EPA has set an enforceable regulation for polychlorinated biphenyls, called a maximum contaminant level (MCL), at 0.0005 mg/L or 500 ppt. MCLs are set as close to the health goals as possible, considering cost, benefits and the ability of public water systems to detect and remove contaminants using suitable treatment technologies.
The Phase II Rule, the regulation for polychlorinated biphenyls, became effective in 1992. The Safe Drinking Water Act requires EPA to periodically review the national primary drinking water regulation for each contaminant and revise the regulation, if appropriate. EPA did review polychlorinated biphenyls as part of the Six Year Review and determined that the zero MCLG and 0.0005 mg/L or 500 ppt MCL for polychlorinated biphenyls are still protective of human health.
States may set more stringent drinking water MCLGs and MCLs for polychlorinated biphenyls than EPA.