Research Highlights

Exposure Guidelines Used to Aid in the Selection of Analytical Methods

Water and Air Risk-based Exposure Guidelines Are Used to Estimate Appropriate Target Levels for Analytical Methods

EPA has identified more than 100 chemical and radiological constituents that are considered homeland security threat contaminants. Within minutes to hours after being released, many of these contaminants can convert to other hazardous contaminants, known as transformation by-products. In order to correctly identify these threat contaminants and transformation by-products after a terrorist event has occurred, it is necessary for laboratories to know what appropriate analytical methods to use. To this end, EPA has researched and compiled Standardized Analytical Methods for Environmental Restoration Following Homeland Security Events (SAM).

Each analytical method has a specific detection limit, which is the lowest concentration the method can analyze. Ideally, methods should be developed with detection limits low enough to analyze threat contaminant concentrations known to produce human health effects. To support this goal, EPA has researched and compiled Risk-Based Criteria to Support Validation of Detection Methods for Drinking Water and Air. This report presents consolidated risk-based information, derived from several sources, for different acute exposure guideline levels and different routes of exposure. This information has been used to establish appropriate analytical method target levels (i.e., goals for detection limits).

Methodology for Estimating Analytical Method Target Levels

Because the current consolidated risk-based information primarily addresses two main exposure routes, inhalation and ingestion, this effort has focused on establishing target levels for contaminants in air and water. Some examples of the consolidated risk-based information include: acute exposure guideline levels (AEGLs); drinking water equivalent levels (DWELs); and maximum contaminant levels (MCLs).

Risk-based information was consolidated for 71 chemicals and 15 radionuclides. After compilation and review of existing risk-based information associated with these contaminants, the following analytical method target levels were established:

• 131 analytical target levels (116 for chemicals and 15 for radionuclides) for air
• 143 analytical target levels (128 for chemicals and 15 for radionuclides) for water

By knowing the concentration level at which human health is affected, a laboratory can better determine which analytical method to use for each contaminant of interest.

Continual Refinement of Analytical Methods

Both Risk-Based Criteria to Support Validation of Detection Methods for Drinking Water and Air and Standardized Analytical Methods for Environmental Restoration Following Homeland Security Events help to establish the most appropriate analytical methods to use in the event of a terrorist event. Additional work, however, is needed. For example, there is a need to:

• Compile information on skin exposure
• Determine if additional evaluations are needed for non-persistent compounds with associated analytical method target levels that are higher than, or, close to exposure guidelines.

As more information is obtained, Standardized Analytical Methods for Environmental Restoration Following Homeland Security Events will be updated to provide laboratories with information on appropriate analytical methods for use after a contamination event.

Contact: Femi Adeshina

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