Out of the 59 public wells sampled, the health Department says 41 tested positive for the compound perfluorobutanoic acid. Not much is known about PFBA, but the compound is part of a class of chemicals used by 3M to manufacture stain and water-resistant products such as Scotchgard.
Two other chemicals in that family, PFOS and PFOA, were detected two years ago in Oakdale and Lake Elmo's water supplies. Those chemicals have been shown to cause harmful changes to the liver and thyroid when used in high concentrations in laboratory studies.
3M phased out production of those chemicals at its Cottage Grove Chemolite plant in 2002.
John Linc Stine, director of the department's Environmental Health Division, says so far there's no evidence to suggest that PFBA poses a health threat.
"I'd say the levels of this compound are very low in their water supply, and there's no immediate cause for concern or for public health threat to be identified," says Stine. "We are, of course, concerned about any contaminant that shows up in groundwater and we're working as fast as we can to understand it and characterize its risk."
Stine says most of the health risk with perfluorochemicals appears to be associated with long-term exposure. He says the health department is not advising residents in any of the six communnities switch from well water to bottled water.
But Stine says residents who are worried about the safety of their drinking water could switch to bottled water, or they could use a carbon filter. But he says the department is not recommending that action.
Finding this chemical at low levels does not pose an immediate health risk for residents.
"So at this time it's hard for us to make a statement that would suggest any radical interventions in the municipal water systems. However, everyone's personal perceptions of risk are different," says Stine.
State officials don't know for sure the source of the PFBAs. But for many years, 3M disposed of industrial waste at three landfills in Washington County.
Michael Kanner with the Minnesota Pollution Control Agency says his agency suspects the chemicals have migrated from the landfills into the groundwater in the area.
"My best judgment on that is, yes, it would be dumpsites. You had large amounts of disposal of materials in the ground, and they occurred many years ago and had the opportunity to go down in the groundwater," says Kanner.
PFBAs were found in the majority of the wells tested. Kanner thinks the compounds actually move through the groundwater more easily than other perfluorochemicals. And they may have moved across the Mississippi River, which would explain why South St. Paul wells tested for PFBA.
"It looks like the PFBAs move at a quicker rate that the other materials. The PFBAs are 4-carbon materials. All of these materials are what you might call slippery -- they don't stick to soil very well so they move through the groundwater. The PFB is a 4-carbon material, as opposed to the PFOA and PFOS which are 8-carbons, which appears to slow them down somewhat," says Kanner.
Kanner says the good news is that PFBAs don't accumulate in the body because they have a simpler structure. That would make them less toxic than PFOA or PFOS.
Still, the news has left some officials wondering what to do next.
"There are more questions than answers right now," says State Sen. Katie Sieben, who represents the Cottage Grove area. "It's hard to know exactly what to make of it. The Department of Health, though, I think has a responsibility to take a leadership position on this. Maybe call on the Environmental Protection Agency for help in researching the extent of the problem."
Cottage Grove city council member and Mayor Pro Tem Myron Bailey says the city is waiting on further information from state officials to learn what the chemical is, and if there are any health issues they should be concerned about.
"As a resident here in Cottage Grove I'm still using the water, I'm still drinking the water. I would not be alarmed," says Bailey. "It's still early in the process to be concerned about what this specifically is because, frankly, we don't know what this is all about. There's not a lot of information out there on this particular item yet."
He says he expects to start discussions with officials from Newport and St. Paul Park, which also have contaminated wells, to share information.
"Rest assured we'll do everything necessary from a city standpoint that the water is of the highest quality and clean to drink in Cottage Grove in the future," says Bailey.
Oakdale recently installed a new municipal treatment facility designed to remove perfluorinated chemicals from its water supply. 3M paid the entire cost of the $2.5 million treatment facility.
Health Department officials will meet with officials from the affected cities next week to further discuss the test results and their implications, and will provide technical support to cities for managing their drinking water systems.
Maplewood-based 3M says it believes low levels of PFBAs do not cause health problems. The company says it will continue to work with the state to determine the source of contamination.
The health department says 3M has exposed lab rats to PFBA in testing that began last fall. The results of those tests have not been released.