Mutagenic activity in drinking water prepared from groundwater: a survey of ten cities in The Netherlands.

A survey of the mutagenic activity (Ames Salmonella/microsome assay) in drinking water prepared from groundwater in 10 cities of The Netherlands is presented. Mutagenic activity with strain TA98 with S-9 mix was found in the drinking water of six cities. There are strong indications that this mutagenic activity is caused by organics of natural origin. In the drinking water of three cities, trichloroethane, trichloroethene and tetrachloroethene were detected, which indicates that in these water-catchment areas organic pollutants have reached groundwater.