Minnesota is a great state for fishing. Anglers benefit from thousands of beautiful lakes and rivers, a wide variety of fish, and a robust program for monitoring fish contaminants that helps people make informed choices about eating the fish they catch. Understanding the contaminants found in fish is also a window into understanding broader environmental effects of pollution, including from a category of human-made chemicals called per- and polyfluoroalkyl substances, also known as PFAS or “forever chemicals.”
The Minnesota Department of Natural Resources (DNR) and Minnesota Pollution Control Agency (MPCA) sample and test fish in bodies of water where known pollution issues may be a concern for human health through fish consumption. Since 1974, the Minnesota Department of Health (MDH) has used this data to advise anglers on fish consumption when levels of mercury or polychlorinated biphenyls (PCBs) may be unsafe for human consumption.
The fish contaminant monitoring program added PFAS in 2004. Since then, MDH has issued specific fish consumption guidance on 51 of Minnesota’s rivers and lakes due to PFAS in fish.
Testing fish for PFAS is one part of Minnesota’s PFAS Blueprint, which is a comprehensive, interagency plan to prevent, manage, and clean up PFAS pollution across the state.
How PFAS enter fish
PFAS are used in thousands of everyday products and industrial applications. These chemicals can contaminate surface water through industrial pollution, some firefighting foams, wastewater, and other pathways. This is a problem across the globe, including every state in the U.S. and every county in Minnesota. Much like mercury, PFAS can accumulate in fish tissue over time, so fish living in contaminated water can have PFAS in their bodies at much greater concentrations than the surrounding water. It is possible for scientists to detect PFAS in fish tissue before there is enough PFAS in the water to be measured. PFAS concentrations in fish can also decrease relatively quickly as PFAS in their habitat decreases.
Testing fish for PFAS in Minnesota
Gathering and analyzing data on PFAS in fish is complex, multi-agency work, but the results are worth it. Data on PFAS in fish inform fish consumption guidance and help us understand, clean up, and prevent PFAS pollution in Minnesota.
Thousands of fish from more than 200 different segments of lakes, rivers, and streams have been tested for PFAS since 2004. Since methods were standardized in 2017, about 85% of waters tested had fish containing PFAS, although usually at levels far below those used by MDH for fish consumption guidance. Perfluorooctane sulfonate (PFOS) is one of the oldest and most common types of PFAS found in fish, but many other types of PFAS, including those recently created, are also detected.
Fish from Minnesota’s lakes, rivers, and streams are tested for PFAS when DNR takes routine sampling and when funds permit a PFAS analysis. Other times, fish are tested based on suspected PFAS pollution in the area. Special funding and partnerships have allowed for occasional additional testing over the years, including a recent study along Minnesota’s Lake Superior shoreline.
Fish consumption guidance for PFAS
Fish from all sources can contain contaminants. MDH’s Safe-Eating Guidelines for fish are set based on the fish you eat and who you are. If you are pregnant, planning to be pregnant, or have children, you and your children need to be more careful about the kinds of fish you eat and how often you eat fish. By following these guidelines, you can lower your exposure to contaminants in fish and still get the benefits of eating fish.
MDH reports that fish provide a good source of protein and vitamins such as D and B2 (riboflavin). Fish are rich in calcium and phosphorus and are a great source of minerals, such as iron, zinc, iodine, magnesium, and potassium. Fish also provide an important source of omega-3 fatty acids. These essential nutrients keep our heart and brain healthy.
As PFAS are the focus of active research and study, we are continuously learning more about how PFAS impact people’s health and about their presence in fish. MDH updates fish consumption guidance on a statewide level based on the latest research of health effects from exposure to PFAS compared with the benefits of eating fish. MDH also provides guidance specific to waterbodies when fish test above certain levels.
MDH’s Statewide Safe-Eating Guidelines are based on average concentrations of PFOS, mercury, and PCBs found in fish. When one or more species of fish in a waterbody has concentrations of a contaminant above these averages, Waterbody Specific Safe-Eating Guidelines are needed. This guidance lists those species in specific waterbodies which have more stringent guidelines. In all cases for mercury and in some cases for PFAS, MDH provides more protective guidelines for sensitive groups, including children under 15, people who are pregnant, people who could become pregnant, and people who are breastfeeding or plan to breastfeed.
To date, MDH has issued statewide guidance for PFOS and Waterbody Specific Safe-Eating Guidelines due to PFOS for fish in 51 water bodies. This guidance is regularly reviewed. The latest information is available on MDH’s Fish Consumption Guidance webpage.
Improving our understanding of PFAS in the environment
Understanding PFAS in fish supports our understanding of PFAS in the ecosystems where they live. Although they may not absorb PFAS in the same way, every organism that interacts with the same water or feeds within a shared food chain are exposed to PFAS. This includes plants growing in the water, deer drinking the water, and birds eating the fish. All these are potential pathways for PFAS to move through the environment and eventually expose humans. Ongoing research into these ecological risks of PFAS will help us manage and prevent PFAS pollution.
Information about PFAS in fish can help identify contamination sites and prove that cleanup efforts are effective. For example, a 2004 University of Minnesota detection of PFAS in fish at Bde Maka Ska (then referred to as Lake Calhoun) in Minneapolis launched a source investigation that led to a chrome-plating facility in the area. Since then, the responsible party has been held accountable, pollution reduction measures were taken at the facility, and those measures were proven successful when PFAS levels in fish subsequently fell by up to 90%. Fish consumption guidance is still in place for Bde Maka Ska.
Greater monitoring and pollution prevention planned
In 2023, the Minnesota Legislature approved budget requests and PFAS pollution prevention measures that directly address concerns about PFAS in fish. Funds were appropriated for several aspects of the state’s comprehensive PFAS Blueprint, including $910,000 from the Clean Water Fund to expand the fish monitoring program. New prohibitions on PFAS in firefighting foam, which is a significant contributor to PFAS in fish, take effect in January 2024. Under Amara’s Law, restrictions on PFAS in many everyday products take effect in 2025 and further prohibitions on avoidable PFAS use are scheduled for 2032. New statewide water quality standards for six types of PFAS are due July 2026, which will enable the MPCA to reduce PFAS entering the environment through permitting.
New laws designed to prevent PFAS pollution are critical to protect public health and the environment. The chemicals’ longevity in the environment, however, means that PFAS in fish will be a problem for the foreseeable future.
Resources
It’s easy to get the latest information on fish consumption guidance and PFAS.
- Check the DNR’s LakeFinder for any fish consumption guidance in the lake you’re planning to fish. If there is none, the statewide fish consumption guidance applies.
- MDH’s fish consumption guidance webpage details statewide fish consumption guidance and a current list of waterbody-specific guidance.
- MDH’s PFAS webpages provide detailed information about general human exposure risks. Speak to your health care provider if you have personal concerns about PFAS exposure.
- MPCA’s PFAS webpages detail the PFAS Blueprint and work toward preventing, managing, and cleaning up PFAS pollution.
PFAS in fish detections by body of water since 2017
This table is a summary of detections of PFAS in fish from 131 different sections of lakes, rivers, and streams since 2017. This information is provided in response to public interest. When reviewing the data, keep in mind that:
- Most detections are at low levels. Average concentrations of PFOS in fish are considered in the Statewide Safe-Eating guidelines; PFOS has resulted in more stringent guidance than mercury or PCBs alone. MDH continues to evaluate full data sets and issues fish consumption guidance when experts believe such advice is necessary to protect health. Consult MDH’s Fish Consumption Guidance webpage for more information.
- If a body of water is absent from the list, that means fish from that body of water have not been tested for PFAS since 2017 or that PFAS were not detected in fish from that body of water that were tested.