Important news for Gull Lake anglers. Newly released guidelines from the Michigan Department of Health and Human Services (MDHHS) recommend limiting the consumption of smelt from Gull Lake to 2 serving per month. The new smelt guidelines are based on elevated levels of perfluorooctane sulfonate (PFOS) found in rainbow smelt from Gull (and 5 other Michigan lakes). PFOS is in the family of chemicals known as per- and polyfluoroalkyl substances (PFAS). These long-lived chemicals can build up in fish and in the people who eat these fish.
The new Michigan Eat Safe Fish consumption guidelines for rainbow smelt are as follows:
• Lake Huron: 6 servings per year.
• Lake Michigan: 1 serving per month.
• Portage Lake in Houghton County: 1 serving per month.
• Gull Lake in Kalamazoo County: 2 servings per month.
• Higgins Lake in Roscommon County: 4 servings per month.
MDHHS also currently recommends that no one eat more than 1 serving per month of rainbow smelt from Lake Superior.
Concerns about PFAS in fish have been much in the news lately (see for example https://www.cnn.com/2023/01/17/health/freshwater-fish-pfas-contamination-wellness/index.html ) and consumption advisories for fish containing high levels of PFAS are becoming increasingly common. PFAS exposure has been linked to a number of adverse health effects including certain cancers, thyroid dysfunction, changes in cholesterol, and small reductions in birth weight. PFAS were commonly found in hundreds of items such as water and stain repellent clothing, cosmetics, fire-fighting foam, and nonstick cookware. Manufacturersagreed in the early 2000s to voluntarily stop usinglong-chain PFAS in US consumer products and the use of PFOS and PFOA in food packaging was phased out in 2016 by the US Food and Drug Administration. But, since PFAS are long-lived chemicals, they remain in the environment and continue to circulate.
PFAS may leak into the environment where they are made, used, disposed of, or spilled. Moreover, their persistence means they can cycle through soils and water without breaking down, as well as build up in fish and other wildlife. Some PFAS can also biomagnify, becoming more concentrated as they move up the food chain. It is unknown why rainbow smelt in particular concentrate PFOS in their bodies, since smelt are relatively short-lived and feed on zooplankton and aquatic insects, not other fish (i.e., they feed in the middle of the food chain).
Should you take the fish consumption advisory for smelt from Gull Lake seriously? The simple answer is YES. There is good scientific evidence that consuming fish with raised levels of PFOS in their bodies will directly increase the levels of these chemicals in the people that eat them. (https://www.sciencedirect.com/science/article/pii/S0013935122024926?via%3Dihub ).
It is natural to ask how Gull Lake smelt ended up on the MDHHS’s fish consumption advisory? It may have more to do with smelt biology then with Gull Lake per se. As noted above, rainbow smelt seem especially prone to concentrate PFOS in their bodies, for reasons that aren’t yet known (smelt consumption advisories have been issued for smelt in other Great Lakes states). Because smelt require deep, cold and well-oxygenated water to live, Gull Lake is one of the few local lakes where smelt are found. Folks familiar with local history may remember that PFAS were one of the multiple toxic chemicals released into the ground water by the former Production Plated Plastics factory located on N 34th St. in Richland. However, it is unlikely that this is the source of PFAS in Gull Lake smelt. Monitoring of private and test-well sites between the contaminated site in Richland and Gull Lake show that the PFAS have moved with groundwater towards the southeast and not towards Gull Lake (https://www.mlive.com/news/kalamazoo/2019/02/pfas-investigation-expands-south-from-source-in-richland-township.html). Moreover, studies have found PFAS in very remote areas in the world leading to research on atmospheric deposition of PFAS. Lastly, PFAS have been used in many household products over the past 50 years, so it is possible that some may have come from septic systems prior to the sewer being installed around the lake.