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

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.

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).

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):

1. 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.
2. This regulation does NOT apply to the following:

3. (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—

4. • (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.

5. • (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.

6. (Emphases have been added.)

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.

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.

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.

The U.S. Army radiation safety program is a three-tiered system that addresses the following:

1. exposure to soldiers doing routine radiation jobs, absent hostilities;
2. exposure that is incident to military operations but that is at levels below those that can cause acute effects; and

3. exposure that is incident to nuclear war and that is at levels that can cause acute effects.