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 For each exposure scenario, the human health exposure assessment estimates
human exposure to COCs in the dredged material at the dredged material
management site. The risk assessment may develop present and likely future
exposure scenarios, depending upon site-specific characteristics. For example, a
newly proposed disposal site may require only an assessment of future risk, while an
existing disposal site for which a new source of dredged material disposal is planned
may also require an analysis of present exposure and risk as well.
The exposure assessment requires iterative steps to characterize the potentially
exposed receptors (Figure 9). These steps are integrated into the site-specific
conceptual model begun during problem formulation, and include:
a. Consulting current EPA guidance and background documents.
b. Quantifying the exposure.
c. Describing the receptors and exposure pathways.
The products of the Exposure Assessment are a conceptual model of the site,
which demonstrates the links between contaminated media and humans, and a
quantitative estimate of the exposure concentration and doses for the individual
defined in the exposure scenarios. There are typically several exposure scenarios
considered for each assessment.
Step 1: Consult USEPA resource documents
There are several USEPA publications that assist in developing the exposure
scenarios. These documents provide such information as how often people eat
seafood, how much seafood is ingested per meal, how much of a particular
contaminant may be absorbed upon ingestion or dermal contact, etc. The risk
assessment uses these factors in calculating exposure to the contaminants of
concern. The following USEPA documents should be consulted as an integral part
of the human health exposure assessment.
a. "Exposure Factors Handbook" (USEPA 1989).
b. "Exposure Factors Handbook" (USEPA/ORD 1995).
c. "Human-Health Evaluation Manual, Supplemental Guidance: Standard
Default Exposure Factors" (USEPA/OSWER 1991a).
d. "Consumption Surveys for Fish and Shellfish. A Review and Analysis of
Survey Methods" (USEPA 1992b).
e. "Final Guidelines for Exposure Assessment" (USEPA 1992c).
f. "Guidance for Assessing Chemical Contaminant Data for Use in Fish
Advisories. Volume I: Fish Sampling and Analysis" (USEPA/OST 1993).
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Chapter 4 Human Health Risk Assessment
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