Summary of the Public Health Goal for Oxamyl

A Public Health Goal (PHG) of 50 ppb is developed for S-methyl N’N’-dimethyl-N-[(methyl-carbamoyl) oxy]-1-thiooxamimidate (oxamyl) in drinking water. The current state and federal Maximum Contaminant Levels (MCLs) for oxamyl are 200 ppb. The available toxicological data on oxamyl and the current drinking water regulations were reviewed in order to develop a PHG for oxamyl. A no-observed-adverse-effect level (NOAEL) of 2.5 mg/kg-day for decreased body weight gain in rats was selected as the critical dose. The PHG was calculated assuming a 10 kg child consuming one liter of water per day, a relative source contribution of 20% and an uncertainty factor of 100. Therefore, based on the scientific information available, a PHG for oxamyl of 0.05 mg/L (50 ppb) is calculated.