The health department has lowered the so-called health based values for PFOA and PFOS.
Both compounds have turned up in private and public drinking water supplies in Oakdale and Lake Elmo. The agency changed the standards in response to updated toxicity studies, according to John Linc Stine, the director of the department's Environmental Health Division.
Stine says these new standards mean some homeowners' private wells in Lake Elmo fall outside safe limits for long-term water consumption. PFOA and PFOS are related to 3m's former Scotchgard operations. The state believes the contaminaton comes from landfills in Washington county where 3M once disposed of industrial waste.
Earlier this year, tests found another 3M chemical, PFBA, in the water supplies of several communities near a third landfill once used by the company.