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Level of Contamination for Human Targets

  • All residentsand students and day care attendees are evaluated for either Level I or Level II concentrations. Potential exposure is evaluated in the nearby population threat.

    • Workers are a separate category in the soil exposure pathway and are not evaluated for level of exposure.
    • Terrestrial sensitive environments are evaluated as though they were subject to actual contamination, Level II, because there are no benchmarks for environmental exposure to contaminated soil.
  • Level I concentrations require that three criteria be met:
    • The person lives or attends school or day care on a property with an area of observed contamination on that property,
    • The residence, school, or day care center is within 200 feet of the area of observed contamination,
    • A sampling point on the property and within 200 feet contains hazardous substances that meet the criteria for observed contamination and also meet or exceed soil exposure benchmark either individually or in the aggregate (the I or the J index)

      Press here for soil exposure benchmarks: SCDM, Soil Benchmarks

      Press here for information on the I or the J index:

    • This third criterion means that Level I cannot be inferred between sampling points.
    • You will need to take this into account in your sampling plan. Level I targets are worth 10 population points each compared to 1 point to Level II.
  • Level II concentrations require that only the first two criteria above be met: an area of observed contamination on the property and within 200 feet of the residence, school, or day care center.
    • Level II concentration does not require there be any sampling points on the property.
    • Where residences, schools, or day care centers have been built over old landfills or impoundments, one sample that documents a point of observed contamination may pick up substantial targets associated with the area of observed contamination.
    • Similarly, when soil contamination is widespread, a relatively few samples that document points of observed contamination can document a large area of observed contamination and may pick up substantial targets.

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