Eating Great Lakes Fish
By Mike Langendorf, CORA Environmental Coordinator
July 2023
We have all likely seen some manner of an article or publication that has been written about the presence of contaminants in freshwater fish. Although environmental contaminants can persist within such fish populations, what about the host of other U.S. food chain items we consume? What about other food items such as saltwater seafood, market beef, pork and poultry and what level of contaminants do they have? Does eating these other foods pose a risk to human health? Why do freshwater fish seem to gain more attention than other food sources? Then what about our nations agricultural products and our drinking water supplies?
Clearly there are many questions that can be asked and sure, we occasionally hear or read about one of these other food chain items having been been found to be exposed to chemicals during processing or perhaps a story emerges about a boil water alert for a contaminated drinking water system, or a recall notice is issued for foods such as lettuce or peanut-butter found to contain bacteria that has the potential for causing illness. But do we really know what levels of contaminants are actually introduced to these other food products through environmental exposure or from chemical processing agents used to produce or package them? In a follow up article, we will look deeper into these questions and try develop the answers about what contaminants are found in other food chain items.
As for this article, an overview of what current contaminant risks and monitoring exists in the Great Lakes fish, and what human health benefits may be derived from consuming these fish as part of a regular dietary intake.
What are some of the concerns about contaminants in Great Lakes Fish?
For decades, the Great Lakes and many of its tributaries had been largely ignored as to their environmental degradation and declining water quality, leaving the lakes poorly managed for their long term health and presence of industrial pollutants such as Mercury and PCB’s among others. In the last few decades and as a result of the implementation of the Clean Water Act, Clean Air Act and the Great Lakes Water Quality Agreement of the 1970’s, there has been great progress made in reducing the overall levels of contaminants found in the Great Lakes. Although some levels of pollutants including Mercury, PCB’s, DDT’s and other legacy pollutants still remain, clean-up efforts combined with reductions in use and industrial emissions, have led to the steady decline in the amounts of these substances being found in the Great Lakes fish populations, including those fish harvested from the 1836 Treaty waters.
As a result of the lingering presence of these legacy contaminants remaining in the lakes, many governmental agencies began the practice of producing fish consumption advisories for fish harvested from the Great Lakes. These advisories were designed to limit exposure to trace levels of contaminants being introduced to humans thru fish consumption. Since the early 1990’s, and today made possible in part by the BIA/EPA Great Lakes Restoration Initiative or “GLRI”, CORA maintains its longstanding contamination monitoring program that collects data used to understand the trends and presence of contaminants in fish from the 1836 Treaty waters. Fish collected for the CORA program are harvested annually by tribal commercial fishers from the 1836 Treaty waters of upper Lakes Michigan and Huron as well as the eastern half of Lake Superior. Sample fish are then later processed and tested for the presence of a variety contaminants. The results from this program can then further be shared with CORA tribes and other agencies that use this data for informing the public regarding the risks and benefits of eating Great Lakes fish. The results from this program have consistently shown declines in the levels of legacy contaminants in the 1836 regions fish, which in many cases has allowed these fish to be placed into consumption advice categories having minimal intake restrictions. (ex., Michigan Dept of Health & Human Services Fish Consumption Value Ranges)
New or emerging contaminant threats to the Great Lakes fish are also monitored for. One of these substances of emerging concern are the man made chemicals that contain per or poly- fluoroalkyl substances, better known as PFAS. These industrial substances have been widely used for decades as fire fighting foams and stain retardents, and in recent years have become more widely reported as having an association with negative effects to human health. During 2021, in response to these growing environmental concerns over PFAS, CORA added PFAS monitoring of fish being harvested from the 1836 waters of Lake Michigan. Results from testing these fish showed relatively low levels of PFAS detected when compared to fish sampled from other regions of Lake Michigan that fell outside the territory of the 1836 waters. As to the levels of PFAS found in the 1836 territory samples, these levels were low enough to place these fish into consumption advice categories that allow for nearly unrestricted consumption. It is not to say that all trace contaminant levels found in Great Lakes fish can go without considering an individuals own health or dietary choices, but rather it is important to be aware that the Great Lakes themselves make up a significant body of water and that not all fish that are consumed from the lakes are subjected to the same contaminants or exposure levels depending on which regions of the lakes a particular population or species of fish may reside in or may eventually be harvested from.
What about chemical contaminants in other food chain items?
With PFAS, as is likely the case with many environmental pollutants, these substances can be found in trace levels in the environment and water supply of most if not all of the United States, not just in the Great Lakes waters and fish. Some studies have shown that soils, plants, animals and foods other than fish, can also be found to have trace levels of PFAS (as is likely with other contaminants), at various levels or by composition when compared among samples from various regions of growth or production that has had differing degrees of environmental influence or processing methods associated with source point pollutants or contaminants.¹ This further underscores the reality that many foods, agricultural products and drinking water found in the domestic food chain, can contribute to the human dietary intake of chemicals such as PFAS. This evidence also suggests that variances in composition or presence of a contaminant such as PFAS is likely to be effected by environmental exposure to source point pollutants present nearby where the item was grown, produced or extracted from and are not specific to just fish. These factors make the overall understanding of where any of your food sources or water comes from, or in some cases where or how it was processed, into an important part of selecting an individuals dietary choice.
Can anything be done to reduce the potential for ingesting contaminants found in fish?
There are some actions that consumers can take to help reduce the overall potential for ingesting contaminants that may be in fish that you can’t necessarily practice with other food items. According to the U.S. Dept of Health and Human Services Agency for Toxic Substances and Disease Registry, with the exception of Mercury (as is likely to be found with other protein binding substances such as PFAS), by removing the fat deposits and skin from the fillet portion of a fish that is then either grilled or baked, can further reduce the remaining combined contaminants by as much as 68%. The American Heart Association also suggests that eating a variety of fish will help minimize any potentially adverse effects due to environmental pollutants. The benefits can far outweigh the potential risks when the amount of fish eaten is within the recommendations established by the FDA and Environmental Protection Agency.
What are the health benefits derived from consuming fish as part of a regular dietary intake?
● According to both the EPA and FDA, eating fish and shellfish that are low in Mercury are considered a good choice for the dietary intake of people due to fish being a good source of protein.
● Similarly, the oils found in many Great Lakes fish, particularly Herring, Whitefish and lean Lake Trout, can also contain Omega-3 rich fatty acids that are essential to the human development needs of young children and in unborn babies carried by their mothers or for mothers who are breast feeding.²
● In order to derive the health benefits of eating fish, the FDA suggests a dietary intake of fish to consist of two 4oz servings per week for an average adult and about two, 2-3oz servings per week for a child.
● The FDA is currently proposing to allow some fish to be included in a new package labelling campaign. This proposal would allow for certain foods to be labelled as “Healthy” when they are found to be a good source of protein and are also low in saturated fats, sugars and sodium³, such as many Great Lakes Fish species typically are.
● The American Heart Association also recommends eating two-4 oz servings of fish per week in order to derive the benefit of the nutrients found in them that helps aid in maintaining a healthy cardio-vascular system, and that many studies have suggested helps to reduce the risks for heart attack and stroke.⁴
● To find out more about the health benefits of consuming fish and the most current consumption advice for the waters you eat fish from, go to;
EPA.gov, FDA.gov or the Michigan Department of Health and Human Services website, or the website for the state or province bordering the waters where your fish may be harvested from.
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¹ Huron River Watershed Council; PFAS contamination in Beef, 1-23-22 ¹ PFAS in Agricultural settings; Maine Center for Disease Control & Prevention, 2/17/22
² FDA/EPA fish consumption guide for children and expectant/breastfeeding mothers
³ FDA.gov/consumer updates
⁴ American Heart Association