Review of the Army's Technical Guides on Assessing and Managing Chemical Hazards to Deployed Personnel (2004) / Chapter Skim
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3 Review of Key Concepts, Assumptions, and Decisions Made in Developing TG-248, TG-230, and RD-230
3 Review of Key Concepts, Assumptions, and Decisions Made in Developing TG-248, TG-230, and RD-230
Pages 47-75
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From page 47... ...
The subcommittee evaluated the following aspects of the Army's guidance: the use and adaptation of pre-existing exposure guidelines for deployment purposes; population susceptibilities; exposure factors; acceptable lifetime cancer risk; immediate and long-term health effects; aggregate exposure and cumulative risk; exposure assessment; and the utility of the guidance for decision makers. USE OF PRE-EXISTING EXPOSURE GUIDELINES Military exposure guidelines (MEGs)
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From page 48... ...
Procedures for Developing Noncancer and Cancer Health Assessments The following procedures typically are used by regulatory and other agencies to establish health-protective exposure guidelines and therefore form bases of the MEGs. Noncancer Assessments Mostnoncancerassessmentsbeginbyselectingano-observed-adverseeffect level (NOAEL)
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From page 49... ...
include all of the UFs except the duration adjustment, because guidelines are developed for several durations. The use of UFs differs among the existing exposure guidelines, leading the current MEGs to vary in their conservatism.
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From page 51... ...
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From page 52... ...
A "slope factor" is generated that is the upper bound (usually the 95% confidence limit) of the increased cancer risk from a lifetime exposure.
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From page 53... ...
Historically, it has been assumed that the healthy men and women volunteers composingthemilitary populationwouldhavefewpredisposingconditions that might make them sensitive or susceptible to environmental chemicals. In contrast, TG-230 and RD-230 assume that deployed populations include a more substantial representation of subpopulations that might be more sensitive to chemical exposures.
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From page 54... ...
The distribution of genetic variability might not reflect the ultimate variability in responses toachemical,becauseadditionalcompensatory mechanisms,suchasredundant pathways, homeostatic mechanisms, and repair processes, could operate. At present, there is insufficient information to explicitly incorporate genetic susceptibility into exposure guidance except in the case of a few chemicals, including chemical warfare agents that act through cholinesterase inhibition.
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From page 55... ...
values, it is assumed that the worker population is composed of relatively healthy adults, and therefore, the standards are not designed to be protective of sensitive subpopulations. There are a few guidelines that have been developed specifically for the military population, including continuous exposure guidance levels (CEGLs)
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From page 56... ...
Toconsidersusceptiblesubpopulationsinthecalculationsforestablishing noncancer exposure guidelines, a UF of 10 for human variability is typically applied (Haber et al.
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From page 57... ...
air ) planning exposure to guidance guidance emergency standa Populations guideline levels)
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From page 58... ...
, which were set to protect exercising angina patients. Angina patients would not be part of the deployed population, so that level of protection is not necessary for military personnel.
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From page 59... ...
. The subcommittee believes that military decision making would be better served by MEGs chosen consistently and likely to protect nearly all exposed deployed military personnel from chemical toxicity, consistent with DOD Safety and Occupational Health Program Instruction 6055.1 (August 19, 1998)
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From page 60... ...
However, the subcommittee decided that it could address this task by reviewing the acceptable risk levels selected by other organizations and making observations about where the Army's acceptable cancer risk threshold lies in comparison and the rationale used to set the threshold. With regard to chemical exposures, "safety" is often defined by various terms that include both scientific components and components that reflect societal values.
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From page 61... ...
. Because 1-year MEGs are established using this risk level, the issue that is addressed is the incremental cancer risk averaged over a lifetime from a 1-year deployment.
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From page 62... ...
; of high-risk activities that have low benefits being rejected; and of low-risk activities that have low benefits being evaluated on a case-by-case basis with considerable subjectivity. Another means of selecting an acceptable risk level is to identify the risks associated with rare events that people face and presumably accept as consequences of everyday life (e.g., deaths from lightning strikes, tornadoes, bee stings, shark attacks)
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From page 63... ...
TG-230 indicates that the acceptable risk level is subject to change depending on the needs and characteristics of specific missions. The selected risk value for deployed military personnel falls within the range used by U.S.
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From page 64... ...
during all phases of military operations, and over the broad spectrum of military activities." · "Reduce the OEH exposures to as low as practicable to minimize short-term and long-term health effects in personnel within the context of thefullspectrumofhealthandsafety risksconfrontingthedeployedpersonnel and consistent with operational risk management principles." Thus, in reviewing the Army's technical guides, the subcommittee was asked to evaluate the balance of emphasis between health effects produced immediately or soon after chemical exposures and possible long-term or delayed health effects (e.g., cancer)
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From page 65... ...
However, it is important for force health protection that some consideration is given to aggregate exposures. (See Chapter 5 for further discussion.)
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From page 66... ...
Exposures that are individually acceptable without appreciable risk might not be so when several are experienced together, and the question of interactions among agents looms particularly large for deployment risk assessment." TG-230 assumes that the toxicity of a mixture of chemicals that have similar modes of action will be equal to the sum of the weighted dose toxicities of the individual chemicals. Although that is generally an accepted practice, it is unclear how cumulative risk should be assessed when multiple hazards are present.
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From page 67... ...
. For deployments, the subcommittee envisions that exposure assessments would, in general, involve identifying potential chemical hazards by using available classified and unclassified site-specific information; assessing the level of potential exposures by using sampling data, modeling, or assumptions;comparingexposureestimateswithCCEGstoassesspotential risks to the mission and to determine what risk trade-offs are necessary to accomplish the specific mission; and comparing exposure estimates with MEGs to assess potential health hazard and, in the event that some health trade-offs must be made, to determine what types of follow-up management actions are necessary to fulfill the military's force health protection responsibilities (e.g., documentation of exposures in medical records, medical monitoring)
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From page 68... ...
Army guidanceshouldclarify theappropriatenessofdifferentexposure metrics for comparison with MEGs and CCEGs, and the differences in sampling methods, frequency, and intensity between exposure assessments conducted to support mission-risk assessments, those conducted to inform force health protection decisions, and others meant to provide documentation of personnel exposures to chemicals. Exposure assessments used for mission-risk assessment are particularly important, because time, access to external support, and data are more likely to be minimal in those situations.
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From page 69... ...
Using exposure assessments to properly estimate risks requires a high degree of professional judgment on the part of preventive-medicine personnel, as noted in TG-230: · "[Trained preventive-medicine personnel] should be familiar with basic methods of exposure assessment of chemicals in the environment.
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From page 70... ...
The first task seems to be in direct conflict with the statement in TG-230 that the guide is "not intended for use by untrained personnel or as a substitute for having trained preventive medicine personnel on-site or in the theater." TG-230 outlines an evaluative process that relies on the use of lookup tables, worksheets, and examples of how to apply those tools. The subcommittee found that TG-230 provides systematic guidance on how to evaluate potential chemical risks, but some of the decisions that must be made while using the guidance require the subjective judgment of experienced personnel.
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From page 71... ...
. · Deployed populations should be considered as healthier than the general population, and pre-existing health conditions do not need to be factored into the exposure guidelines.
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From page 72... ...
. The guidance should explain the differing approaches needed to support course-of-action decisions and to inform force health protection efforts.
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From page 73... ...
Interim Acute Exposure Guideline Levels (AEGLs)
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From page 74... ...
7664-39-3) Interim Acute Exposure Guideline Levels (AEGLs)
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From page 75... ...
A Companion Docu ment to USACHPPM Technical Guide (TG) 230 Chemical Exposure Guidelines for Deployed Military Personnel.
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