Environmental fate and effects of chlorothalonil: A Canadian perspective

A review of the environmental chemistry, fate, and toxicology of the nonsystemic fungicide chlorothalonil was conducted. It is used extensively in the eastern Canadian provinces, and it has occasionally been detected in surface and groundwater. In freshwater, chlorothalonil residues can usually be found in biota. Its half-life in a water/sediment system was found to be <2 h; however, residues were still detected 30 d later. In soil, it is immobile and persistent, with a half-life of I to 2 months. It can immobilize Daphnia magna at a concentration of 1.8 mu g/l and affect the renal system of rats at a level of 1.5 mg/kg/d. This environmental and toxicological information was used to derive Canadian Water Quality Guidelines for chlorothalonil to protect freshwater and marine water life, livestock, and crops from agricultural uses of this fungicide.