Potential Radiation Exposure in Military Operations: Protecting the Soldier Before, During, and After (1999)

In determining whether the guidance from the North Atlantic Treaty Organization embodied in the Allied Command Europe (ACE) Directive adequately follows generally accepted practices of radiation protection, the committee first reviewed standard practice. The international basis of radiation protection practice has been developed explicitly by the International Commission on Radiological Protection (ICRP). This has been considered and adapted for use in the United States by the National Council on Radiation Protection and Measurements. On the basis of their own needs and the recommendations of these organizations, various federal agencies, such as the U.S. Nuclear Regulatory Commission and the Environmental Protection Agency, have developed and continue to develop specific implementing regulations.

In this section, the committee summarizes current radiation protection philosophy and procedure in the United States. Later, in Chapter 5, this will be a yardstick against which the ACE Directive is compared.

The philosophy of radiation protection and the practices that ensure radiation safety must include social as well as scientific judgments to provide an appropriate standard of protection without unduly limiting military operations. The overall goal of radiation protection, regardless of the specifics of the situation that leads to exposure, is to prevent the occurrence of acute effects (e.g., cataracts, radiation burns, and acute radiation sickness) and to ensure that all reasonable steps are taken to reduce the potential long-term effects, such as cancer (ICRP, 1991a), to a level that is acceptable to society. The methods applied to

achieve that aim will vary, depending upon the radiation exposure scenario. The two types of exposure scenarios addressed here are (1) practices (routine and potential) and (2) interventions.

The first of these, a practice, is an intentional activity in which the practitioner is routinely at risk of exposure. Workers who are exposed to radiation during the course of their duties include, for example, x-ray technicians in hospitals, nuclear power plant workers, and researchers who use radioactive materials. The practices in which they engage include taking x rays of patients, maintaining a nuclear reactor (or nuclear electric generating station), or taking measurements using radioactive sources. These occupationally exposed individuals are trained to appreciate the hazards of radiation, to acknowledge those risks as a condition of employment, and to follow safety precautions to minimize their exposure.

Any practice may involve exposures that do not routinely occur (e.g., accidents). If these have not yet happened, they are called potential exposures. Both the probability that such events will happen and the magnitude of the expected radiation doses can be calculated in the planning of responses. These also should be considered in the introduction and management of new practices. If an accident actually happens, interventions are taken to reduce exposure.

An intervention is an action that one takes to reduce radiation exposure (often to other individuals or groups) from specific radiation sources by (ICRP, 1993, p. 1):

1. reducing or removing the existing sources,
2. improving the reliability of the existing sources,
3. modifying pathways,¹ or
4. reducing the number of exposed individuals.

• limits or reference levels.

Radiation exposure is generally considered something to be avoided unless it can be adequately justified. As mentioned in Chapter 1, radiation at low doses (less than 50 millisievert [mSv]) has not been observed to have effects in humans. However, because of the uncertainty surrounding the effects of low doses, most radiation protection philosophy presumes that even low doses of radiation may produce some deleterious effects. For that reason, the first principle of radiation protection is justification: All practices that involve exposure should produce a benefit that outweighs the potential harm (ICRP, 1991 a).

As an example of justification, consider the use of medical x rays. Technicians may receive low doses of radiation and may receive some harm, but the greater good provided to patients by the diagnostic x ray is high; hence, the practice is deemed justified. Justification is essential in developing radiation protection for practices and interventions and is also applied in planning for potential exposures.

Once an activity involving exposure has been justified, one must then minimize the exposure that will result from that action. Optimization is the word used by ICRP to describe that minimization process. An activity is optimized when the resulting dose is reduced to a level that is "as low as is reasonably achievable (ALARA), economic and social factors having been taken into account" (ICRP, 1991 a, paragraph I 112(b)).

Finally, even when a practice is justified and has been optimized, there are limits above which people should not be routinely exposed. Dose limits, when observed, provide protection against exposure to radiation at levels that are clearly unacceptable. This could happen in a poorly controlled occupational situation involving radiation. Dose limits apply only to practices.

For interventions—where the primary goal is to accomplish the emergency action—dose limits should not be used. Nor are dose limits applicable in planning for potential exposures. When the potential exposure is realized—such as in an accident—the response is often an intervention rather than a practice. In the case of a postaccident intervention, application of an occupational dose limit could prevent emergency workers from performing critical actions necessary to limit great harm to a large population. Dose limits do not apply to (or include) doses received from natural background radiation. Nor do they apply to patients undergoing medical procedures that involve radiation exposure.

Thus far, the committee has discussed radiation protection principles without regard to the population that is being protected. Although the principles apply to anyone, the implementation depends on the circumstances under which one is exposed. Workers who are exposed to radiation as a consequence of their employment have chosen to accept that exposure and the practice of protection as condi-

tions of employment. Members of the general public may also be exposed to radiation sources beyond that from the natural environment (e.g., while waiting in a radiology clinic or a cancer therapy department). Unlike workers who are exposed to radiation as part of their occupations, however, members of the general public do not receive direct compensation in return for their exposure, nor do they formally accept the risks of exposure. Therefore, limits set for exposures are significantly lower for the public. Occupational doses are currently limited (CFR, 1991) to 50 mSv per year, whereas exposures to the general public are limited to 1/50 of that: I mSv per year (approximately the same as the annual background dose from sources excluding radon) (CFR, 1991; NCRP, 1987a). Although both of these limits apply to both males and females, more stringent occupational exposure limits apply to an embryo or fetus during the period of gestation. The exposure limit for embryos and fetuses during the 9-month period of gestation is 5 mSv, which is 10 times lower than the usual limit for workers for 1 year (50 mSv).³

Dose limits can easily be misinterpreted. They are not intended as demarcations of safety. Keeping doses below the limits does not guarantee the absence of increased risk of radiation-induced cancer, nor does going above the limit give certainty to future cancer development. Dose limits represent, for a defined set of practices, a level of dose above which the consequences for the individual would be widely regarded as unacceptable (ICRP, 1991a).

Interventions that limit damage after a nuclear accident (urgent actions) present their own set of problems (ICRP, 1991b). People who are in the immediate vicinity can be exposed to radiation levels that can be estimated only after the incident. Those who respond to the situation (firefighters and other emergency workers) may be exposed to doses in excess of the annual U.S. occupational limit of 50 mSv in trying to protect valuable equipment, save lives, or prevent large populations from being exposed to radiation. In this scenario, the principles of justification and optimization continue to apply. However, since worker exposures may be unpredictable, unknown, and difficult to control in the earliest stages of an accident, adherence to dose limits is inappropriate. Nevertheless, ICRP recommends that, where possible, the effective dose to individuals be kept below 1,000 mSv to limit deterministic effects. Where possible, except to save a life, the effective dose should not exceed 500 mSv and the equivalent dose to the skin should be limited to 5,000 mSv. Also, ICRP (1991b) and the Environmental Protection Agency (EPA, 1991) have recommended intervention levels for sheltering and evacuation, contamination levels for foodstuffs, and procedures for thyroid protection.

After the urgent action phase of an accident, additional personnel may assist with evacuation of the local population, provide emergency medical care, or provide security around the accident site. During that phase, principles of justifi-

cation and at least crude optimization are applied (ICRP, 1991b). ICRP also recommends that doses be kept within occupational limits, if possible.

Finally, once the accident and radiation exposure are under control, a recovery period begins. During this recovery period the hazard at the site is brought under permanent control. Since this may take an extended period of time, during which the urgency of the situation is diminished, conventional occupational radiation protection controls are appropriate.

In summary, radiation protection is based on justification, optimization, and, in the case of routine practices, dose limits. However, it would be unacceptably inefficient to go through the justification and optimization processes every time that a recurring situation arises. For many recurring situations, it may be possible to go through these processes once and define what actions should be taken in response to a set of similar circumstances when a particular level of exposure or dose is exceeded. The resulting reference levels (ICRP, 1991a) take into account justification, optimization, and dose limits in directing radiation protection policy changes, administrative responses, or other actions.

Reference levels are fundamentally different from dose limits. Whereas dose limits specify (usually with regulatory authority) a dose that should not be exceeded during routine operations, reference levels give guidance that certain decisions should be made or certain actions should be taken if and when the level is exceeded.

A variety of organizations have recommended dose limits and reference levels (Table 3-1). These are applicable to a number of different populations in a variety of exposure scenarios. The table is by no means an inclusive list but provides comparisons that put different circumstances of radiation exposure into perspective.

In implementing this underlying philosophy, radiation safety and protection programs include provisions for actions such as monitoring compliance, recordkeeping, training, health surveillance, and defining the responsibilities of management and governmental authorities.

Training is an essential part of all radiation protection programs (NCRP, 1983). It is the mechanism by which those at risk are notified of the likelihood of exposure to radiation and the accompanying risk of adverse effects. Training provides the knowledge by which those at risk can minimize their dose and, therefore, the potential adverse effects on their health. A clear understanding of the risk from radiation in comparison with risks from other competing hazards allows one to weigh various risks to make better-informed decisions. A cavalier attitude toward radiation can lead to actions that yield unnecessarily high exposures. Likewise, excessive fear of radiation can produce decisions that trigger more severe risks and consequences than the radiation itself would have occasioned.

The U.S. Nuclear Regulatory Commission is an independent federal agency with the overall mission of protecting the public health and safety in the use of nuclear materials. It is responsible for the licensure and regulation of various entities-such as reactors, disposal sites, and research facilities (Nuclear Regu-

latory Commission, 1998). Nuclear Regulatory Commission Regulatory Guide 8.29, "Instruction Concerning Risks from Occupational Radiation Exposure," states that all individuals who in the course of their employment are likely to receive an occupational dose in excess of I mSv (100 millirem [mrem]) in a year are required to be instructed in the health protection issues associated with exposure to radioactive materials or radiation (Nuclear Regulatory Commission, 1981). This regulatory guide, which supports Title 10 requirements, describes information that should be provided to workers by licensees about health risks from occupational exposure. It requires that Nuclear Regulatory Commission licensees use procedures and engineering controls to the extent practicable to achieve occupational doses that are ALARA.

Radiation protection training for workers who are occupationally exposed to ionizing radiation is an essential component of any program designed to ensure compliance with Nuclear Regulatory Commission regulations. The Nuclear Regulatory Commission material was written with the belief that a clear understanding of what is presently known about the biological risks associated with exposure to radiation would result in more effective radiation protection training and therefore less unnecessary exposure. The employer should make available to occupationally exposed persons 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 instruction will develop respect for the risks involved rather than excessive fear or indifference.

The regulations state that instruction should be given prior to occupational exposure and periodically thereafter. The extent of this instruction should be commensurate with the radiological risks present in the workplace. The instruction should be presented orally, in printed form, or using any other effective communications media. Individuals should be given an opportunity to discuss the information and to ask questions. Testing is recommended, and each trainee should acknowledge in writing that the instruction has been received and understood.

The 17-page regulatory guide presents instruction in the form of question and answer segments. Some of the questions are as follows (Nuclear Regulatory Commission, 1981, pp. 4-14):

1. What is meant by health risk?
2. What are the possible health effects of exposure to radiation'?
3. What is meant by early effects and delayed or late effects?
4. What is the difference between acute and chronic radiation dose?
5. What is meant by external and internal exposure?
6. How does radiation cause cancer?
7. Who developed radiation risk estimates?
8. What are the estimates of the risk of fatal cancer from radiation exposure?
9. If I receive a radiation dose that is within occupational limits, will it cause me to get cancer?
10. How can we compare the risk of cancer from radiation to other kinds of health risks?

11. What are the health risks from radiation exposure to the embryo/ fetus?
12. Can a worker become sterile or impotent from normal occupational radiation exposure?
13. What are the NRC [Nuclear Regulatory Commission] occupational dose limits?
14. What is meant by ALARA?
15. What are background radiation exposures?
16. What are the typical radiation doses received by workers?
17. How do I know how much my occupational dose (exposure) is?
18. What happens if a worker exceeds the annual dose limit?
19. What is meant by a "planned special exposure"?
20. Why do some facilities establish administrative control levels that are below the NRC [Nuclear Regulatory Commission] limits?
21. Why aren't medical exposures considered as part of a worker's allowed dose?
22. How should radiation risks be considered in an emergency?
23. How were radiation dose limits established?
24. Does the NRC [Nuclear Regulatory Commission] plan to reduce the regulatory limits?
25. What are the options if a worker decides that the risks associated with occupational radiation exposure are too high?
26. Where can one get additional information on radiation risk?

• (a)	All individuals who in the course of employment are likely to receive in a year an occupational dose in excess of 100 mrem (1 mSv) shall be-

• • (1)	Kept informed of the storage, transfer, or use of radiation and/or radioactive material;

  • (2)	Instructed in the health protection problems associated with exposure to radiation and/or radioactive material, in precautions or procedures to minimize exposure, and in the purposes and functions of protective devices employed;

  • (3)	Instructed in, and required to observe, to the extent within the workers' control, the applicable provisions of Commission regulations and licenses for the protection of personnel from exposure to radiation and/or radioactive material;

  • (4)	Instructed of their responsibility to report promptly to the licensee any condition which may lead to or cause a violation of Commission regulations and licenses or unnecessary exposure to radiation and/or radioactive material;

• (5)	Instructed in the appropriate response to warnings made in the event of any unusual occurrence or malfunction that may involve exposure to radiation and/or radioactive material; and

• (6)	Advised as to the radiation exposure reports which workers may request pursuant to Sec. 19.13.

• (b)

  In determining those individuals subject to the requirements of paragraph (a) of this section, licensees must take into consideration assigned activities during normal and abnormal situations involving exposure to radiation and/or radioactive material which can reasonably be expected to occur during the life of a licensed facility. The extent of these instructions must be commensurate with potential radiological health protection problems present in the work place.

Managers are trained to understand that most decisions are made with an absence of adequate data. If data were sufficient, the objective balancing of the decision would be clear (leaving only the influence of personal and societal values to make the choice complicated). Decisions for radiation safety are most always made with insufficient data. To account for large uncertainties in the knowledge of radiation and its effects, one must make many assumptions. Evaluations of radiation risks are therefore very difficult to make—even for trained specialists in radiation safety. The process can lead to extensive debate, especially when the evaluation concerns low radiation doses. Yet, one expects radiation workers to make decisions on the basis of an informed understanding.

Central to the concept of informed understanding is the recognition that decisions regarding radiation safety involve many uncertainties. Such uncertainties arise from:

• limitations associated with data regarding the radiation source, including its type and form, concentration, containment, and environmental transport;
• limitations associated with radiation measurement, including improper application, calibration, and operation and reading of instrumentation-all of which are components of quality assurance;
• limitations arising from inappropriate interpretation of instrument readings and inappropriate use of statistical techniques;
• limitations associated with data regarding the mode of radiation exposure (e.g., internal versus external exposure and the conditions in which exposure occurred);
• limitations regarding knowledge of the quantification of radiation energy deposition in the human body, including organ dose, quality factor, dose rate, and appropriate dose measure (e.g., gray or sievert);

• limitations regarding knowledge of the effects of radiation, including the dose-response relationship; stochastic and deterministic effects; latent period; and the modifying effects of age, sex, and medical history;
• limitations associated with the ability to communicate and understand the risks associated with radiation (e.g., jargon, commonly held perceptions and mental images, fears, and cultural and language barriers);
• limitations regarding the understanding of how best to weigh the benefits and competing risks associated with radiation exposure (justification and optimization);
• limitations imposed by ill-defined ethical, legal, and liability issues associated with radiation exposure (e.g., current and future obligations, the interpretation of future risks, and concerns for mistakes); and
• limitations due to the uncertainties involved in the choice of activity objectives that may result in radiation exposure risks.

Because of the complexity of radiation risk analyses, resulting in part from the uncertainties outlined above, it is customary to make many simplifying assumptions. International scientific organizations and regulatory authorities regularly perform risk analyses and develop guidelines for radiation safety practices. In any specific circumstance, a manager may make a decision regarding radiation safety by comparing the exposures or doses with the guidelines. However, information with which to estimate the radiation dose, especially for estimating dose from internally deposited radionuclides, is not always readily available. The processes of risk perception and risk communication are complex and are the subjects of a substantial body of literature (for example, Covello, 1991; Fischhoff et al., 1984; Morgan et al., 1992; National Research Council, 1989, 1996; Slovic, 1996; Wilson, 1979). In this report, the committee provides only a brief overview.

Individuals assess risk in disparate ways on the basis of their past experiences. Some individuals would take a I in 100,000 risk, thinking that the adverse event would not happen to them. Others would not take that risk, expecting the event's occurrence. Such decisions assume cause and effect for radiation exposure without analysis of any of the uncertainties defined above.

Workers come to radiation safety training with preexisting ideas and impressions about radiation risks. These come from previous training, the attitudes of coworkers, the news media, and advice from friends and relatives. Workers filter the information presented in radiation safety training through these perceptions. Whether they hear and subsequently accept the information presented in training depends, in part, on whether the training agrees with their previous ideas. When trainers present information that is different from preconceived notions, trainees may not only be unreceptive to the new information but may also

be suspicious or doubtful of the training and therefore react with resistance or hostility. Radiation safety training therefore is more effective if risk perceptions are addressed at the beginning of a training session.

With radiation safety training, workers may change their impressions but only to the extent that the instructor helps them create new images to replace the old ones. To change impressions, trainees must see evidence that is stronger than the basis for their impressions. This means that radiation safety training must not be presented as abstract concepts but by demonstration, which allows the students to confirm new information with their own eyes and ears.

Workers or students should be invited to compare the instructor's data or information with their own experience or expectations. The challenge for an instructor is to provide new experiences and data to revise old images. This can be accomplished by inviting the class to challenge the radiation concepts that the instructor provides. This allows the instructor the opportunity to prove such concepts through the use of demonstrations or anecdotes with which the class can identify. As students absorb the proofs, they may change their images or impressions of radiation. New images lead to changes in risk perceptions, becoming a foundation for decisions based on informed understanding.

Radiation safety programs are designed and used to protect persons against ionizing radiation exposures that are unnecessary in the workplace or that are considered unacceptable to the general public. Protection limits are used and further efforts are made to keep exposures as low as reasonably achievable. The health objectives of a radiation safety program are to prevent and avoid exposures that can result in severe acute health effects and to minimize exposures that may increase the risk of developing cancer and other radiation-related health effects. To meet these objectives, the recording and maintenance of all relevant exposure information is essential (ICRP, 1991 a) and serves to (NCRP, 1992)

• aid in the protection of individuals;
• evaluate the effectiveness of the radiation protection programs;
• provide for accuracy, reliability, confidentiality, and retrievability of data;
• provide evidence of regulatory compliance;
• provide data for epidemiologic studies; and
• provide information for making or contesting claims for radiation-induced injury.

As an example of the scope of information contained in radiological exposure records, the International Atomic Energy Agency (IAEA, 1996) requires that occupational exposure records be maintained for each worker. These records should include (IAEA, 1996, Appendix I):

• (a)	information on the general nature of the work involving occupational exposure;

• (b)	information on doses, exposures and intakes at or above the relevant recording levels and the data upon which the dose assessments have been based;

• (c)	when a worker is or has been occupationally exposed while in the employ of more than one employer, information on the dates of employment with each employer and the doses, exposures and intakes in each such employment; and

• (d)	records of any doses, exposures or intakes due to emergency interventions or accidents, which shall be distinguished from doses, exposures or intakes during normal work and which shall include references to reports of any relevant investigations.

Workers are provided access to information in their own exposure record; however, due care and attention must be given to the maintenance of the appropriate confidentiality of the records.

Exposure records are to be preserved not only during the worker's working life but also at least until the worker attains or would have attained the age of 75 years and for not less than 30 years after the termination of the work involving occupational exposure.

The U.S. Department of Energy requires of its operations a records management program that includes the following (DOE, 1994, p. 7-3):

1. Radiological Policy Statements
2. Radiological Control Procedures
3. Individual Radiological Doses
4. Internal and External Dosimetry Policies and Procedures (including Bases Documents)
5. Personnel Training (course records and individual records)
6. As Low as Reasonably Achievable (ALARA) Records
7. Radiological Instrumentation Test, Repair and Calibration Records
8. Radiological Surveys
9. Area Monitoring Dosimetry Results
10. Radiological Work Permits
11. Radiological Performance Indicators and Assessments
12. Radiological Safety Analysis and Evaluation Reports
13. Quality Assurance Records
14. Radiological Incident and Occurrence Reports (and Critique Reports, if applicable)
15. Accountability Records for Sealed Radioactive Sources
16. Records for Release of Material to Controlled Areas
17. Reports of Loss of Radioactive Material.

18. The following are among the commonly kept records on radiation exposures.

Program documents record any authorizations and accreditations that allow or regulate the exposure of individuals to radiation (e.g., radioactive material licenses from the U.S. Nuclear Regulatory Commission or U.S. Department of Defense authorizations to possess radioactive commodities). They also include all documentation necessary to define the radiation protection program that safeguards the health and well-being of workers. Among these records one would find records of training programs, dosimetry procedures, environmental monitoring plans, and documentation of efforts to keep exposures ALARA.

Individual records document relevant data on each individual exposed to radiation as part of his or her occupational duties. These include items such as exposure categories for individuals (e.g., managers who receive minimal radiation doses versus technicians who receive larger doses). Also of interest are individual dose records (internal and external), training records, and details of any overexposures, as well as age, sex, and other identification data that allow individuals to be followed in epidemiologic studies. Records should follow the individual as he or she changes employer or work situation. It also is useful to record individual work history and conditions. This allows the calculation of accumulated internal dose and, when necessary, verification of external dosimetry information after an exposure occurs.

Workplace records document activities and conditions in the environs of the individual exposures. These records include data on radiation levels in various areas, descriptions of restricted areas, descriptions of activities that require personnel exposures (work permits), records of movements of radioactive materials, data on the availability and condition of protective equipment, and documentation of accidents and incidents.

Environmental records document radiologically significant characteristics of the environment and include results of measurements of the radionuclide contents of the air, ground, and water. These records can be valuable in reconstructing the doses received by personnel who may have been exposed during a release of radioactivity.

Instrumentation records are maintained to document the availability, calibration, maintenance, and capability of radiation detection and measurement devices. These records are used for quality control purposes to ensure the accuracy of radiological measurements.

Regulations require that Nuclear Regulatory Commission licensees advise each worker annually of his or her total radiation dose for that year and the total career dose. If a former worker requests dose information, a licensee must furnish a report of that worker's exposure within 30 days of the time of the request or within 30 days after the exposure has been determined by the licensee (CFR, 1998b).