Environmental Health Criteria 214

HUMAN EXPOSURE ASSESSMENT
the ideal, they are very costly; decisions therefore need to be made
on the most important elements for inclusion. For any study, the
purpose must first be defined. Possible purposes include environmental
epidemiology, risk assessment, risk management or status and trend
analysis (see Chapter 2). The data elements and measuring approaches
that are needed for this purpose are then determined. Table 3
summarizes the basic information that is required for each study. It
should be mentioned that different elements of the exposure assessment
framework might be selected to meet different study requirements.
Table 3. Basic information needed for exposure assessments in
different contexts
Information required
Risk assessment Point estimates or distributions of
exposure and dose
Duration of exposure and dose
Risk management Pollutant source contributing to
(conducted once hazard exposure and dose
is identified) Personal activities contributing
to exposure and dose
Effectiveness of intervention measures
Status and trend Change of exposure and dose of
populations over time
Epidemiology Individual and population exposures and
doses, exposure dose categories
1.4 Approaches to quantitative exposure assessment
Quantitative estimation of exposure is often the central feature
of assessment activities. The quantitative estimation of exposure can
be approached in two general ways: direct assessment, including
point-of-contact measurements and biological indicators of exposure;
and indirect assessment, including environmental monitoring,
modelling, questionnaires (US NRC, 1991b) (see Chapter 3.5). These two
generic approaches to quantitative estimation of exposure are
independent and complementary. Each relies on different kinds of data
and has different strengths and weaknesses. It is potentially useful,
therefore, to employ multiple approaches as a way of checking the
robustness of results. Among other factors, the choice of which method
to use will depend on the purpose of the assessment and the
availability of suitable methods, measurements and models.
Direct approaches for air, water and food include personal air
monitors, measurements of water at the point of use and measurement of
the food being consumed. Indirect approaches include
microenvironmental air monitoring and measurements of the water supply
and food supply (contents of a typical food basket, for instance).
Exposure models are constructed to assess or predict personal
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