Neutral chloroacetamide herbicide degradates and related compounds in Midwestern United States drinking water sources.

Recent studies have revealed the presence of neutral degradates of chloroacetamide herbicides in the Chesapeake Bay at concentrations greatly in excess of the parent compounds. As some degradates are being considered for regulation in drinking water, exposure of human populations to such micropollutants is of interest. Here we report the results of a survey of source waters used by 12 drinking water utilities in the Midwestern United States. Analytes included 20 neutral and six ionic chloroacetamide degradates, four parent chloroacetamide herbicides, three triazine herbicides, and two triazine degradates. Samples were collected during Fall 2003 and Spring 2004. In the fall samples, 16 of 20 neutral chloroacetamide degradates were detected, while 18 of 20 neutral chloroacetamide degradates were detected in the spring samples. Concentrations of most parent chloroacetamides and neutral degradates were somewhat to substantially higher in the spring than in the fall, with median concentrations of approximately 10-100 ng/L. Groundwater sources tended to have lower concentrations of parents and neutral degradates than surface water sources in the fall, although concentrations of parents and degradates in groundwater were similar to those in surface water in the spring.