The Minnesota Department of Health Department announced a new health-based exposure limit Thursday for the 3M perfluorochemical known as perfluorobutanoic acid, or PFBA. The chemical is in the drinking water of more than 143,000 residents.
The new limit is seven times higher than it was a year ago when the Department first established a drinking water guideline for the little-known contaminant.
Health Department officials said the new PFBA limit of 7 parts per billion is based primarily on the results of three studies. Two were commissioned by 3M and performed by an independent testing laboratory. The third was conducted by Environmental Protection Agency scientists. The studies revealed that PFBA is less toxic than health officials previously thought. Environmental Health Division director John Linc Stine said researchers discovered that the chemical passes through the body within days, rather than years like other perfluorchemicals of concern.
"PFBA has a significantly shorter half-life in a human being's body. And so that shorter duration within the human body is the primary reason for lessening our concern," Stine said.
The revised exposure number means that all of the east metro municipal wells that had previously tested positive for PFBA, are now well below the safety limit. However, there are still about 50 private wells in Washington county that exceed the limit and require water treatment.
PFBA was manufactured by 3M for use in photographic film. The company no longer makes the chemical. Leaking landfills are blamed for the contaminant reaching the groundwater in the east metro.
3M spokesman Bill Nelson said the company is still studying the Health Department's announcement, though 3M officials believe the scientific data supports an even more relaxed limit.
"I guess our calculation would be a number much, much larger," Nelson said. "But to that end, I guess you know I want to make it very clear that the 7 parts per billion includes an extremely large margin of safety, and again, we hope that that number will offer the folks of the east metro area peace of mind regarding the safety of their municipal drinking water."
Sen. Katie Sieben, DFL-Newport, said the new limit doesn't give her a lot of comfort. She said no level of exposure to PFBA is acceptable. Now with the higher safety threshold Sieben said it is even less likely that residents on the municipal system will get help if they want their water filtered.
"I was hopeful that the number would be lower so that more people would get remedial water actions taken so that they and their families wouldn't be exposed to any of this PFBA," Sieben said.
But Sieben said she doubts the new guidelines are the last word on PFBA. She said the Health Department revised safety limits downward several times for two other perflorochemicals as more research became available.
Rep. Karla Bigham, DFL-Cottage Grove, said she will push public health officials to continue studying PFBA, particularly its effects on pregnant women and children.
"I still have concerns," she said. "And I will always have concerns until we get more investigation about the long-term health effects from being consistently exposed to this."
The Minnesota Department of Health will hold a series of public meetings beginning next week to update east metro residents on the new PFBA exposure limits and research on drinking water treatment options.