Environmental Health Criteria 214

HUMAN EXPOSURE ASSESSMENT
continuum, seriously impairs efforts to establish the link between
exposure and dose.
We are thus left with a situation in which we can measure
specific events on either side of the body's absorption boundaries,
but we can relate them to each other only by using a series of
unsubstantiated assumptions. Yet it is this relationship between
exposure and dose that is critical to, for example, establishing cause
and effect relationships between exposure and diseases.
1.6 Summary
Exposure requires the occurrence of the presence of an
environmental toxicant at a particular point in space and time; and
the presence of a person or persons at the same location and time. In
addition, the amount which comes in contact with the outer boundary of
the human body is required.
As the intrinsic value of exposure-related information has become
recognized, "exposure analysis" has emerged as an important field of
scientific investigation, complementing such traditional public health
disciplines as epidemiology and toxicology, and is an essential
component in informed environmental health decision-making (Goldman et
al., 1992; Sexton et al., 1992, 1994; Wagener et al., 1995).
2. USES OF HUMAN EXPOSURE INFORMATION
2.1 Introduction
Exposure assessments collect data on the route magnitude,
duration, frequency and distributions of exposures to hazardous agents
for individuals and populations. Human exposure data have been used
for the evaluation and protection of environmental health in four
interrelated disciplines: epidemiology, risk assessment, risk
management, and status and trends analysis. The fundamental goal of
exposure assessment studies is to reduce the uncertainty of the
exposure estimates that are used within each discipline to make public
policy decisions or reach research conclusions.
Epidemiology is the examination of the link between human
exposures and health outcomes (Sexton et al., 1992). Risk
assessment is the estimation of the likelihood, magnitude and
uncertainty of population health risks associated with exposures. In
contrast, risk management is the determination of the source and
level of health risks and which health risks are acceptable and what
to do about them. Status and trends analysis comprises the evaluation
of historical patterns, current status and possible future changes in
human exposures.
The purpose of this chapter is to describe the disciplines from
environmental epidemiology through risk assessment. It also describes
how human exposure assessment data are used in each of these
disciplines
2.2 Human exposure information in environmental epidemiology
Epidemiology is the study of the determinants and distribution of
health status (or health-related events) in human populations.
Environmental epidemiology searches for statistical associations
between environmental exposures and adverse health effects (presumed)
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