WASHINGTONLOS ANGELES CHICAGO — - The Environmental Protection Agency is tightening drinking-water standards to impose stricter limits on four contaminants that can cause cancer. EPA Administrator Lisa Jackson said the agency is developing stricter regulations for four compounds (tetrachloroethylene, trichloroethylene, acrylamide and epichlorohydrin). All four chemical compounds can cause cancer. Tetrachloroethylene and trichloroethylene are used in industrial and textile processing and can seep into drinking water from contaminated groundwater or surface water. Acrylamide and epichlorohydrin are impurities that can be introduced into drinking water during the water-treatment process. Jackson said the EPA will issue new rules on the four chemical compounds within the next year.