How did NAWQA assess potential effects?
To help place pesticide-occurrence data in a human-health or environmental context, NAWQA assessed potential effects based on comparing measured concentrations to water-quality benchmarks, which are estimates of the concentrations above which pesticides may have adverse effects on humans, aquatic life, or fish-eating wildlife. This “screening-level” assessment provides an initial perspective on the relevance of pesticide concentrations to human and environmental health, and is intended to identify and prioritize sites and pesticides that may require further investigation. Benchmarks are only indicators and should not be confused with detailed risk and toxicity assessments that are conducted by EPA in determining the safety of pesticides. Most of the benchmarks used in the NAWQA screening-level assessment were derived from standards and guidelines established by EPA, toxicity values from EPA pesticide risk assessments, and selected guidelines from other sources. Most of the water-qualit
