Strategies to Protect the Health of Deployed U.S. Forces Assessing Health Risks to Deployed U.S. Forces: Workshop Proceedings (2000) / Chapter Skim
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4 The Nature of Risk Assessment and Its Application to Deployed U.S. Forces
4 The Nature of Risk Assessment and Its Application to Deployed U.S. Forces
Pages 35-58
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From page 35... ...
Rather, in the current context its purpose is to allow DOD decision-makers sufficient information to examine a range of risks that might arise in rapidly changing deployment conditions, and to balance competing risks so that overall risks to deployed forces can be · · · 1 mlulmlcea. INTRODUCTION The National Research Council (NRC)
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From page 36... ...
In addition, the paper describes the specific problems encountered in the application or risk-assessment methodologies to the evaluation of risks faced by deployed forces. The overall purpose of the paper is thus to provide a broad, analytical framework for the assessment of the wide range of health risks potentially encountered by forces deployed to unfamiliar environments.
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From page 37... ...
Second, it might be used to describe the attempt to predict risks in individuals that are not the subject of study, but who might become exposed to stressors that, under other conditions, are known to pose risks. Predictive risk assessment, which is the subject of the present paper, necessarily involves the use of risk information collected under one set of conditions (including information collected in experimental settings)
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From page 38... ...
Thus, all risk assessments involve, as a first step, a careful description of the specific stressors of concern, and the specific groups of individuals that might become exposed to those stressors. Once the stressors and population groups that are the subject of the risk assessment are specified, information is collected regarding the following questions (see Figure 1~: The Stressor Steps ~ and 2 Hazard Identification - What adverse effects - Has causation been estahli$hed7 Dose-Response Evaluation - How clo severity and incidence of adverse effects change with exposure conditions?
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From page 39... ...
The results of the hazard identification and dose-response evaluations are then integrated with the results of: Step 3: Human Exposure Assessment. Under what conditions are the individuals of concern exposed or potentially exposed to the stressor?
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From page 40... ...
A final point on the issue of uncertainty in risk assessments is that the regulatory defaults listed in Text Box 1 are offered in the absence of data relevant to specific stressors. Thus, in all specific cases, actual data, when sufficient, override defaults (also discussed later)
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From page 41... ...
Finally, in many cases, the selection of risk-reduction goals is influenced by considerations other than public health protection technical feasibility, costs that are dictated by the requirements of applicable laws. The model for using risk-assessment results described above is not the only possible one, and is probably not the most useful one for decision-makers who are asked to protect the health of deployed forces.
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From page 42... ...
1 Second, Establish standards (limiting concentrations) Estimate expected doses of stressor in so that maximum allowable exposure levels Population.
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From page 43... ...
Even certain medical treatments designed to protect forces from certain risks might, themselves, pose other kinds of health threats (Medical NBC Battlebook, U.S. Army Center for Health Promotion and Preventive Medicine)
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From page 44... ...
Thus, for example, little effort need be devoted to inhalation toxicity data for chemicals that are likely to reach deployed forces only through drinking water, and little effort need be expended researching for chronic hazard information for stressors that forces are likely to encounter only rarely and for very limited periods of time. DOD has already assembled much information regarding stressors, their sources, and the ways in which forces might encounter them (The Medical NBC Battlebook, The U.S.
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From page 45... ...
Army Center for Health Promotion and Preventive Medicine. HAZARD IDENTIFICATION Definition 45 Under the risk-assessment framework proposed here, the hazard identification step involves a description and critical scientific review of the available data concerning the types of adverse health effects (diseases or injuries)
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From page 46... ...
Generally, the hazard identification narrative and the final hazard characterization section (Text Box 2) will include an extensive discussion of the specific conditions of exposure under which specific types of hazards are produced.
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From page 47... ...
Mixtures and Interactions Data relevant to the combined effects of two or more stressors of concern to deployed forces should be included in the hazard identification narratives of each of the stressors involved. Such descriptions should include the conditions of exposure under which interactions can occur, the likelihood that such conditions could occur under the conditions experienced by deployed forces, any evidence that the adverse effects are simply additive, or that they arise out of some different type of interaction (antagonistic or synergistic)
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From page 48... ...
Under the criteria for sound risk assessments, it is recommended that whatever measures of dose are used, they should be those measures that are known to relate to response. It is important that the dose-response evaluation include a discussion of the reasons for the selection of specific measures of dose.
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From page 49... ...
These responses will have been tabulated, discussed, and critically reviewed in the hazard identification step. Out of the information set forth there, dose-response profiles can be developed for acute, intermediate, and chronic exposure conditions.
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From page 50... ...
Considerations in the Development of Dose-Response Information for Table 2 Thresholds For many if not most of the stressors of concern, there will be some dose (broadly defined to include all relevant conditions of exposure) that must be exceeded before even minimal adverse effects are produced.
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From page 51... ...
For such stressors, it might be that all doses are to be considered harmful, and the critical assessment of risks comes only in the exposure assessment step, where the probability of exposure becomes the determinant of risk. Some chemical carcinogens and forms of radiation are thought to pose risks at all nonzero exposures (NRC 1994, EPA 1996~.
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From page 52... ...
STRATEGIES TO PROTECT THE HEALTH OF DEPLOYED U.S. FORCES: WORKSHOP PROCEEDINGS D2dep O2ob$ 03obs FIGURE 3 Hypothetical dose-response relationships for exposure to a hazardous stressor.
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From page 53... ...
No particular UP is to be inferred from Figure 3, although UFs of differing magnitude, including UFs of magnitude 1, are possible, depending upon the nature of the database used to develop the composite Curve A Text Box 1 presented some UFs commonly used by regulatory agencies for assessing variability in thresholds for toxic chemicals among humans and differences in response between experimental animals and humans.
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From page 54... ...
It is proposed that Table 2 be accompanied by a narrative statement of its basis. With this table and statement, the hazard identification and dose-response steps of the risk assessment will be complete.
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From page 55... ...
No doubt some of the information used to develop available occupational standards can be used for assessing risks to deployed forces, but wholesale adoption of such standards without critical reVleW Will lead to a wholly clltterent and tar less useful risk-assessment model. l he earlier point, that deployed forces might not be similar in sensitivity to ordinary occupational cohorts, needs also to be considered.
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From page 56... ...
The first can be used for planning purposes, and can guide risk management on the stressors expected to be of greatest concern during specific deployments. The second can provide direct measurement data during deployment; by quick reference to the dose-response information, immediate knowledge of potential health risks can be acquired.
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From page 57... ...
: description and use in health risk assessments. Regul.
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From page 58... ...
FORCES: WORKSHOP PROCEEDINGS USACHPPM.(U.S. Army Center for Health Promotion and Preventive Medicine)
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