Summary of the Public Health Goal for Dinoseb
A Public Health Goal (PHG) of 14 ppb is developed for dinoseb in drinking water. The PHG was calculated based on a lowest-observed-adverse-effect-level (LOAEL) of 1 mg/kg-day for cystic endometrial hyperplasia in female mice and hypospermatogenesis and atrophy/degeneration of the testes in male. This is the identical LOAEL used by the U.S. Environmental Protection Agency (U.S. EPA) to promulgate its Maximum Contaminant Level (MCL) for dinoseb of 0.007 mg/L (7 ppb). The federal MCL is based upon a Drinking Water Equivalent Level (DWEL) of 0.035 mg/L (rounded by U.S. EPA to 40 m g/L). No new scientific information was identified that would justify a change in the use of the LOAEL of 1 mg/kg-day. However, we identified three assumptions (body weight, relative source contribution and water consumption) previously used by U.S. EPA in the calculation of its MCL for which we have determined more appropriate values for use in PHG development based on current methodology which includes exposure contributions from inhalation and dermal contact with water-borne dinoseb, and the fact that dinoseb is no longer registered for use in California. Therefore, OEHHA calculates a PHG of 0.014 mg/L (14 ppb) for dinoseb in drinking water.
- Dinoseb