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For decades the goals of industrial hygiene were to recognize, evaluate, and control workplace exposures from hazardous biological, chemical, and physical agents. As a discipline originating in epidemiology, industrial hygiene sought to recognize the potential for occupational disease and to control exposure to the causative agent through engineering, personal protective, or administrative measures. To evaluate occupational exposures, the industrial hygienist (IH) typically measured exposures among highly exposed workers to determine whether permissible exposure limits (PELs) or occupational exposure limits (OELs) were exceeded, often without detailed analyses of either exposure or risk to the remaining low-exposure cohorts.
In contrast to the practice of industrial hygiene, risk assessment is a process intended to anticipate exposures from hazardous agents and to estimate the potential for health risks from those exposures.(1,2) Risk assessment is intended to be a description of dose-effect relationships between the agent and adverse health effects, an assessment of exposures, the projection of risks from predicted or measured exposures, and a detailed discussion of the uncertainties in the overall process. Risk assessment, as used in health risk assessment, is decidedly population based, in contrast to the industrial hygiene focus on highly exposed subgroups of the population.
The industrial hygiene focus arose partly from the practical need to determine compliance with PELs and other standards. By targeting exposure monitoring on high-exposure groups, compliance with PELs can be readily documented throughout a facility. Low-exposure groups are assumed to be protected by default, since the PEL was derived for an acceptable level of risk with an added margin of safety. Therefore, less-than-PEL exposures must entail risks smaller than acceptable limits occurring from PE exposures.
Similarly, many environmental, health, and food safety standards were built around default assumptions of exposures in "maximally exposed individuals."(3) However, there is an expanding use of distribution-based estimates of risk in all areas of health risk assessment,(3) such that thorough risk assessments are generally thought to require characterization of risks to populations at all levels of exposure. This is particularly true for stochastic end points, i.e., cancer, in which risks of contracting cancer are projected legitimately on populations rather than individuals.
In addition to its use by regulatory agencies to develop occupational health standards, the risk assessment process is increasingly recognized as an important...