The Minnesota Department of Health says it's unlikely that people in the east metro who have been exposed to PFCs will experience adverse health effects.
Many people in Washington County and parts of other counties were exposed to PFCs from well water that was contaminated by dump sites formerly used by 3M. The contamination is related to chemicals formerly made by 3M.
3M disposed of its chemicals in perfectly legal fashion at several east metro landfills from the 1950s through the 1970s. But in the 1990s the company's landfills were found to be leaking PFCs, or perfluorinated chemicals, into groundwater.
The PFCs were related to 3M's production of Scotchgard and other products. The pollutants traveled through aquifers, and turned up in municipal and private wells.
In its study, the Minnesota Department of Health sampled the blood of about 200 residents, looking for compounds such as PFOS or PFOA, both of which are types of PFCs.
PFOA showed up in tested residents at about 4 times the rate as it appears in the general population. For PFOS, tested residents had about 1.5 times as much as the U.S. Population.
Read more from the Minnesota Department of Health about PFCs.
In a new report, the Department of Health compared elevated levels of PFCs in people's blood with a range of animal studies, and concluded the levels are not high enough to cause disease.
Some local residents say they feel there's more cancer in the area than there should be. But Jim Kelly, a Department of Health scientist who co-wrote the study, said the Cancer Surveillance System analyzed cancer rates in the affected communities.
"They really didn't find a whole lot, which isn't necessarily unexpected because we don't have clear evidence these chemicals would be carcinogenic to people," he said. "Nonetheless, it should be comforting to folks concerned about that particular area."
Kelly said the main effect on lab animals is on liver chemistry. He said the Department of Health hasn't been hearing from residents about liver problems. He said some animal studies show developmental effects, but he's seen no evidence of that in humans.
However, there is some evidence that PFCs can have an effect on humans.
Matt Simcik teaches Environmental Health Science at the University of Minnesota and said a study published in the June 2010 edition of the journal Environmental Health Perspectives links increased blood levels of PFCs with a slightly increased chance of attention deficit hyperactivity disorder.
"Lipids or fats in the blood of developing children and fetuses is very important for brain development," Simcik said. "This recent study that has linked PFC exposure to increased ADHD diagnosis would make sense scientifically from a standpoint of these chemicals monkeying with lipids and later brain development."
Furthermore, the Department of Health report is drawing its conclusions from blood levels of people who have had carbon filters attached to their wells, or are drinking bottled water. Levels could have been higher before the problem was recognized. It's impossible at this point to know how high the levels were.
But Department of Health scientists say the plume of contamination is stable, and clean-up measures now underway will very slowly reduce contamination in water supplies.
Under plans approved by the Minnesota Pollution Control Agency, 3M is collecting groundwater from the Woodbury landfill and treating it with a huge carbon filter. The company is also cleaning up the sites in Cottage Grove, Woodbury, Lake Elmo, and Oakdale.
The report's co-author, Ginny Yingling, a hydrogeologist with the Department of Health said that's like cutting off the monster's head.
"So we're watching the death throes of this plume, we've cut off its source, we're not adding anything new to it, then over a very long period of time, it should allow the aquifer to flush itself out," she said.
Yingling said her department will be monitoring the situation for decades to come.
A 3M spokesman said the company has not read the report and cannot comment.