Hazard assessment of vinyl acetate, an item for Further Study in drinking water

Abstract

The Drinking Water Quality Standards for lifetime exposure of contaminants have been established for 51 items under the Japanese Water Supply Act. In addition, non-legally binding target values are also notified for “Complementary Items” and “Items for Further Study” that can be detected in drinking water or water sources. Vinyl acetate is used in materials of drinking water apparatus directory contact to drinking water and listed in “Items for Further Study.” The target value of vinyl acetate in drinking water has not been established; therefore, we conducted the hazard assessment of vinyl acetate to derive a health-based guidance value. Carcinogenetic potential was observed in rat and mouse 2-year drinking water studies. We conducted the benchmark dose analysis for incidences of squamous cell carcinoma and/or papilloma in rats and mice. The most appropriate BMDL₁₀ of 231 mg/kg/day was obtained for male rat squamous cell carcinoma in oral cavity. The reference values were derived as both a genotoxic carcinogen and a non-genotoxic carcinogen because its genotoxicity was inconclusive. The Tolerable Daily Intake (TDI) was calculated as 0.231 mg/kg/day with an Uncertainty Factor of 1000, and the Virtually Safe Dose (VSD) at 10^-5 risk level was calculated as 0.0231 mg/kg/day. The above TDI and VSD values will be useful to establish the target value of vinyl acetate in drinking water. ACKNOWLEGMENT: This study was supported by a Health and Labour Sciences Research Grant (19LA1005) from the Ministry of Health, Labour and Welfare, Japan.