National Standards and Guidelines for Pesticides in Water, Sediment, and Aquatic Organisms: Application to Water-Quality Assessments

Abstract

National standards and guidelines for pesticides can be useful tools in water-quality assessment for evaluating potential human health or ecological effects of measured pesticide residues in water, bed sediment, or aquatic organisms. However, valid use of a given standard or guideline requires an understanding of its technical basis and underlying assumptions. Each type of standard or guideline is specific for one sampling medium (water, bed sediment, and fish and shellfish tissue) and is aimed at protection of one or more beneficial uses of the hydrologic system (drinking water, fish and shellfish consumption, aquatic organisms, and wildlife). These characteristics can be used to identify which standards and guidelines are appropriate for comparison with measured pesticide concentrations in environmental samples from a given hydrologic system. A review of standards and guidelines can be restricted to the applicable sampling medium. Then, the beneficial uses of the hydrologic system need to be identified and the measured pesticide concentrations compared with standards and guidelines for all beneficial uses that apply to that system. Several key factors that must be considered when applying this general process to water-quality assessment are summarized below. Two precautions need to be considered regarding sampling media: 1. Standards and guidelines for water distinguish between finished drinking water (potable water, often treated) and ambient surface water. If standards and guidelines for drinking water (EPA primary drinking-water regulations and drinking-water health advisories) are applied to measured pesticide concentrations in ambient water samples, the effects of water treatment (such as filtration) need to be considered. 2. Standards and guidelines for fish and shellfish tissue distinguish between edible fish and shellfish tissue and whole fish tissue. Comparison of pesticide concentrations in whole fish tissue with standards or guidelines for edible fish and shellfish tissue is appropriate only as a screening procedure to determine whether additional sampling and analysis for contaminants in edible fish fillets are warranted. For some sampling media (water, fish and shellfish tissues), both standards and guidelines may exist for a given pesticide. Standards and guidelines may differ in their technical bases and in the implications or consequences of finding measured concentrations in exceedance of the standard or guideline value. Therefore, comparison of measured pesticide concentrations with both standards and guidelines is useful because each provides different information about the hydrologic system.(ABSTRACT TRUNCATED AT 400 WORDS)