Leaching properties of some degradation products of alachlor and metolachlor

Once in soil, pesticides undergo degradation processes that give rise to a complex pattern of metabolites. Those presenting a significant percentage of formation, genotoxic and leaching properties may pose a threat to human health associated with the consumption of drinking water. The aim of this study is to assess the hazard potential of some metabolites that may occur in ground water. 2,6-diethylaniline, 2-chloro-2',6'-diethylacetanilide, 2-hydroxy-2',6'-diethylacetanilide, metabolites of alachlor and 2-ethyl-6-methylaniline, metabolite of metolachlor, were chosen for their genotoxic properties. Under laboratory conditions, these metabolites showed DT50 = 1-5 days and K-oc = 45-357. Their leaching potential, calculated according to Gustafson, is very low and, therefore, they should not be regarded as contaminants of ground waters. Aged residue leaching studies as well as preliminary studies on well waters seem to confirm these findings. (C) 2000 Elsevier Science Ltd. All rights reserved.