Human exposure to metals. Pathways of exposure, biomarkers of effect, and host factors.

1. Source of contaminant release into the environment. 2. Environmental media (including groundwater, surface water, air, soil, sediment, household dust, biota) serve to move contaminants from the source to points where human exposure can occur. 3. Point of exposure (a location where humans contact a contaminated medium, such as a playground, water body, well water, and food services). 4. Route of exposure (means by which the contaminant actually enters or contacts the body, such as ingestion, inhalation, and dermal absorption). 5. Receptor population (persons who are exposed to the contaminants of concern at a point of exposure).