Environmental Health Criteria 214

HUMAN EXPOSURE ASSESSMENT
Using a deterministic model for a given contaminant, exposure
concentration is estimated as a concentration averaged over a given
period of time (see Eq. 3.1, p. 46).
For the inhalation and dermal exposure routes, concentrations in
the different microenvironments occupied by a person are integrated
over time. The integrated time period is usually 24 h, 1 year or a
lifetime of 70 years, although any time period may be used. The
concept of microenvironment is often unnecessary for the ingestion
route. In this case, the concentration of contaminants in the food
consumed and the amount of food and beverages consumed during a given
period of time are sufficient to determine exposure.
6.3 Environmental media and exposure media
In exposure analysis, we use human exposure assessments to
translate contaminant levels in environmental media into quantitative
estimates of the amount of contaminant that comes in contact with the
human-environment boundaries, that is, the lungs, the gastrointestinal
tract and the skin surface of individuals within a specified
population. Environmental media of principal relevance to human
exposure include air, ground-surface soil, root-zone soil, plants,
groundwater and surface water in the contaminated landscape. As
described in Chapter 2, exposure pathways define a link between an
environmental medium and an exposure medium. Important exposure media
include outdoor air, indoor air, food (commercial and homegrown),
exterior soil, interior soil or household dust, and drinking and
cooking water. Exposure then occurs by contact with contaminants in
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