Fish from 54 Minnesota lakes outside the Twin Cities have low or undetectable levels of PFOS, the chemical formerly in Scotchguard, fire retardants and nonstick cookware that has raised health concerns in recent years.
The Minnesota Department of Health reported the results today from tests conducted by the U.S. Environmental Protection Agency and recently published in the scientific journal Environmental Science and Technology.
PFOS, perfluorooctane sulfonate, and related chemicals have been traced to immune system and other health issues. Over the past four years they have been found at high levels in some Twin Cities' lakes and rivers and in groundwater.
The EPA study, while not a comprehensive sampling of the state's more than 10,000 lakes, seems to indicate that the chemicals aren't widely distributed in the state.
"This is the first time we've taken a statewide look at the problem, and the good news is that PFOS weren't found in most fish outside the metro area, or were found in levels so low that they wouldn't trigger an elevated fish consumption advisory," Doug Schultz, spokesman for the Minnesota Department of Health, said.
ADVERTISEMENT
Among the 55 non-metro lakes tested in the recent study, only one lake outside the Twin Cities, Lake Zumbro near Rochester, had high enough levels of PFOS to raise the state's fish consumption advisory from "unrestricted" to "once a week."
Among five Twin Cities lakes tested for the latest study, McCarron's Lake in Roseville had higher levels of PFOS.
Previous testing in past years already showed higher levels of PFOS in 15 Twin Cities waterways as well as Wild Rice Lake and Fish Lake Reservoir north of Duluth. The Minnesota Pollution Control Agency is tracking the source of PFOS that researchers started looking for in fish in 2006.
For Fish and Wild Rice Lakes, the state recommends eating only one meal of most species of fish per week because of PFOS or mercury contamination, or both.
According to the health department, high concentrations of PFOS and similar compounds cause harmful changes in the liver and other organs in laboratory animal studies. Developmental problems have been seen in the offspring of rats and mice exposed to the chemicals. PFOS in high concentrations over a long period of time also cause cancer in laboratory animals.
There are not many studies of health effects in people, the health department said, but studies by 3M of workers exposed to the chemicals during manufacturing show no apparent impact on their health.
"There are, however, some recent development tests that show some issues in people," said Pat McCann, environmental health expert for the Minnesota Department of Health.
