PESTICIDES IN-GROUND WATER - DO ATRAZINE METABOLITES MATTER

Atrazine and atrazine-residue (atrazine + two metabolites - deethylatr azine and deisopropylatrazine) concentrations were examined to determi ne if consideration of these atrazine metabolites substantially adds t o our understanding of the distribution of this pesticide in groundwat er of the midcontinental United States. The mean of atrazine-residue c oncentrations was 53 percent greater than that of atrazine alone for t hose observations above the detection limit (> 0.05 mu g/l). Furthermo re, a censored regression analysis using atrazine-residue concentratio ns revealed significant factors not identified when only atrazine conc entrations were used. Thus, knowledge of concentrations of these atraz ine metabolites is required to obtain a true estimation of risk of usi ng these aquifers as sources for drinking water, and such knowledge al so provides information that ultimately may be important for future ma nagement policies designed to reduce atrazine concentrations in ground water.