Human health risk assessment of 2-mercaptobenzothiazole in drinking water

2-Mercaptobenzothiazole (MBT) is used as a vulcanization accelerator in rubber products that come into contact with potable drinking water. When such products are evaluated for contact with potable water and submitted for ANSI/NSF Standard 61 certification, any chemical extracting from these products must be below an appropriate action level of exposure. As defined by Standard 61, a total allowable concentration (TAC) is the maximum concentration of a nonregulated contaminant allowed in a public drinking water supply, and the single product allowable concentration (SPAC) is 10% of the TAC. Currently, MBT has a TAC of 40 mg/L and a SPAC of 4 mg/L. A comprehensive health effects evaluation of MBT was performed to determine whether these action levels should be revised. Epidemiological investigations indicate that workers occupationally exposed to MBT have an increased risk of death from bladder cancer. Genotoxicity investigations in bacterial and mammalian test systems provide some evidence indicating that ...