that has a detectable level of radiation above 3x background as measured on a scintillation counter.

When possible, scintillation vials should be packaged in the original trays for subsequent pick-up by EH&S.  Write on the trays the category of scintillation waste, e.g., "Deminimus" or "Regulated”.

If the original trays are not available, the waste vials must be double bagged in the 4-mil yellow transparent plastic waste bags marked with the “Caution Radioactive Materials” and trefoil radioactive symbol.  Each bag must have a Radioactive Waste Tag attached with the proper category written on the tag, e.g., "Deminimus" or "Regulated".  Contaminated trays/bags and leaking bags will not be picked-up.

Vials must not contain stock solutions of radioisotopes; biological specimens, or foreign objects. All lids must be securely fastened to prevent leakage.

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f.     Biological Waste (Radioactive)

Radioactive waste that contains biologic, pathogenic, or infectious material must be segregated into general categories: carcass and non-carcass.  Carcass waste consists only of animal carcasses and/or large carcass parts.  Non-carcass waste may consist of the following:

i.      Human or animal specimen cultures.

ii.     Cultures and stocks of infectious agents.

iii.    Waste from the production of bacteria, viruses, spores, live and attenuated vaccines, and culture dishes and devices used to transfer, inoculate and mix cultures.

iv.   Microbiological specimens.

v.    Human surgery specimens or tissues removed at surgery or autopsy.

vi.   Material containing fluid blood or blood products.

vii.  Material containing excreta, exudate, or secretions from humans or animals.

viii. Sharps (items or materials that can cut or pierce; such as needles, blades, teeth, razor blades, etc.).

ix.   Test tubes, capillary tubes, general tubing which have come in contact with such materials.

In addition, radioactive biological waste must be segregated by radioisotopes as follows:

  •    32P only
  •    <90 days half-life, e.g., 125I, 51Cr, 35S
  •    >90 days half-life, e.g., 3H, 14C

Every attempt should be made to segregate all categories of waste by INDIVIDUAL isotope.

Carcass waste containing only 14C and/or 3H with a total concentration not exceeding 1.85 KBq per gram (0.05 microcuries/g) of tissue averaged over the weight of the entire carcass or carcass part may be classified as "deminimus" with the approval of the RSO.  Disposing of waste under this classification may reduce the disposal cost.  Please contact DSA for further information.

Sharps contaminated with radioactivity must be placed in a sharps container labeled with “Caution Radioactive Materials” and trefoil radioactive symbol. Pipettes can be placed in hard sided containers that have a UCSF Radioactive Waste Tag attached. 

Biological material must be double-bagged in 4-mil red plastic waste bags and labeled with radioactive label tape.  Bags must be secured, closed with tape and the UCSF Radioactive Waste Tag must be attached to each bag.

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Pick-up of radioactive biological waste:

Radioactive biological waste is not picked up by EH&S personnel. Laboratory personnel must deliver the waste to the approved radioactive biological waste storage cooler. You must make arrangements to meet an EH&S Technician at the cooler by calling one of the following numbers:

  •    Parnassus:  476-1771
  •    Mt. Zion:  502-1129
  •    Gallo Research:  985-3115
  •    Mission Bay, SFGH, and all other campuses:  514-4107
g.    Clinical Waste (Nuclear Medicine and Radiation Oncology)

May contain isotopes with half-lives not to exceed 90 days.  Dry waste must be packaged in one cubic foot cardboard boxes.  Sharps must be packaged in sharps containers.  

After a waste disposal request is submitted in RIO by a nuclear medicine tech, the EH&S Technician will meet you at your waste collection area and will measure the exposure rate at the surface of each waste container. The EH&S Technician will mark the package.  EH&S Technicians may request that the waste be stored in the clinical waste collection area for an additional period of time to decay in order to decrease the exposure rate from the package.

h.    Beta Plates

Beta plates are plastic sheets that contain scintillation media;  they must be double bagged in 4-mil transparent yellow radioactive waste bags. The concentration of radioactive material in Beta plates must not exceed 1.85 KBq per milliliter (0.05 microcuries/ml). 

i.      Bactec Vials

Bacteria culture in an aqueous liquid medium, sealed in a vial of less than 40-ml capacity and containing not more than 148 KBq (4 microcuries).  These vials must be autoclaved prior to disposal. Package the vials in their original container if possible or double bag. 

j.      Uranium Compounds (uranyl acetate, uranyl nitrate)

Dry uranyl compounds should be packaged in 4-mil transparent yellow radioactive waste bags. Uranyl compounds in solution must be packaged in airtight plastic liquid containers.  Laboratories with an RUA can request pickup by submitting an online request in RIO.  Laboratories without an RUA can request a pick up by calling on of the following numbers:

  •    Parnassus:  476-1771
  •    Mt. Zion:  502-1129
  •    Gallo Research:  985-3115
  •    Mission Bay, SFGH, and all other campuses:  514-4107

Sharps are items or material that can cut or pierce. Examples are syringes (all), needles, blades, broken glass, pipettes, slides, teeth, etc. All sharps, including syringes with or without needles, must be placed in rigid puncture proof sharps containers complete with lids. 

Sharps contaminated with radioactive, biological or infectious material must be classified as radioactive biological waste. Package sharps inside an approved hard-sided plastic sharps container that displays the universal biohazard symbol. Broken glass may be placed in hard-sided cardboard glass disposal boxes.

Sharps that are not contaminated with infectious material may be classified as dry waste. All markings, labeling, or coloring that would indicate the presence of biological or infectious material, e.g., the universal biohazard symbol (red) on any sharps waste packaging must be removed or obliterated.

l.      Contaminated Serological Pipettes 

Pipettes may be placed into cardboard pipette disposal sleeves that display the universal biohazard symbol.  The sleeves may then be placed into 4-ml red plastic waste bags labeled with radioactive tape.


The UCSF Radioactive Materials License specifically prohibits the decay of radioactive waste materials and subsequent disposal into the ordinary trash or sanitary sewer by laboratory personnel.  Decay programs are only authorized to be carried out by EH&S under the direct supervision of the RSO at locations approved by State of California Department of Public Health, Radiologic Health Branch.

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Radioactive waste must be stored in an approved secure radioactive materials use location. Each laboratory should designate a single location within the laboratory where waste will be consolidated for pick-up by EH&S technicians. The location should cleaned regularly and surveyed for contamination. 

All waste prepared for disposal must be kept off of the floor, preferably in a dedicated waste containment vessel such as a metal trash can with a step lid or a lucite box. The containment vessel must be labeled for use with radioactive waste material. Color-coded container labels are available from EH&S. Secondary containment is recommended for liquids. 


Container Label Color Codes


32P only


Half-life less than 90 days


Half-life greater than 90 days






If you cannot determine the proper category classification for your radioactive waste, contact your DSA. 

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Each package of radioactive waste must have the appropriate color-coded radioactive tag securely attached (with some exceptions, e.g., vials in trays, clinical dry waste).

Waste Tag Color Codes

32P only


Half-life less than 90 days


Half-life greater than 90 days



Waste which has not been packaged according to established UCSF policies and procedures will not be collected by EH&S. A Radioactive Waste Deficiency Form will be left with the lab which identifies the reason that the waste was not collected. Upon correction of the deficiency, the waste will be picked-up.



Requesting waste pickups is done online through RIO.  If you would like to schedule a specific date/time for pickup based on when you will be in the lab, call one of the following numbers:

  •    Parnassus:  476-1771
  •    Mt. Zion:  502-1129
  •    Gallo Research:  985-3115
  •    Mission Bay, SFGH, and all other campuses:  514-4107

If the EH&S Technician cannot complete the pick-up on the scheduled day (door locked, documentation incomplete or not available, lab closed, etc.), the Technician will leave an Attempt to Pick Up Notice. 


Technicians have been instructed to only collect waste that is packaged in accordance with established UCSF policies and procedures. 

Waste must be packaged so that the exposure rate at one meter from the surface of the package does not exceed (5.0 mR/hr) 0.05 mSv/hr and the exterior of the package must not be contaminated.  If the waste exceeds this exposure rate criteria, please notify EH&S prior to the pick-up so that appropriate shielding can be utilized.


Recharge rates for radioactive waste can be found on the EH&S webpage and are based on the type and volume of waste.

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All laboratories using gamma emitting radioisotopes, or beta emitting radioisotopes that have an average energy in excess of 100 keV, must have access to an appropriate and properly calibrated survey instrument.  This instrument must be operating properly and be appropriate for the type of radioisotope used (e.g. thin end window G-M probe for beta and gamma emitters, NaI for iodine). The Radiation Safety Program will review (and advise on) the appropriateness of the instrumentation used. 

All survey instruments shall be calibrated at intervals not to exceed 12 months.  Instruments that are out of calibration shall not be used for monitoring of radiation fields.  The PI will receive notification from the Radiation Safety Program regarding calibration approximately thirty days prior to the expiration date; it is then the responsibility of the PI to arrange to have the instrument calibrated by the Radiation Safety Program. Calibration can be arranged by contacting EH&S at 476-1771.

NOTE: If the Radiation Safety Office finds contamination which was not detected by the laboratory due to inadequate, or lack of sufficient access to appropriate instrumentation, the laboratory will be required to purchase such equipment. 


Fixed instruments used for counting wipes, such as liquid scintillation counters and gamma counters, should receive regular preventive maintenance to ensure their proper operation.

The Radiation Safety Program also recommends institution of a quarterly quality assurance program which includes counting efficiency for the radioisotopes analyzed and stability of the counting background.  Such a program will yield valuable data concerning the status of the electronics and photo multiplier systems in the counter.

Any fixed instrument which contains a radioactive sealed reference source requires that the PI have approval to possess the sealed source on the RUA. This approval must be obtained prior to purchasing the instrument.  All sealed sources must be removed and properly disposed of prior to the sale or surplus of the fixed instrument.

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Monitoring devices will be issued to personnel who work in a laboratory which uses the types or quantities of radionuclides requiring such devices. The need will be determined at the time of RUA approval and the need for, or type of, monitoring device will be noted on the RUA for each individual listed as an authorized user.  Persons must wear the dosimeter when the possibility of such exposure exists.

Dosimeters are not capable of detecting alpha or soft beta emitters with an average energy less than 100 keV.  The RSC or RSO may require the use of additional monitoring devices when it is felt necessary.

Each person assigned a dosimeter shall be responsible for assuring that it is returned to the departmental representative at the pre-arranged date.  The Radiation Safety Program will arrange for routine changes of dosimeters, evaluate exposures, and maintain and provide PIs with the records of radiation exposure.  Any significant increase in the monthly exposure reading will be investigated to determine probable cause and the appropriate remedial measures to be taken.


A coordinator shall be designated for each dosimetry location.  It is the individual user's responsibility to exchange their dosimetry badges with the coordinator.  All dosimetry badges are to be exchanged monthly.  It is imperative that this exchange be made promptly at the end of the month to facilitate the legal responsibility to maintain current and accurate radiation dosimetry records.  A "control badge" is issued with each group of dosimetry badges.  This control will determine the background radiation exposure to the shipment of dosimetry badges and will serve to evaluate any exposures to the shipment during transit.  The control must be stored away from any radioactive sources and in a cool, dry place.  In addition to the monthly exchanges, dosimeters can also be exchanged on request by an individual or his group designated person.


a.    Only the person who is assigned a dosimetry badge shall wear it.  Do not loan a badge or use it for monitoring an area.  Area monitors will be provided through the RSP on request.

b.    The dosimetry badge should be worn such that monitoring is optimized (usually on the collar) when working with ionizing radiation.  Other acceptable locations include the trunk of the body, sleeves or shirt pocket.  Ring dosimeters should be worn when there is a possibility of significant exposure to the hand.  It is important to wear ring dosimeters on the hand that is favored.  Usually the index finger receives the greatest exposure.  The ring dosimeter should be worn under gloves to protect it from contamination.  The thermoluminescent detector (TLD) detector should always be turned to face the source of radiation.

c.    The radiation dosimeter should always be worn whenever there is a possibility of being exposed to ionizing radiation during the work day.  The dosimeter should never leave the campus.  It should be stored in a safe, radiation-free location when not in use. It should not be stored at high temperatures or in areas of high humidity.  The radiation dosimeter shall not be worn when receiving a medical radiation exposure as a patient.

d.    When wearing a lead apron, the badge should be placed on the collar or belt outside the apron.  For individuals monitored using two dosimetry badges, one should be worn on the collar (outside the apron) and the other should be worn at the waist level under the apron.

e.     The dosimeters must be promptly returned for processing. Delay in returning the dosimeter results in considerable extra work and delays in obtaining dosimetry reports.  A dosimeter which is returned late cannot be processed with the control badge supplied with the shipment. Badges not processed during the proper time period may have their results impaired by image degradation.

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A dosimeter request form is available from your DSA and/or the EH&S webpage under Radiation Safety forms.  The applicant must supply the following information so proper records may be maintained:

  •    Full name of individual.
  •    Individual's sex.
  •    Date of birth.
  •    Social security number
  •    Department.
  •    Name of PI or Laboratory Supervisor.
  •    Work areas.
  •    Campus extension.
  •    Radionuclide use
  •    X-ray device type (e.g., radiographic).
  •    A series of questions pertaining to previous dosimetry history.


Upon written request to the Radiation Safety Program any individual may obtain a report of his/her radiation dosimetry history.  The written request must include the individual's name, date of birth, social security number (last 6 digits), the department where the individual worked, and the dates that the dosimeter was worn at this location. The dosimetry results of the current month, quarterly, yearly, and lifetime dosimetry are available from the Radiation Safety Program.  A copy of the monthly report is sent to each badge coordinator for dissemination to users.


If you will be away from UCSF for over one month but less than six months, notify the Radiation Safety Program.  Your dosimeter will be kept inactive for the duration of your leave and reissued upon return.  Please obtain any records of occupational exposure if you have been working with radiation sources in another institution.  If you plan to be away from UCSF for over six months, or if you are terminating employment, please return your dosimeter and email the dosimetry coordinator at dosimetry.coordinator@ucsf.edu.


No one shall knowingly expose themselves or others to levels of radiation greater than those given in the table below, except in cases of extreme emergency. These exposure limits do not apply to patient medical and dental diagnosis or therapy.




Whole body

5 rem

Lens of eyes

15 rem

Extremities or skin

50 rem

Any individual organ or tissue

50 rem

Declared pregnant worker dose to fetus (over gestation period)

0.5 rem



0.1 rem

Dose in any unrestricted area cannot exceed 2 mrem in any hour or 100 mrem in any year


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As indicated above, the need for dosimetry will be determined during the RUA approval process for each individual. The general criteria are as follows:

a. Dosimetry badges will be issued to users of 20 mCi or more of gamma emitting or beta emitting. (Eav>100 KeV) radionuclides.

b. Finger rings will be issued to users of 5 mCi or more of gamma emitting or beta emitting (Eav>100 KeV) radionuclides.

Type of Radioactive Use

Type of Dosimeter Required


Quarterly Collar/Waist

Interventional Radiology

Monthly Collar/Waist

Nuclear Medicine/ PET

Monthly Body and Ring

Portable X-Ray

Quarterly Collar

Radiation Oncology - Machines

Quarterly Body

Radiation Oncology - Materials

Quarterly Body and Ring

Research - Any amount of Low Energy Beta ***


Research - Greater than 5 mCi/Exp emitting High Energy Beta/Gamma**

Quarterly Ring

Research - Greater than 20 mCi/Exp emitting High Energy Beta/Gamma**

Quarterly Body and Ring


Quarterly Body and Ring

* I-125 or Tc-99m
** P-32, PET Isotopes
*** H-3, C-14, S-35, P-33

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Report any actual or suspected over-exposure to radiation immediately to the Radiation Safety Program.  Depending upon circumstances, the Radiation Safety Program will take all necessary actions.  This may take form as a note to the file, a note to the individual dosimetry badge record, or referral to a physician. The physician shall be instructed to inform the RSO whenever an individual is diagnosed as having received a radiation exposure related injury or disease, or whenever any individual claims the existence of such an injury or disease.


Current National Council on Radiation Protection and Measurements recommendations and Nuclear Regulatory Commission Regulations state that during the entire gestation period, the maximum permissible dose equivalent to the embryo-fetus from occupational exposure of the expectant mother should not exceed 5 mSv (500 mrem).  (For more information, see Appendices H and I.)


When quantities of radioactive material present a potential for internal contamination, a bioassay will be required.  Specific routine requirements established for personnel using radioiodine, tritium, and other isotopes are listed in the RUA approval.  (For more information, see Appendix D.)


The Radiation Safety Office will investigate all exposures exceeding the guidelines below.  When indicated, a bioassay will be performed. The record of these investigations will be added to the radiation exposure file of the individual, and the individual and his Laboratory Supervisor will be informed of the results. The RSO is responsible for notification to the California Department of Public Health in cases of known or suspected exposures that exceed the permitted limits. Whenever these exposure limits have been reached or exceeded, depending upon the extent of the overexposure, personnel may be required to avoid future work with radiation for a period of time.

a. UCSF Investigational/Action Limits

Due to UCSF's commitment to the of As Low As is Reasonably Achievable (ALARA) principle, the investigational/action limits have been set as follows:

Monthly ALARA Alerts

Quarterly ALARA Alerts

DDE Level 1 - 75 mrem

DDE Level 1- 125 mrem

LDE Level 1 - 250 mrem

LDE Level 1 - 375 mrem

SDE Level 1 - 1000 mrem

SDE Level 1 - 1250 mrem

DDE Level 2 - 200 mrem

DDE Level 2 - 375 mrem

LDE Level 2 - 500 mrem

LDE Level 2 - 1125 mrem

SDE Level 2 - 2000 mrem

SDE Level 2 - 3750 mrem

DDE Level 3 - 350 mrem

DDE Level 3 - 1000 mrem

LDE Level 3 - 1000 mrem

LDE Level 3 - 3000 mrem

SDE Level 3 - 3500 mrem

SDE Level 3 - 10000 mrem

b. Radiation workers exceeding ALARA Level 1 will be notified of their exposure. Copies of notifications will be kept in the EH&S office for review. No response from radiation worker is required.

c.  Radiation workers exceeding ALARA level 2 will be alerted to their exposure. In addition to notification, a questionnaire will be given to the worker. The purpose of the questionnaire is to aid EH&S to investigate if safe practice is being followed, if any training is necessary, or if any safeguards are required. Response from radiation worker is required.

d.  Radiation workers exceeding ALARA Level 3 will be notified and be given the questionnaire. Level 3 exposures are at risk of exceeding the occupational dose limits and require EH&S to interview the individual to determine how to lower radiation exposure.


The Radiation Safety Program maintains complete and accurate personnel dosimetry records for review by the RSC and for transmittal to authorized agencies outside the University.  Copies of monthly dosimetry reports are sent to each PI for his/her group.  An individual can obtain his own exposure record by request to the Radiation Safety Program.  In cases of exposures which require notification to the State of California Department of Health Services, a report will be provided to the individual involved.  Copies of internal dosimetry reports are sent to each individual for his/her personnel records.  The law requires that dosimetry records of non-UCSF exposures be obtained and retained on file.  Each individual who has previously used radioactive material or worked with sources of ionizing radiation will need to complete the institutional section at the bottom of the Dosimetry Request Form (available online on the UCSF EH&S website, Radiation Safety section).


The PI is responsible for the presence of either outside contractor employees, visitors, or guests in any radiation laboratory or radiation-producing facility.  They shall inform the RSO of the presence of any such person prior to their entry.  The RSO will decide whether or not the visitors will be permitted to enter the laboratory and if so, what personnel dosimetry is necessary.

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PIs should notify the DSA in advance of performing any experiment or procedure involving new, unusual, or unknown potential radiation hazards.  When necessary, special monitoring can be provided.


The DSA will perform leakage testing of all non-exempt radioactive sources.  UCSF will comply with all statutory sealed source leak test requirements.  As needed, additional sealed source leak tests may be performed.


In an attempt to follow the guidelines of the ALARA concept of radiation exposure, UCSF has established that the maximum permissible radiation exposure on this campus shall not exceed the investigational limits set.  

The exposure of personnel not directly involved with the use of radiation on campus shall not be greater than 1 mSv (100 mrem) per year.


All users must maintain written records of receipt, use, transfer and disposal of all radioactive materials.

A usage log giving the date of receipt, identity and activity of the radioisotope, the manufacturer's lot number, the date and the amount of usage must be maintained for each radioisotope.  A physical inventory and correction of the log must be done at frequencies prescribed by the RSC/RSO.

The Radiation Safety Program requires that records showing the monitoring of the laboratory area(s) and equipment must be maintained.  These records must be available for periodic review by the Radiation Safety Office and may be requested by the RSC.  In general the formats presented in the "Laboratory Radiation Safety Logbook" should be followed (available from your DSA).  

Note: Usage, Transfer and Disposal must be recorded on the UCSF form provided by EH&S.  Any variances from record keeping requirements must be pre-approved by the RSO and/or RSC.



Each loss or theft must be reported to EH&S as soon as it is discovered.  Any quantitative discrepancy in a shipment of radioactive material received from a vendor is considered reportable.


  • Actual, or suspected exposure of the whole body to 1 mSv (100 mrem) or more of radiation, or exposure of the skin, feet, ankles, hands or forearms to 5 mSv (500 mrem) or more must be immediately reported to the RSO.
  • Any ingestion or personnel contamination must be immediately reported to the RSO.
  • Any accidental release of radioactive material to the environment must be reported immediately to the RSO for monitoring and decontamination assistance.
  • PIs are required to document carefully any losses or incidents that occur.

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FOR ALL EMERGENCIES CALL:  9-911 at all locations

San Francisco General Hospital (SFGH):  206-8522 or 9-911



The Radiation Safety Officer (RSO) is to be notified as soon as possible of any unplanned occurrence involving ionizing radiation.  This includes, but is not limited to: accidental direct radiation exposure, substantial (10,000 dpm) contamination of floors and work surfaces, or contamination of laboratory personnel.  If it is anticipated that a procedure may result in contamination or other hazard, prior approval from the RSO is required. Call the UCSF Police emergency number (9-911), this will activate the Environment, Health and Safety (EH&S) 24 hour emergency response program.


If the incident exceeds limits set forth in 10 CFR 20.2201 to 2206, the State of California Department of Health Services must be notified. In addition to the immediate notification, the State of California Department of Health Services may require written reports of the incidents within 30 days.  Such reports will be prepared by the RSO from information provided by the applicant and/or department personnel and will be reviewed by the Radiation Safety Committee (RSC). The RSO will make the necessary telephone reports to the regulatory agencies.


1.    Major (mCi) area contamination involving potential health hazard:

In the event of spread, or a suspected spread of radioactive contamination over a significant portion of a room or larger area:

a.    Vacate the area, leaving behind clothing and other articles which may be contaminated.

b.    Keep all persons out of the area, except for monitoring and rescue teams. 

c.    Call EH&S immediately (Activate the 24 hr emergency response program by calling 9-911.).

d.    Do not attempt decontamination except as expressly directed by EH&S.

2.    Minor (μCi) contamination amounts involving no immediate health hazard:

a.    Define the contaminated area at once and keep all persons away. 

b.    Wear double gloves, lab coats, appropriate dosimetry, and other protective equipment as needed.

c.    Work from the outside inward to avoid spreading contamination. 

d.    Have a plastic bag available to deposit contaminated gloves and paper towels, etc.

e.    Wipe test the area to confirm successful decontamination. Call the Radiation Safety Office for assistance as needed at 476-1300.

Note: If you do not feel adequately equipped to deal with the emergency call 9-911.

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In the event that persons are contaminated as a result of contamination incident:

1.    Administer first aid measures, as necessary. The person should be taken to Hospital Emergency or Employee Health Service if they require medical attention.

2.    Remove the person from the contaminated area and hold at a transfer point. 

3.    Report the incident immediately to the RSO.

4.    Flush the contaminated skin area with water and soap using care not to abrade the skin.

5.    Refer suspected internal contamination immediately to the RSO.

6.    Personnel are not to leave UCSF property for the purpose of decontaminating themselves unless specifically advised to do so by the EH&S.

Note: If applicable, have a survey meter available to monitor the area, clothing, shoes, etc. and to prevent the spread of contamination.


Under extreme conditions, the RSO may restrict or prohibit access to contaminated areas and/or suspend radiation work so long as hazardous conditions exist. The RSC Chair shall be advised of such action in a timely manner. 


The EH&S Radiation Safety 24 hour emergency response number is 9-911 at all locations except San Francisco General Hospital (SFGH). At SFGH call 9-911 for Fire and 206-8522 for all other emergencies.

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The RSO must be notified immediately after the ingestion of radioactive materials. Treat ingestion of radioactive material like any other acute poisoning. Induce vomiting rapidly by swallowing large volumes of water and stimulate the throat with the fingers.  Mild emetics (an agent that induces vomiting) may be added to the water. Repeat this once or twice.


Any wounds from radioactive contaminated glassware, instruments, or needles should be treated immediately.  Wash the injured area under a strong stream of water (see procedures described below).


The best method of decontamination is thorough washing with soap and water (see washing procedures below), unless the contamination is very localized. For localized decontamination, swabbing of a masked area is preferable, as this prevents the spreading of the contamination.

If the nature of the contaminant is known, a suitable reagent may be used to immerse the skin, followed by washing.  Detergents and wetting agents are also useful. Organic solvents must not be used as they may increase skin penetration. Notify EH&S for assistance.


a.    Wash for 2 or 3 minutes under tepid water, using a mild and pure soap. Create a lather using light scrubbing, to avoid eroding the skin and causing further penetration.  Pay attention to the areas between fingers and under nails and to the outer edges of the hands, which are often neglected. Rinse thoroughly and monitor.

b.    If monitoring still reveals contamination, rinse again using a soft brush to create a lather.  Rinse and lather repeatedly.

c.    If contamination with radioiodine is present:

Apply a freshly prepared 5% solution of sodium acid sulfite in the same way as above.  Use a hand brush and tepid water and scrub for no longer than two minutes.

This may be repeated several times, as long as the permanganate solution is not applied for more than two minutes during any one washing.  Contamination of other parts of the body can be treated with the same solution and applied with swabs.

Contact EH&S for bioassays and or assistance and surveys.


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1.    Notify everyone in the room and area at once.

2.    Monitor personnel before they leave and then change clothes or lab coat, as necessary.

3.    Put on disposable gloves to prevent contamination of your hands.  Wash your hands first if they are contaminated following the UCSF Radiation Safety Manual procedures for decontamination of the hands and skin. 

4.    Survey, mark, or block off the contaminated area with warning signs or labels.

5.    Use absorbent paper or absorbent material on the spill to limit the spread of contamination.

6.    Start decontamination procedures as soon as possible.  Normal cleaning agents or commercial decontamination agents should be adequate.  Put on shoe covers and begin procedures by using paper towels with the decontamination agent.  Scrub from the outermost edges of the contaminated areas and work inward, reducing the area that is contaminated.

7.    Put all contaminated objects and cleaning materials into containers to prevent spread of contamination.

8.    In the case of large spills, block off the area. Assign a person equipped with a survey meter and wipe test the materials to help prevent the accidental spread of contamination.

9.    Decontaminate the area to background count rates. There should be no removable contamination on the surface after decontamination.

10.  Report the accident to the Principal Investigator (PI) and Laboratory Supervisor, and submit full documentation to the Radiation Safety Program as soon as possible.

11.  Notify the Radiation Safety Office of the accident as soon as possible at 476-1300.

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Each application for the use of radioisotopes is classified by the Radiation Safety Officer (RSO) according to the proposed usage. The following laboratory classification system is used.

i.      Class I Projects 

These involve small quantities of a sealed radioactive materials, (μCi -low mCi ) low toxicities, simple operations, use of sealed sources in special devices, or a combination of these factors resulting in minimal hazards.  Projects in this class may be performed in a level 1 work facility such as a standard chemical or biological laboratory.

ii.    Class II Projects  

These involve moderate quantities of radioactive materials (10's of mCi) moderate toxicities, more complex operations, or a combination of such factors. Projects in this class must be performed in a level 2 or 3 work facility.  In addition to the requirements needed for a level 1 facility, the following may be required:

  •   Special shielding or barrier protection may be required for use and storage of isotopes.
  •    Remote handling devices may be needed.
  •    Exhaust ventilation controls, such as fume hoods, may be required.
  •    Trays should be used to provide double containment on all wet chemistry operations.

Substantial exposure reduction can be achieved by proper design and utilization of facilities and equipment required for the uses of radioactive materials.  The details and particulars of each would depend on the types and quantities of radioactive materials, however, some general guidelines which apply in all cases are outlined below:

The facility layout shall be planned to maintain employee exposures As Low As is Reasonably Achievable (ALARA) while at the same time ensuring that exposure to persons in other areas are not increased.  The following are general considerations which should be followed:

i.      Providing optimum distance between areas of frequent occupancy and radiation sources or contamination.

ii.     Placement of fume hood in remote areas of the laboratory.

iii.    Designation of clearly marked stainless sinks for rinsing and disposing of secondary washes of radioactive waste.  These sinks should be those less commonly used for other purposes.

iv.   Foot or elbow operated faucets.

v.    Provisions for appropriate placement of radiation-monitoring and contamination-monitoring instruments in the work area.

vi.   Use of radioactive materials only in properly designed and designated laboratories.

vii.  One piece of vinyl flooring with 4" covings to the walls and cabinets.

viii. The facility must have means of securing the radioactive materials (i.e. lockable doors).

ix.   All work surfaces (e.g. bench tops, counters, etc.,) must be impervious to the chemical used.

x.    When applicable, lead shielding must be incorporated to the structure. The Radiation Safety Program will determine the need for the shielding.

xi.   Storage and consumption of food in areas where radioactive materials are used and/or stored is strictly prohibited.  Therefore, the design of the laboratory must incorporate adequate additional facilities for this purpose.

xii.  The wall paint must be washable for ease of decontamination.  Gloss paint is the recommended type.

xiii. The laboratory must comply with the general fire and physical safety requirement for radioactive usage areas.

xiv. If the laboratory proposes to use volatile radionuclides, the fume hood is subject to one or more of the following controls:

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  •    The laboratory must have a dedicated fume hood.  This fume hood must have a dedicated exhaust line.
  •    The fume hood must have a minimum of 100 linear feet per minute average face velocity.  An average face velocity of 125 linear feet per minute is more desirable.
  •    The need for installation of filtration systems will be evaluated and determined by the RSO based on the types and quantities of volatile radionuclides being used.
  •    The duct material must be made of non-corrosive material (e.g. 316 stainless steel).  The joints must be completely sealed and leak proof.
  •    The inside of the fume hood must be steel (316).
  •    The exhaust should be checked by EH&S.

The RSO shall review all such facilities for compliance prior to start of construction or remodeling. 


These involve large quantities, high toxicities, complex operations, or a combination of these factors resulting in substantial hazards. Specialized procedures, equipment, and facilities will be required, and work can only be conducted in a specified level 3 work facility.  In addition to the previous requirements, a level 3 facility may require the following:

i.      Special ventilation and confinement controls, such as isolation bags or glove boxes.

ii.     Special control procedures and security systems.  These may involve access controls.

iii.    Special handling equipment and/or clothing.


Fume hoods are classified according to their use and type. This classification is not related to work facility levels.  All fume hoods shall comply with the latest CAL/OSHA Title 8 requirements for design and installation.

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These may be used for radioactive work, provided that the face velocity averages 100 linear feet per minute (with no individual measurement below 70 feet per minute).  All hoods used for volatile radioactive work must meet this standard and be single ducted.  The need for filter systems will be determined by the RSO.


NO RADIOACTIVE MATERIALS may be used in these hoods, which are designed for product and provide no personnel protection.


If these hoods are directly exhausted onto the roof, they may be used for low level radioactive work. If these hoods are exhausted into the room, no radioisotopes can be used unless it can be proven that no volatile or particulate escape can occur.


These units are kept under negative pressure, and are exhausted to the roof. They provide the best protection and are recommended for high level iodinations or similar work.


No volatile radioactive materials may be used in these cabinets.

Use of non-volatile materials is contingent upon approval of the RSO and the Biosafety Officer.  In general, approval will depend upon the quantities of radioactive materials used as well as types of procedures performed.


  •    All fume hoods will be checked annually for flow rate accuracy. The testing will be done by Industrial Hygiene staff qualified to do so.  The Air Sampling instruments are calibrated in accordance with the manufacturer's specifications.
  •    Existing laboratories with equivalent facilities will be acceptable.  During remodeling of existing, or construction of new laboratories, these features will be incorporated.
  •    Roof implies outside the building, and away from air intake ducts.



All laboratories using radioisotopes will be audited every calendar quarter. The Radiation Safety Committee (RSC) / Radiation Safety Officer (RSO) may require more frequent inspection of laboratories based on the compliance history of the particular laboratory.  


Audits are conducted to assure compliance with State of California and Campus regulations. Records are maintained of all audits.  Items of non-compliance are discussed with the users as a form of education and to ensure future compliance.  Copies of audit correspondence are sent to the Principal Investigator (PI).  Copies regarding laboratories with major or repetitive violations are sent to the RSC. The RSO also reviews the audit reports. 


a.    The audit program will be conducted according to the schedule described above.  The DSA will use a checklist approved by the RSC. 

b.    The DSA will send the audit report to the PI who will list violations and state the required correction. 

c.    The results of all inspections indicating major, repeat or flagrant violations will be submitted to the RSC for their review.  The RSC will decide on the appropriate course of action which could include: 

i.      Requiring more frequent inspections of the lab. 

ii.     Requiring the PI and/or authorized users to re-take the user certification test.

iii.    Assignment of a Health Physicist to the lab for re-training of the lab personnel. 

iv.   Withdrawal of radioisotopes. 

v.    Suspension of the Radiation Use Authorization (RUA).

d.    The RSO will notify the PI of any penalties imposed by the RSC for violations and call attention to required corrections. 

e.    If violations have not been corrected as determined by reinspection, the Chair of RSC will be notified.  The RUA may be suspended, or radioisotopes may be impounded. 

f.     RUA reinstatement can only be authorized by the RSC.  In making a finding regarding reinstatement, the RSC will consider the PI’s corrective actions (taken or planned) and the results of an additional inspection. 


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The laboratories must maintain records of the receipt, usage and disposal of all radionuclides received. The Radioisotope Usage Form provided by the Radiation Safety Office must be used for this purpose. There will be one form given to the laboratory for each vial, the Radiation Safety Office will complete the information in Section 1. 

All laboratories are required to submit a Quarterly Radioisotope Inventory Report to EH&S.  This can be done electronically using the RIO link on the EH&S web site.  Hard copy forms are also available from your DSA.

Any exemptions to record keeping requirements must be pre-approved by the Radiation Safety Committee (RSC).


The laboratories must complete the appropriate Waste Disposal Form and attach the proper tag to the waste bag. The form must be complete and include the following information:

  •    Principal Investigator (PI) Name or Radiation Use Authorization (RUA) #
  •    Date
  •    Activity in mCi (activity of EACH isotope must be listed individually)
  •    Volume of waste
  •    MUST be signed by the laboratory representative

A copy of the document will be given to the lab representative at the time of pick up. Incomplete or inaccurate information may result in the waste not being picked up, or issuance of a Waste Deficiency Form.


The laboratories must perform routine wipe surveys of their usage areas. The RUA will specify the requirements and frequency of each laboratory. The results of these surveys, and any decontamination, must be maintained by the laboratories. The records must include a lab diagram with the location of the wipes taken clearly indicated. The Laboratory Radiation Safety Logbook has a sample of an acceptable format you may wish to follow.

NOTE:  Copies of the necessary forms are on the UCSF EH&S website and are included in the Laboratory Radiation Safety Logbook.  Additional copies may be obtained by contacting your Department Safety Advisor.

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Bioassays are performed on persons who use unsealed quantities of radioactive materials to determine whether any activity has entered the body.  The results are used to:

  •    Estimate internal organ doses.
  •    Determine the presence of airborne radioactive materials.
  •    Evaluate work habits, experimental and facility design.

Bioassays are performed either by:

  •    Analyzing samples of blood, urine, or tissue OR
  •    Monitoring the organ of interest to determine the presence and quantity of radioisotopes.

The method chosen depends upon the type of radioisotope involved (e.g. urine analysis for 3H or thyroid scanning for 125I).

1.    BIOASSAY PROGRAM FOR 3H, 14C, 32P, 33P AND 35S, and other radioactive materials except radio-iodine.


Bioassays should ideally be performed:

i.      After each procedure where there is a potential for airborne activity, or personnel exposure.

ii.     When there is a suspicion that internal contamination might have occurred.

The University of California, San Francisco (UCSF) bioassay policy requires that each individual handling greater than 100 millicuries of potentially volatile 3H, or greater than 50 millicuries of potentially volatile 14C, 35S, and 32P MUST perform a bioassay after such uses and document the results in a logbook. However, it is strongly recommended that all individuals using millicurie quantities of any volatile radioisotope per experiment perform a urine assay after such uses.


  •    The quantity HANDLING refers to the activity of the stock solution from which it is drawn. This will be obtained from the Single Purchase Amount listed on the Radiation Use Authorization (RUA).
  •    The Radiation Safety Program will determine the need for bioassays; this will be indicated in the RUA approval.

Urine is analyzed to estimate any uptake of radioactive materials other than radioiodine.

i.      Place 1.0 cc of urine in a scintillation counting vial.

ii.     Add 9 cc of liquid scintillation cocktail.

iii.    Set the counter for the appropriate radioisotope.

iv.   Count the sample for 1 minute.

v.     Count a 10 cc LS cocktail for 1 minute as a background count (Cb).

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i.      Obtain net count (Cn).

Cn = Cs - Cb

ii.     Divide the net count by counter efficiency to obtain dpm.

dpm = Cn / efficiency

iii.    Convert dpm to activity (μCi).

iv.   Log the results in the appropriate radioisotope bioassay record sheet.  The results of the calculations on the record sheet should be compared with those given below.


Reference Annual Limit of Intake (ALI) 10 CFR 20 Appendix B.  The activity should not exceed the following values:


ALI (μCi)


8 x 104


2 x 103


6 x 102


1 x 104


If the calculated body burdens exceed 10% of ALI values, inform the Radiation Safety Officer (RSO) so that an investigation can be conducted to determine the causes of the uptake and recommendations for remedial can action be made. 

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The bioassay program is developed for persons working with radioiodine to aid in determining the extent, if any, of an individual's exposure to concentrations of airborne radioiodine.  Bioassays are performed by measuring the emissions from radioiodine within the thyroid.  Routine bioassays are performed for those quantities listed below:

FOR  125I     

Single Purchase Authorization (mCi)


1.0 – 15.0



15.1 – 20.0





Within 14 days





  •    The bioassay frequency is based on the activity in the vial of the 125I stock handled to perform the iodination.
  •    Single Purchase Authorization is the maximum activity the laboratory can receive in each vial. This determines the frequency.
  •    The bioassay frequency will be communicated to the Principal Investigator (PI) in the RUA conditions. The usage quantity is not the determinant factor but "A" quantity is!
  •    Bioassays must be performed by those individuals who have used radioiodine in the laboratory during the period (e.g. month, quarter etc.).

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FOR 123I AND 131I

123I users must obtain a bioassay within 24 hours if the iodination utilizes more than 5.0 mCi.

131I users must obtain a bioassay within 1 week of any iodination utilizing more than 1.0 mCi. 

Individuals administering volatile quantities of 131I for therapeutic purposes, in excess of five (5) millicurie must obtain a bioassay within two weeks of administration. This does not include other personnel in the room at the time of the administration or subsequent patient care.  However, it is strongly recommended that all persons in the room during such an administration should obtain a bioassay within two weeks.  If capsules are used no bioassays are required, unless an unusual event takes place.


Thyroid monitoring will be performed at the locations listed below:

125I and 131I

  •    Radiation Receiving, L-235, Parnassus Campus (476-1771)
  •    N-121 Genentech Hall, Mission Bay campus (514-4107)

123I and 131I

  •    Nuclear Medicine Department, Long Hospital 3rd Floor (353-1509)

The annual limits on intakes are as follows:

Isotope to be Monitored



3000 μCi


40 μCi


30 μCi

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The action levels set are 10% of the ALIs.  When action levels are exceeded the following steps should be taken:

i.      An investigation of the operation involved, including air sampling, will be carried out to determine the causes of exposure and to evaluate the potential for further exposures.


ii.     If the investigation indicates that further work in the area might result in exposure of a worker to concentrations exceeding the Derived Air Concentrations (DAC) the worker will be restricted from further exposure until the cause of exposure is discovered and corrected.

iii.    Corrective actions that will eliminate or lower the potential for further exposures will be implemented.

iv.   A repeat bioassay will be taken within 2 weeks of the previous measurement and should be evaluated within 24 hours after measurement in order to confirm the presence of internal radioiodine, and to obtain an estimate of its effective half-life for use in estimating dose commitment.

v.    If the thyroid burden exceeds 50% of ALI, refer the case to appropriate medical consultation as soon as possible for recommendations regarding therapeutic procedures that may be carried out to accelerate removal of radioactive iodine from the body.  This should be done within 2-3 hours after exposure when the time of exposure is known so that any prescribed thyroid blocking agent would be effective.

NOTE:   All exposures exceeding the ALI will be reported to the California Department of Public Health immediately by telephone and followed by additional reports and actions prescribed by the State of California.


Contact the RSO if an incident or unusual event occurs involving any radioisotope other than radioiodine.  The RSO will request that a urine sample be submitted for examination to determine if an exposure occurred.

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BETA EMITTERS - Optimum visibility and shielding needs are met with the use of lucite "L" blocks (remember all shields should be marked with the radiation symbol).

Caution: Do not use dense materials such as lead to shield beta emitters.

Use of such materials may cause bremsstrahlung (x-ray) exposure.




None needed


None needed except for close work (<2 feet use 0.1)


None needed except for close work (<2 feet use 0.1)







GAMMA EMITTERS - Lead glass gives best visibility, but lead sheet or bricks provide better attenuation. Lead "L" Blocks with lead glass in the 45% angle top plate are a good compromise when visibility is the prime concern.  Any lead glass or other shielding (such as steel) used should have equivalency to the lead value specified.  Generally speaking, 10 times the half value layer is adequate for most isotopes, as this will reduce the exposure by three orders of magnitude.

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Half Value Layer

Lead (cm)


Half Value Layer

Lead (cm)






















































Density (gm/cc)





Regular glass


Lead glass

4.2 – 6.0






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All radiation detection and measurements used in the laboratories will be calibrated by the Radiation Safety Program annually. The Radiation Safety Program will inform the user when the instrument is due for calibration. After calibration is completed a Certificate of Calibration will be issued to the user. The instrument will also be labeled to indicate the date of calibration and next calibration date due.  If the instrument is inoperable, or needs repair, it will be "tagged out" and the user will be contacted to make the necessary arrangements. 

NOTE:  Do not use instruments which are tagged out.


All sealed sources are subject to a quarterly inventory. The DSA will inform the Principal Investigator (PI) of the due date and will verify the presence of all sealed sources. Records of the inventories will be maintained by DSA, with a copy forwarded to the PI.

PIs should notify the DSA when they do not need the source in order to have the source disposed of properly.

The DSA will also perform the leakage testing of all non-exempt sources.  UCSF will comply with all statutory sealed source leak test requirements.  As needed, additional sealed source leak tests may be performed.

Contact the DSA for assistance on proper disposal of any sealed source.





A controlled area is "...any area access which is controlled by the user for purposes of radiation safety pursuant to the provisions of this regulation (10 CFR 20.1003, Definitions)...high radiation areas, and radiation area(s) shall be considered controlled areas." Controlled area designation at the University of California, San Francisco (UCSF) shall be the responsibility of the Radiation Safety Officer (RSO) under the direction of the Radiation Safety Committee (RSC). Examples are inside fume hoods, microcentrifuge, freezers, storage cabinets used for radioactive material usage.


A basic philosophy of the UCSF Radiation Safety Program is to restrict radiation exposure to levels as low as reasonably achievable.  Toward this As Low As is Reasonably Achievable (ALARA) goal, we have adopted a “General User Limit" of 3 mSv (300 mrem) per quarter to the whole body for all occupationally exposed individuals. For Clinical Nuclear Medicine and Radiation Oncology users the limit is set at 4.5 mSv (450 mrem) per quarter. With regard to pregnant workers, this "guide limit" is reduced to 0.5 mSv (50 mrem) per month to maintain the dose to the fetus at a level below the 5 mSv (500 mrem) per gestation period required by the U.S. Nuclear Regulatory Commission. The Radiation Safety Program will then review all dosimetry reports to assess compliance with these limits. Doses exceeding the limits will be cause for an evaluation of the reasons for the exposure.  During this investigation, the practices, facilities, and other factors which could prevent a recurrence of the exposure will be examined.


i.      In uncontrolled areas the net removable surface contamination on floors or door handles shall not exceed three times (3x) above background. 

ii.     In controlled areas, (e.g. fume hoods or storage boxes etc.) net removable surface contamination on surfaces and equipment shall not exceed twenty-five times (25X) above background. 

Levels will be determined by wipe testing of the surfaces, followed by counting of the wipes with a suitable instrument.  The background count rate of the wipe/instrument system shall always be subtracted when contamination levels are being measured.  Laboratory coats or gowns and disposable gloves shall be worn whenever handling isotopes or contacting surfaces which are suspected to be contaminated.  The Principal Investigator (PI) shall be held responsible for maintenance of the contamination levels in his areas.  Wipe tests should be performed daily or after each experiment.  Wipe testing shall be performed and recorded for areas in which radioactive materials are used in accordance with the criteria specified in the Radiation Use Authorization (RUA).  Wipe test records shall be examined by the DSA during inspections. Controlled areas being "decommissioned" to uncontrolled status must be evaluated for contamination levels by the Radiation Safety Program prior to being used.

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Laboratories should monitor after each usage, however, the wipe testing requirement criteria for facilities are based on "activity per approved experiment" as follows:


Less than

100 μCi


Greater than or equal

100 μCi


Storage areas



All exceptions are to be approved by RSO and noted on the RUA.


If contamination in a controlled area (e.g. hoods, waste containers, lucite storage boxes, centrifuges, etc.) exceeds twenty-five times (25x) above background, the areas must be decontaminated to levels below this limit. If this is not possible, the RSO must be notified.  The RSO will evaluate the situation and propose appropriate action.  If the RSO determines that the higher levels of contamination do not pose a hazard of high exposures or spread of contamination, the RSO may approve the presence of the higher levels and label the area appropriately.


In controlled areas, continuous dose rates shall be restricted to levels not exceeding 0.05 mSv (5.0 mrem) per hr to the whole body (and lens of the eye), and 1 mSv (100 mrem) per hr to body extremities.  Higher dose rates are acceptable for short periods of time during radioisotope transfers and waste handling as long, as the integrated dose in one month shall not exceed the "Radiation Exposure to Personnel" limits established above.  Radioactive waste materials must be packaged so that the dose rate at one meter from the container surface does not exceed 0.05 mSv (5.0 mrem) per hr during transport.  Dose rates should be evaluated at regular intervals when isotopes are being handled.  Dose rates shall be evaluated with appropriate instrumentation. Records of dose rates found shall be kept with the wipe records.  Again, dose rate records shall be examined by the EH&S during inspections.


In a controlled area, these shall not be allowed to exceed the specifications in Appendix B to 10 CFR 20, Table 1.  The EH&S is to be consulted prior to performing any activity where an isotope might be released into the air or water.


An uncontrolled area "...means any area which is not a controlled area." 

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Radiation exposure to non-occupational individuals will not be allowed to exceed the 1 mSv (100 mrem) per yr whole body dose specified in 10 CFR 20.1201.


In uncontrolled areas (e.g. floors in labs), the net removable surface contamination shall not exceed a level of three times the background count rate per 100 cm2.  The methodology used shall be the same as in Controlled Areas "b" above.


If contamination in an uncontrolled area (e.g. floors, refrigerator handles, etc.) exceeds three times background, then the areas must be decontaminated to levels below this limit.  If this is not possible or if the contamination is fixed, the RSO must be notified.  The RSO will evaluate the situation and propose an appropriate remedial action which could include:

i.      Removal of the contaminated surfaces

ii.     Covering the surfaces with impervious material lucite, plastic).

iii.    Labeling the area.


In order to insure that the limits established in 10 CFR 20.1301 are not violated, the following limits for whole body dose in uncontrolled areas are specified:

i.      0.02 mSv (2.0 mrem) in any one hour.

ii.     1 mSv (100 mrem) in any one year.

The only exception to these limits is the 0.05 mSv (5.0 mrem) per hr dose rate at one meter allowed during the transportation of radioactive waste through uncontrolled areas.


In an uncontrolled area, these shall not exceed the limits specified in 10 CFR 20.  The Radiation Safety Office is to be consulted prior to performing any action which may release radioisotopes to the environment.  

EXEMPTIONS: Any exemptions, or variances, from wipe testing frequencies must be pre-approved by the RSO.


REMOVABLE CONTAMINATION: The term removable contamination refers to the unwanted radioactive material on the surfaces of structures, areas, objects or personnel that can be detected by wipe testing.

FIXED CONTAMINATION:  The term fixed contamination refers to any contamination which may not be detected by means of wipe testing but is detectable by direct contamination monitoring.

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During the gestation period, the maximum permissible dose equivalent to the fetus from occupational exposure of the expectant mother should not exceed 500 mrem.  This policy is in keeping with the recommendations of the National Council on Radiation Protection and Measurements and the Nuclear Regulatory Commission.  The following plan is recommended to departments and services where ionizing radiation sources are used:

1.    Each Principal Investigator (PI) is responsible for advising all employees, students, and personnel working under his/her authorization of this policy. All personnel must be familiar with the contents of the Appendix to Regulatory Guide 8.13, "Instruction Concerning Prenatal Radiation Exposure", which is reproduced in Appendix I.

2.    As soon as pregnancy is known (or suspected), individuals should notify their Laboratory Supervisor or PI (in writing) so that appropriate appraisal of their potential radiation exposure may be made.  The Radiation Safety Officer (RSO) is available for consultation and advice to personnel and their Laboratory Supervisor.

3.    The individual's workload and schedule will be revised to reduce or avoid procedures where the potential exists for radiation exposures above limits set by the National Council on Radiation Protection and Measurements / the Nuclear Regulatory Commission.

4.    A second dosimetry badge will be issued to be worn at the waist level and will record the dose to the mother.  (The exposure to the fetus will be less than the mother's skin dose by a factor that varies with the energy of the radiation, inverse square law, etc.). 

5.    Badges will be processed monthly.  If the integrated readings of the badge at the waist are greater than 50 mrem during any month, the workload again requires critical review.  If the integrated readings total 300 mrem within 6 months or less, the pregnant worker should consider transfer or leave.  When the readings total 500 mrem, transfer or leave is mandatory and the individual shall not use radioactive materials until completion of the gestation period.

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Revision 3: June 1999




The Code of Federal Regulations in 10 CFR Part 19, “Notices, Instructions and Reports to Workers: Inspection and Investigations,” in Section 19.12, “Instructions to Workers,” requires instruction in “the health protection problems associated with exposure to radiation and/or radioactive material, in precautions or procedures to minimize exposure, and in the purposes and functions of protective devices employed.” The instructions must be “commensurate with potential radiological health protection problems present in the work place.”

The Nuclear Regulatory Commission's (NRC's) regulations on radiation protection are specified in 10 CFR Part 20, “Standards for Protection Against Radiation”; and 10 CFR 20.1208, “Dose to an Embryo/Fetus,” requires licensees to “ensure that the dose to an embryo/fetus during the entire pregnancy, due to occupational exposure of a declared pregnant woman, does not exceed 0.5 rem (5 mSv).” Section 20.1208 also requires licensees to “make efforts to avoid substantial variation above a uniform monthly exposure rate to a declared pregnant woman.” A declared pregnant woman is defined in 10 CFR 20.1003 as a woman who has voluntarily informed her employer, in writing, of her pregnancy and the estimated date of conception.

This regulatory guide is intended to provide information to pregnant women, and other personnel, to help  them make decisions regarding radiation exposure during pregnancy. This Regulatory Guide 8.13 supplements Regulatory Guide 8.29, “Instruction Concerning Risks from Occupational Radiation Exposure” (Ref. 1), which contains a broad discussion of the risks from exposure to ionizing radiation.

Other sections of the NRC's regulations also specify requirements for monitoring external and internal occupational dose to a declared pregnant woman.  In 10 CFR 20.1502, “Conditions Requiring Individual Monitoring of External and Internal Occupational Dose,” licensees are required to monitor the occupational dose to a declared pregnant woman, using an individual monitoring device, if it is likely that the declared pregnant woman will receive, from external sources, a deep dose equivalent in excess of 0.1 rem (1 mSv). According to Paragraph (e) of 10 CFR 20.2106, “Records of Individual Monitoring Results,” the licensee must maintain records of dose to an embryo/fetus if monitoring was required, and the records of dose to the embryo/fetus must be kept with the records of dose to the declared pregnant woman. The declaration of pregnancy must be kept on file, but may be maintained separately from the dose records. The licensee must retain the required form or record until the Commission terminates each pertinent license requiring the record.

The information collections in this regulatory guide are covered by the requirements of 10 CFR Parts 19 or 20, which were approved by the Office of Management and Budget, approval numbers 3150-0044 and 3150-0014, respectively. The NRC may not conduct or sponsor, and a person is not required to respond to, a collection of information unless it displays a currently valid OMB control number.


As discussed in Regulatory Guide 8.29 (Ref. 1), exposure to any level of radiation is assumed to carry with it a certain amount of risk. In the absence of scientific certainty regarding the relationship between low dose exposure and health effects, and as a conservative assumption for radiation protection purposes, the scientific community generally assumes that any exposure to ionizing radiation may cause undesirable biological effects and that the likelihood of these effects increases as the dose increases. At the occupational dose limit for the whole body of 5 rem (50 mSv) per year, the risk is believed to be very low.

The magnitude of risk of childhood cancer following in utero exposure is uncertain in that both negative and positive studies have been reported.  The data from these studies “are consistent with a lifetime cancer risk resulting from exposure during gestation which is two to three times that for the adult” (NCRP Report No. 116, Ref. 2). The NRC has reviewed the available scientific literature and has concluded that the 0.5 rem (5 mSv) limit specified in 10 CFR 20.1208 provides an adequate margin of protection for the embryo/fetus. This dose limit reflects the desire to limit the total lifetime risk of leukemia and other cancers associated with radiation exposure during pregnancy.

In order for a pregnant worker to take advantage of the lower exposure limit and dose monitoring provisions specified in 10 CFR Part 20, the woman must declare her pregnancy in writing to the licensee. A form letter for declaring pregnancy is provided in this guide or the licensee may use its own form letter for declaring pregnancy. A separate written declaration should be submitted for each pregnancy.

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1.  Who Should Receive Instruction

Female workers who require training under 10 CFR 19.12 should be provided with the information contained in this guide. In addition to the information contained in Regulatory Guide 8.29 (Ref. 1), this information may be included as part of the training required under 10 CFR 19.12.

2.  Providing Instruction

The occupational worker may be given a copy of this guide with its Appendix, an explanation of the contents of the guide, and an opportunity to ask questions and request additional information. The information in this guide and Appendix should also be provided to any worker or supervisor who may be affected by a declaration of pregnancy or who may have to take some action in response to such a declaration.

Classroom instruction may supplement the written information. If the licensee provides classroom instruction, the instructor should have some knowledge of the biological effects of radiation to be able to answer questions that may go beyond the information provided in this guide. Videotaped presentations may be used for classroom instruction. Regardless of whether the licensee provides classroom training, the licensee should give workers the opportunity to ask questions about information contained in this Regulatory Guide 8.13. The licensee may take credit for instruction that the worker has received within the past year at other licensed facilities or in other courses or training.

3.  Licensee's Policy on Declared Pregnant Women

The instruction provided should describe the licensee's specific policy on declared pregnant women, including how those policies may affect a woman's work situation. In particular, the instruction should include a description of the licensee's policies, if any, that may affect the declared pregnant woman's work situation after she has filed a written declaration of pregnancy consistent with 10 CFR 20.1208.

The instruction should also identify who to contact for additional information as well as identify who should receive the written declaration of pregnancy. The recipient of the woman's declaration may be identified by name (e.g., John Smith), position (e.g., immediate supervisor, the radiation safety officer), or department (e.g., the personnel department).

4.  Duration of Lower Dose Limits for the Embryo/Fetus

The lower dose limit for the embryo/fetus should remain in effect until the woman withdraws the declaration in writing or the woman is no longer pregnant. If a declaration of pregnancy is withdrawn, the dose limit for the embryo/fetus would apply only to the time from the estimated date of conception until the time the declaration is withdrawn. If the declaration is not withdrawn, the written declaration may be considered expired one year after submission.

5.  Substantial Variations Above a Uniform Monthly Dose Rate

According to 10 CFR 20.1208(b), “The licensee shall make efforts to avoid substantial variation above a uniform monthly exposure rate to a declared pregnant woman so as to satisfy the limit in paragraph (a) of this section,” that is, 0.5 rem (5 mSv) to the embryo/fetus. The National Council on Radiation Protection and Measurements (NCRP) recommends a monthly equivalent dose limit of 0.05 rem (0.5 mSv) to the embryo/fetus once the pregnancy is known (Ref. 2). In view of the NCRP recommendation, any monthly dose of less than 0.1 rem (1 mSv) may be considered as not a substantial variation above a uniform monthly dose rate and as such will not require licensee justification. However, a monthly dose greater than 0.1 rem (1 mSv) should be justified by the licensee.


The purpose of this section is to provide information to licensees and applicants regarding the NRC staff's plans for using this regulatory guide.

Unless a licensee or an applicant proposes an acceptable alternative method for complying with the specified portions of the NRC's regulations, the methods described in this guide will be used by the NRC staff in the evaluation of instructions to workers on the radiation exposure of pregnant women.

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1.    USNRC, “Instruction Concerning Risks from Occupational Radiation Exposure,” Regulatory Guide 8.29, Revision 1, February 1996.

2.    National Council on Radiation Protection and Measurements,  Limitation of Exposure to Ionizing Radiation, NCRP Report No. 116, Bethesda, MD, 1993.




1.  Why am I receiving this information?

California and NRC regulations require that licensees instruct individuals working with licensed radioactive materials in radiation protection as appropriate for the situation. The instruction below describes information that occupational workers and their supervisors should know about the radiation exposure of the embryo/fetus of pregnant women.

The regulations allow a pregnant woman to decide whether she wants to formally declare her pregnancy to take advantage of lower dose limits for the embryo/fetus. This instruction provides information to help women make an informed decision whether to declare a pregnancy.

2.  If I become pregnant, am I required to declare my pregnancy?

No. The choice whether to declare your pregnancy is completely voluntary. If you choose to declare your pregnancy, you must do so in writing and a lower radiation dose limit will apply to your embryo/fetus. If you choose not to declare your pregnancy, you and your embryo/fetus will continue to be subject to the same radiation dose limits that apply to other occupational workers.

3.  If I declare my pregnancy in writing, what happens?

If you choose to declare your pregnancy in writing, the licensee must take measures to limit the dose to your embryo/fetus to 0.5 rem (5 millisievert) during the entire pregnancy. This is one-tenth of the dose that an occupational worker may receive in a year. If you have already received a dose exceeding 0.5 rem (5 mSv) in the period between conception and the declaration of your pregnancy, an additional dose of 0.05 rem (0.5 mSv) is allowed during the remainder of the pregnancy. In addition, 10 CFR 20.1208, “Dose to an Embryo/Fetus,” requires licensees to make efforts to avoid substantial variation above a uniform monthly dose rate so that all the 0.5 rem (5 mSv) allowed dose does not occur in a short period during the pregnancy.

This may mean that, if you declare your pregnancy, the licensee may not permit you to do some of your normal job functions if those functions would have allowed you to receive more than 0.5 rem, and you may not be able to have some emergency response responsibilities.

4.  Why do the regulations have a lower dose limit for the embryo/fetus of a declared pregnant woman than for a pregnant worker who has not declared?

A lower dose limit for the embryo/fetus of a declared pregnant woman is based on a consideration of greater sensitivity to radiation of the embryo/fetus and the involuntary nature of the exposure. Several scientific advisory groups have recommended (References 1 and 2) that the dose to the embryo/fetus be limited to a fraction of the occupational dose.

5.  What are the potentially harmful effects of radiation exposure to my embryo/fetus?

The occurrence and severity of health effects caused by ionizing radiation are dependent upon the type and total dose of radiation received, as well as the time period over which the exposure was received.  See Regulatory Guide 8.29, “Instruction Concerning Risks from Occupational Exposure” (Ref. 3), for more information. The main concern is embryo/fetal susceptibility to the harmful effects of radiation such as cancer.

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6.  Are there any risks of genetic defects?

Although radiation injury has been induced experimentally in rodents and insects, and in the experiments was transmitted and became manifest as hereditary disorders in their offspring, radiation has not been identified as a cause of such effect in humans. Therefore, the risk of genetic effects attributable to radiation exposure is speculative. For example, no genetic effects have been documented in any of the Japanese atomic bomb survivors, their children, or their grandchildren.

7.  What if I decide that I do not want any radiation exposure at all during my pregnancy?

You may ask your employer for a job that does not involve any exposure at all to occupational radiation dose, but your employer is not obligated to provide you with a job involving no radiation exposure. Even if you receive no occupational exposure at all, your embryo/fetus will receive some radiation dose (on average 75 mrem (0.75 mSv)) during your pregnancy from natural background radiation.

The NRC has reviewed the available scientific literature and concluded that the 0.5 rem (5 mSv) limit provides an adequate margin of protection for the embryo/fetus. This dose limit reflects the desire to limit the total lifetime risk of leukemia and other cancers. If this dose limit is exceeded, the total lifetime risk of cancer to the embryo/fetus may increase incrementally. However, the decision on what level of risk to accept is yours. More detailed information on potential risk to the embryo/fetus from radiation exposure can be found in References 2-10.

8.  What effect will formally declaring my pregnancy have on my job status?

Only the licensee can tell you what effect a written declaration of pregnancy will have on your job status. As part of your radiation safety training, the licensee should tell you the company's policies with respect to the job status of declared pregnant women. In addition, before you declare your pregnancy, you may want to talk to your supervisor or your radiation safety officer and ask what a declaration of pregnancy would mean specifically for you and your job status.

In many cases you can continue in your present job with no change and still meet the dose limit for the embryo/fetus.  For example, most commercial power reactor workers (approximately 93%) receive, in 12 months, occupational radiation doses that are less than 0.5 rem (5 mSv) (Ref. 11).  The licensee may also consider the likelihood of increased radiation exposures from accidents and abnormal events before making a decision to allow you to continue in your present job.

If your current work might cause the dose to your embryo/fetus to exceed 0.5 rem (5 mSv), the licensee has various options. It is possible that the licensee can and will make a reasonable accommodation that will allow you to continue performing your current job, for example, by having another qualified employee do a small part of the job that accounts for some of your radiation exposure.

9.  What information must I provide in my written declaration of pregnancy?

You should provide, in writing, your name, a declaration that you are pregnant, the estimated date of conception (only the month and year need be given), and the date that you give the letter to the licensee.  A form letter that you can use is included at the end of these questions and answers. You may use that letter, use a form letter the licensee has provided to you, or write your own letter.

10. To declare my pregnancy, do I have to have documented medical proof that I am pregnant?

NRC regulations do not require that you provide medical proof of your pregnancy. However, NRC regulations do not preclude the licensee from requesting medical documentation of your pregnancy, especially if a change in your duties is necessary in order to comply with the 0.5 rem (5 mSv) dose limit.

11. Can I tell the licensee orally rather than in writing that I am pregnant?

No. The regulations require that the declaration must be in writing.

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12. If I have not declared my pregnancy in writing, but the licensee suspects that I am pregnant, do the lower dose limits apply?

No. The lower dose limits for pregnant women apply only if you have declared your pregnancy in writing. The United States Supreme Court has ruled (in United Automobile Workers International Union v. Johnson Controls, Inc., 1991) that “Decisions about the welfare of future children must be left to the parents who conceive, bear, support, and raise them rather than to the employers who hire those parents” (Reference 7). The Supreme Court also ruled that your employer may not restrict you from a specific job “because of concerns about the next generation.” Thus, the lower limits apply only if you choose to declare your pregnancy in writing.

13. If I am planning to become pregnant but am not yet pregnant and I inform the licensee of that in writing, do the lower dose limits apply?

No.  The requirement for lower limits applies only if you declare in writing that you are already pregnant.

14. What if I have a miscarriage or find out that I am not pregnant?

If you have declared your pregnancy in writing, you should promptly inform the licensee in writing that you are no longer pregnant. However, if you have not formally declared your pregnancy in writing, you need not inform the licensee of your nonpregnant status.

15. How long is the lower dose limit in effect?

The dose to the embryo/fetus must be limited until you withdraw your declaration in writing or you inform the licensee in writing that you are no longer pregnant. If the declaration is not withdrawn, the written declaration may be considered expired one year after submission.

16. If I have declared my pregnancy in writing, can I revoke my declaration of pregnancy even if I am still pregnant?

Yes, you may. The choice is entirely yours. If you revoke your declaration of pregnancy, the lower dose limit for the embryo/fetus no longer applies.

17. What if I work under contract at a licensed facility?

The regulations state that you should formally declare your pregnancy to the licensee in writing. The licensee has the responsibility to limit the dose to the embryo/fetus.

18. Where can I get additional information?

The references to this Appendix contain helpful information, especially Reference 3,   NRC's Regulatory Guide 8.29, “Instruction Concerning Risks from Occupational Radiation Exposure,” for general information on radiation risks. The licensee should be able to give this document to you.

For information on legal aspects, see Reference 7, “The Rock and the Hard Place: Employer Liability to Fertile or Pregnant Employees and Their Unborn Children—What Can the Employer Do?” which is an article in the journal Radiation Protection Management.

You may telephone the NRC Headquarters at (301) 415-7000. Legal questions should be directed to the Office of the General Counsel, and technical questions should be directed to the Division of Industrial and Medical Nuclear Safety.

You may also telephone the NRC Regional Offices at the following numbers:  Region I, (610) 337-5000; Region II, (404) 562-4400; Region III, (630) 829-9500; and Region IV, (817) 860-8100. Legal questions should be directed to the Regional Counsel, and technical questions should be directed to the Division of Nuclear Materials Safety.

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1.    National Council on Radiation Protection and Measurements,  Limitation of Exposure to Ionizing Radiation, NCRP Report No. 116, Bethesda, MD, 1993.

2.    International Commission on Radiological Protection,  1990 Recommendations of the  International Commission on Radiological Protection, ICRP Publication 60, Ann. ICRP 21: No. 1-3, Pergamon Press, Oxford, UK, 1991.

3.    USNRC, “Instruction Concerning Risks from Occupational Radiation Exposure,” Regulatory Guide 8.29, Revision 1, February 1996.11 (Electronically available at www.nrc.gov/NRC/RG/index.html)

4.    Committee on the Biological Effects of Ionizing Radiations, National Research Council, Health Effects of Exposure to Low Levels of Ionizing Radiation (BEIR V), National Academy Press, Washington, DC,1990.

5.    United Nations Scientific Committee on the Effects of Atomic Radiation, Sources and Effects of Ionizing Radiation, United Nations, New York, 1993.

6.    R. Doll and R. Wakeford, “Risk of Childhood Cancer from Fetal Irradiation,” The British Journal of Radiology, 70, 130-139, 1997.

7.    David Wiedis, Donald E. Jose, and Timm O. Phoebe, “The Rock and the Hard Place: Employer Liability to Fertile or Pregnant Employees and Their Unborn Children—What Can the Employer Do?” Radiation Protection Management, 11, 41-49, January/February 1994.

8.    National Council on Radiation Protection and Measurements, Considerations Regarding the Unintended Radiation Exposure of the Embryo, Fetus, or Nursing Child, NCRP Commentary No. 9, Bethesda, MD, 1994.

9.    National Council on Radiation Protection and Measurements, Risk Estimates for Radiation Protection, NCRP Report No. 115, Bethesda, MD, 1993.

10.  National Radiological Protection Board, Advice on Exposure to Ionising Radiation During Pregnancy, National Radiological Protection Board, Chilton, Didcot, UK, 1998.

11.  M.L. Thomas and D. Hagemeyer, “Occupational Radiation Exposure at Commercial Nuclear Power Reactors and Other Facilities, 1996,” Twenty-Ninth Annual Report, NUREG-0713, Vol. 18, USNRC, 1998.22




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This form letter is provided for your convenience. 

To make your written declaration of pregnancy, you may fill in the blanks in this form letter or you may write your own letter.




  •   Dosimetry Coordinator, Box 0942

Environment, Health and Safety, UCSF

In accordance with the NRC's regulations at 10 CFR 20.1208, "Dose to an Embryo/Fetus," I am declaring that I am pregnant. I believe I became pregnant in ________________________ (only the month and year need be provided).

I understand the radiation dose to my embryo/fetus during my entire pregnancy will not be allowed to exceed 0.5 rem (5 millisievert) (unless that dose has already been exceeded between the time of conception and submitting this letter). I also understand that meeting the lower dose limit may require a change in job or job responsibilities during my pregnancy.

Your Signature:  __________________________________

Your Name Printed:  ________________________________

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Forms are available on the UCSF EH&S website.

The Radiation Safety section includes links to many of the necessary forms, as well as other resources.  In addition, copies can be obtained from your Departmental Safety Advisor (DSA).

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Symbol for mass number

Absorbed dose

The amount of energy imparted to matter by ionizing radiation per unit mass of irradiated material at the place of interest (see rad or Gray).


The process by which radiation imparts some or all of its energy to material through which it passes.

Absorption coefficient

The fractional decrease in the intensity of a beam of X-rays or gamma radiation.

  •    Linear absorption coefficient (per unit lengths)
  •    Mass absorption coefficient (per mass thickness)
  •    Atomic absorption coefficient (per atom)


The policy of maintaining radiation levels of exposure As Low As is Reasonably Achievable.

Alpha Particles

Highly energetic helium nuclei.


Positive electrode; electrode to which negative ions (or electrons) are attracted.

Area monitoring

Routine monitoring of the level of radioactive contamination of any particular area, building, room or equipment.

Atomic mass

The mass of a neutral atom of a nuclide is usually expressed in atomic mass units (amu) which is 1/12 the mass of the neutral 12C atom.

Atomic number

The number of protons in the nucleus of an atom of a nuclide (symbol).


Radiation due to gamma radiation from radioactive materials in the earth, such as radium and potassium 40, and cosmic radiation coming down through the atmosphere.  Levels in buildings can be appreciably higher or lower than levels out of doors, depending on the materials of construction.

Becquerel (Bq)

Special name for the SI Unit of activity of radionuclide. One Bq equals one disintegration per second.

     1 curie = 3.7E10 Bq

     1 mCi = 37 MBq

Beta particles

These are emitted from the nucleus and are identical to orbital electrons in mass (1/1840 amu) and charge (1 negative unit).  As the result of the emission of a beta-particles (negative), a neutron is converted to a proton in the nucleus so that the atomic number is increased by one.  The atomic mass number remains the same.  Beta-particles will produce 50-200 ion pairs per centimeter of track length in air.  Beta-particles are emitted in a spectrum of energies; the average energy is 1/3 of the maximum.


A quantitative determination of the absorbed dose to a target organ.  Bioassays are commonly conducted through analysis of urine or by direct measurement of a target organ, such as the thyroid gland.


Electromagnetic radiation produced when charged particles decelerate in matter.  The production of bremsstrahlung depends directly upon the energy of the particle and the atomic number of the absorber.  This means that large-activity, high-energy beta sources require shielding with sufficient thickness of low atomic number substances such as plastic.  At low energies the fraction of energy converted to bremsstrahlung approximately equals ZE/1000, where "Z" is the atomic number of the absorber and "E" is the average of energy of the beta-particles.  Usually associated with energetic beta-emitters, e.g., 32P.

Broad License

Normally, the State of California Department of Health Services issues a specific license for each proposed radiation use.  In exceptional cases, a Type A Broad Scope Radioactive Material License is issued to an organization for the use of different quantities and types of radioactive materials in research, development or humans use.  The University of California, San Francisco (UCSF) has a Broad License.

Carrier Free 

A radionuclide that has not been diluted into a stable isotope of similar form.

Contamination, Radioactive

Deposition of radioactive material in any location where it is not desired, particularly where its presence may be harmful.  The harm may be in vitiating an experiment or a procedure, or in actually being a source of danger to personnel.

Controlled Area

Any area access which is controlled by the user for purposes of radiation safety.

Curie (Ci) 

A unit of radioactivity defined as the quantity of any radionuclide that will produce 3.7 x 10E10 disintegrations per second.  This unit has been replaced in the literature with the term becquerel.

Critical Organ

The organ which receives the greatest exposure as the result of the ingestion of a particular radionuclide. 

Decay, Radioactive 

Disintegration of an unstable nuclide by the spontaneous emission of charged particles and/or photons.


A term denoting the quantity of radiation energy absorbed per unit mass.

eV (Electron Volt)

The energy required to accelerate an electron across a potential of one volt.

Gamma-Rays and X-Rays

These are part of the electromagnetic energy spectrum. Gamma-rays and X-rays differ only in their source.  Gamma-rays arise from the atomic nucleus while X-rays arise from outside the nucleus and directly cause ionization of atoms.  Both of these radiations interact with matter mainly by transferring energy to orbital electrons of absorber atoms causing ionization.

Geiger Muller (GM) Counter 

A highly sensitive gas-filled detector and associated circuitry used for radiation detection and measurements.

Gray (Gy) 

A unit of radiation dose namely, absorption of 1 joule per kilogram of matter.  One Gray equals 100 rads (see rad).

Half-life, Biological

The time required for a body to eliminate one half of any substance.

Half-life, Effective

The time required for a radioactive nuclide in a system to be diminished 50% as a result of the combined action of radioactive decay and biological elimination.

     Teff = Tbio x Trad / (Tbio + Trad)

Half-life, Radioactive   

The time required for a radioactive substance to lose 50% of its activity by decay.  Each radionuclide has a unique half-life.

Half-value Layer (HVL)

The thickness of a material which, if placed in a radiation beam will reduce the intensity of the beam by half.

Hazard Guide Value

Values computed by the formula HGV = QTUA, where "Q" equals quantity of radionuclides in mCi; "T" equals relative toxicity factor based on permissible air concentration of radionuclides; "U" equals use factor, and "A" is assessment factor.

Health Physics

A term in common use for that branch of radiological science dealing with the protection of personnel from harmful effects of ionizing radiation.

High radiation area

Any area accessible to individuals in which there exists radiation at such levels that an individual could receive in any one hour a dose to the whole body in excess of 100 mrem.

Inverse square law

The intensity of radiation at any distance from a point source varies inversely as the square of that distance.  For example, if the radiation exposure rate is 50 mR/hr at 1 cm from a source, the exposure rate will be .5 mR/hr at 10 cm.


The process by which a neutral atom or molecule acquires a positive or negative electrical charge. 

Ionizing Radiation

Any electromagnetic or particulate radiation capable of producing ions in its passage through matter.  In general, it refers to gamma-rays and X-rays, alpha and beta-particles, neutrons, protons, and high speed electrons.


Nuclides having the same number of protons in their nuclei, (the same atomic number).  Essentially identical chemical properties exist between isotopes of a particular element but they can have different nuclear decay properties.


One-thousand electron volts.  This is a unit used to specify the energy of ionizing radiation.

Mass number 

The number of nucleons (protons and neutrons) in the nucleus of an atom (Symbol A).

Maximum permissible dose (MPD)

The maximum dose of radiation which may be received by an individual working with ionizing radiation. 


One million electron volts.  This is a unit used to specify the energy of ionizing radiation.


Checking for presence of sources of radiation under a specific set of conditions.  Monitoring includes measurements of levels of radiation or concentrations of radioactivity.


Electrically neutral particles with a mass of about 1 amu. Neutrons can interact with nuclei and transmute stable nuclides into radioactive nuclides. 

Personnel Dosimetry

Determination of the cumulative dose of radiation to an individual by various means.


These are positively charged beta-particles (equivalent in mass to electrons).  They are emitted from the nucleus in the same manner as negatively charged electrons.  The process results in a proton being transformed to a neutron.  The resulting nucleus will have one less positive charge and the same mass number as the original nucleus.  Positrons are emitted with a spectrum of energies.  When the positron collides with a negative electron, both particles are annihilated.  The masses of the positron and electron (each of which has a mass 1/1840 of an atomic mass unit) are totally converted to energy in accordance with formula E = mc2.  Two photons with energies of 0.511 MeV are produced. Since the annihilation radiations have the same characteristics as gamma-rays, position sources require shielding like that for gamma sources.

Quality Factor (QF)

The number relating the Rad (radiation absorbed dose) to the Rem (measure of biological damage).  Absorbed doses are  multiplied by the QF to obtain dose for radiation protection purposes.  The QF for X-rays, gamma-rays and beta-particles is approximately one.

Rad (Radiation Absorbed Dose)

A unit of absorbed dose. A dose of one rad means the absorption of 100 ergs of radiation energy per gram of absorber or 0.01 joule per kilogram of absorbing material.  This term has been superseded in the literature by the term Gray. 100 rads is equivalent to one Gray.

Radioactive materials

Any material that emits ionizing radiation spontaneously.

Radiological Survey 

An evaluation of the radiation hazards incident to the production, use or existence of radioactive materials or other sources of radiation under a specific set of conditions.  Such evaluation customarily includes a physical survey of the disposition of materials and equipment, measurements or estimates of the levels of radiation that may be involved, and a sufficient knowledge of processes using or affecting these materials to predict hazards resulting from expected or possible changes in materials or equipment.


A term referring to the potential of an radionuclide to cause damage to living tissue by absorption of energy from the disintegration of the radioactive material introduced into the body.

Relative Biological Effectiveness (RBE)

The factor used to compare the biological effectiveness of absorbed radiation doses caused by different types of ionizing radiation.  This factor is usually 1 for commonly used X-ray, gamma and beta sources.

Rem (Roentgen Equivalent Man)

The unit of dose equivalence.  The dose equivalent in rems is numerically equal to the absorbed dose in rads multiplied by the quality factor, the distribution factor and other necessary modifying factors.  This term has been superseded in the literature by the term "sievert".  100 rem equal one sievert.

Restricted Area

For purposes of radiation safety and for controlling exposure to ionizing radiation, UCSF areas where radioactive materials are used or stored, or ionizing radiation generators are in use, are considered restricted areas. Same as Controlled Area.

Roentgen (R) 

A measure of ionization that is defined for X-rays and gamma-rays up to the energy of 3 MeV.  It is about equivalent to 100 ergs per gram of energy deposited in air.  (Survey meter readings of pure beta- emitters must be monitored on the count rate scale not the mR/hr scale).

Scintillation Counter 

A counter in which light flashes produced in a scintillator by ionizing radiation are converted into electric pulses by a photo multiplier tube.  This may be obtained by the use of a liquid fluor and sample or within or against a solid crystal.

Sealed Source

A radioactive source that is hermetically sealed and not intended to be opened. 

Sievert (Sv) 

Special name for the SI unit of dose equivalence.  One sievert equals 100 rem.

Specific Activity

Total radioactivity of a given nuclide per gram of a compound, element or radioactive nuclide.

Tenth Value Layer (TVL)

The thickness of a substance which if introduced into a beam of radiation (for example, as a shield) will reduce the intensity of the beam by a factor of 10.

Tracer, Isotopic

Radionuclides which may be incorporated into a sample to make possible observation of the course of these nuclides through a chemical, biological, or physical system.  The observations may be made by measurement of radioactivity or of isotopic abundance. 


Any person who uses radionuclides, including students, staff, visiting appointees, and faculty.  Users are specifically authorized by the Radiation Safety Committee (RSC) following an evaluation of their training and experience. Each authorized user must pass an examination and receive a training number from the Radiation Safety Office.

Wipe Test 

A procedure in which a swab, e.g., a circle of filter paper, is rubbed on a surface, generally over an area of approximately 100 cm2, and its radioactivity measured to determine if the surface is contaminated with removable radioactive material.


Part of the electromagnetic energy spectrum, which also includes radio waves, infrared, visible light and ultraviolet light, etc.  X-rays and gamma-rays have very high energies; they have short wave lengths and readily penetrate matter.  Gamma-rays and X-rays differ only in their source.  Gamma-rays arise from the atomic nucleus, while X-rays arise from orbital electron energy transitions. X-rays produced by machines usually have two components: bremsstrahlung and characteristic X-rays.

Both of these radiations interact with matter mainly by transferring energy to orbital electrons of absorber atoms causing ionization.  The ejected orbital electrons then decelerate and lose energy, in the same manner as beta-particles.  Because the photons have no mass or electrical charge, the probabilities of interaction are small and the radiations are difficult to attenuate. Dense materials with high atomic numbers, i.e., lead, uranium, etc., make the best shields against these radiations.

Symbol for atomic number.

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