Unsafe at Low Levels: Adopt a Federal MCL for 1,2,3-Trichloropropane in United States’ Drinking Water

1,2,3-trichloropropane (TCP) is a toxic, man-made chemical used widely in agricultural and other contexts from the 1940s to 1980s. TCP has settled into groundwater supplies nearly everywhere it was used. In 2009, Environmental Protection Agency (EPA) included on Third Contaminant Candidate list (CCL3) listed safe oral reference dose (RfD) for at 0.004 milligrams per kilogram day. Since then, we have learned that scope of contamination problem greater than first understood. At least 13 states one territory contaminated wells. Animal studies show potent carcinogen, toxicology suggest unsafe levels above its 5 ppt detection limit. Three states, California, Hawaii, New Jersey adopted enforceable maximum contaminant groundwater. As become aware levels, likely some them will also regulate TCP, but could take many years. Federal legislation mandate EPA advisories sooner state legislation. The limit as chemical, 1,2-Dibromo-3-chloropropane (DBCP), common co-contaminant TCP. We recommend adopt TCP’s lowest level, ppt, federal level