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--> 4 Current Paradigms for Radiation Protection in the U.S. Army The U.S. Army has three separate programs to control the radiation exposures of soldiers. One is applied to those individuals whose duties parallel those of civilian radiation workers. These include military personnel such as x-ray technicians, radiologists who do radiological examinations, researchers who use radioisotopes, and technicians who maintain radioactive commodities such as radiation detection instruments and calibration sources. The second applies to soldiers whose primary occupation does not usually expose them to radiation. These are the soldiers who might respond to a military situation, such as that covered by Allied Command Europe Directive (ACE) 8063 (NATO, 1996), in which radiation is present, but at doses not exceeding 700 millisievert (mSv). The Army's third radiation protection program is intended to apply only during situations of extremely high radiation exposure, such as nuclear war. Occupational Exposure In peacetime, radiation exposures of soldiers who are considered to be at such risk in the execution of their duties are governed by radiation protection regulations (DoDI, 1996) that are comparable to those of their civilian counterparts. The radiation limits prescribed by these regulations (see examples in Table 2-3) are derived from U.S. Nuclear Regulatory Commission standards, which for the most part reflect the recommendations of the International Commission on Radiation Protection (ICRP) and the National Council on Radiation Protection and Measurements (NCRP).
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--> Radioactive commodities in the U.S. Army are controlled, as they are in civilian industrial operations, under licenses issued by the Nuclear Regulatory Commission. Exposures that could result from the fabrication, maintenance, or application of these radioactive commodities are subject to control under civilian regulations (CFR, 1991) that tend to adhere to the general philosophy and implement practices espoused by ICRP and NCRP. Army-specific requirements for control and safe handling of radioactive commodities are under the jurisdiction of the Army Materiel Command (AMC, 1980), whereas the protection of individual soldiers is a medical function under the purview of the Office of the Surgeon General (OTSG, 1995a, b). Two medical documents from the Office of the Surgeon General constitute the bulk of the individual radiation protection program in the Army. Although the regulations provide a measure of radiation protection for soldiers that parallels that for civilians in similar environments and under similar circumstances, they do not extend that same protection in militarily unique missions, as the following excerpt from Army (Medical) Regulation 40-14 demonstrates (OTSG, 1995a): Applicability. This regulation applies to Department of the Army (DA) and Defense Logistics Agency (DLA) installations and activities. This includes the Army National Guard of the United States (ARNGUS), U.S. Army Reserve (USAR), and civilians under contract with the DA or DLA who perform tasks involving occupational exposure to DA and DLA controlled radioactive material or radiation-producing devices. This publication is not applicable during mobilization or anytime the U.S. Army adopts a state of readiness directly preparatory to actual or imminent armed conflict in a geographical zone where peacetime occupational radiation exposure conditions cannot reasonably be construed to prevail. In particular, this regulation remains applicable to DA and DLA personnel deployed on either humanitarian or peacekeeping missions where the degree of readiness to respond to hostile fire requires the availability of radioactive commodities, such as depleted uranium ammunition, as a contingency. This regulation does NOT apply to the following: (1) Personnel exposed to ionizing radiation and radioactive materials resulting from the use of ionizing radiation sources and devices in geographical areas or zones where— (a) Hostile fire or combat already exists or is strongly anticipated to occur, or (b) Combat missions are intentionally going to be conducted by Department of Defense personnel. (2) Patients exposed to ionizing radiation in the course of medical and dental examination, diagnosis, or treatment. This exception does not apply to health care providers. (3) Human research subjects exposed to ionizing radiation in the course of voluntary participation in medical research programs. (4) Doses received from natural background radiation. (Emphases have been added.)
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--> Non-Occupational Exposures up to 700 Millisievert Between the 50-mSv occupational annual dose limit and the 700-mSv threshold for the development of acute health effects that become a concern during nuclear war, there is a broad band that has just recently been addressed by Army planners. ACE Directive 80-63 (NATO, 1996), developed by Army and North American Treaty Organization (NATO) planners, is an encouraging step in filling that void. This committee's interim report (IOM, 1997) described and offered a detailed critique of the August 1996 version of NATO ACE Directive 80-63. The ACE Directive (NATO, 1996) is reprinted as Appendix A of this report. The guidance for radiation safety in this middle ground is evolving as the Army considers this committee's interim report recommendations and develops policies and procedures regarding the needs of the soldier for radiation safety in the field. Since the Institute of Medicine publication of the interim report, NATO and the U.S. Army have each held meetings to further develop policies related to low level radiation. The U.S. Army Nuclear and Chemical Agency (USANCA) coordinated a joint-service meeting to establish recommended U.S. positions for representatives of the United States to take to NATO meetings. Among other recommendations (USANCA, 1998), that group drafted a revised Operational Exposure Guidelines table. Table 4-1 displays the table as it appeared in the August 1996 draft of the ACE Directive (NATO, 1996). Table 4-2 is the revised version distributed by the U.S. Army in May 1998. The revised table differs from the ACE Directive Annex A most by replacing the use of the narrative descriptors of ''State"-expressed as No, Normal, Minimal, Limited, Increased, or Significant Risk-with quantitative estimates of "Increased Risk of Long Term Fatal Cancer"-expressed as None, 1:4,000, 1:400, 1:200, 1:80, and 1:30. The footnotes have been revised minimally. High-Level Exposures in Nuclear War During times of war the radiation to which soldiers are exposed has been assumed to be the result of nuclear weapons detonation. Soldiers have been trained to operate in a nuclear environment since the advent of nuclear weapons, and such training continues to this day (HQDA, 1983, 1992, 1993). The radiation protection practices to be used under these conditions have been driven by the need for soldiers to survive to accomplish their immediate missions. In this scenario, the risk of stochastic effects, including cancer, has been a secondary concern.
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--> TABLE 4-1. Draft (August 2, 1996) Operational Exposure Guidance for Low-Level Radiation Total Cumulative Dose (cGy)a Radiation Exposure State Category Stateb Actions [<0.5 mGy] <0.05 cGy 0 No risk None [0.5-5 mGy] 0.05-0.5 cGy 1A Normal risk Record individual dose readings Initiate periodic monitoring [5-50 mGy] 0.5-5 cGy 1B Minimal risk Record individual dose readings and continue monitoring Initiate rad survey Prioritize tasks Establish dose control measures as part of operations [50-100 mGy] 5-10 cGy 1C Limited risk Record individual dose readings Continue monitoring and update survey Continue dose control measures Execute priority tasks onlyc [100-250 mGy]d 10-25 cGy 1D Increased risk Record individual dose readings Continue monitoring and update survey Continue dose control measures Execute critical tasks onlyd [250-700 mGy]e 25-70 cGy 1E Significant risk Record individual dose readings Continue monitoring and update survey Continue dose control measures Execute critical tasks only
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--> a Dose is uniform to the entire body due to whole-body irradiation. This table does not consider the intake of radioactive material. This is assumed because of the employment of effective respiratory protection and other measures. All doses should be kept as low as reasonably achievable (ALARA). This will reduce the risk to the individual soldier and will retain maximum operational flexibility for future employment of exposed soldiers. The use of the measurement millisievert (mSv) is preferred in all cases. However, due to the fact that normally the military has only the capability to measure centigray (cGy), as long as the ability to obtain measurements in millisievert is not possible, ACE forces will use centigray. For whole-body gamma irradiation, 1 cGy is equivalent to 10 mSv. b Risk is of long-term health consequences, primarily induction of fatal cancer starting 2 years postexposure. Total lifetime risk is assumed to be 4 to 7 percent per 100 cGy (1,000 mSv). This is in addition to the 20 to 25 percent incidence of fatal cancer among the general population. Additional health risks that may occur are teratogenesis and mutagenesis and their associated psychological and social consequences. It must be noted that higher radiation dose rates produce proportionally more other health risk than the same total dose given over a longer period. c Examples of priority tasks are those missions required to avert danger to persons or to prevent damage from spreading. Examples of critical tasks are those missions required to save human lives. d During peacetime this dose shall not be exceeded except to save human lives. e RES [Radiation Exposure State] category 1E covers a wide range of doses and its lower level (25 cGy = 250 mSv) is the peacetime maximum operational dose in many NATO nations. This category is normally applicable only in wartime. Intentional exposures to doses in this category (25 to 70 cGy = 250 to 700 mSv) require additional justification. SOURCE: NATO. ACE Policy for Defensive Measures against Low Level Radiological Hazards during Military Operations; ACE Directive Number 80-63. Brussels, Belgium: Supreme Allied Headquarters Europe, August 2, 1996 (with minor editorial revisions).
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--> TABLE 4-2. Revised, Low Level Radiation Guidance for Military Operations (Draft, Received May 1998) Total Cumulative Dosea Radiation Exposure State Category Recommended Actions Increased Risk of Long-Term Fatal Cancerb [<0.5 mGy] 0-0.05 cGy 0 None None [0.5-5 mGy] 0.05-0.5 cGy 1A Record individual dose readings Initiate periodic monitoring 1:4,000 [5-50 mGy] 0.5-5 cGy 1B Record individual dose readings Continue monitoring Initiate rad survey Prioritize tasks Establish dose control measure as part of operations 1:400 [50-100 mGy] 5-10 cGy 1C Record individual dose readings Continue monitoring Update survey Continue dose control measures Execute priority tasks onlyc 1:200 [100-250 mGy] 10-25 cGy 1D Record individual dose readings Continue monitoring Update survey Continue dose control measures Execute critical tasks onlyd 1:80 [250-700 mGy] 25-70 cGy 1E Record individual dose readings Continue monitoring Update survey Continue dose control measures Execute critical tasks onlye 01:30 a The use of the measurement millisievert is preferred in all cases. However, due to the fact that normally the military has only the capability to measure centigray (cGy), as long as the ability to obtain measurements in millisievert is not possible, U.S. forces will use centigray. For whole-body gamma irradiation, 1 cGy is equal to 10 mSv. All doses should be kept as low as reasonably achievable (ALARA). This will reduce the risk to individual soldiers and will retain maximum operational flexibility for future employment of exposed soldiers.
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--> b This is in addition to the 1:5 and 1:4 incidence of fatal cancer among the general population. Increased risk is given for induction of fatal cancer (losing an average of 24 years of life for personnel ages 20 to 30 years). Total lifetime risk is assumed to be 4 to 7 percent per 100 cGy (-1,000 mSv). It must be noted that higher radiation dose rates produce proportionally more health risks than the same total dose given over a longer period. c Examples of priority tasks are those missions to avert danger to persons or to prevent damage from spreading. d Examples of critical tasks are those missions required to save lives. SOURCE: USANCA. Current U.S. Positions on Low Level Radiation (LLR) in Military Operations. Memorandum for Committee on Battlefield Radiation Exposure Criteria, Institute of Medicine, May 18, 1998 (with minor editorial revisions). NATO Standardization Agreement 2083 (NATO, 1986) defines exposure criteria for use in planning for the commitment of troops to a radiologically contaminated area that would result in high-level exposures to radiation. The U.S. Army implements these criteria through the use of Field Manual 3-3-1 (HQDA, 1994) to control the cumulative radiation dose received by combat units. One of four radiation exposure state (RES) categories (Table 4-3) is assigned to a unit, depending on its cumulative dose. The unit dose is an average of the doses to individuals in the unit who have dosimeters. Protocol requires that during operations in a nuclear environment, individual dosimeters be read daily and that the readings be passed up the chain of command. Records of summary exposure data are maintained at the battalion level for subordinate company- and platoon-sized units and are then forwarded to higher commands, which keep more broadly aggregated records. Currently, the U.S. Army does not record the doses received by individual soldiers who are exposed to radiation on the battlefield. Doctrine requires that two soldiers per squad (about 25 percent; a platoon usually has three squads) have self-reading dosimeters. Until it implements the use of individual dosimeters, the Army assumes that each soldier receives an individual dose equal to that of the average for the platoon (HQDA, 1994). The Army eventually plans to equip each soldier with a dosimeter, but the type expected to be deployed (DT236) will be useful for recording only external doses in excess of about 100 mSv. Since the platoon is the lowest aggregate level for which records are kept, replacements for exposed units are made at the platoon level. When a soldier leaves an exposed unit, the RES for that platoon (not the soldier's individual dose) is noted in the soldier's personnel file. Where possible, soldiers are reassigned to platoons with the same RES category. Although this creates severe management problems, it is intended to keep personnel from incapacitation due to overexposure to radiation.
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--> TABLE 4-3. Nuclear Radiation Exposure Status and Degree of Risk Exposure Radiation Exposure Status Categorya Total Past Cumulative Doseb Possible Exposure Criteria for a Single Operation That Will Not Result in Exceeding the Dose Criteria for the Stated Degree of Riskc RES-0 No exposure Negligible risk: ≤50 cGy (500 mGy) Moderate risk: ≤70 cGy (700 mGy) Emergency risk: ≤ 150 cGy (1,500 mGy) RES-1 More than 0, but less than or equal to 70 cGy (700 mGy) Negligible risk: <10 cGy (100 mGy) Moderate risk: ≤30 cGy (300 mGy) Emergency risk: ≤110 cGy (1.100 mGy) RES-2 More than 70 cGy (700 mGy), but less than or equal to 150 cGy (1,500 mGy) Any further exposure is considered to exceed a negligible or moderate risk. Emergency risk: ≤40 cGy (400 mGy) RES-3 More than 150 cGy (1,500 mGy) Any further exposure will exceed the emergency risk. a Radiation status categories are based on previous exposure to radiation. Reclassification of units from one radiation status category to a less serious one is made by the commander, upon advice of the surgeon, after ample observation of the actual state of health of exposed personnel. b All exposures to radiation are considered total body and simply additive. No allowance is made for body recovery from radiation injury. c Risk levels are graduated within each status category to provide more stringent criteria as the total radiation dose accumulated becomes more serious. The exposure criteria given for RES-1 and RES-2 units should be used only when the numerical value of a unit's total past cumulative dose is unknown. Each of the degrees of risk can be applied to radiation hazards resulting from enemy or friendly weapons, or both, and from initial nuclear radiation resulting from planned friendly supporting fire. SOURCE: HQDA. Nuclear Contamination Avoidance, Field Manual 3-3-1. Washington, D.C.: Headquarters, Department of the Army, 1994. Summary of Existing Army Programs The U.S. Army radiation safety program is a three-tiered system that addresses the following: exposure to soldiers doing routine radiation jobs, absent hostilities; exposure that is incident to military operations but that is at levels below those that can cause acute effects; and
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--> exposure that is incident to nuclear war and that is at levels that can cause acute effects. The first level is comparable to civilian radiation safety programs and treats soldiers in a manner similar to that in which occupational workers who are engaged in radiation practices are treated. At the second level, soldiers are engaged in military activities that may or may not be comparable to routine practices and that can resemble emergency response activities. Unlike in the first level, in the second level the military mission may override or curtail radiation safety considerations. The highest level is uniquely military and involves combat in times of nuclear war. At these radiation exposures, lethality or acute effects are expected. This level is beyond the scope of this report and will not be discussed further. In the next chapter, the committee discusses how the current military programs, when augmented by the proposed guidance, meet the scientific, ethical, and legal requirements discussed previously.
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