ML003739438

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

ML003739438
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Issue date:	02/29/1996
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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 Section 19.12 of 10 CFR Part 19, "Notices, In-structions and Reports to Workers: Inspection and In-vestigations," requires that all individuals who in the course of their employment are likely to receive in a year an occupational dose in excess of 100 mrem (1 mSv) be instructed in the health protection issues asso-ciated with exposure to radioactive materials or radi-ation. Section 20.1206 of 10 CFR Part 20, "Standards for Protection Against Radiation," requires that before a planned special exposure occurs the individuals in-volved are, among other things, to be informed of the estimated doses and associated risks.

This regulatory guide describes the information that should be provided to workers by licensees about health risks from occupational exposure. This revision conforms to the revision of 10 CFR Part 20 that be-came effective on June 20, 1991, to be implemented by licensees no later than January 1, 1994. The revi-sion of 10 CFR Part 20 establishes new dose limits based on the effective dose equivalent (EDE), requires the summing of internal and external dose, establishes a requirement that licensees use procedures and engi-neering controls to the extent practicable to achieve occupational doses and doses to members of the public that are as low as is reasonably achievable (ALARA),

provides for planned special exposures, establishes a dose limit for the embryo/fetus of an occupationally exposed declared pregnant woman, and explicitly states that Part 20 is not to be construed as limiting action that may be necessary to protect health and safety during emergencies.

Any information collection activities mentioned in this regulatory guide are contained as requirements in 10 CFR Part 19 or 10 CFR Part 20. These regulations provide the regulatory bases for this guide. The infor-mation collection requirements in 10 CFR Parts 19 and 20 have been cleared under OMB Clearance Nos.

3150-0044 and 3150-0014, respectively.

B. DISCUSSION It is important to qualify the material presented in this guide with the following considerations.

The coefficient used in this guide for occupational radiation risk estimates, 4 x 10-4 health effects per rem, is based on data obtained at much higher doses and dose rates than those encountered by workers.

The risk coefficient obtained at high doses and dose rates was reduced to account for the reduced effective-ness of lower doses and dose rates in producing the stochastic effects observed in studies of exposed humans.

The assumption of a linear extrapolation from the lowest doses at which effects are observable down to USNRC REGULATORY GUIDES Regulatory Guides are Issued todescribe and make availableto thepublic such information as methods acceptable to the NRC staff for Implement-ing specific parts of the Commission's regulations, techniques used by the staff in evaluating specific problems or postulated accidents, and data needed by the NRC staff In Its review of applications for permits and licenses. Regulatory guides are not substitutes for regulations, and com-pliance with them Is not required. Methods and solutions different from those set out In the guides will be acceptable If they provide a basis for the findings requisite to the Issuance or continuance of a permit or license by the Commission.

This guide was Issued after consideration of comments received from the public. Comments and suggestions for Improvements In these guides are encouraged at all times, and guides will be revised, as appropriate, to accommodate comments and to reflect new information or experience.

Written comments may be submitted to the Rules Review and Directives Branch, DFIPS, ADM, U.S. Nuclear Regulatory Commission, Washing-ton, DC 20555-0001.

The guides are issued in the following ten broad divisions:

1. Power Reactors

6. Products

2. Research and Test Reactors 7, Transportation 3, Fuels and Materials Facilities

8. Occupational Health

4. Environmental and Siting

9. Antitrust and Financial Review

5. Materials and Plant Protection

10. General Single copies of regulatory guides may be obtained free of charge by writ-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.

Issued guides may also be purchased from the National Technical Infor-mation Service on a standing order basis. Details on this service may be obtained by writing NTIS, 5285 Port Royal Road, Springfield, VA22161.

I i-the occupational range has considerable uncertainty.

The report of the Committee on the Biological Effects of Ionizing Radiation (Ref. 1) states that

"... departure from linearity cannot be ex-cluded at low doses below the range of obser-vation. Such departures could be in the direc-tion of either an increased or decreased risk.

Moreover, epidemiologic data cannot rigor-ously exclude the existence of a threshold in the 100 mrem dose range. Thus, the possibil-ity that there may be no risk from exposures comparable to external natural background radiation cannot be ruled out. At such low doses and dose rates, it must be acknowl-edged that the lower limit of the range of un-certainty in the risk estimates extends to zero. "

The issue of beneficial effects from low doses, or hormesis, in cellular systems is addressed by the United Nations Scientific Committee on the Effects of Atomic Radiation (Ref. 2). UNSCEAR states that "...

it would be premature to conclude that cellular adap-tive responses could convey possible beneficial effects to the organism that would outweigh the detrimental effects of exposures to low doses of low-LET radiation."

In the absence of scientific certainty regarding the relationship between low doses and health effects, and as a conservative assumption for radiation protection purposes, the scientific community generally assumes that any exposure to ionizing radiation can cause bio-logical effects that may be harmful to the exposed per-son and that the magnitude or probability of these ef-fects is directly proportional to the dose. These effects may be classified into three categories:

Somatic Effects: Physical effects occurring in the exposed person. These effects may be ob-servable after a large or acute dose (e.g., 100 rems1 (1 Sv) or more to the whole body in a few hours); or they may be effects such as cancer that may occur years after exposure to radiation.

Genetic Effects: Abnormalities that may oc-cur in the future children of exposed individu-als and in subsequent generations (genetic ef-fects exceeding normal incidence have not been observed in any of the studies of human populations).

Teratogenic Effects: Effects such as cancer or congenital malformation that may be ob-served in children who were exposed during the fetal and embryonic stages of develop-ment (these effects have been observed from In the International System of Units (SI), the rem is replaced by the sievert; 100 rerns is equal to 1 sievert (Sv).

high, i.e., above 20 rems (0.2 Sv), acute ex-posures).

The normal incidence of effects from natural and manmade causes is significant. For example, approxi-mately 20% of people die from various forms of cancer whether or not they ever receive occupational expo-sure to radiation. To avoid increasing the incidence of such biological effects, regulatory controls are imposed on occupational doses to adults and minors and on doses to the embryo/fetus from occupational expo-sures of declared pregnant women.

Radiation protection training for workers who are occupationally exposed to ionizing radiation is an es-sential component of any program designed to ensure compliance with NRC regulations. A clear understand-ing of what is presently known about the biological risks associated with exposure to radiation will result in more effective radiation protection training and should generate more interest on the part of the workers in complying with radiation protection standards. In ad-dition, pregnant women and other occupationally ex-posed workers should have available to them relevant information on radiation risks to enable them to make informed decisions regarding the acceptance of these risks. It is intended that workers who receive this in-struction will develop respect for the risks involved, rather than excessive fear or indifference.

C. REGULATORY POSITION Instruction to workers performed in compliance with 10 CFR 19.12 should be given prior to occupa-tional exposure and periodically thereafter. The fre-quency of retraining might range from annually for li-censees with complex operations such as nuclear power plants, to every three years for licensees who possess, for example, only low-activity sealed sources.

If a worker is to participate in a planned special expo-sure, the worker should be informed of the associated risks in compliance with 10 CFR 20.1206.

In providing instruction concerning health protec-tion problems associated with exposure to radiation, all occupationally exposed workers and their supervisors should be given specific instruction on the risk of bio-logical effects resulting from exposure to radiation.

The extent of these instructions should be commensu-rate with the radiological risks present in the work-place.

The instruction should be presented orally, in printed form, or in any other effective communication media to workers and supervisors. The appendix to this guide provides useful information for demonstrat-ing compliance with the training requirements in 10 CFR Parts 19 and 20. Individuals should be given an opportunity to discuss the information and to ask ques-tions. Testing is recommended, and each trainee should be asked to acknowledge in writing that the in-struction has been received and understood.

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D.

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

Except in those cases in which an applicant or li-censee proposes acceptable alternative methods for complying with specified portions of the Commission's regulations, the guidance and instructional materials in this guide will be used in the evaluation of applications for new licenses, license renewals, and license amend-ments and for evaluating compliance with 10 CFR 19.12 and 10 CFR Part 20.

REFERENCES

1.

National Research Council, Health Effects of Ex-posure to Low Levels of Ionizing Radiation, Re-port of the Committee on the Biological Effects of Ionizing Radiation (BEIR V), National Academy Press, Washington, DC, 1990.

2.

United Nations Scientific Committee on the Ef-fects of Atomic Radiation (UNSCEAR), Sources and Effects of Ionizing Radiation, United Na-tions, New York, 1993.

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L APPENDIX INSTRUCTION CONCERNING RISKS FROM OCCUPATIONAL RADIATION EXPOSURE This instructional material is intended to provide the user with the best available information about the health risks from occupational exposure to ionizing ra-diation. Ionizing radiation consists of energy or small particles, such as gamma rays and beta and alpha par-ticles, emitted from radioactive materials, which can cause chemical or physical damage when they deposit energy in living tissue. A question and answer format is used. Many of the questions or subjects were devel-oped by the NRC staff in consultation with workers, union representatives, and licensee representatives ex-perienced in radiation protection training.

This Revision 1 to Regulatory Guide 8.29 updates the material in the original guide on biological effects and risks and on typical occupational exposure. Addi-tionally, it conforms to the revised 10 CFR Part 20, "Standards for Protection Against Radiation," which was required to be implemented by licensees no later than January 1, 1994. The information in this appen-dix is intended to help develop respect by workers for the risks associated with radiation, rather than unjusti-fied fear or lack of concern. Additional guidance con-cerning other topics in radiation protection training is provided in other NRC regulatory guides.

1. What is meant by health risk?

A health risk is generally thought of as something that may endanger health. Scientists consider health risk to be the statistical probability or mathematical chance that personal injury, illness, or death may re-sult from some action. Most people do not think about health risks in terms of mathematics. Instead, most of us consider the health risk of a particular action in terms of whether we believe that particular action will, or will not, cause us some harm. The intent of this ap-pendix is to provide estimates of, and explain the bases for, the risk of injury, illness, or death from occupa-tional radiation exposure. Risk can be quantified in terms of the probability of a health effect per unit of dose received.

When x-rays, gamma rays, and ionizing particles interact with living materials such as our bodies, they may deposit enough energy to cause biological dam-age. Radiation can cause several different types of events such as the very small physical displacement of 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-ical damage can occur as a result of chemical bonds being broken and cells being damaged or killed. These effects can result in observable clinical symptoms.

The basic unit for measuring absorbed radiation is the rad. One rad (0.01 gray in the International Sys-tem of units) equals the absorption of 100 ergs (a small but measurable amount of energy) in a gram of materi-al such as tissue exposed to radiation. To reflect bio-logical risk, rads must be converted to rems. The new international unit is the sievert (100 rems = 1 Sv). This conversion accounts for the differences in the effec-tiveness of different types of radiation in causing dam-age. The rem is used to estimate biological risk. For beta and gamma radiation, a rem is considered equal to a rad.

2. What are the possible health effects of expo-sure to radiation?

Health effects from exposure to radiation range from no effect at all to death, including diseases such as leukemia or bone, breast, and lung cancer. Very high (100s of rads), short-term doses of radiation have been known to cause prompt (or early) effects, such as vomiting and diarrhea,' skin burns, cataracts, and even death. It is suspected that radiation exposure may be linked to the potential for genetic effects in the chil-dren of exposed parents. Also, children who were ex-posed to high doses (20 or more rads) of radiation prior to birth (as an embryo/fetus) have shown an in-creased risk of mental retardation and other congenital malformations. These effects (with the exception of genetic effects) have been observed in various studies of medical radiologists, uranium miners, radium work-ers, radiotherapy patients, and the people exposed to radiation from atomic bombs dropped on Japan. In addition, radiation effects studies with laboratory ani-mals, in which the animals were given relatively high doses, have provided extensive data on radiation-in-duced health effects, including genetic effects.

It is important to note that these kinds of health effects result from high doses, compared to occupa-tional levels, delivered over a relatively short period of time.

Although studies have not shown a consistent cause-and-effect relationship between current levels of occupational radiation exposure and biological effects, it is prudent from a worker protection perspective to assume that some effects may occur.

IThese symptoms are early indicators of what is referred to as the acute radiation syndrome, caused by high doses delivered over a short time period, which includes damage to the blood-forming organs such as bone marrow, damage to the gastroin-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 or late effects?

EARLY EFFECTS Early effects, which are also called immediate or prompt effects, are those that occur shortly after a large exposure that is delivered within hours to a few days. They are observable after receiving a very large dose in a short period of time, for example, 300 rads (3 Gy) received within a few minutes to a few days.

Early effects are not caused at the levels of radiation exposure allowed under the NRC's occupational limits.

Early effects occur when the radiation dose is large enough to cause extensive biological damage to cells so that large numbers of cells are killed. For early effects to occur, this radiation dose must be received within a short time period. This type of dose is called an acute dose or acute exposure. The same dose received over a long time period would not cause the same effect. Our body's natural biological processes are constantly re-pairing damaged cells and replacing dead cells; if the cell damage is spread over time, our body is capable of repairing or replacing some of the damaged cells, re-ducing the observable adverse conditions.

For example, a dose to the whole body of about 300-500 rads (3-5 Gy), more than 60 times the annu-al occupational dose limit, if received within a short time period (e.g., a few hours) will cause vomiting and diarrhea within a few hours; loss of hair, fever, and weight loss within a few weeks; and about a 50 percent chance of death if medical treatment is not provided.

These effects would not occur if the same dose were accumulated gradually over many weeks or months (Refs. 1 and 2). Thus, one of the justifications for es-tablishing annual dose limits is to ensure that occupa-tional dose is spread out in time.

It is important to distinguish between whole body and partial body exposure. A localized dose to a small volume of the body would not produce the same effect as a whole body dose of the same magnitude. For ex-ample, if only the hand were exposed, the effect would mainly be limited to the skin and underlying tissue of the hand. An acute dose of 400 to 600 rads (4-6 Gy) to the hand would cause skin reddening; recovery would occur over the following months and no long-term damage would be expected. An acute dose of this magnitude to the whole body could cause death within a short time without medical treatment. Medical treat-ment would lessen the magnitude of the effects and the chance of death; however, it would not totally elimi-nate the effects or the chance of death.

DELAYED EFFECTS Delayed effects may occur years after exposure.

These effects are caused indirectly when the radiation changes parts of the cells in the body, which causes the normal function of the cell to change, for example, normal healthy cells turn into cancer cells. The poten-tial for these delayed health effects is one of the main concerns addressed when setting limits on occupation-al doses.

A delayed effect of special interest is genetic ef-fects. Genetic effects may occur if there is radiation damage to the cells of the gonads (sperm or eggs).

These effects may show up as genetic defects in the children of the exposed individual and succeeding gen-erations. However, if any genetic effects (i.e., effects in addition to the normal expected number) have been caused by radiation, the numbers are too small to have been observed in human populations exposed to radi-ation. For example, the atomic bomb survivors (from Hiroshima and Nagasaki) have not shown any signifi-cant radiation-related increases in genetic defects (Ref. 3). Effects have been observed in animal studies conducted at very high levels of exposure and it is known that radiation can cause changes in the genes in cells of the human body. However, it is believed that by maintaining worker exposures below the NRC limits and consistent with ALARA, a margin of safety is pro-vided such that the risk of genetic effects is almost eliminated.

4. What is the difference between acute and chronic radiation dose?

Acute radiation dose usually refers to a large dose of radiation received in a short period of time. Chronic dose refers to the sum of small doses received repeat-edly over long time periods, for example, 20 mrem (or millirem, which is 1-thousandth of a rem) (0.2 mSv) per week every week for several years. It is assumed for radiation protection purposes that any radiation dose, either acute or chronic, may cause delayed ef-fects. However, only large acute doses cause early ef-fects; chronic doses within the occupational dose limits do not cause early effects. Since the NRC limits do not permit large acute doses, concern with occupational radiation risk is primarily focused on controlling chronic exposure for which possible delayed effects, such as cancer, are of concern.

The difference between acute and chronic radi-ation exposure can be shown by using exposure to the sun's rays as an example. An intense exposure to the sun can result in painful burning, peeling, and growing of new skin. However, repeated short exposures pro-vide time for the skin to be repaired between expo-sures. Whether exposure to the sun's rays is long term or spread over short periods, some of the injury may not be repaired and may eventually result in skin cancer.

Cataracts are an interesting case because they can be caused by both acute and chronic radiation. A cer-tain threshold level of dose to the lens of the eye is required before there is any observable visual impair-ment, and the impairment remains after the exposure is stopped. The threshold for cataract development 8.29-5

I from acute exposure is an acute dose on the order of 100 rads (1 Gy). Further, a cumulative dose of 800 rads (8 Gy) from protracted exposures over many years to the lens of the eye has been linked to some level of visual impairment (Refs. 1 and 4). These doses exceed the amount that may be accumulated by the lens from normal occupational exposure under the current regulations.

5.

What is meant by external and internal ex-posure?

A worker's occupational dose may be caused by exposure to radiation that originates outside the body, called "external exposure," or by exposure to radi-ation from radioactive material that has been taken into the body, called 'internal exposure." Most NRC-licensed activities involve little, if any, internal expo-sure. It is the current scientific consensus that a rem of radiation dose has the same biological risk regardless of whether it is from an external or an internal source.

The NRC requires that dose from external exposure and dose from internal exposure be added together, if each exceeds 10% of the annual limit, and that the total be within occupational limits. The sum of external and internal dose is called the total effective dose equivalent (TEDE) and is expressed in units of rems (Sv).

Although unlikely, radioactive materials may en-ter the body through breathing, eating, drinking, or open wounds, or they may be absorbed through the skin. The intake of radioactive materials by workers is generally due to breathing contaminated air. Radioac-tive materials may be present as fine dust or gases in the workplace atmosphere. The surfaces of equipment and workbenches may be contaminated, and these materials can be resuspended in air during work activities.

If any radioactive material enters the body, the material goes to various organs or is excreted, depend-ing on the biochemistry of the material. Most radioiso-topes are excreted from the body in a few days. For example, a fraction of any uranium taken into the body will deposit in the bones, where it remains for a longer time. Uranium is slowly eliminated from the body, mostly by way of the kidneys. Most workers are not exposed to uranium. Radioactive iodine is prefer-entially deposited in the thyroid gland, which is located in the neck..

To limit risk to specific organs and the total body, an annual limit on intake (ALI) has been established for each radionuclide. When more than one radionu-clide is involved, the intake amount of each radionu-clide is reduced proportionally. NRC regulations speci-fy the concentrations of radioactive material in the air to which a worker may be exposed for 2,000 working hours in a year. These concentrations are termed the derived air concentrations (DACs). These limits are the total amounts allowed if no external radiation is received. The resulting dose from the internal radi-ation sources (from breathing air at 1 DAC) is the maximum allowed to an organ or to the worker's whole body.

6. How does radiation cause cancer?

The mechanisms of radiation-induced cancer are not completely understood. When radiation interacts with the cells of our bodies, a number of events can occur. The damaged cells can repair themselves and permanent damage is not caused. The cells can die, much like the large numbers of cells that die every day in our bodies, and be replaced through the normal bio-logical processes. Or a change can occur in the cell's reproductive structure, the cells can mutate and subse-quently be repaired without effect, or they can form precancerous cells, which may become cancerous. Ra-diation is only one of many agents with the potential for causing cancer, and cancer caused by radiation cannot be distinguished from cancer attributable to any other cause.

Radiobiologists have studied the relationship be-tween large doses of radiation and cancer (Refs. 5 and 6). These studies indicate that damage or change to genes in the cell nucleus is the main cause of radiation-induced cancer. This damage may occur directly through the interaction of the ionizing radiation in the cell or indirectly through the actions of chemical prod-ucts produced by radiation interactions within cells.

Cells are able to repair most damage within hours; however, some cells may not be repaired properly.

Such misrepaired damage is thought to be the origin of cancer, but misrepair does not always cause cancer.

Some cell changes are benign or the cell may die; these changes do not lead to cancer.

Many factors such as age, general health, inher-ited traits, sex, as well as exposure to other cancer-causing agents such as cigarette smoke can affect sus-ceptibility to the cancer-causing effects of radiation.

Many diseases are caused by the interaction of several factors, and these interactions appear to increase the susceptibility to cancer.

7. Who developed radiation risk estimates?

Radiation risk estimates were developed by several national and international scientific organizations over the last 40 years. These organizations include the Na-tional Academy of Sciences (which has issued several reports from the Committee on the Biological Effects of Ionizing Radiations, BEIR), the National Council on Radiation Protection and Measurements (NCRP), the International Commission on Radiological Protection (ICRP), and the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR).

Each of these organizations continues to review new research findings on radiation health risks.

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Several reports from these organizations present new findings on radiation risks based upon revised esti-mates of radiation dose to survivors of the atomic bombing at Hiroshima and Nagasaki. For example, UNSCEAR published risk estimates in 1988 and 1993 (Refs. 5 and 6). The NCRP also published a report in 1988, "New Dosimetry at Hiroshima and Nagasaki and Its Implications for Risk Estimates" (Ref. 7). In January 1990, the National Academy of Sciences re-leased the fifth report of the BEIR Committee, "Health Effects of Exposure to Low Levels of Ionizing Radiation" (Ref. 4). Each of these publications also provides extensive bibliographies on other published studies concerning radiation health effects for those who may wish to read further on this subject.

8. What are the estimates of the risk of fatal cancer from radiation exposure?

We don't know exactly what the chances are of getting cancer from a low-level radiation dose, primari-ly because the few effects that may occur cannot be distinguished from normally occurring cancers. How-ever, we can make estimates based on extrapolation from extensive knowledge from scientific research on high dose effects. The estimates of radiation effects at high doses are better known than are those of most chemical carcinogens (Ref. 8).

From currently available data, the NRC has adopted a risk value for an occupational dose of 1 rem (0.01 Sv) Total Effective Dose Equivalent (TEDE) of 4 in 10,000 of developing a fatal cancer, or approxi-mately 1 chance in 2,500 of fatal cancer per rem of TEDE received. The uncertainty associated with this risk estimate does not rule out the possibility of higher risk, or the possibility that the risk may even be zero at low occupational doses and dose rates.

The radiation risk incurred by a worker depends on the amount of dose received. Under the linear model explained above, a worker who receives 5 reins (0.05 Sv) in a year incurs 10 times as much risk as another worker who receives only 0.5 rem (0.005 Sv).

Only a very few workers receive doses near 5 rems (0.05 Sv) per year (Ref. 9).

According to the BEIR V report (Ref. 4), approxi-mately one in five adults normally will die from cancer from all possible causes such as smoking, food, alco-hol, drugs, air pollutants, natural background radi-ation, and inherited traits. Thus, in any group of 10,000 workers, we can estimate that about 2,000 (20%) will die from cancer without any occupational radiation exposure.

To explain the significance of these estimates, we will use as an example a group of 10,000 people, each exposed to 1 rem (0.01 Sv) of ionizing radiation. Using the risk factor of 4 effects per 10,000 rem of dose, we estimate that 4 of the 10,000 people might die from delayed cancer because of that 1-rem dose (although the actual number could be more or less than 4) in addition to the 2,000 normal cancer fatalities expected to occur in that group from all other causes. This means that a 1-rem (0.01 Sv) dose may increase an individual worker's chances of dying from cancer from 20 percent to 20.04 percent. If one's lifetime occupa-tional dose is 10 rems, we could raise the estimate to 20.4 percent. A lifetime dose of 100 rems may in-crease chances of dying from cancer from 20 to 24 percent. The average measurable dose for radiation workers reported to the NRC was 0.31 rem (0.0031 Sv) for 1993 (Ref. 9). Today, very few workers ever accumulate 100 rems (1 Sv) in a working lifetime, and the average career dose of workers at NRC-licensed facilities is 1.5 rems (0.015 Sv), which represents an estimated increase from 20 to about 20.06 percent in the risk of dying from cancer.

It is important to understand the probability fac-tors here. A similar question would be, "If you select one card from a full deck of cards, will you get the ace of spades?" This question cannot be answered with a simple yes or no. The best answer is that your chance is 1 in 52. However, if 1000 people each select one card from full decks, we can predict that about 20 of them will get an ace of spades. Each person will have 1 chance in 52 of drawing the ace of spades, but there is no way we can predict which persons will get that card.

The issue is further complicated by the fact that in a drawing by 1000 people, we might get only 15 suc-cesses, and in another, perhaps 25 correct cards in 1000 draws. We can say that if you receive a radiation dose, you will have increased your chances of eventu-ally developing cancer. It is assumed that the more ra-diation exposure you get, the more you increase your chances of cancer.

The normal chance of dying from cancer is about one in five for persons who have not received any oc-cupational radiation dose. The additional chance of developing fatal cancer from an occupational exposure of 1 rem (0.01 Sv) is about the same as the chance of drawing any ace from a full deck of cards three times in a row. The additional chance of dying from cancer from an occupational exposure of 10 rem (0.1 Sv) is about equal to your chance of drawing two aces succes-sively on the first two draws from a full deck of cards.

It is important to realize that these risk numbers are only estimates based on data for people and re-search animals exposed to high levels of radiation in short periods of time. There is still uncertainty with re-gard to estimates of radiation risk from low levels of exposure. Many difficulties are involved in designing research studies that can accurately measure the proj-ected small increases in cancer cases that might be caused by low exposures to radiation as compared to the normal rate of cancer.

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These estimates are considered by the NRC staff to be the best available for the worker to use to make an informed decision concerning acceptance of the risks associated with exposure to radiation. A worker who decides to accept this risk should try to keep expo-sure to radiation as low as is reasonably achievable (ALARA) to avoid unnecessary risk.

9.

If I receive a radiation dose that is within occupational limits, will it cause me to get cancer?

Probably not. Based on the risk estimates pre-viously discussed, the risk of cancer from doses below the occupational limits is believed to be small. Assess-ment of the cancer risks that may be associated with low doses of radiation are projected from data avail-able at doses larger than 10 rems (0.1 Sv) (Ref. 3). For radiation protection purposes, these estimates are made using the straight line portion of the linear qua-dratic model (Curve 2 in Figure 1). We have data on cancer probabilities only for high doses, as shown by the solid line in Figure 1. Only in studies involving radi-ation doses above occupational limits are there de-pendable determinations of the risk of cancer, primari-ly because below the limits the effect is small compared to differences in the normal cancer incidence from year to year and place to place. The ICRP, NCRP, and other standards-setting organizations assume for radi-ation protection purposes that there is some risk, no matter how small the dose (Curves 1 and 2). Some scientists believe that the risk drops off to zero at some low dose (Curve 3), the threshold effect. The ICRP and NCRP endorse the linear quadratic model as a conservative means of assuring safety (Curve 2).

For regulatory purposes, the NRC uses the straight line portion of Curve 2, which shows the number of effects decreasing linearly as the dose decreases. Be-cause the scientific evidence does not conclusively demonstrate whether there is or is not an effect at low doses, the NRC assumes for radiation protection pur-poses, that even small doses have some chance of caus-ing cancer. Thus, a principle of radiation protection is to do more than merely meet the allowed regulatory limits; doses should be kept as low as is reasonably achievable (ALARA). This is as true for natural car-cinogens such as sunlight and natural radiation as it is for those that are manmade, such as cigarette smoke, smog, and x-rays.

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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 radiation to other kinds of health risks?

One way to make these comparisons is to compare the average number of days of life expectancy lost because of the effects associated with each particular health risk. Estimates are calculated by looking at a large number of persons, recording the age when death occurs from specific causes, and estimating the average number of days of life lost as a result of these early deaths. The total number of days of life lost is then averaged over the total observed group.

Several studies have compared the average days of life lost from exposure to radiation with the number of days lost as a result of being exposed to other health risks. The word "average" is important because an in-dividual who gets cancer loses about 15 years of life expectancy, while his or her coworkers do not suffer any loss.

Some representative numbers are presented in Table 1. For categories of NRC-regulated industries with larger doses, the average measurable occupational dose in 1993 was 0.31 rem (0.0031 Sv). A simple cal-culation based on the article by Cohen and Lee (Ref.

10) shows that 0.3 rem (0.003 Sv) per year from age 18 to 65 results in an average loss of 15 days. These estimates indicate that the health risks from occupa-tional radiation exposure are smaller than the risks as-sociated with many other events or activities we en-counter and accept in normal day-to-day activities.

It is also useful to compare the estimated average number of days of life lost from occupational exposure to radiation with the number of days lost as a result of working in several types of industries. Table 2 shows average days of life expectancy lost as a result of fatal work-related accidents. Table 2 does not include non-accident types of occupational risks such as occupa-tional disease and stress because the data are not available.

These comparisons are not ideal because we are comparing the possible effects of chronic exposure to radiation to different kinds of risk such as accidental death, in which death is inevitable if the event occurs.

This is the best we can do because good data are not available on chronic exposure to other workplace car-cinogens. Also, the estimates of loss of life expectancy for workers from radiation-induced cancer do not take into consideration the competing effect on the life ex-pectancy of the workers from industrial accidents.

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

During certain stages of development, the embryo/

fetus is believed to be more sensitive to radiation dam-age than adults. Studies of atomic bomb survivors ex-posed to acute radiation doses exceeding 20 rads (0.2 Gy) during pregnancy show that children born after receiving these doses have a higher risk of mental re-tardation. Other studies suggest that an association ex-ists between exposure to diagnostic x-rays before birth and carcinogenic effects in childhood and in adult life.

Scientists are uncertain about the magnitude of the risk. Some studies show the embryo/fetus to be more sensitive to radiation-induced cancer than adults, but other studies do not. In recognition of the possibility 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.

8.29-9

I Table 2 Estimated Loss of Life Expectancy from Industrial Accidentsa Estimated Days of Life Industry Type Expectancy Lost (Average)

All industries 60 Agriculture 320 Construction 227 Mining and Quarrying 167 Transportation and Public Utilities 160 Government 60 Manufacturing 40 Trade 27 Services 27 aAdapted from Reference 10.

embryo/fetus is involuntary on the part of the embryo/

fetus, a more restrictive dose limit has been established for the embryo/fetus of a declared pregnant radiation worker. See Regulatory Guide 8.13, "Instruction Con-cerning Prenatal Radiation Exposure."

If an occupationally exposed woman declares her pregnancy in writing, she is subject to the more restric-tive dose limits for the embryo/fetus during the remain-der of the pregnancy. The dose limit of 500 mrems (5 mSv) for the total gestation period applies to the em-bryo/fetus and is controlled by restricting the exposure to the declared pregnant woman. Restricting the wom-an's occupational exposure, if she declares her preg-nancy, raises questions about individual privacy rights, equal employment opportunities, and the possible loss of income. Because of these concerns, the declaration of pregnancy by a female radiation worker is volun-tary. Also, the declaration of pregnancy can be with-drawn for any reason, for example, if the woman be-lieves that her benefits from receiving the occupational exposure would outweigh the risk to her embryo/fetus from the radiation exposure.

12. Can a worker become sterile or impotent from normal occupational radiation exposure?

No. Temporary or permanent sterility cannot be caused by radiation at the levels allowed under NRC's occupational limits. There is a threshold below which these effects do not occur. Acute doses on the order of 10 rems (0.1 Sv) to the testes can result in a measur-able but temporary reduction in sperm count. Tempo-rary sterility (suppression of ovulation) has been ob-served in women who have received acute doses of 150 rads (1.5 Gy). The estimated threshold (acute) radi-ation dose for induction of permanent sterility is about 200 rads (2 Gy) for men and about 350 rads (3.5 Gy) for women (Refs. 1 and 4). These doses are far greater than the NRC s occupational dose limits for workers.

Although acute doses can affect fertility by reduc-ing sperm count or suppressing ovulation, they do not have any direct effect on one's ability to function sexu-ally. No evidence exists to suggest that exposures with-in the NRC's occupational limits have any effect on the ability to function sexually.

13. What are the NRC occupational dose limits?

For adults, an annual limit that does not exceed:

a 5 rems (0.05 Sv) for the total effective dose equiv-alent (TEDE), which is the sum of the deep dose equivalent (DDE) from external exposure to the whole body and the committed effective dose equivalent (CEDE) from intakes of radioactive material.

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-mitted dose equivalent (CDE) from intakes of ra-dioactive material to any individual organ or tis-sue, other than the lens of the eye.

15 rems (0.15 Sv) for the lens dose equivalent (LDE), which is the external dose to the lens of the eye.

50 rems (0.5 Sv) for the shallow dose equivalent (SDE), which is the external dose to the skin or to any extremity.

For minor workers, the annual occupational dose limits are 10 percent of the dose limits for adult work-ers.

For protection of the embryolfetus of a declared pregnant woman, the dose limit is 0.5 rem (5 mSv) during the entire pregnancy.

The occupational dose limit for adult workers of 5 rems (0.05 Sv) TEDE is based on consideration of the potential for delayed biological effects. The 5-rem (0.05 Sv) limit, together with application of the con-cept of keeping occupational doses ALARA, provides a level of risk of delayed effects considered acceptable by the NRC. The limits for individual organs are below the dose levels at which early biological effects are ob-served in the individual organs.

The dose limit for the embryo/fetus of a declared pregnant woman is based on a consideration of the possibility of greater sensitivity to radiation of the em-bryo/fetus and the involuntary nature of the exposure.

14. What is meant by ALARA?

ALARA means 'as low as is reasonably achiev-able." In addition to providing an upper limit on an individual's permissible radiation dose, the NRC re-quires that its licensees establish radiation protection 8.29-10

programs and use procedures and engineering controls to achieve occupational doses, and doses to the public, as far below the limits as is reasonably achievable.

"Reasonably achievable" also means "to the extent practicable." What is practicable depends on the pur-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 part of each licensee's radiation protection program, it does not mean that each radiation exposure must be kept to an absolute minimum, but rather that "reason-able" efforts must be made to avert dose. In practice, ALARA includes planning tasks involving radiation exposure so as to reduce dose to individual workers and the work group.

There are several ways to control radiation doses, e.g., limiting the time in radiation areas, maintaining distance from sources of radiation, and providing shielding of radiation sources to reduce dose. The use of engineering controls, from the design of facilities and equipment to the actual set-up and conduct of work activities, is also an important element of the ALARA concept.

An ALARA analysis should be used in determin-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-nal and internal doses. For example, the use of respi-rators can lead to increased work time within radiation areas, which increases external dose. The advantage of using respirators to reduce internal exposure must be evaluated against the increased external exposure and related stresses caused by the use of respirators. Heat stress, reduced visibility, and reduced communication associated with the use of respirators could expose a worker to far greater risks than are associated with the internal dose avoided by use of the respirator. To the extent practical, engineering controls, such as contain-ments and ventilation systems, should be used to re-duce workplace airborne radioactive materials.

15. What are background radiation exposures?

The average person is constantly exposed to ioniz-ing radiation from several sources. Our environment and even the human body contain naturally occurring radioactive materials (e.g., potassium-40) that contrib-ute to the radiation dose that we receive. The largest source of natural background radiation exposure is ter-restrial radon, a colorless, odorless, chemically inert gas, which causes about 55 percent of our average, nonoccupational exposure. Cosmic radiation originat-ing in space contributes additional exposure. The use of x-rays and radioactive materials in medicine and dentistry adds to our population exposure. As shown below in Table 3, the average person receives an annu-al radiation dose of about 0.36 rem (3.6 mSv). By age 20, the average person will accumulate over 7 rems (70 mSv) of dose. By age 50, the total dose is up to 18 rems (180 mSv). After 70 years of exposure this dose is up to 25 rems (250 mSv).

Table 3 Average Annual Effective Dose Equiva-lent to Individuals in the U.S.a Effective Dose Source Equivalent (mrems)

Natural Radon 200 Other than Radon 100 Total 300 Nuclear Fuel Cycle 0.05 Consumer Productsb 9

Medical Diagnostic X-rays 39 Nuclear Medicine 14 Total 53 Total about 360 mrems/year aAdapted from Table 8.1, NCRP 93 (Ref. 11).

bIncludes building material, television receivers, lumi-nous watches, smoke detectors, etc. (from Table S.1, NCRP 93, Ref. 11).

16. What are the typical radiation doses received by workers?

For 1993, the NRC received reports on about a quarter of a million people who were monitored for occupational exposure to radiation. Almost half of those monitored had no measurable doses. The other 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 received less than 2 rems (20 mSv); and the highest reported dose was for two individuals who each re-ceived between 5 and 6 rems (50 and 60 mSv).

Table 4 lists average occupational doses for work-ers (persons who had measurable doses) in various oc-cupations based on 1993 data. It is important to note that beginning in 1994, licensees have been required to sum external and internal doses and certain licensees are required to submit annual reports. Certain types of licensees such as nuclear fuel fabricators may report a significant increase in worker doses because of the exposure to long-lived airborne radionuclides and the requirement to add the resultant internal dose to the calculation of occupational doses.

8.29-11

I Table 4 Reported Occupational Doses for 1993a Average Measurable Occupational Dose per Worker Subgroup (millirems)

Industrial Radiography 540 Commercial Nuclear Power Reactors 310 Manufacturing and Distribution of Radioactive Materials 300 Low-Level Radioactive Waste Disposal 270 Independent Spent Nuclear Fuel Storage 260 Nuclear Fuel Fabrication 130 aFrom Table 3.1 in NUREG-0713 (Ref. 9).

17. How do I know how much my occupational dose (exposure) is?

If you are likely to receive more than 10 percent of the annual dose limits, the NRC requires your employ-er, the NRC licensee, to monitor your dose, to main-tain records of your dose, and, at least on an annual basis for the types of licensees listed in 10 CFR 20.2206, "Reports of Individual Monitoring," to in-form both you and the NRC of your dose. The purpose of this monitoring and reporting is so that the NRC can be sure that licensees are complying with the occupa-tional dose limits and the ALARA principle.

External exposures are monitored by using indi-vidual monitoring devices. These devices are required to be used if it appears likely that external exposure will exceed 10 percent of the allowed annual dose, i.e.,

0.5 rem (5 mSv). The most commonly used monitor-ing devices are film badges, thermoluminescence do-simeters (TLDs), electronic dosimeters, and direct reading pocket dosimeters.

With respect to internal exposure, your employer is required to monitor your occupational intake of ra-dioactive material and assess the resulting dose if it ap-pears likely that you will receive greater than 10 per-cent of the annual limit on intake (ALI) from intakes in 1 year. Internal exposure can be estimated by mea-suring the radiation emitted from the body (for exam-ple, with a "whole body counter") or by measuring the radioactive materials contained in biological samples such as urine or feces. Dose estimates can also be made if one knows how much radioactive material was in the air and the length of time during which the air was breathed.

18. What happens if a worker exceeds the annual dose limit?

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

The licensee may be subject to NRC enforcement ac-tion such as a fine (civil penalty), just as individuals are subject to a traffic fine for exceeding a speed limit. The fines and, in some serious or repetitive cases, suspen-sion of a license are intended to encourage licensees to comply with the regulations.

Radiation protection limits do not define safe or unsafe levels of radiation exposure. Exceeding a limit does not mean that you will get cancer. For radiation protection purposes, it is assumed that risks are related to the size of the radiation dose. Therefore, when your 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, even though you may not actually have an accident.

Those who set speed limits have determined that the risks of driving in excess of the speed limit are not ac-ceptable. In the same way, the revised 10 CFR Part 20 establishes a limit for normal occupational exposure of S reins (0.05 Sv) a year. Although you will not neces-sarily get cancer or some other radiation effect at doses above the limit, it does mean that the licensee's safety program has failed in some way. Investigation is war-ranted to determine the cause and correct the condi-tions leading to the dose in excess of the limit.

19. What is meant by a "planned special exposure"?

A "planned special exposure" (PSE) is an infre-quent exposure to radiation, separate from and in ad-dition to the radiation received under the annual occu-pational limits. The licensee can authorize additional dose in any one year that is equal to the annual occu-pational dose limit as long as the individual's total dose from PSEs does not exceed five times the annual dose limit during the individual's lifetime. For example, li-censees may authorize PSEs for an adult radiation worker to receive doses up to an additional 5 rems (0.05 Sv) in a year above the 5-rem (0.05-Sv) annual TEDE occupational dose limit. Each worker is limited to no more than 25 rems (0.25 Sv) from planned spe-cial exposures in his or her lifetime. Such exposures are only allowed in exceptional situations when alter-natives for avoiding the additional exposure are not available or are impractical.

Before the licensee authorizes a PSE, the licensee must ensure that the worker is informed of the purpose and circumstances of the planned operation, the esti-mated doses expected, and the procedures to keep the doses ALARA while considering other risks that may 8.29-12

be present. (See Regulatory Guide 8.35, "Planned Special Exposures.")

20. Why do some facilities establish administra-tive control levels that are below the NRC limits?

There are two reasons. First, the NRC regulations state that licensees must take steps to keep exposures to radiation ALARA. Specific approval from the li-censee for workers to receive doses in excess of admin-istrative limits usually results in more critical risk-bene-fit analyses as each additional increment of dose is approved for a worker. Secondly, an administrative control level that is set lower than the NRC limit pro-vides a safety margin designed to help the licensee avoid doses to workers in excess of the limit.

21. Why aren't medical exposures considered as part of a worker's allowed dose?

NRC rules exempt medical exposure, but equal doses of medical and occupational radiation have equal risks. Medical exposure to radiation is justified for reasons that are quite different from the reasons for occupational exposure. A physician prescribing an x-ray, for example, makes a medical judgment that the benefit to the patient from the resulting medical infor-mation justifies the risk associated with the radiation.

This judgment may or may not be accepted by the pa-tient. Similarly, each worker must decide on the bene-fits and acceptability of occupational radiation risk, just as each worker must decide on the acceptability of any other occupational hazard.

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 be justified on medical grounds. If the worker had also received 2 rems (0.02 Sv) on the job, the combined dose of 5 rems (0.05 Sv) would in no way incapacitate the worker. Restricting the worker from additional job exposure during the remainder of the year would not have any effect on the risk from the 3 rems (0.03 Sv) already received from the medical exposure. If the in-dividual worker accepts the risks associated with the x-rays on the basis of the medical benefits and accepts the risks associated with job-related exposure on the basis of employment benefits, it would be unreason-able to restrict the worker from employment involving exposure to radiation for the remainder of the year.

22. How should radiation risks be considered in an emergency?

Emergencies are "unplanned" events in which ac-tions to save lives or property may warrant additional doses for which no particular limit applies. The revised 10 CFR Part 20 does not set any dose limits for emer-gency or lifesaving activities and states that nothing in Part 20 "shall be construed as limiting actions that may be necessary to protect health and safety."

Rare situations may occur in which a dose in ex-cess of occupational limits would be unavoidable in or-der to carry out a lifesaving operation or to avoid a large dose to large populations. However, persons called upon to undertake any emergency operation should do so only on a voluntary basis and with full awareness of the risks involved.

For perspective, the Environmental Protection Agency (EPA) has published emergency dose guide-lines (Ref. 2). These guidelines state that doses to all workers during emergencies should, to the extent prac-ticable, be limited to 5 rems (0.05 Sv). The EPA fur-ther states that there are some emergency situations for which higher limits may be justified. The dose resulting from such emergency exposures should be limited to 10 rems (0.1 Sv) for protecting valuable property, and to 25 rems (0.25 Sv) for lifesaving activities and the protection of large populations. In the context of this guidance, the dose to workers that is incurred for the protection of large populations might be considered justified for situations in which the collective dose to others that is avoided as a result of the emergency op-eration is significantly larger than that incurred by the workers involved.

Table 5 presents the estimates of the fatal cancer risk for a group of 1,000 workers of various ages, as-suming that each worker received an acute dose of 25 rems (0.25 Sv) in the course of assisting in an emer-gency. The estimates show that a 25-rem emergency dose might increase an individual's chances of devel-oping fatal cancer from about 20% to about 21%.

Table 5 Risk of Premature Death from Exposure to 25-Rems (0.25-Sv) Acute Dose Estimated Risk Age at of Premature Death Exposure (Deaths per 1,000 (years)

Persons Exposed) 20-30 9.1 30-40 7.2 40-50 5.3 50-60

3.5 Source

EPA-400-R-92-001 (Ref. 2).

23. How were radiation dose limits established?

The NRC radiation dose limits in 10 CFR Part 20 were established by the NRC based on the recommen-dations of the ICRP and NCRP as endorsed in Federal radiation protection guidance developed by the EPA 8.29-13

I (Ref. 12). The limits were recommended by the ICRP and NCRP with the objective of ensuring that working in a radiation-related industry was as safe as working in other comparable industries. The dose limits and the principle of ALARA should ensure that risks to work-ers are maintained indistinguishable from risks from background radiation.

24. Several scientific reports have recommended that the NRC establish lower dose limits.

Does the NRC plan to reduce the regulatory limits?

Since publication of the NRC's proposed rule in 1986, the ICRP in 1990 revised its recommendations for radiation protection based on newer studies of radi-ation risks (Ref. 13), and the NCRP followed with a revision to its recommendations in 1993. The ICRP recommended a limit of 10 rems (0.1 Sv) effective dose equivalent (from internal and external sources),

over a 5-year period with no more than 5 rems (0.05 Sv) in 1 year (Ref. 13). The NCRP recommended a cumulative limit in rerns, not to exceed the individual's age in years, with no more than 5 rems (0.05 Sv) in any year (Ref. 14).

The NRC does not believe that additional reduc-tions in the dose limits are required at this time. Be-cause of the practice of maintaining radiation expo-sures ALARA (as low as is reasonably achievable), the average radiation dose to occupationally exposed per-sons is well below the limits in the current Part 20 that became mandatory January 1, 1994, and the average doses to radiation workers are below the new limits recommended by the ICRP and the NCRP.

25. What are the options if a worker decides that the risks associated with occupational radi-ation exposure are too high?

If the risks from exposure to occupational radi-ation are unacceptable to a worker, he or she can re-quest a transfer to a job that does not involve exposure to radiation. However, the risks associated with the ex-posure to radiation that workers, on the average, ac-tually receive are comparable to risks in other indus-tries and are considered acceptable by the scientific groups that have studied them. An employer is not ob-ligated to guarantee a transfer if a worker decides not to accept an assignment that requires exposure to radi-ation.

Any worker has the option of seeking other em-ployment in a nonradiation occupation. However, the studies that have compared occupational risks in the nuclear industry to those in other job areas indicate that nuclear work is relatively safe. Thus, a worker may find different kinds of risk but will not necessarily find significantly lower risks in another job.

26. Where can one get additional information on radiation risk?

The following list suggests sources of useful infor-mation on radiation risk:

The employer-the radiation protection or health physics office where a worker is employed.

Nuclear Regulatory Commission Regional Offices:

King of Prussia, Pennsylvania (610) 337-5000 Atlanta, Georgia (404) 331-4503 Lisle, Illinois (708) 829-9500 Arlington, Texas (817) 860-8100 U.S. Nuclear Regulatory Commission Headquarters Radiation Protection & Health Effects Branch Office of Nuclear Regulatory Research Washington, DC 20555 Telephone: (301) 415-6187 Department of Health and Human Services Center for Devices and Radiological Health 1390 Piccard Drive, MS HFZ-1 Rockville, MD 20850 Telephone:

(301) 443-4690 U.S. Environmental Protection Agency Office of Radiation and Indoor Air Criteria and Standards Division 401 M Street NW.

Washington, DC 20460 Telephone: (202) 233-9290 8.29-14

REFERENCES

1.

B.R. Scott et al., "Health Effects Model for Nu-clear Power Plant Accident Consequence Analy-sis," Part I: Introduction, Integration, and Sum-mary, U.S. Nuclear Regulatory Commission, NUREG/CR-4214, Revision 2, Part I, October 1993.*

2.

U.S. Environmental Protection Agency, Manual of Protective Action Guides and Protective Ac-tions for Nuclear Incidents, EPA-400-R 001, May 1992.

3.

International Commission on Radiological Pro-tection, Annals of the ICRP, Risks Associated with Ionising Radiation, Volume 22, No.1, Per-gamon Press, Oxford, UK, 1991.

4.

National Research Council, Health Effects of Ex-posure to Low Levels of Ionizing Radiation, Re-port of the Committee on the Biological Effects of Ionizing Radiation (BEIR V), National Academy Press, Washington, DC, 1990.

5.

United Nations Scientific Committee on the Ef-fects of Atomic Radiation (UNSCEAR); Sources, Effects and Risks of Ionizing Radiation, Report E.88.IX.7, United Nations, New York, 1988.

6.

United Nations Scientific Committee on the Ef-fects of Atomic Radiation (UNSCEAR), Sources and Effects of Ionizing Radiation, United Na-tions, New York, 1993.

7.

National Council on Radiation Protection and Measurements, New Dosimetry at Hiroshima and Nagasaki and Its Implications for Risk Esti-mates, Proceedings of the Twenty-third Annual Meeting of the National Council on Radiation Protection and Measurements Held on April 8-9, 1987 (1988).

8.

National Council on Radiation Protection.and Measurements, Comparative Carcinogenicity of Ionizing Radiation and Chemicals, NCRP Report No. 96, March 1989.

9.

C.T. Raddatz and D. Hagemeyer, "Occupational Radiation Exposure at Commercial Nuclear Pow-er Reactors and Other Facilities, 1993," U.S.

Nuclear Regulatory Commission, NUREG-0713, Volume 15, January 1995.'

10. B.L. Cohen and I.S. Lee, "Catalog of Risks Ex-tended and Updated," Health Physics, Vol. 61, September 1991.

11. National Council on Radiation Protection and Measurements, Ionizing Radiation Exposure of the Population of the United States, NCRP Re-port No. 93, September 1987.

12. U.S. Environmental Protection Agency, "Radi-ation Protection Guidance to Federal Agencies for Occupational Exposure," Federal Register, Vol. 52, No. 17, January 27, 1987.

13. International Commission on Radiological Pro-tection, 1990 Recommendations of the Interna-tional Commission on Radiological Protection, ICRP Publication 60, Pergamon Press, Oxford, UK, 1991.

14. National Council on Radiation Protection and Measurements, Limitation of Exposure to Ioniz-ing Radiation, NCRP Report No. 116, March 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 Nuclear Power Plant Accident Consequence Analy-sis, " Part II: Scientific Bases for Health Effects Mod-els, U.S. Nuclear Regulatory Commission, NUREG/

CR-4214, Rev. 1, Part II, May 1989.1 Abrahamson, S., et al., "Health Effects Models for Nuclear Power Plant Accident Consequence Analysis, Modifications of Models Resulting From Recent Re-ports on Health Effects of Ionizing Radiation, Low LET Radiation," Part II: Scientific Basis for Health Effects Models, U.S. Nuclear Regulatory Commission, NUREG/CR-4214, Rev. 1, Part II, Addendum 1, Au-gust 1991.'

Abrahamson, S., et al., "Health Effects Models for Nuclear Power Plant Accident Consequence Analysis, Modifications of Models Resulting From Addition of Effects of Exposure to Alpha-Emitting Radionu-clides," Part II: Scientific Bases for Health Effects

Models, U.S.

Nuclear Regulatory Commission, NUREG/CR-4214, Rev. 1, Part II, Addendum 2, May 1993.1 International Commission on Radiological Protection, Radiation Protection, Recommendations of the Inter-national Commission on Radiological Protection, ICRP Publication 26, Pergamon Press, Oxford, UK, January 1977.

National Council on Radiation Protection and Mea-surements, Public Radiation Exposure From Nuclear Power Generation in the United States, NCRP Report No. 92, December 1987.

National Council on Radiation Protection and Mea-surements, Exposure of the Population in the United

'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 20555-0001; 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 (telephone (202) 512-2249); or from the National Technical Information Ser-vice by writing NTIS at 5285 Port Royal Road, Springfield, VA 22161.

States and Canada from Natural Background Radi-ation, NCRP Report No. 94, De6ember 1987.

National Council on Radiation Protection and Mea-surements, Exposure of the U.S. Population From Oc-cupational Radiation, NCRP Report No. 101, June 1989.

National Council on Radiation Protection and Mea-surements, Risk Estimates for Radiation Protection, NCRP Report No. 115, December 1993.

National Council on Radiation Protection and Mea-surements, Limitation of Exposure to Ionizing Radi-ation, NCRP Report No. 116, March 1993.

National Safety Council, Accident Facts, 1993 Edi-tion, Itasca, Illinois, 1993.

U.S. Environmental Protection Agency, "Radiation Protection Guidance to Federal Agencies for Occupa-tional Exposure," Federal Register, Vol. 52, No. 17, January 27, 1987.

U.S. Nuclear Regulatory Commission, "Instruction Concerning Prenatal Radiation Exposure," Regulatory Guide 8.13, Revision 2, December 1987.2 U.S. Nuclear Regulatory Commission, "Monitoring Criteria and Methods To Calculate Occupational Radi-ation Doses," Regulatory Guide 8.34, July 1992.2 U.S. Nuclear Regulatory Commission, "Planned Spe-cial Exposures," Regulatory Guide 8.35, June 1992.2 U.S. Nuclear Regulatory Commission, "Radiation Dose to the Embryo/Fetus," Regulatory Guide 8.36, July 1992.2 2Single copies of regulatory guides may be obtained free of charge by writing the Office of Administration, Attn: Distri-bution and Services Section, USNRC, Washington, DC 20555, or by fax at (301) 415-2260. 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 20555-0001; telephone (202) 634-3273; fax (202) 634-3343.

8.29-16

REGULATORY ANALYSIS A separate regulatory analysis was not prepared for this Revision 1 to Regulatory Guide 8.29. A value/

impact statement, which evaluated essentially the same subjects as are discussed in a regulatory analysis, ac-companied Regulatory Guide 8.29 when it was issued in July 1981.

This Revision 1 to Regulatory Guide 8.29 is need-ed to conform with the Revised 10 CFR Part 20, "Stan-dards for Protection Against Radiation," as published May 21, 1991 (56 FR 23360). The regulatory analysis prepared for 10 CFR Part 20 provides the regulatory basis for this Revision 1 of Regulatory Guide 8.29, and it examines the costs and benefits of the rule as im-plemented by the guide. A copy of the 'Regulatory Analysis for the Revision of 10 CFR Part 20" (PNL-6712, November 1988), is available for inspec-tion and copying for a fee in the NRC's Public Docu-ment Room at 2120 L Street NW., Washington, DC 20555-0001.

8.29-17

Federal Recycling Program

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