The Environmental Protection Agency announced pollution standards Wednesday for eight common contaminants of drinking water that, if complied with, should avert 32 cases of cancer a year, officials said.
The eight chemicals, many of them widely used as solvents, include two known causes of cancer, three probable causes, two suspected causes and one toxin that does not cause cancer.
Twenty-nine of the 32 cancer cases that would be avoided result from exposure to just one of the chemicals, vinyl chloride, a known cause of cancer.
The eight new pollution standards, all in the class called volatile organic (carbon-causing) compounds, affect an estimated 1,800 water systems supplied by groundwater and serving about 10 million people where concentrations exceed the new limits. The chemicals generally evaporate from surface water systems, officials said.
The chemicals and the "maximum contaminant level," or the amount in parts per billion that will be permitted in drinking water after Dec. 31, are: the two causes of cancer in humans, benzene, 5 ppb, and vinyl chloride, 2 ppb; three classified as probable causes of cancer because they induce it in laboratory animals, trichloroethylene, carbon tetrachloride and 1,2-dichloroethane, all 5 ppb; two classified as possible carcinogens, para-dichlorobenzene, 75 ppb, and 1,1-dichloroethylene, 7 ppb, and 1,1,1-trichloroethane, 200 ppb, a non-carcinogen that can damage the liver, circulatory system and nervous system.
Activated carbon and aeration can remove the chemicals at $3 per household per year for a large system, or as much as $91 per household for small systems, the agency said.