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Step 5. Using Comparison Values

Selection Process

The selection of comparison values takes into account the conditions at the particular site.

Click on the entries below  to consider aspects of the selection process.

Initial selection

The health assessor organizes the environmental sampling data by media, air, soil, and water. The health assessor initially selects the lowest comparison value for the chemical in each media table and compares it to the highest level of the chemical found in that medium at the site. If the amount found in the sample is higher than the comparison value, the health assessor selects the chemical for further evaluation.

Site-specific considerations

The assessor might use a different comparison value if exposure conditions warrant.

No comparison values are available

The assessor either selects the chemical for further evaluation or confers with toxicologists to develope a conservative comparison value.

Advanced Exercise on comparison value selection.