Summary of the Public Health Goal for Alachlor

A Public Health Goal (PHG) of 0.004 mg/L (4 ppb) is developed for alachlor in drinking water. Review of the recent literature for alachlor did not identify any new studies that would be more appropriate for deriving a PHG for alachlor than studies used previously by the U.S. Environmental Protection Agency (U.S. EPA) to develop a Maximum Contaminant Level Goal (MCLG) and a Maximum Contaminant Level (MCL) of 0 ppb and 2 ppb, respectively. The basis for these levels is the carcinogenic potential of alachlor. Recent reevaluation of carcinogenic potential of alachlor supports a non-linear approach to risk assessment. Therefore, the Office of Environmental Health Hazard Assessment (OEHHA) determined that 0.5 mg/kg-day (no tumor response level for the nasal turbinate tumors), the lowest level among all no-observed-response-levels for adverse effects observed in animal studies, is the point of departure for calculating a PHG using the non-linear approach for carcinogenic risk assessment. Based on these data and methods, OEHHA calculates a PHG of 4 ppb for alachlor in drinking water.