Deploying military personnel in hostile or unfamiliar environments is inherently risky. Unlike garrison environments, which are reasonably well-protected, well-known, and well-controlled, deployment environments are imposed by the military mission. Deployment can present a novel array of military and nonmilitary threats, and mission objectives often dictate that those threats be addressed. Many deployment activities are not routine. Tasks must be accomplished with limited means, despite the potential dangers of the setting. In the deployment environment, time, materiel, and attention are at a premium, and excessive precautions can engender their own risks or jeopardize the military mission.

In the past, health-based risk-assessment and risk-management strategies for deployment situations focused primarily on warfare-related mission impacts. However, recent wars and conflicts, such as operations Desert Shield and Desert Storm, have highlighted the need for the U.S. military to protect its forces from health threats that do not directly impact the mission, are indirectly related to battle, or could appear after the deployment has ended. Thus, the U.S. Department of Defense (DOD) has developed a force health protection plan that is a “unified and comprehensive strategy that aggressively promotes a healthy and fit force and provides full protection from all potential health hazards throughout the deployment process. Its major ingredients include healthy and fit force promotion, casualty and injury prevention, and casualty care and management” (U.S. Department of

the Army 2001). “Deployment” is defined as a troop movement to a land-based location outside the continental United States that does not have a permanent medical treatment facility (i.e., funded by the Defense Health Program). Deployment is the result of a Joint Chiefs of Staff/Unified Command deployment order and lasts for 30 or more consecutive days (U.S. Department of the Army 2001).

The role of U.S. military forces has changed and expanded. Increasingly, U.S. troops are deployed for operations other than war, including peacekeeping, humanitarian, and nation-building missions of varying scope and duration. (See Figure 1-1 for an illustration of potential conflicts and likelihood of occurrence.) Deployments differ in the degree and nature of tactical risks (i.e., risk due to the presence of an enemy or adversary). However, with or without tactical threats, there are risks of accident, disease, and illness inherent in deployment. Those might arise from contaminated local environments, from the intensive activities of the deployed forces, from exposure to hazards associated with mission tasks, from intentional exposures to pesticides and prophylactic agents, and from the rigors of exposure to climatic extremes.

In deployment situations, commanders must balance the effects of multiple risks. Effects can include casualties, impacts on civilians, damage to the environment, loss of equipment, and levels of public reaction against the value of the mission objectives. The Army’s Field Manual 100-14 (U.S. Department of the Army 1998) outlines the principles, procedures, and responsibilities of applying an operational risk-management (ORM) process to conserve combat power and resources. The manual defines risk management as “the process of identifying, assessing, and controlling risks arising from operational factors and making decisions that balance risk costs with mission benefits. . . . It applies to all missions and environments across the wide range of Army operations.” The ORM process is a cycle of (1) identifying hazards, (2) assessing the risk associated with those hazards, (3) developing controls and making risk decisions, (4) implementing the controls, and (5) supervising and evaluating the effectiveness of the controls. The process is depicted in Figure 1-2. The basic principles for implementing the process include the following:

• Integrating risk management into mission planning, preparation, and execution. Leaders and staff continuously identify hazards and assess both accidental and tactical risks. They then develop and coordinate control measures. They determine the level of residual risk for accidental hazards in order to evaluate courses of action, and they integrate control

FIGURE 1-2 Continuous application of risk management. Source: Modified from U.S. Department of the Army 1998.

measures into staff estimates, operational plans (OPLANs), operation orders (OPORDs), and missions. Commanders assess the areas in which they might take tactical risks. They approve control measures that will reduce risks. Leaders ensure that all soldiers understand and properly execute risk controls. They continuously assess variable hazards and implement new risk controls.

• Making risk decisions at the appropriate level in the chain of command. The commander should address risks in his guidance. He should base his risk guidance on established Army and other appropriate policies and on his higher commander’s direction. He then gives guidance on how much risk he is willing to accept and delegate. Subordinates seek

the commander’s approval to accept risks that might imperil the next higher commander’s intent.

• Accepting no unnecessary risk. Commanders compare and balance risks against mission expectations and accept risks only if the benefits outweigh the potential costs or losses. Commanders alone decide whether to accept the residual risk to accomplish the mission.

As part of the DOD’s force health protection program, the U.S. Army is developing strategies and methods for assessing the broad range of potential occupational and environmental health (OEH) threats that might occur as a result of deployment. Those threats include chemical, radiological, biological, entomological, and endemic-disease hazards. In the past, Army policies addressed health threats under only two deployment conditions—garrison peacetime deployment and wartime deployment. No guidance was available for the range of deployments that fall between those mission extremes. Recognizing this need for guidance, the Army developed an OEH policy intended to address the broad spectrum of possible military operations, activities, and scenarios (U.S. Department of the Army 2001). The goal of the policy is to allow commanders to make informed decisions about OEH hazards and there by minimize the total risk to soldiers and civilian personnel executing a range of military operations. To help commanders consider chemical OEH threats in their strategic decision-making process, the Army has developed two technical guides (Technical Guide 230 and Technical Guide 248) and one reference guide (Reference Document 230) that propose methods for assessing and managing chemical risks to deployed personnel. This NRC report reviews those documents for their scientific validity and their conformance with current understanding of risk-assessment practices.

The technical guides and reference document were informed by the efforts of several task forces and committees that have spent years evaluating the health of veterans; ensuring appropriate evaluation and care of veterans’ health concerns; determining connections between service in the Persian Gulf, specific exposures, and veterans’ health status; and developing guidance to help prevent and reduce unanticipated illnesses in future deployments. Reports from these groups include Presidential Review Directive 5 (NSTC 1998), Potential Radiation Exposure in Military Operations (IOM 1999a), DOD Strategy to Address Low-Level Exposures to Chemical Warfare Agents (DOD 1999), and Protecting Those Who Serve (IOM 2000) and its supporting reports, Strategies to Protect the Health of Deployed U.S.

Forces (IOM 1999b; NRC 1999; 2000a,b). The following considerations from those reports were instrumental in shaping the Army guidance:

• Full range of deployment scenarios (as illustrated in Figure 1-1).

• Broad range of chemical types, including those that are unique to the military (e.g., chemical warfare agents, depleted uranium, smokes, and obscurants) and those that might be present at the deployment site (e.g., pesticides, toxic industrial chemicals).

• Low-level exposures. The military has focused on exposures to high concentrations of chemicals because those exposures are the most likely to have direct negative consequences on the success of missions. However, more attention is being given to possible health effects from exposures to low concentrations of chemicals, particularly exposures that occur over an extended period of time.

• Personnel assumptions. In the past, deployed military populations were assumed to consist of healthy, physically fit men and nonpregnant women. Although personnel must meet certain health and fitness requirements, the military now recognizes that deployed populations (active duty, reserve, and National Guard personnel) can include individuals with health factors that might make them more susceptible to certain chemicals.

• Broad range of health effects. Historically, the military primarily was concerned with health threats that would affect deployed personnel immediately, because those might have the potential to affect the success of the mission. Operational planning now includes more emphasis on considering the risk of health effects that could occur months or even years after exposure.

Technical Guide 248 (TG-248) (USACHPPM 2001) proposes processes and tools to be used by preventive-medicine personnel for evaluating and communicating the occupational and environmental health (OEH) and endemic disease (ED) risks of deployment to commanders in accordance with the Army’s ORM process. The process it proposes is intended to (1) document OEH/ED hazards and exposures to soldiers and the force, (2) characterize the risk of OEH/ED hazards during all phases of deployment, (3) communicate risks in understandable terms to commanders and operational planners, (4) allow the commanders’ staffs to develop courses of

action that consider and/or minimize OEH/ ED risks to the force, and (5) provide data to assist in post-deployment health assessments and evaluations of OEH/ED operational risk-management processes. The overall goal of TG-248 is to characterize OEH/ED risks in such a way that they can be placed in a similar ranking scale with each other and with other operational hazards. This report focuses on the usefulness of TG-248 for evaluating chemical hazards only, and not radiological, biological, entomological, or endemic disease hazards.

Technical Guide 230 (TG-230) (USACHPPM 2002a) presents proposed military exposure guidelines (MEGs) for chemicals in air, water, and soil. A MEG is an estimated chemical concentration above which certain types of adverse health effects might begin to occur in individuals within the exposed population after a continuous, single exposure of specified duration. MEGs are used for deployment purposes only and are different from occupational standards for garrison situations. MEGs are used to assess the significance of field exposures to chemical hazards during deployment. They are designed to address a variety of exposure conditions not covered by occupational or other standards used in garrisons, such as a single catastrophic release of large amounts of a chemical, temporary exposures lasting hours or days, continuous ambient environmental conditions (e.g., regional pollution), use of a contaminated water supply, or persistent soil contamination.

MEGs were developed for chemicals for which information was readily available and for chemicals that were otherwise identified by the Army as key hazards of concern, including chemical warfare agents and toxic industrial chemicals. For air contaminants, the Army developed MEGs for exposure durations of 1 hour, 8 hours, 24 hours, 14 days, and 1 year. For water contaminants, MEGs were developed for exposure durations of 5 days, 14 days, and 1 year. For soil contaminants, only 1-year MEGs were developed, because short-term exposure guidelines were deemed unnecessary. The Army does not anticipate that soil contamination will be an immediate or severe hazard. Severely contaminated soils are often easily detected because of odors, dead or discolored vegetation, or free chemical product.

TG-230 proposes a standardized process for using MEGs to characterize the levels of health and mission risk associated with chemical exposures in accordance with the military’s ORM paradigm. The guidance is intended for use by preventive-medicine personnel, environmental staff officers, industrial hygienists, health risk assessors, and other medically trained personnel. An important element of the assessment process outlined in TG-230 involves the distinction between a “health threat” and a “medical

threat.” A health threat would affect an individual soldier’s health, whereas a medical threat refers to a subset of health threats that have the potential to degrade a unit’s combat (or mission) effectiveness.

TG-230 is supported by Reference Document 230 (RD-230) (USACHPPM 2002b), which provides details of the scientific rationale and assumptions that were used to derive the MEGs. The general approach for deriving MEGs was to select the most relevant existing exposure guidelines or peerreviewed toxicological estimates developed for workers and the general population by government agencies or other organizations and to accept or adjust those values for deployment scenarios. The Army selected that approach because it was the most expedient and least costly way to develop exposure guidance for a large number of chemicals.

The National Research Council (NRC) was asked to independently review TG-248, TG-230, and RD-230 for their scientific validity, completeness, and conformance to current risk-assessment practices. The subcommittee was asked to review the Army’s documents, identify deficiencies, and make recommendations for improvements. The subcommittee was asked to focus specifically on the following issues:

1. The Army’s risk assessment, hazard-ranking, and risk-management processes described in TG-230 and its supporting documents.

2. The use of pre-existing exposure guidelines developed by the NRC and other agencies and organizations and the hierarchical scheme used by the Army in selecting from those various guidelines.

3. The Army’s approaches to deriving MEGs for criteria pollutants, lead, soil contaminants, and other chemical contaminants.

4. Technical aspects of the Army’s risk-management framework (as presented in TG-248) regarding competing health risks from different chemicals.

5. The assumption that the military population includes susceptible subpopulations (e.g., personnel with unknown health conditions, asthma, undetected pregnancies in the first trimester) and the use of uncertainty factors in the derivation of MEGs.

6. The adjustments of exposure guideline values to account for differences in exposure durations in the derivation of MEGs.

7. The exposure assumptions and mathematic models used for the derivation of MEGs for air, water, and soil contaminants.

8. Technical aspects of the Army’s acceptable cancer risk level of 1 in 10,000.

9. The balance of emphasis between health effects that are produced immediately or soon after exposure and possible delayed effects (e.g., cancer) in the derivation of MEGs for chemical warfare agents and toxic industrial chemicals.

10. The use of a single risk-assessment methodology for assessing the toxicological risk from exposures to chemical warfare agents and toxic industrial chemicals rather than separate risk-assessment methodologies.

11. The assumption that the toxicity of a mixture of chemicals that have similar modes of action will be equal to the sum of the toxicities of individual chemicals in the mixture.

12. The utility of TG-248, TG-230, and RD-230 for decision makers (who might not be knowledgeable about toxicology or the science behind the health risk-assessment process) who will be using MEGs in the field.

To accomplish its task, the subcommittee held four meetings between October 2002 and August 2003. The first two meetings involved data-gathering sessions that were open to the public. The subcommittee heard presentations from DOD, on its force health protection program, and from the U.S. Army Center for Health Promotion and Preventive Medicine, the service organization responsible developing TG-230, RD-230, and TG-248. The subcommittee critically evaluated TG-230, RD-230, and TG-248 as well as other supporting documentation from the Army. The documents were evaluated for their technical soundness, conformance with current risk-assessment practice, and utility for the intended user.

This report is organized into four chapters. Chapter 2 reviews the framework provided in TG-248 and TG-230 for assessing and managing mission and health risks from chemical exposures. Chapter 3 reviews the key concepts, assumptions, and decisions made in developing TG-248, TG-230, and RD-230. Chapter 4 outlines the subcommittee’s recommended approach to characterizing mission risks, and Chapter 5 presents how MEGs should be improved to support health risk assessment and determine health risk management options. Table 1-1 presents a list of tasks and the corresponding chapters and relevant pages.

Ciesla, J.J. 2002. Military Operational Deployments. An Information Brief for the National Research Council. Presentation at the First Meeting on Toxicological Risk to Deployed Military Personal, October 2, 2002, Washington, DC.

DOD (U.S. Department of Defense). 1999. DOD Strategy to Address Low-Level Exposures to Chemical Warfare Agents (CWAs). May 1999. [Online]. Available: http://chppm-www.apgea.army.mil/chemicalagent/caw/lowlevestrategy.PDF [accessed November 25, 2003]

IOM (Institute of Medicine). 1999a. Potential Radiation Exposure in Military Operations: Protecting the Soldier Before, During, and After. Washington, DC: National Academy Press.

IOM (Institute of Medicine). 1999b. Strategies to Protect the Health of Deployed U.S. Forces: Medical Surveillance, Record Keeping, and Risk Reduction. Washington, DC: National Academy Press.

IOM (Institute of Medicine). 2000. Protecting Those Who Serve: Strategies to Protect the Health of Deployed U.S. Forces. Washington, DC: National Academy Press.

NRC (National Research Council). 1999. Strategies to Protect the Health of Deployed U.S. Forces: Force Protection and Decontamination. Washington, DC: National Academy Press.

NRC (National Research Council). 2000a. Strategies to Protect the Health of Deployed U.S. Forces: Analytical Framework for Assessing Risks. Washington, DC: National Academy Press.

NRC (National Research Council). 2000b. Strategies to Protect the Health of Deployed U.S. Forces: Detecting, Characterizing, and Documenting Exposures. Washington, DC: National Academy Press.

NSTC (National Science and Technology Council). 1998. A National Obligation Planning for Health Preparedness for and Readjustment of the Military, Veterans, and Their Families after Future Deployments. Presidential Review Directive 5, Executive Office of the President, Office of Science and Technology Policy, Washington, DC.

USACHPPM (U.S. Army Center for Health Promotion and Preventive Medicine). 2001. Guide for Deployed Preventive Medicine Personnel on Health Risk Management. Technical Guide 248. U.S. Army Center for Health Promotion and Preventive Medicine. August 2001. [Online]. Available: http://chppm-www.apgea.army.mil/deployment/ [accessed November 25, 2003].

USACHPPM (U.S. Army Center for Health Promotion and Preventive Medicine). 2002a. Chemical Exposure Guidelines for Deployed Military Personnel. Technical Guide 230. U.S. Army Center for Health Promotion and Preventive Medicine. January 2002. [Online]. Available: http://chppm-www.apgea.army.mil/deployment/ [accessed November 25, 2003].

USACHPPM (U.S. Army Center for Health Promotion and Preventive Medicine). 2002b. Chemical Exposure Guidelines for Deployed Military Personnel. A Companion Document to USACHPPM Technical Guide (TG) 230 Chemical Exposure Guidelines for Deployed Military Personnel. Reference Document (RD) 230. U.S. Army Center for Health Promotion and Preventive Medicine January 2002. [Online]. Available: http://chppm-www.apgea.army.mil/deployment/ [accessed November 25, 2003].

U.S. Department of the Army. 1998. Risk Management, Field Manual No. 100-14. U.S. Department of the Army, Washington, DC. April 23, 1998.

U.S. Department of the Army. 2001. Force Health Protection (FHP): Occupational and Environmental Health (OEH) Threats. HQDA Ltr 1-0-1. U.S. Department of the Army, Washington, DC. June 27, 2001.