Traces of a gasoline additive have been found in the public water supply of four Attleboro area communities, according to a report released today by a water quality advocacy group.

Tiny, but detectable amounts of MtBe -- which is classified as a carcinogen by California where water standards are the nation's toughest -- were found in 86 Massachusetts communities, including Foxboro, Norfolk, Norton and Wrentham, according to the report, which is based on state test samples taken between 2001 and 2004.

The report by Clean Water Action, released on the 30th anniversary of the federal Safe Drinking Water Act, urges that the state toughen standards for MtBE and two other chemicals, DCPA and perchlorate.

For complete story, see today's Sun Chronicle.