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Overview of the Threat

  • This threat assesses the relative risk that nearby individuals (residents, students, and day care children) may travel to the site and come into contact with hazardous substances.

    • "(T)he weighting of the nearby population relative to the resident population has been reduced to better reflect the relative levels of exposure for those threats" (Preamble to the HRS, 55 FR, page 51560, Section N).

  • The threat will contribute very low scores to the soil exposure pathway unless:

    • The area of observed contamination is 9 acres or more and includes an area that is regularly used for public recreation.

    • Surrounding population density is heavily urban so that many people are potentially exposed to the observed contamination.

  • Highlight 9-18 in the HRS Guidance Manual may help you estimate the nearby population score. Urban population densities in major U.S. cities averages about 5,000 people per square mile and can run as high as 20,000 in some areas like to Bronx or Queens.

  • The threat to nearby individuals, as contrasted to resident individuals, can usually be addressed effectively and much more quickly by the removal authorities of CERCLA rather than by recourse to placement on the NPL.

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