ML003739438

Regulatory Guide 8.29 (Draft Issued as DG-8012) Revision 1 Instruction Concerning Risks from Occupational Radiation Exposure

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RG-8.29 Rev 1
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U.S. NUCLEAR REGULATORY COMMISSION Revision 1 February 1996 REGULATORY GUIDE OFFICE OF NUCLEAR REGULATORY RESEARCH REGULATORY GUIDE 8.29 (Draft was issued as DG-8012)

INSTRUCTION CONCERNING RISKS FROM OCCUPATIONAL RADIATION EXPOSURE A. INTRODUCTION dose limit for the embryo/fetus of an occupationally exposed declared pregnant woman, and explicitly Section 19.12 of 10 CFR Part 19, "Notices, In- states that Part 20 is not to be construed as limiting structions and Reports to Workers: Inspection and In- action that may be necessary to protect health and vestigations," requires that all individuals who in the safety during emergencies.

course of their employment are likely to receive in a Any information collection activities mentioned in year an occupational dose in excess of 100 mrem (1 this regulatory guide are contained as requirements in mSv) be instructed in the health protection issues asso- 10 CFR Part 19 or 10 CFR Part 20. These regulations ciated with exposure to radioactive materials or radi- provide the regulatory bases for this guide. The infor-ation. Section 20.1206 of 10 CFR Part 20, "Standards mation collection requirements in 10 CFR Parts 19 and for Protection Against Radiation," requires that before 20 have been cleared under OMB Clearance Nos.

a planned special exposure occurs the individuals in- 3150-0044 and 3150-0014, respectively.

volved are, among other things, to be informed of the estimated doses and associated risks. B. DISCUSSION This regulatory guide describes the information It is important to qualify the material presented in that should be provided to workers by licensees about this guide with the following considerations.

health risks from occupational exposure. This revision The coefficient used in this guide for occupational conforms to the revision of 10 CFR Part 20 that be- radiation risk estimates, 4 x 10- 4 health effects per came effective on June 20, 1991, to be implemented rem, is based on data obtained at much higher doses by licensees no later than January 1, 1994. The revi- and dose rates than those encountered by workers.

sion of 10 CFR Part 20 establishes new dose limits The risk coefficient obtained at high doses and dose based on the effective dose equivalent (EDE), requires rates was reduced to account for the reduced effective-the summing of internal and external dose, establishes ness of lower doses and dose rates in producing the a requirement that licensees use procedures and engi- stochastic effects observed in studies of exposed neering controls to the extent practicable to achieve humans.

occupational doses and doses to members of the public that are as low as is reasonably achievable (ALARA), The assumption of a linear extrapolation from the provides for planned special exposures, establishes a lowest doses at which effects are observable down to USNRC REGULATORY GUIDES Written comments may be submitted to the Rules Review and Directives Branch, DFIPS, ADM, U.S. Nuclear Regulatory Commission, Washing-Regulatory Guides are Issued todescribe and make availableto thepublic ton, DC 20555-0001.

such information as methods acceptable to the NRC staff for Implement- The guides are issued in the following ten broad divisions:

ing specific parts of the Commission's regulations, techniques used by the staff in evaluating specific problems or postulated accidents, and 1. Power Reactors 6. Products data needed by the NRC staff In Its review of applications for permits and 2. Research and Test Reactors 7, Transportation licenses. Regulatory guides are not substitutes for regulations, and com- 3, Fuels and Materials Facilities 8. Occupational Health pliance with them Is not required. Methods and solutions different from 4. Environmental and Siting 9. Antitrust and Financial Review those set out In the guides will be acceptable If they provide a basis for the 5. Materials and Plant Protection 10. General findings requisite to the Issuance or continuance of a permit or license by Single copies of regulatory guides may be obtained free of charge by writ-the Commission. Ing the Office of Administration, Attention: Distribution and Services Section, U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001; or by fax at (301)415-2260.

This guide was Issued after consideration of comments received from the public. Comments and suggestions for Improvements In these guides are Issued guides may also be purchased from the National Technical Infor-encouraged at all times, and guides will be revised, as appropriate, to mation Service on a standing order basis. Details on this service may be accommodate comments and to reflect new information or experience. obtained by writing NTIS, 5285 Port Royal Road, Springfield, VA22161.

I i-the occupational range has considerable uncertainty. high, i.e., above 20 rems (0.2 Sv), acute ex-The report of the Committee on the Biological Effects posures).

of Ionizing Radiation (Ref. 1) states that The normal incidence of effects from natural and

"... departure from linearity cannot be ex- manmade causes is significant. For example, approxi-cluded at low doses below the range of obser- mately 20% of people die from various forms of cancer vation. Such departures could be in the direc- whether or not they ever receive occupational expo-tion of either an increased or decreased risk. sure to radiation. To avoid increasing the incidence of Moreover, epidemiologic data cannot rigor- such biological effects, regulatory controls are imposed ously exclude the existence of a threshold in on occupational doses to adults and minors and on the 100 mrem dose range. Thus, the possibil- doses to the embryo/fetus from occupational expo-ity that there may be no risk from exposures sures of declared pregnant women.

comparable to external natural background Radiation protection training for workers who are radiation cannot be ruled out. At such low occupationally exposed to ionizing radiation is an es-doses and dose rates, it must be acknowl-sential component of any program designed to ensure edged that the lower limit of the range of un-compliance with NRC regulations. A clear understand-certainty in the risk estimates extends to ing of what is presently known about the biological zero. " risks associated with exposure to radiation will result in The issue of beneficial effects from low doses, or more effective radiation protection training and should hormesis, in cellular systems is addressed by the generate more interest on the part of the workers in United Nations Scientific Committee on the Effects of complying with radiation protection standards. In ad-Atomic Radiation (Ref. 2). UNSCEAR states that "... dition, pregnant women and other occupationally ex-it would be premature to conclude that cellular adap- posed workers should have available to them relevant tive responses could convey possible beneficial effects information on radiation risks to enable them to make to the organism that would outweigh the detrimental informed decisions regarding the acceptance of these effects of exposures to low doses of low-LET risks. It is intended that workers who receive this in-radiation." struction will develop respect for the risks involved, In the absence of scientific certainty regarding the rather than excessive fear or indifference.

relationship between low doses and health effects, and C. REGULATORY POSITION as a conservative assumption for radiation protection purposes, the scientific community generally assumes Instruction to workers performed in compliance that any exposure to ionizing radiation can cause bio- with 10 CFR 19.12 should be given prior to occupa-logical effects that may be harmful to the exposed per- tional exposure and periodically thereafter. The fre-son and that the magnitude or probability of these ef- quency of retraining might range from annually for li-fects is directly proportional to the dose. These effects censees with complex operations such as nuclear may be classified into three categories: power plants, to every three years for licensees who possess, for example, only low-activity sealed sources.

Somatic Effects: Physical effects occurring in If a worker is to participate in a planned special expo-the exposed person. These effects may be ob- sure, the worker should be informed of the associated servable after a large or acute dose (e.g., 100 risks in compliance with 10 CFR 20.1206.

rems1 (1 Sv) or more to the whole body in a few hours); or they may be effects such as In providing instruction concerning health protec-cancer that may occur years after exposure to tion problems associated with exposure to radiation, all radiation. occupationally exposed workers and their supervisors should be given specific instruction on the risk of bio-Genetic Effects: Abnormalities that may oc- logical effects resulting from exposure to radiation.

cur in the future children of exposed individu- The extent of these instructions should be commensu-als and in subsequent generations (genetic ef- rate with the radiological risks present in the work-fects exceeding normal incidence have not place.

been observed in any of the studies of human populations). The instruction should be presented orally, in printed form, or in any other effective communication Teratogenic Effects: Effects such as cancer or media to workers and supervisors. The appendix to congenital malformation that may be ob- this guide provides useful information for demonstrat-served in children who were exposed during ing compliance with the training requirements in 10 the fetal and embryonic stages of develop- CFR Parts 19 and 20. Individuals should be given an ment (these effects have been observed from opportunity to discuss the information and to ask ques-tions. Testing is recommended, and each trainee In the International System of Units (SI), the rem is replaced by should be asked to acknowledge in writing that the in-the sievert; 100 rerns is equal to 1 sievert (Sv). struction has been received and understood.

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D. IMPLEMENTATION complying with specified portions of the Commission's The purpose of this section is to provide informa- regulations, the guidance and instructional materials in tion to applicants and licensees regarding the NRC this guide will be used in the evaluation of applications staff's plans for using this regulatory guide. for new licenses, license renewals, and license amend-Except in those cases in which an applicant or li- ments and for evaluating compliance with 10 CFR censee proposes acceptable alternative methods for 19.12 and 10 CFR Part 20.

REFERENCES

1. National Research Council, Health Effects of Ex- 2. United Nations Scientific Committee on the Ef-posure to Low Levels of Ionizing Radiation, Re- fects of Atomic Radiation (UNSCEAR), Sources port of the Committee on the Biological Effects of and Effects of Ionizing Radiation, United Na-Ionizing Radiation (BEIR V), National Academy tions, New York, 1993.

Press, Washington, DC, 1990.

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APPENDIX INSTRUCTION CONCERNING RISKS FROM OCCUPATIONAL RADIATION EXPOSURE This instructional material is intended to provide The basic unit for measuring absorbed radiation is the user with the best available information about the the rad. One rad (0.01 gray in the International Sys-health risks from occupational exposure to ionizing ra- tem of units) equals the absorption of 100 ergs (a small diation. Ionizing radiation consists of energy or small but measurable amount of energy) in a gram of materi-particles, such as gamma rays and beta and alpha par- al such as tissue exposed to radiation. To reflect bio-ticles, emitted from radioactive materials, which can logical risk, rads must be converted to rems. The new cause chemical or physical damage when they deposit international unit is the sievert (100 rems = 1 Sv). This energy in living tissue. A question and answer format is conversion accounts for the differences in the effec-used. Many of the questions or subjects were devel- tiveness of different types of radiation in causing dam-oped by the NRC staff in consultation with workers, age. The rem is used to estimate biological risk. For union representatives, and licensee representatives ex- beta and gamma radiation, a rem is considered equal perienced in radiation protection training. to a rad.

This Revision 1 to Regulatory Guide 8.29 updates the material in the original guide on biological effects 2. What are the possible health effects of expo-sure to radiation?

and risks and on typical occupational exposure. Addi-tionally, it conforms to the revised 10 CFR Part 20, Health effects from exposure to radiation range "Standards for Protection Against Radiation," which from no effect at all to death, including diseases such was required to be implemented by licensees no later as leukemia or bone, breast, and lung cancer. Very than January 1, 1994. The information in this appen- high (100s of rads), short-term doses of radiation have dix is intended to help develop respect by workers for been known to cause prompt (or early) effects, such as the risks associated with radiation, rather than unjusti- vomiting and diarrhea,' skin burns, cataracts, and fied fear or lack of concern. Additional guidance con- even death. It is suspected that radiation exposure may cerning other topics in radiation protection training is be linked to the potential for genetic effects in the chil-provided in other NRC regulatory guides. dren of exposed parents. Also, children who were ex-posed to high doses (20 or more rads) of radiation

1. What is meant by health risk? prior to birth (as an embryo/fetus) have shown an in-A health risk is generally thought of as something creased risk of mental retardation and other congenital that may endanger health. Scientists consider health malformations. These effects (with the exception of risk to be the statistical probability or mathematical genetic effects) have been observed in various studies chance that personal injury, illness, or death may re- of medical radiologists, uranium miners, radium work-sult from some action. Most people do not think about ers, radiotherapy patients, and the people exposed to health risks in terms of mathematics. Instead, most of radiation from atomic bombs dropped on Japan. In us consider the health risk of a particular action in addition, radiation effects studies with laboratory ani-terms of whether we believe that particular action will, mals, in which the animals were given relatively high or will not, cause us some harm. The intent of this ap- doses, have provided extensive data on radiation-in-pendix is to provide estimates of, and explain the bases duced health effects, including genetic effects.

for, the risk of injury, illness, or death from occupa- It is important to note that these kinds of health tional radiation exposure. Risk can be quantified in effects result from high doses, compared to occupa-terms of the probability of a health effect per unit of tional levels, delivered over a relatively short period of dose received. time.

When x-rays, gamma rays, and ionizing particles Although studies have not shown a consistent interact with living materials such as our bodies, they cause-and-effect relationship between current levels of may deposit enough energy to cause biological dam- occupational radiation exposure and biological effects, age. Radiation can cause several different types of it is prudent from a worker protection perspective to events such as the very small physical displacement of assume that some effects may occur.

molecules, changing a molecule to a different form, or ionization, which is the removal of electrons from atoms and molecules. When the quantity of radiation energy deposited in living tissue is high enough, biolog- IThese symptoms are early indicators of what is referred to as the acute radiation syndrome, caused by high doses delivered ical damage can occur as a result of chemical bonds over a short time period, which includes damage to the blood-being broken and cells being damaged or killed. These forming organs such as bone marrow, damage to the gastroin-effects can result in observable clinical symptoms. testinal system, and, at very high doses, can include damage to the central nervous system.

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3. What is meant by early effects and delayed normal healthy cells turn into cancer cells. The poten-or late effects? tial for these delayed health effects is one of the main concerns addressed when setting limits on occupation-EARLY EFFECTS al doses.

Early effects, which are also called immediate or A delayed effect of special interest is genetic ef-prompt effects, are those that occur shortly after a fects. Genetic effects may occur if there is radiation large exposure that is delivered within hours to a few damage to the cells of the gonads (sperm or eggs).

days. They are observable after receiving a very large These effects may show up as genetic defects in the dose in a short period of time, for example, 300 rads children of the exposed individual and succeeding gen-(3 Gy) received within a few minutes to a few days. erations. However, if any genetic effects (i.e., effects Early effects are not caused at the levels of radiation in addition to the normal expected number) have been exposure allowed under the NRC's occupational limits. caused by radiation, the numbers are too small to have Early effects occur when the radiation dose is large been observed in human populations exposed to radi-enough to cause extensive biological damage to cells so ation. For example, the atomic bomb survivors (from that large numbers of cells are killed. For early effects Hiroshima and Nagasaki) have not shown any signifi-to occur, this radiation dose must be received within a cant radiation-related increases in genetic defects short time period. This type of dose is called an acute (Ref. 3). Effects have been observed in animal studies dose or acute exposure. The same dose received over a conducted at very high levels of exposure and it is long time period would not cause the same effect. Our known that radiation can cause changes in the genes in body's natural biological processes are constantly re- cells of the human body. However, it is believed that pairing damaged cells and replacing dead cells; if the by maintaining worker exposures below the NRC limits cell damage is spread over time, our body is capable of and consistent with ALARA, a margin of safety is pro-repairing or replacing some of the damaged cells, re- vided such that the risk of genetic effects is almost ducing the observable adverse conditions. eliminated.

For example, a dose to the whole body of about 4. What is the difference between acute and 300-500 rads (3-5 Gy), more than 60 times the annu- chronic radiation dose?

al occupational dose limit, if received within a short Acute radiation dose usually refers to a large dose time period (e.g., a few hours) will cause vomiting and of radiation received in a short period of time. Chronic diarrhea within a few hours; loss of hair, fever, and dose refers to the sum of small doses received repeat-weight loss within a few weeks; and about a 50 percent edly over long time periods, for example, 20 mrem (or chance of death if medical treatment is not provided. millirem, which is 1-thousandth of a rem) (0.2 mSv)

These effects would not occur if the same dose were per week every week for several years. It is assumed accumulated gradually over many weeks or months for radiation protection purposes that any radiation (Refs. 1 and 2). Thus, one of the justifications for es- dose, either acute or chronic, may cause delayed ef-tablishing annual dose limits is to ensure that occupa- fects. However, only large acute doses cause early ef-tional dose is spread out in time. fects; chronic doses within the occupational dose limits It is important to distinguish between whole body do not cause early effects. Since the NRC limits do not and partial body exposure. A localized dose to a small permit large acute doses, concern with occupational volume of the body would not produce the same effect radiation risk is primarily focused on controlling as a whole body dose of the same magnitude. For ex- chronic exposure for which possible delayed effects, such as cancer, are of concern.

ample, if only the hand were exposed, the effect would mainly be limited to the skin and underlying tissue of The difference between acute and chronic radi-the hand. An acute dose of 400 to 600 rads (4-6 Gy) ation exposure can be shown by using exposure to the to the hand would cause skin reddening; recovery sun's rays as an example. An intense exposure to the would occur over the following months and no long- sun can result in painful burning, peeling, and growing term damage would be expected. An acute dose of this of new skin. However, repeated short exposures pro-magnitude to the whole body could cause death within vide time for the skin to be repaired between expo-a short time without medical treatment. Medical treat- sures. Whether exposure to the sun's rays is long term ment would lessen the magnitude of the effects and the or spread over short periods, some of the injury may chance of death; however, it would not totally elimi- not be repaired and may eventually result in skin nate the effects or the chance of death. cancer.

Cataracts are an interesting case because they can DELAYED EFFECTS be caused by both acute and chronic radiation. A cer-Delayed effects may occur years after exposure. tain threshold level of dose to the lens of the eye is These effects are caused indirectly when the radiation required before there is any observable visual impair-changes parts of the cells in the body, which causes the ment, and the impairment remains after the exposure normal function of the cell to change, for example, is stopped. The threshold for cataract development 8.29-5

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from acute exposure is an acute dose on the order of the total amounts allowed if no external radiation is 100 rads (1 Gy). Further, a cumulative dose of 800 received. The resulting dose from the internal radi-rads (8 Gy) from protracted exposures over many ation sources (from breathing air at 1 DAC) is the years to the lens of the eye has been linked to some maximum allowed to an organ or to the worker's whole level of visual impairment (Refs. 1 and 4). These doses body.

exceed the amount that may be accumulated by the lens from normal occupational exposure under the 6. How does radiation cause cancer?

current regulations.

The mechanisms of radiation-induced cancer are

5. What is meant by external and internal ex- not completely understood. When radiation interacts posure? with the cells of our bodies, a number of events can occur. The damaged cells can repair themselves and A worker's occupational dose may be caused by permanent damage is not caused. The cells can die, exposure to radiation that originates outside the body, much like the large numbers of cells that die every day called "external exposure," or by exposure to radi-in our bodies, and be replaced through the normal bio-ation from radioactive material that has been taken logical processes. Or a change can occur in the cell's into the body, called 'internal exposure." Most NRC- reproductive structure, the cells can mutate and subse-licensed activities involve little, if any, internal expo-quently be repaired without effect, or they can form sure. It is the current scientific consensus that a rem of precancerous cells, which may become cancerous. Ra-radiation dose has the same biological risk regardless diation is only one of many agents with the potential of whether it is from an external or an internal source.

for causing cancer, and cancer caused by radiation The NRC requires that dose from external exposure cannot be distinguished from cancer attributable to and dose from internal exposure be added together, if any other cause.

each exceeds 10% of the annual limit, and that the total be within occupational limits. The sum of external Radiobiologists have studied the relationship be-and internal dose is called the total effective dose tween large doses of radiation and cancer (Refs. 5 and equivalent (TEDE) and is expressed in units of rems 6). These studies indicate that damage or change to (Sv) . genes in the cell nucleus is the main cause of radiation-induced cancer. This damage may occur directly Although unlikely, radioactive materials may en- through the interaction of the ionizing radiation in the ter the body through breathing, eating, drinking, or cell or indirectly through the actions of chemical prod-open wounds, or they may be absorbed through the ucts produced by radiation interactions within cells.

skin. The intake of radioactive materials by workers is Cells are able to repair most damage within hours; generally due to breathing contaminated air. Radioac- however, some cells may not be repaired properly.

tive materials may be present as fine dust or gases in Such misrepaired damage is thought to be the origin of the workplace atmosphere. The surfaces of equipment cancer, but misrepair does not always cause cancer.

and workbenches may be contaminated, and these Some cell changes are benign or the cell may die; these materials can be resuspended in air during work changes do not lead to cancer.

activities.

Many factors such as age, general health, inher-If any radioactive material enters the body, the ited traits, sex, as well as exposure to other cancer-material goes to various organs or is excreted, depend-causing agents such as cigarette smoke can affect sus-ing on the biochemistry of the material. Most radioiso-ceptibility to the cancer-causing effects of radiation.

topes are excreted from the body in a few days. For Many diseases are caused by the interaction of several example, a fraction of any uranium taken into the factors, and these interactions appear to increase the body will deposit in the bones, where it remains for a susceptibility to cancer.

longer time. Uranium is slowly eliminated from the body, mostly by way of the kidneys. Most workers are 7. Who developed radiation risk estimates?

not exposed to uranium. Radioactive iodine is prefer-entially deposited in the thyroid gland, which is located Radiation risk estimates were developed by several in the neck.. national and international scientific organizations over the last 40 years. These organizations include the Na-To limit risk to specific organs and the total body, tional Academy of Sciences (which has issued several an annual limit on intake (ALI) has been established reports from the Committee on the Biological Effects for each radionuclide. When more than one radionu- of Ionizing Radiations, BEIR), the National Council on clide is involved, the intake amount of each radionu- Radiation Protection and Measurements (NCRP), the clide is reduced proportionally. NRC regulations speci- International Commission on Radiological Protection fy the concentrations of radioactive material in the air (ICRP), and the United Nations Scientific Committee to which a worker may be exposed for 2,000 working on the Effects of Atomic Radiation (UNSCEAR).

hours in a year. These concentrations are termed the Each of these organizations continues to review new derived air concentrations (DACs). These limits are research findings on radiation health risks.

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Several reports from these organizations present delayed cancer because of that 1-rem dose (although new findings on radiation risks based upon revised esti- the actual number could be more or less than 4) in mates of radiation dose to survivors of the atomic addition to the 2,000 normal cancer fatalities expected bombing at Hiroshima and Nagasaki. For example, to occur in that group from all other causes. This UNSCEAR published risk estimates in 1988 and 1993 means that a 1-rem (0.01 Sv) dose may increase an (Refs. 5 and 6). The NCRP also published a report in individual worker's chances of dying from cancer from 1988, "New Dosimetry at Hiroshima and Nagasaki 20 percent to 20.04 percent. If one's lifetime occupa-and Its Implications for Risk Estimates" (Ref. 7). In tional dose is 10 rems, we could raise the estimate to January 1990, the National Academy of Sciences re- 20.4 percent. A lifetime dose of 100 rems may in-leased the fifth report of the BEIR Committee, crease chances of dying from cancer from 20 to 24 "Health Effects of Exposure to Low Levels of Ionizing percent. The average measurable dose for radiation Radiation" (Ref. 4). Each of these publications also workers reported to the NRC was 0.31 rem (0.0031 provides extensive bibliographies on other published Sv) for 1993 (Ref. 9). Today, very few workers ever studies concerning radiation health effects for those accumulate 100 rems (1 Sv) in a working lifetime, and who may wish to read further on this subject. the average career dose of workers at NRC-licensed facilities is 1.5 rems (0.015 Sv), which represents an

8. What are the estimates of the risk of fatal estimated increase from 20 to about 20.06 percent in cancer from radiation exposure? the risk of dying from cancer.

We don't know exactly what the chances are of It is important to understand the probability fac-getting cancer from a low-level radiation dose, primari- tors here. A similar question would be, "If you select ly because the few effects that may occur cannot be one card from a full deck of cards, will you get the ace distinguished from normally occurring cancers. How- of spades?" This question cannot be answered with a ever, we can make estimates based on extrapolation simple yes or no. The best answer is that your chance is from extensive knowledge from scientific research on 1 in 52. However, if 1000 people each select one card high dose effects. The estimates of radiation effects at from full decks, we can predict that about 20 of them high doses are better known than are those of most will get an ace of spades. Each person will have 1 chemical carcinogens (Ref. 8).

chance in 52 of drawing the ace of spades, but there is From currently available data, the NRC has no way we can predict which persons will get that card.

adopted a risk value for an occupational dose of 1 rem The issue is further complicated by the fact that in a (0.01 Sv) Total Effective Dose Equivalent (TEDE) of drawing by 1000 people, we might get only 15 suc-4 in 10,000 of developing a fatal cancer, or approxi- cesses, and in another, perhaps 25 correct cards in mately 1 chance in 2,500 of fatal cancer per rem of 1000 draws. We can say that if you receive a radiation TEDE received. The uncertainty associated with this dose, you will have increased your chances of eventu-risk estimate does not rule out the possibility of higher ally developing cancer. It is assumed that the more ra-risk, or the possibility that the risk may even be zero at diation exposure you get, the more you increase your low occupational doses and dose rates. chances of cancer.

The radiation risk incurred by a worker depends The normal chance of dying from cancer is about on the amount of dose received. Under the linear one in five for persons who have not received any oc-model explained above, a worker who receives 5 reins cupational radiation dose. The additional chance of (0.05 Sv) in a year incurs 10 times as much risk as developing fatal cancer from an occupational exposure another worker who receives only 0.5 rem (0.005 Sv). of 1 rem (0.01 Sv) is about the same as the chance of Only a very few workers receive doses near 5 rems drawing any ace from a full deck of cards three times in (0.05 Sv) per year (Ref. 9). a row. The additional chance of dying from cancer According to the BEIR V report (Ref. 4), approxi- from an occupational exposure of 10 rem (0.1 Sv) is mately one in five adults normally will die from cancer about equal to your chance of drawing two aces succes-from all possible causes such as smoking, food, alco- sively on the first two draws from a full deck of cards.

hol, drugs, air pollutants, natural background radi-It is important to realize that these risk numbers ation, and inherited traits. Thus, in any group of are only estimates based on data for people and re-10,000 workers, we can estimate that about 2,000 search animals exposed to high levels of radiation in (20%) will die from cancer without any occupational short periods of time. There is still uncertainty with re-radiation exposure.

gard to estimates of radiation risk from low levels of To explain the significance of these estimates, we exposure. Many difficulties are involved in designing will use as an example a group of 10,000 people, each research studies that can accurately measure the proj-exposed to 1 rem (0.01 Sv) of ionizing radiation. Using ected small increases in cancer cases that might be the risk factor of 4 effects per 10,000 rem of dose, we caused by low exposures to radiation as compared to estimate that 4 of the 10,000 people might die from the normal rate of cancer.

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These estimates are considered by the NRC staff ly because below the limits the effect is small compared to be the best available for the worker to use to make to differences in the normal cancer incidence from an informed decision concerning acceptance of the year to year and place to place. The ICRP, NCRP, and risks associated with exposure to radiation. A worker other standards-setting organizations assume for radi-who decides to accept this risk should try to keep expo- ation protection purposes that there is some risk, no sure to radiation as low as is reasonably achievable matter how small the dose (Curves 1 and 2). Some (ALARA) to avoid unnecessary risk. scientists believe that the risk drops off to zero at some low dose (Curve 3), the threshold effect. The ICRP

9. If I receive a radiation dose that is within and NCRP endorse the linear quadratic model as a occupational limits, will it cause me to get conservative means of assuring safety (Curve 2).

cancer?

For regulatory purposes, the NRC uses the straight Probably not. Based on the risk estimates pre- line portion of Curve 2, which shows the number of viously discussed, the risk of cancer from doses below effects decreasing linearly as the dose decreases. Be-the occupational limits is believed to be small. Assess- cause the scientific evidence does not conclusively ment of the cancer risks that may be associated with demonstrate whether there is or is not an effect at low low doses of radiation are projected from data avail- doses, the NRC assumes for radiation protection pur-able at doses larger than 10 rems (0.1 Sv) (Ref. 3). For poses, that even small doses have some chance of caus-radiation protection purposes, these estimates are ing cancer. Thus, a principle of radiation protection is made using the straight line portion of the linear qua- to do more than merely meet the allowed regulatory dratic model (Curve 2 in Figure 1). We have data on limits; doses should be kept as low as is reasonably cancer probabilities only for high doses, as shown by achievable (ALARA). This is as true for natural car-the solid line in Figure 1. Only in studies involving radi- cinogens such as sunlight and natural radiation as it is ation doses above occupational limits are there de- for those that are manmade, such as cigarette smoke, pendable determinations of the risk of cancer, primari- smog, and x-rays.

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i DOSE (REMS) 50 REMS Figure 1. Some Proposed Models for How the Effects of Radiation Vary With Doses at Low Levels 8.29-8

10. How can we compare the risk of cancer from working in several types of industries. Table 2 shows radiation to other kinds of health risks? average days of life expectancy lost as a result of fatal One way to make these comparisons is to compare work-related accidents. Table 2 does not include non-the average number of days of life expectancy lost accident types of occupational risks such as occupa-because of the effects associated with each particular tional disease and stress because the data are not health risk. Estimates are calculated by looking at a available.

large number of persons, recording the age when death These comparisons are not ideal because we are occurs from specific causes, and estimating the average comparing the possible effects of chronic exposure to number of days of life lost as a result of these early radiation to different kinds of risk such as accidental deaths. The total number of days of life lost is then death, in which death is inevitable if the event occurs.

averaged over the total observed group. This is the best we can do because good data are not Several studies have compared the average days of available on chronic exposure to other workplace car-life lost from exposure to radiation with the number of cinogens. Also, the estimates of loss of life expectancy days lost as a result of being exposed to other health for workers from radiation-induced cancer do not take risks. The word "average" is important because an in- into consideration the competing effect on the life ex-dividual who gets cancer loses about 15 years of life pectancy of the workers from industrial accidents.

expectancy, while his or her coworkers do not suffer

11. What are the health risks from radiation any loss. exposure to the embryo/fetus?

Some representative numbers are presented in During certain stages of development, the embryo/

Table 1. For categories of NRC-regulated industries fetus is believed to be more sensitive to radiation dam-with larger doses, the average measurable occupational age than adults. Studies of atomic bomb survivors ex-dose in 1993 was 0.31 rem (0.0031 Sv). A simple cal- posed to acute radiation doses exceeding 20 rads (0.2 culation based on the article by Cohen and Lee (Ref. Gy) during pregnancy show that children born after

10) shows that 0.3 rem (0.003 Sv) per year from age receiving these doses have a higher risk of mental re-18 to 65 results in an average loss of 15 days. These tardation. Other studies suggest that an association ex-estimates indicate that the health risks from occupa- ists between exposure to diagnostic x-rays before birth tional radiation exposure are smaller than the risks as- and carcinogenic effects in childhood and in adult life.

sociated with many other events or activities we en- Scientists are uncertain about the magnitude of the counter and accept in normal day-to-day activities. risk. Some studies show the embryo/fetus to be more It is also useful to compare the estimated average sensitive to radiation-induced cancer than adults, but number of days of life lost from occupational exposure other studies do not. In recognition of the possibility of to radiation with the number of days lost as a result of increased radiation sensitivity, and because dose to the Table 1 Estimated Loss of Life Expectancy from Health Risksa Estimate of Life Expectancy Lost Health Risk (average)

Smoking 20 cigarettes a day 6 years Overweight (by 15%) 2 years Alcohol consumption (U.S. average) 1 year All accidents combined 1 year Motor vehicle accidents 207 days Home accidents 74 days Drowning 24 days All natural hazards (earthquake, lightning, flood, etc.) 7 days Medical radiation 6 days Occupational Exposure 0.3 rem/y from age 18 to 65 15 days 1 remly from age 18 to 65 51 days aAdapted from Reference 10.

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for women (Refs. 1 and 4). These doses are far greater Table 2 Estimated Loss of Life Expectancy than the NRC s occupational dose limits for workers.

from Industrial Accidentsa Although acute doses can affect fertility by reduc-Estimated Days of Life ing sperm count or suppressing ovulation, they do not Industry Type Expectancy Lost (Average) have any direct effect on one's ability to function sexu-ally. No evidence exists to suggest that exposures with-All industries 60 in the NRC's occupational limits have any effect on the Agriculture 320 ability to function sexually.

Construction 227 13. What are the NRC occupational dose limits?

Mining and Quarrying 167 For adults, an annual limit that does not exceed:

Transportation and Public Utilities 160 a 5 rems (0.05 Sv) for the total effective dose equiv-Government 60 alent (TEDE), which is the sum of the deep dose equivalent (DDE) from external exposure to the Manufacturing 40 whole body and the committed effective dose Trade 27 equivalent (CEDE) from intakes of radioactive Services 27 material.

aAdapted from Reference 10.

• 50 rems (0.5 Sv) for the total organ dose equiva-lent (TODE), which is the sum of the DDE from external exposure to the whole body and the com-embryo/fetus is involuntary on the part of the embryo/

mitted dose equivalent (CDE) from intakes of ra-fetus, a more restrictive dose limit has been established dioactive material to any individual organ or tis-for the embryo/fetus of a declared pregnant radiation sue, other than the lens of the eye.

worker. See Regulatory Guide 8.13, "Instruction Con-cerning Prenatal Radiation Exposure."

• 15 rems (0.15 Sv) for the lens dose equivalent (LDE), which is the external dose to the lens of If an occupationally exposed woman declares her the eye.

pregnancy in writing, she is subject to the more restric-tive dose limits for the embryo/fetus during the remain-

• 50 rems (0.5 Sv) for the shallow dose equivalent der of the pregnancy. The dose limit of 500 mrems (5 (SDE), which is the external dose to the skin or to mSv) for the total gestation period applies to the em- any extremity.

bryo/fetus and is controlled by restricting the exposure For minor workers, the annual occupational dose to the declared pregnant woman. Restricting the wom- limits are 10 percent of the dose limits for adult work-an's occupational exposure, if she declares her preg- ers.

nancy, raises questions about individual privacy rights, equal employment opportunities, and the possible loss For protection of the embryolfetus of a declared of income. Because of these concerns, the declaration pregnant woman, the dose limit is 0.5 rem (5 mSv) of pregnancy by a female radiation worker is volun- during the entire pregnancy.

tary. Also, the declaration of pregnancy can be with- The occupational dose limit for adult workers of 5 drawn for any reason, for example, if the woman be- rems (0.05 Sv) TEDE is based on consideration of the lieves that her benefits from receiving the occupational potential for delayed biological effects. The 5-rem exposure would outweigh the risk to her embryo/fetus (0.05 Sv) limit, together with application of the con-from the radiation exposure. cept of keeping occupational doses ALARA, provides a level of risk of delayed effects considered acceptable

12. Can a worker become sterile or impotent by the NRC. The limits for individual organs are below from normal occupational radiation the dose levels at which early biological effects are ob-exposure?

served in the individual organs.

No. Temporary or permanent sterility cannot be caused by radiation at the levels allowed under NRC's The dose limit for the embryo/fetus of a declared occupational limits. There is a threshold below which pregnant woman is based on a consideration of the these effects do not occur. Acute doses on the order of possibility of greater sensitivity to radiation of the em-10 rems (0.1 Sv) to the testes can result in a measur- bryo/fetus and the involuntary nature of the exposure.

able but temporary reduction in sperm count. Tempo-rary sterility (suppression of ovulation) has been ob- 14. What is meant by ALARA?

served in women who have received acute doses of 150 ALARA means 'as low as is reasonably achiev-rads (1.5 Gy). The estimated threshold (acute) radi- able." In addition to providing an upper limit on an ation dose for induction of permanent sterility is about individual's permissible radiation dose, the NRC re-200 rads (2 Gy) for men and about 350 rads (3.5 Gy) quires that its licensees establish radiation protection 8.29-10

programs and use procedures and engineering controls al radiation dose of about 0.36 rem (3.6 mSv). By age to achieve occupational doses, and doses to the public, 20, the average person will accumulate over 7 rems (70 as far below the limits as is reasonably achievable. mSv) of dose. By age 50, the total dose is up to 18 rems "Reasonably achievable" also means "to the extent (180 mSv). After 70 years of exposure this dose is up practicable." What is practicable depends on the pur- to 25 rems (250 mSv).

pose of the job, the state of technology, the costs for averting doses, and the benefits. Although implemen-tation of the ALARA principle is a required integral Table 3 Average Annual Effective Dose Equiva-part of each licensee's radiation protection program, it lent to Individuals in the U.S.a does not mean that each radiation exposure must be kept to an absolute minimum, but rather that "reason- Effective Dose able" efforts must be made to avert dose. In practice, Source Equivalent (mrems)

ALARA includes planning tasks involving radiation exposure so as to reduce dose to individual workers Natural and the work group. Radon 200 Other than Radon 100 There are several ways to control radiation doses, 300 Total e.g., limiting the time in radiation areas, maintaining distance from sources of radiation, and providing Nuclear Fuel Cycle 0.05 shielding of radiation sources to reduce dose. The use Consumer Productsb 9 of engineering controls, from the design of facilities Medical and equipment to the actual set-up and conduct of Diagnostic X-rays 39 work activities, is also an important element of the Nuclear Medicine 14 ALARA concept. 53 Total An ALARA analysis should be used in determin- Total about 360 mrems/year ing whether the use of respiratory protection is advis-able. In evaluating whether or not to use respirators, the goal should be to achieve the optimal sum of exter- aAdapted from Table 8.1, NCRP 93 (Ref. 11).

nal and internal doses. For example, the use of respi- bIncludes building material, television receivers, lumi-rators can lead to increased work time within radiation nous watches, smoke detectors, etc. (from Table S.1, areas, which increases external dose. The advantage of NCRP 93, Ref. 11).

using respirators to reduce internal exposure must be evaluated against the increased external exposure and related stresses caused by the use of respirators. Heat 16. What are the typical radiation doses received stress, reduced visibility, and reduced communication by workers?

associated with the use of respirators could expose a worker to far greater risks than are associated with the For 1993, the NRC received reports on about a internal dose avoided by use of the respirator. To the quarter of a million people who were monitored for extent practical, engineering controls, such as contain- occupational exposure to radiation. Almost half of ments and ventilation systems, should be used to re- those monitored had no measurable doses. The other duce workplace airborne radioactive materials. half had an average dose of about 310 mrem (3.1 mSv) for the year. Of these, 93 percent received an annual dose of less than 1 rem (10 mSv); 98.7 percent

15. What are background radiation exposures? received less than 2 rems (20 mSv); and the highest reported dose was for two individuals who each re-The average person is constantly exposed to ioniz- ceived between 5 and 6 rems (50 and 60 mSv).

ing radiation from several sources. Our environment and even the human body contain naturally occurring Table 4 lists average occupational doses for work-radioactive materials (e.g., potassium-40) that contrib- ers (persons who had measurable doses) in various oc-ute to the radiation dose that we receive. The largest cupations based on 1993 data. It is important to note source of natural background radiation exposure is ter- that beginning in 1994, licensees have been required to restrial radon, a colorless, odorless, chemically inert sum external and internal doses and certain licensees gas, which causes about 55 percent of our average, are required to submit annual reports. Certain types of nonoccupational exposure. Cosmic radiation originat- licensees such as nuclear fuel fabricators may report a ing in space contributes additional exposure. The use significant increase in worker doses because of the of x-rays and radioactive materials in medicine and exposure to long-lived airborne radionuclides and the dentistry adds to our population exposure. As shown requirement to add the resultant internal dose to the below in Table 3, the average person receives an annu- calculation of occupational doses.

8.29-11

I

18. What happens if a worker exceeds the Table 4 Reported Occupational Doses for 1993a annual dose limit?

If a worker receives a dose in excess of any of the annual dose limits, the regulations prohibit any occu-Average Measurable pational exposure during the remainder of the year in Occupational Dose per Worker which the limit is exceeded. The licensee is also re-Subgroup (millirems) quired to file an overexposure report with the NRC and provide a copy to the individual who received the dose.

Industrial Radiography 540 The licensee may be subject to NRC enforcement ac-Commercial Nuclear Power Reactors tion such as a fine (civil penalty), just as individuals are 310 subject to a traffic fine for exceeding a speed limit. The Manufacturing and Distribution of Radioactive Materials fines and, in some serious or repetitive cases, suspen-300 sion of a license are intended to encourage licensees to Low-Level Radioactive Waste comply with the regulations.

Disposal 270 Independent Spent Nuclear Fuel Radiation protection limits do not define safe or Storage unsafe levels of radiation exposure. Exceeding a limit 260 does not mean that you will get cancer. For radiation Nuclear Fuel Fabrication 130 protection purposes, it is assumed that risks are related to the size of the radiation dose. Therefore, when your aFrom Table 3.1 in NUREG-0713 (Ref. 9). dose is higher your risk is also considered to be higher.

These limits are similar to highway speed limits. If you drive at 70 mph, your risk is higher than at 55 mph,

17. How do I know how much my occupational even though you may not actually have an accident.

dose (exposure) is? Those who set speed limits have determined that the risks of driving in excess of the speed limit are not ac-If you are likely to receive more than 10 percent of ceptable. In the same way, the revised 10 CFR Part 20 the annual dose limits, the NRC requires your employ- establishes a limit for normal occupational exposure of er, the NRC licensee, to monitor your dose, to main- S reins (0.05 Sv) a year. Although you will not neces-tain records of your dose, and, at least on an annual sarily get cancer or some other radiation effect at doses basis for the types of licensees listed in 10 CFR above the limit, it does mean that the licensee's safety 20.2206, "Reports of Individual Monitoring," to in- program has failed in some way. Investigation is war-form both you and the NRC of your dose. The purpose ranted to determine the cause and correct the condi-of this monitoring and reporting is so that the NRC can tions leading to the dose in excess of the limit.

be sure that licensees are complying with the occupa-tional dose limits and the ALARA principle. 19. What is meant by a "planned special exposure"?

External exposures are monitored by using indi- A "planned special exposure" (PSE) is an infre-vidual monitoring devices. These devices are required quent exposure to radiation, separate from and in ad-to be used if it appears likely that external exposure dition to the radiation received under the annual occu-will exceed 10 percent of the allowed annual dose, i.e., pational limits. The licensee can authorize additional 0.5 rem (5 mSv). The most commonly used monitor- dose in any one year that is equal to the annual occu-ing devices are film badges, thermoluminescence do- pational dose limit as long as the individual's total dose simeters (TLDs), electronic dosimeters, and direct from PSEs does not exceed five times the annual dose reading pocket dosimeters. limit during the individual's lifetime. For example, li-censees may authorize PSEs for an adult radiation With respect to internal exposure, your employer worker to receive doses up to an additional 5 rems is required to monitor your occupational intake of ra- (0.05 Sv) in a year above the 5-rem (0.05-Sv) annual dioactive material and assess the resulting dose if it ap- TEDE occupational dose limit. Each worker is limited pears likely that you will receive greater than 10 per- to no more than 25 rems (0.25 Sv) from planned spe-cent of the annual limit on intake (ALI) from intakes cial exposures in his or her lifetime. Such exposures in 1 year. Internal exposure can be estimated by mea- are only allowed in exceptional situations when alter-suring the radiation emitted from the body (for exam- natives for avoiding the additional exposure are not ple, with a "whole body counter") or by measuring the available or are impractical.

radioactive materials contained in biological samples Before the licensee authorizes a PSE, the licensee such as urine or feces. Dose estimates can also be must ensure that the worker is informed of the purpose made if one knows how much radioactive material was and circumstances of the planned operation, the esti-in the air and the length of time during which the air mated doses expected, and the procedures to keep the was breathed.

doses ALARA while considering other risks that may 8.29-12

be present. (See Regulatory Guide 8.35, "Planned Part 20 "shall be construed as limiting actions that may Special Exposures.") be necessary to protect health and safety."

Rare situations may occur in which a dose in ex-

20. Why do some facilities establish administra- cess of occupational limits would be unavoidable in or-tive control levels that are below the NRC der to carry out a lifesaving operation or to avoid a limits? large dose to large populations. However, persons There are two reasons. First, the NRC regulations called upon to undertake any emergency operation should do so only on a voluntary basis and with full state that licensees must take steps to keep exposures awareness of the risks involved.

to radiation ALARA. Specific approval from the li-censee for workers to receive doses in excess of admin- For perspective, the Environmental Protection istrative limits usually results in more critical risk-bene- Agency (EPA) has published emergency dose guide-fit analyses as each additional increment of dose is lines (Ref. 2). These guidelines state that doses to all approved for a worker. Secondly, an administrative workers during emergencies should, to the extent prac-control level that is set lower than the NRC limit pro- ticable, be limited to 5 rems (0.05 Sv). The EPA fur-vides a safety margin designed to help the licensee ther states that there are some emergency situations for avoid doses to workers in excess of the limit. which higher limits may be justified. The dose resulting from such emergency exposures should be limited to

21. Why aren't medical exposures considered as 10 rems (0.1 Sv) for protecting valuable property, and part of a worker's allowed dose? to 25 rems (0.25 Sv) for lifesaving activities and the protection of large populations. In the context of this NRC rules exempt medical exposure, but equal guidance, the dose to workers that is incurred for the doses of medical and occupational radiation have protection of large populations might be considered equal risks. Medical exposure to radiation is justified justified for situations in which the collective dose to for reasons that are quite different from the reasons for others that is avoided as a result of the emergency op-occupational exposure. A physician prescribing an x- eration is significantly larger than that incurred by the ray, for example, makes a medical judgment that the workers involved.

benefit to the patient from the resulting medical infor-mation justifies the risk associated with the radiation. Table 5 presents the estimates of the fatal cancer This judgment may or may not be accepted by the pa- risk for a group of 1,000 workers of various ages, as-tient. Similarly, each worker must decide on the bene- suming that each worker received an acute dose of 25 fits and acceptability of occupational radiation risk, rems (0.25 Sv) in the course of assisting in an emer-just as each worker must decide on the acceptability of gency. The estimates show that a 25-rem emergency any other occupational hazard. dose might increase an individual's chances of devel-oping fatal cancer from about 20% to about 21%.

Consider a worker who receives a dose of 3 rems (0.03 Sv) from a series of x-rays in connection with an injury or illness. This dose and any associated risk must Table 5 be justified on medical grounds. If the worker had also Risk of Premature Death from Exposure received 2 rems (0.02 Sv) on the job, the combined to 25-Rems (0.25-Sv) Acute Dose dose of 5 rems (0.05 Sv) would in no way incapacitate the worker. Restricting the worker from additional job Estimated Risk exposure during the remainder of the year would not of Premature Death Age at have any effect on the risk from the 3 rems (0.03 Sv) (Deaths per 1,000 Exposure already received from the medical exposure. If the in- Persons Exposed)

(years) dividual worker accepts the risks associated with the x-rays on the basis of the medical benefits and accepts 9.1 20-30 the risks associated with job-related exposure on the 7.2 30-40 basis of employment benefits, it would be unreason- 5.3 able to restrict the worker from employment involving 40-50 50-60 3.5 exposure to radiation for the remainder of the year.

22. How should radiation risks be considered in Source: EPA-400-R-92-001 (Ref. 2).

an emergency?

23. How were radiation dose limits established?

Emergencies are "unplanned" events in which ac-tions to save lives or property may warrant additional The NRC radiation dose limits in 10 CFR Part 20 doses for which no particular limit applies. The revised were established by the NRC based on the recommen-10 CFR Part 20 does not set any dose limits for emer- dations of the ICRP and NCRP as endorsed in Federal gency or lifesaving activities and states that nothing in radiation protection guidance developed by the EPA 8.29-13

I - -

(Ref. 12). The limits were recommended by the ICRP tries and are considered acceptable by the scientific and NCRP with the objective of ensuring that working groups that have studied them. An employer is not ob-in a radiation-related industry was as safe as working in ligated to guarantee a transfer if a worker decides not other comparable industries. The dose limits and the principle of ALARA should ensure that risks to work- to accept an assignment that requires exposure to radi-ation.

ers are maintained indistinguishable from risks from background radiation. Any worker has the option of seeking other em-ployment in a nonradiation occupation. However, the

24. Several scientific reports have recommended studies that have compared occupational risks in the that the NRC establish lower dose limits. nuclear industry to those in other job areas indicate Does the NRC plan to reduce the regulatory that nuclear work is relatively safe. Thus, a worker may limits? find different kinds of risk but will not necessarily find Since publication of the NRC's proposed rule in significantly lower risks in another job.

1986, the ICRP in 1990 revised its recommendations

26. Where can one get additional information on for radiation protection based on newer studies of radi- radiation risk?

ation risks (Ref. 13), and the NCRP followed with a revision to its recommendations in 1993. The ICRP The following list suggests sources of useful infor-recommended a limit of 10 rems (0.1 Sv) effective mation on radiation risk:

dose equivalent (from internal and external sources),

• The employer-the radiation protection or health over a 5-year period with no more than 5 rems (0.05 physics office where a worker is employed.

Sv) in 1 year (Ref. 13). The NCRP recommended a cumulative limit in rerns, not to exceed the individual's

• Nuclear Regulatory Commission Regional Offices:

age in years, with no more than 5 rems (0.05 Sv) in any King of Prussia, Pennsylvania (610) 337-5000 year (Ref. 14). Atlanta, Georgia (404) 331-4503 Lisle, Illinois (708) 829-9500 The NRC does not believe that additional reduc- Arlington, Texas tions in the dose limits are required at this time. Be- (817) 860-8100 cause of the practice of maintaining radiation expo-

• U.S. Nuclear Regulatory Commission sures ALARA (as low as is reasonably achievable), the Headquarters average radiation dose to occupationally exposed per- Radiation Protection & Health Effects Branch sons is well below the limits in the current Part 20 that Office of Nuclear Regulatory Research became mandatory January 1, 1994, and the average Washington, DC 20555 doses to radiation workers are below the new limits Telephone: (301) 415-6187 recommended by the ICRP and the NCRP.

• Department of Health and Human Services Center for Devices and Radiological Health

25. What are the options if a worker decides that 1390 Piccard Drive, MS HFZ-1 the risks associated with occupational radi- Rockville, MD 20850 ation exposure are too high? Telephone: (301) 443-4690 If the risks from exposure to occupational radi-

• U.S. Environmental Protection Agency ation are unacceptable to a worker, he or she can re-Office of Radiation and Indoor Air quest a transfer to a job that does not involve exposure Criteria and Standards Division to radiation. However, the risks associated with the ex-401 M Street NW.

posure to radiation that workers, on the average, ac-Washington, DC 20460 tually receive are comparable to risks in other indus-Telephone: (202) 233-9290 8.29-14

REFERENCES

1. B.R. Scott et al., "Health Effects Model for Nu- Protection and Measurements Held on April 8-clear Power Plant Accident Consequence Analy- 9, 1987 (1988).

sis," Part I: Introduction, Integration, and Sum-mary, U.S. Nuclear Regulatory Commission, 8. National Council on Radiation Protection .and NUREG/CR-4214, Revision 2, Part I, October Measurements, Comparative Carcinogenicity of 1993.* Ionizing Radiation and Chemicals, NCRP Report No. 96, March 1989.

2. U.S. Environmental Protection Agency, Manual of Protective Action Guides and Protective Ac- 9. C.T. Raddatz and D. Hagemeyer, "Occupational tions for Nuclear Incidents, EPA-400-R Radiation Exposure at Commercial Nuclear Pow-001, May 1992. er Reactors and Other Facilities, 1993," U.S.

Nuclear Regulatory Commission, NUREG-0713,

3. International Commission on Radiological Pro- Volume 15, January 1995.'

tection, Annals of the ICRP, Risks Associated with Ionising Radiation, Volume 22, No.1, Per- 10. B.L. Cohen and I.S. Lee, "Catalog of Risks Ex-gamon Press, Oxford, UK, 1991. tended and Updated," Health Physics, Vol. 61, September 1991.

4. National Research Council, Health Effects of Ex-posure to Low Levels of Ionizing Radiation, Re- 11. National Council on Radiation Protection and port of the Committee on the Biological Effects of Measurements, Ionizing Radiation Exposure of Ionizing Radiation (BEIR V), National Academy the Population of the United States, NCRP Re-Press, Washington, DC, 1990. port No. 93, September 1987.

5. United Nations Scientific Committee on the Ef- 12. U.S. Environmental Protection Agency, "Radi-fects of Atomic Radiation (UNSCEAR); Sources, ation Protection Guidance to Federal Agencies Effects and Risks of Ionizing Radiation, Report for Occupational Exposure," Federal Register, E.88.IX.7, United Nations, New York, 1988. Vol. 52, No. 17, January 27, 1987.

6. United Nations Scientific Committee on the Ef- 13. International Commission on Radiological Pro-fects of Atomic Radiation (UNSCEAR), Sources tection, 1990 Recommendations of the Interna-and Effects of Ionizing Radiation, United Na- tional Commission on Radiological Protection, tions, New York, 1993. ICRP Publication 60, Pergamon Press, Oxford, UK, 1991.

7. National Council on Radiation Protection and Measurements, New Dosimetry at Hiroshima 14. National Council on Radiation Protection and and Nagasaki and Its Implicationsfor Risk Esti- Measurements, Limitation of Exposure to Ioniz-mates, Proceedings of the Twenty-third Annual ing Radiation, NCRP Report No. 116, March Meeting of the National Council on Radiation 1993.

Copies are available for inspection or copying for a fee from the NRC Public Document Room at 2120 L Street NW., Washington, DC; the PDR's mailing address is Mail Stop LL-6, Washington, DC 20555; telephone (202) 634-3273; fax (202) 634-3343. Copies may be purchased at current rates from the U. S. Government Printing Office, P. O. Box 37082, Washington, DC 20402-9328 (tele-phone (202) 512-2249); or from the National Technical Information Service by writing NTIS at 5285 Port Royal Road, Springfield, VA 22161.

8.29-15

BIBLIOGRAPHY Abrahamson, S., et al., "Health Effects Models for States and Canada from Natural Background Radi-Nuclear Power Plant Accident Consequence Analy-ation, NCRP Report No. 94, De6ember 1987.

sis, " Part II: Scientific Bases for Health Effects Mod-els, U.S. Nuclear Regulatory Commission, NUREG/ National Council on Radiation Protection and Mea-CR-4214, Rev. 1, Part II, May 1989.1 surements, Exposure of the U.S. PopulationFrom Oc-cupational Radiation, NCRP Report No. 101, June Abrahamson, S., et al., "Health Effects Models for 1989.

Nuclear Power Plant Accident Consequence Analysis, Modifications of Models Resulting From Recent Re- National Council on Radiation Protection and Mea-ports on Health Effects of Ionizing Radiation, Low surements, Risk Estimates for Radiation Protection, LET Radiation," Part II: Scientific Basis for Health NCRP Report No. 115, December 1993.

Effects Models, U.S. Nuclear Regulatory Commission, NUREG/CR-4214, Rev. 1, Part II, Addendum 1, Au- National Council on Radiation Protection and Mea-gust 1991.' surements, Limitation of Exposure to Ionizing Radi-ation, NCRP Report No. 116, March 1993.

Abrahamson, S., et al., "Health Effects Models for Nuclear Power Plant Accident Consequence Analysis, National Safety Council, Accident Facts, 1993 Edi-Modifications of Models Resulting From Addition of tion, Itasca, Illinois, 1993.

Effects of Exposure to Alpha-Emitting Radionu-clides," Part II: Scientific Bases for Health Effects U.S. Environmental Protection Agency, "Radiation Models, U.S. Nuclear Regulatory Commission, Protection Guidance to Federal Agencies for Occupa-NUREG/CR-4214, Rev. 1, Part II, Addendum 2, May tional Exposure," Federal Register, Vol. 52, No. 17, 1993.1 January 27, 1987.

International Commission on Radiological Protection, U.S. Nuclear Regulatory Commission, "Instruction Radiation Protection, Recommendations of the Inter- Concerning Prenatal Radiation Exposure," Regulatory national Commission on Radiological Protection, ICRP Guide 8.13, Revision 2, December 1987.2 Publication 26, Pergamon Press, Oxford, UK, January 1977. U.S. Nuclear Regulatory Commission, "Monitoring Criteria and Methods To Calculate Occupational Radi-National Council on Radiation Protection and Mea- ation Doses," Regulatory Guide 8.34, July 1992.2 surements, Public Radiation Exposure From Nuclear Power Generationin the United States, NCRP Report U.S. Nuclear Regulatory Commission, "Planned Spe-No. 92, December 1987. cial Exposures," Regulatory Guide 8.35, June 1992.2 National Council on Radiation Protection and Mea- U.S. Nuclear Regulatory Commission, "Radiation surements, Exposure of the Population in the United Dose to the Embryo/Fetus," Regulatory Guide 8.36, July 1992.2

'Copies are available for inspection or copying for a fee from the NRC Public Document Room at 2120 L Street NW., 2 Washington, DC; the PDR's mailing address is Mail Stop Single copies of regulatory guides may be obtained free LL-6, Washington, DC 20555-0001; telephone (202) of charge by writing the Office of Administration, Attn: Distri-634-3273; fax (202) 634-3343. Copies may be purchased bution and Services Section, USNRC, Washington, current rates from the U.S. Government Printing Office, P.O.

at 20555, or by fax at (301) 415-2260. Copies are available DC

• Box 37082, Washington, DC 20402-9328 (telephone for inspection or copying for a fee from the NRC Public Document 512-2249); or from the National Technical Information(202) Room at 2120 L Street NW., Washington, DC; the PDR's Ser-vice by writing NTIS at 5285 Port Royal Road, Springfield, mailing address is Mail Stop LL-6, Washington, DC VA 22161. 20555-0001; telephone (202) 634-3273; fax (202) 634-3343.

8.29-16

REGULATORY ANALYSIS A separate regulatory analysis was not prepared May 21, 1991 (56 FR 23360). The regulatory analysis for this Revision 1 to Regulatory Guide 8.29. A value/ prepared for 10 CFR Part 20 provides the regulatory impact statement, which evaluated essentially the same basis for this Revision 1 of Regulatory Guide 8.29, and subjects as are discussed in a regulatory analysis, ac- it examines the costs and benefits of the rule as im-companied Regulatory Guide 8.29 when it was issued plemented by the guide. A copy of the 'Regulatory in July 1981. Analysis for the Revision of 10 CFR Part 20" (PNL-6712, November 1988), is available for inspec-This Revision 1 to Regulatory Guide 8.29 is need- tion and copying for a fee in the NRC's Public Docu-ed to conform with the Revised 10 CFR Part 20, "Stan- ment Room at 2120 L Street NW., Washington, DC dards for Protection Against Radiation," as published 20555-0001.

8.29-17

Federal Recycling Program UNITED STATES NUCLEAR REGULATORY COMMISSION FIRST CLASS MAIL POSTAGE AND FEES PAID WASHINGTON, DC 20555-0001 USNRC PERMIT NO. 0-7 OFFICIAL BUSINESS PENALTY FOR PRIVATE USE, $300