Overview of the Pathway
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This exposure pathway differs from the three migration pathways (ground water, surface water, air) in several respects:
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The likelihood that targets will be exposed to hazardous substances where these substances are currently located is the focus. In a sense, this could be called a "people migration pathway" rather than a hazardous substance migration pathway.
- The evaluation is based on "areas of observed contamination" rather than HRS sources.
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The likelihood that targets will be exposed to hazardous substances where these substances are currently located is the focus. In a sense, this could be called a "people migration pathway" rather than a hazardous substance migration pathway.
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Although the traditional name for this exposure pathway is "soil exposure," materials other than soil are considered. Any hazardous wastes with which a person might come into contact can be considered, providing they meet certain criteria discussed below.
- Surface impoundments, tanks, and piles are examples.
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Two threats are evaluated and summed HRS
rule, Table 5-1, page 51646
- The nearby population threat evaluates people who, upon leaving their home or daycare, might come into contact with hazardous substances on nearby contaminated properties.
- The resident population threat evaluates people, sensitive environments, and resources that are currently located on contaminated properties.
- In terms of scoring dynamics, this threat is equivalent to an observed release and actual contamination of targets in a migration pathway.
- The nearby population threat evaluates people who, upon leaving their home or daycare, might come into contact with hazardous substances on nearby contaminated properties.
- In terms of scoring dynamics, this threat is equivalent to potential to release and potential contamination of targets in a migration pathway.
- Both threats emphasize property boundaries. The essential step in the evaluation of the threats is to overlay a map of property boundaries on the map of the areas of observed contamination.
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