In our Jan. 27 edition, I reported on a recent study in the journal Environmental Research that linked higher levels of chemicals known as PFAS and PFOS in human blood to the regular consumption of freshwater fish. These chemicals, which are slowly being phased out by most product manufacturers in the U.S., including Minnesota-based 3M, have been slowly accumulating in our environment ever since they came into widespread use in the 1950s. In more recent years, we’ve come to better understand their danger to public health.
The study was concerning, and we followed it up with an editorial the following week urging better guidance from state health officials about the levels of PFAS in fish in Minnesota lakes. We do know that Minnesota lakes, including those here in northern Minnesota, contain these chemicals, which don’t break down naturally.
Since then, I’ve learned more about the issue and it turns out the Minnesota Department of Health is now providing some general guidance on the safe consumption of fish from Minnesota lakes based on typical levels of contaminants like mercury and PFAS and PFOS.
Those recommendations vary somewhat, depending on the circumstances of an individual. For pregnant women, women who could become pregnant, or children under age 15, the DOH recommends no more than one meal per month of common locally-caught fish, such as walleye, northern pike, bass, or lake trout. Fish that feed lower on the food chain, like perch, sunfish, whitefish, and stream trout, can safely be eaten once a week according to the DOH.
For males over age 15 and women who don’t plan to become pregnant, the DOH recommends no more than one meal per week of walleye, northern pike, or bass.
These are statewide recommendations which don’t take into account the fact that there are significant differences in the levels of PFAS and PFOS in fish depending on the lake. In general, it appears that inland lakes in northern Minnesota have lower levels of PFAS and PFOS than in other parts of the state, which is encouraging up to a point. Lake Superior, and the rest of the Great Lakes, are known to have higher levels of these chemicals than many other lakes and that’s prompted another recent health advisory, for the rainbow smelt that many Minnesotans net along the shores of Lake Superior in the spring. The states of Minnesota, Wisconsin, and Michigan have all issued advisories recommending no more than one meal per month of these small fish, which for reasons unknown appear to accumulate PFOS more readily than other fish.
It should be noted that another organization, the Great Lakes Consortium for Fish Consumption Advisories, which is made up of all the Great Lakes states, has issued its own guidance for PFAS and PFOS, which is both more specific but in a way not as helpful. According to guidance they’ve issued, you can eat an unrestricted amount of fish if it contains less than 10 micrograms/kilogram of these chemicals, two meals per week if it contains between 10-20 mg/kg, no more than one meal per week if it contains 20-50 mg/kg, and no more than one meal per month if it contains 50-200 mg/kg. Any fish with over 200 mg/kg of PFOS and PFAS should not be eaten.
That would all be helpful information if we only knew the level of PFAS or PFOS in that walleye we just caught. That’s why we have argued for more lake-specific testing, particularly from some of the state’s most popular fishing lakes. There’s reason to believe that the fish caught in lakes like Vermilion is relatively low in PFAS and PFOS. Indeed, a graphic included in the recent study showed fish tested from a handful of northern Minnesota lakes had PFAS or PFOS in the 1,000-10,000 parts per trillion range. That’s pretty low and would mean you could eat fish from lakes in our region without much concern about PFAS and PFOS. But the testing also found that contamination levels varied quite a bit in different water bodies and different species of fish. It would be nice to know with some certainty, which is what more testing could provide.
When we’re talking about fish and fishing, there’s a lot at stake for Minnesota, and particularly northeastern Minnesota. If those who enjoy catching and eating fish can continue to do so in our region with relative peace of mind, that would be good news, indeed.