Fish taken in 2010 from nine of Minnesota's 10 largest walleye lakes had levels of perfluorooctane sulfonate that were either very low or undetectable, suggesting those lakes have very little or no contamination from perfluorochemicals.
That is one of the early findings from new data for fish contamination recently received by the Minnesota Department of Health from the Minnesota DNR and the Minnesota Pollution Control Agency.
The results of the PFC testing mean that advice on how much fish can be eaten safely from those walleye lakes will not be impacted by perfluorochemicals.
The walleye lakes tested were Kabetogama, Rainy, Vermilion, Mille Lacs, Lake of the Woods, Leech, Winnibigoshish, Cass and Upper Red Lake.
Minnesota's 10 largest walleye lakes are the most important fishing waters in the state, according to the DNR. They account for about 40 percent of the statewide walleye harvest and are usually among the most popular lakes with sport anglers.
After PFCs were discovered in fish from Lake Calhoun in the metro area in 2007, state officials began to look for PFCs in fish from other waters of the state. PFOS is the perfluorochemical that accumulates most in fish.
Under the 2010 round of testing, state scientists retested some of the waters, or connected waters, that had higher levels of PFCs in fish from previous testing. The levels found were similar to previous measurements. New waters tested for PFCs included several rivers in Greater Minnesota and some additional metro area lakes. Results from the testing indicate no need for advice to limit consumption in any new areas based on PFCs. Those waters may have existing advice to limit consumption based on mercury or PCBs.
The 2010 collections of PFC data will be included, along with new data on mercury and PCBs from 2009 and 2010 collections, when MDH updates its fish consumption guidelines in June. The DNR collects fish for testing by the Minnesota Department of Agriculture. MDH then analyzes the test data and establishes the consumption advisories. The guidelines provide consumers and anglers with information to help them make choices about the fish they eat.