Officials have revised the recommended maximum levels, saying the chemicals found in water supplies may be more dangerous than thought.
Chemicals formerly manufactured by the 3M Co. and found in groundwater in the metro area are potentially more dangerous than previously believed, according to state health officials on Thursday.
The Minnesota Department of Health revised its recommended maximum concentrations of PFOA and PFOS, two chemicals found in the city wells of Oakdale and more than 200 private wells in Lake Elmo during the past three years.
John Linc Stine, environmental health division director for the Health Department, said the decision will have little effect on the two communities, because Oakdale last year installed carbon filters on its main wells to remove the chemicals and nearly all of the affected homes in Lake Elmo have switched to city water.
The decision does not affect six other communities in the east metro where a different 3M chemical, PFBA, was detected in city wells in January.
The changes demonstrate how the toxicological science of the 3M chemicals continues to evolve, and how state officials are revising their concerns about potential health risks.
Stine said that values for the chemicals PFOA and PFOS were lowered after ongoing laboratory research around the country showed that exposure to the chemicals was affecting the liver and thyroid functions in various monkeys and that it appears to be causing developmental problems in mice.
"It does suggest that there's a greater concern for toxicity and human health risk," Stine said of the research.
Rita Conlin, a former member of the Lake Elmo City Council, said the Health Department's decision is worrisome. "It's frightening, because we don't know how long that's been in our water," Conlin said. Her home and others in the Tablyn Park neighborhood were recently connected to city water.
The Health Department decided that the health-based value for PFOA should be lowered from 1.0 parts per billion to 0.5 parts per billion, and for PFOS from 0.6 parts per billion to 0.3 parts per billion.
The values are concentrations that health officials believe pose virtually no risk if consumed over a lifetime.
The two chemicals have been found in a large underground plume in the Lake Elmo and Oakdale area, ranging in concentrations from a few parts per billion or less in some neighborhoods to more than 15 parts per billion near two former dumps.
An Environmental Protection Agency scientific panel recommended last year that PFOA be classified as a likely carcinogen.
Last November, EPA lowered its "drinking water action level" for PFOA to 0.5 parts per billion for a groundwater cleanup plan in West Virginia that involved DuPont, which also used the chemical.
3M spokesman Bill Nelson said that the company had no comment on the technical aspects of the Health Department's decision. "Nothing about these changes affects 3M's confidence that neither PFOS nor PFOA nor PFBA for that matter have adverse impacts on human health at the levels we've seen it in the environment," Nelson said.
PFOA and PFOS were manufactured at the company's Cottage Grove plant for decades until 2002 and were used in stain repellents, nonstick cookware, firefighting foam and other products. The chemical wastes were disposed in at least three dumps in the east metro area between 1956 and 1974, and began to be detected in groundwater near those areas when the state started testing for the chemicals in 2004.
The Health Department's Stine said that as a result of Thursday's decision, a handful of private wells in Lake Elmo that were below the previous health-based values are now above them. Health and pollution control officials will identify those households and begin providing them with bottled water or carbon filters, he said.
"They better take quick action here to take care of people who are not on city water," said Conlin, the Lake Elmo resident.
Susan Stafford, another Lake Elmo resident, said she's not surprised that the 3M chemicals are proving to be more dangerous as scientists learn more about them. "I think they're going to find even more problems in the future," Stafford said.