In a draft report, California says only extremely low levels of two toxic “forever chemicals” are safe for humans to drink in water.
A July 22 draft report from the California Environmental Protection Agency would set a science-based safe level—called a public health goal—of 0.007 part per trillion for perfluorooctanoic acid (PFOA) and 1 ppt for perfluorooctanesulfonic acid (PFOS) in drinking water.
The two compounds are the two most common per- and polyfluoroalkyl substances (PFAS)—a group of environmentally persistent synthetic molecules—found as contaminants in drinking water. PFOA and PFOS were used commercially for decades but phased out in the US by 2015. Exposure to them is linked to cancer and other serious health problems.
California’s draft levels contrast with US federal advisory levels established in 2016 by the Environmental Protection Agency: 70 ppt for PFOA and PFOS, individually or combined.
Neither California’s public health goals nor the federal agency’s health advisories are binding regulatory limits for water utilities.
But once finalized, California’s public health goals influence drinking water regulation. California’s State Water Resources Control Board must set legally binding limits as close to the public health goal for a drinking water contaminant as economically and technologically feasible. Public drinking water utilities in California must meet those limits, called maximum contaminant levels, by filtering out or diluting contaminants.
California’s draft public health goal for PFOA is based on data linking kidney cancer in humans with exposure to this substance. The draft goal for PFOS is based on data showing that laboratory animals developed cancer after exposure to the compound.