Water Quality Standards

Summary information extracted from: Guidelines for drinking-water quality, 2nd ed. - Vol. 1. Recommendations. - Geneva, World Health Organization, 1993. p. 61.

1,1-Dichloroethene, or vinylidene chloride, is an occasional contaminant of drinking-water. It is usually found together with other chlorinated hydrocarbons. There are no data on levels in food, but levels in air are generally less than 40 ng/m3 except at some manufacturing sites.

Following oral or inhalation exposure, 1,1-dichloroethene is almost completely absorbed, extensively metabolized, and rapidly excreted. It is a central nervous system depressant and may cause liver and kidney toxicity in occupationally exposed humans. It causes liver and kidney damage in laboratory animals.

IARC has placed 1,1-dichloroethene in Group 3. It was found to be genotoxic in a number of test systems in vitro but was not active in the dominant lethal assay in vivo. It induced kidney tumours in mice in one inhalation study but was reported not to be carcinogenic in a number of other studies, including several in which it was given in drinking-water.

A TDI of 9 µg/kg of body weight was calculated from a LOAEL of 9 mg/kg of body weight per day in a 2-year drinking-water study in rats, using an uncertainty factor of 1000 (100 for intra- and interspecies variation and 10 for the use of a LOAEL in place of a NOAEL and the potential for carcinogenicity). This gives a guideline value of 30 µg/litre (rounded figure) for a 10% contribution to the TDI from drinking-water.