The Great Lakes have long been a source of nutritious food for people who live along its shores, with an abundance of aquatic life like walleye, yellow perch, catfish, and bass. This is still the case, though pollutants in the waterways mean anglers need to pay attention to what they eat and how often.
Harmful substances like mercury, dioxins and polychlorinated biphenyls (PCBs) have been entering the lakes for decades, where they make their way into the food web. New and emerging chemicals such as pharmaceuticals and the flame-retardant polybrominated diphenyl ethers (PBDEs) also may be entering the food web. These can accumulate in fish and work their way up from preyfish to predators, posing a risk to human health. The province ofOntario and the eight Great Lakes states – Minnesota, Wisconsin, Illinois, Indiana, Michigan, Ohio, Pennsylvania and New York -- issue fish consumption advisories to help residents know how much of any given species is safe to eat in a given timeframe. Eating more contaminated fish doesn’t mean health problems will develop in a person, just that it’s more likely.
Developing these advisory guidelines takes work in the field and the lab. Fish are collected by state or provincial agencies and tested for chemicals of concern in the meat, fat and other tissues, according to Jennifer Gray, a toxicologist with the Michigan Department of Health and Human Services. The fish are prepared as if they were being eaten, such as if a particular species typically has the skin removed or the fat cut off.
Based on what substances are left, governments issue consumption guidelines. These can be different depending on where the fish was caught, as different locations have different amounts of contaminants. Since fish move throughout the water system without regard to political boundaries, however, an advisory in one area doesn’t mean fish from elsewhere, with different guidelines, aren’t also there.
“It really depends on where you are and the inputs (of pollutants) and what industries may have impacted the rivers, and all rivers flow to the Great Lakes,” said Michelle Bruneau, project manager and health educator with the Michigan Department of Health and Human Services.
Each state and province has its own methodology for consumption guidelines, she added, and while there are efforts underway to harmonize these practices Bruneau doesn’t believe all entities will adopt identical standards. Raw data is shared between governments, however – Ontario shares contaminant data collected by its scientists in the Great Lakes with the US states, who all share experiences on best ways of communicating advisories, said Satyendra Bhavsar, a research scientist with the Ontario Ministry of Environment and Climate Change’s (OMECC) fish contaminant monitoring program.
“We try to capitalize on advancements from both sides of the border,” Bhavsar said.
IJC’s Health Professionals Advisory Board noted in a 2014 report that risks and benefits should be considered when deciding to consume Great Lakes fish. Fish supply healthy unsaturated fats and high-quality protein, but may contain contaminants at high enough levels to impact human health. Common alternative foods to fish may provide health promoting nutritional value, but also saturated fats or sugars and contaminants of their own. These chemicals aren’t a reason to avoid the health benefits of eating fish from the Great Lakes, as long as consumers are aware of and use the guidelines available to help them choose and eat fish that are lower in contaminants.
Some chemicals like mercury, Gray said, collect more heavily in the meat of the fish, leaving few options to reduce the amount an angler would be eating. Dioxins and PCBs tend to collect more in the fat of a fish and can be reduced by cleaning away the fat, removing flesh around the belly area, and cooking the meat over a rack or grill so the remaining fat can drip away. The US National Cancer Institutewarns not to let the flesh char while grilling, as that can cause compounds linked to cancer to form. And since contaminants tend to collect at the bottom of a waterway, Bruneau said people should check the consumption guidelines before eating bottom-feeding fish like catfish or drum.
One of the most helpful choices an angler can make is to choose smaller fish of a species. Bhavsar said a smaller fish is likely going to have significantly fewer contaminants than a larger one of the same species, as it’ll probably be younger and thus have less of an opportunity for these contaminants to accumulate in its tissues. Fish eggs can contain higher concentrations because of their higher fat content, he added, and should be avoided. Additionally, the province of Ontario recommends leaner fish from the Great Lakes, such as pike or walleye, and choosing panfish – fish that don’t grow larger than a standard frying pan.
In some places, guidelines are different for “sensitive populations,” such as children, pregnant women or women who could become pregnant, Bhavsar said. Excessive contaminants can impact a child’s development, or get passed along in the womb from a pregnant woman. In other areas, such as Michigan, guidelines take these populations into account when recommending serving sizes.
Having guidelines is one thing, but making sure people are aware of them is another. Thanks to Great Lakes Restoration Initiative funds, US states have been working to inform communities, recreational and subsistence anglers and vulnerable populations about the recommended limits on fish consumption. Bruneau said that this has included contacting community organizations that can spread the word, including working with tribal governments, Women, Infants and Children departments and sportsmen clubs to assist in their own areas.
In Ontario, Bhavsar said the ministry works with local health agencies – such as Toronto Public Health – and other stakeholders, and with First Nations communities to get the word out about the consumption advisories. Fact sheets are available in 17 languages, including English, French, Cree and Ojibwe, and written copies of the advisories are available for free through Service Ontario.
Another tricky area is fish purchased in a store, a farmers market or served in a restaurant. It’s often difficult to pinpoint where a particular fish was caught on the Great Lakes, and since each part of the lakes is unique in its degree and makeup of contaminants, it’s also difficult to say what specific guidelines would apply. In the US, the Food and Drug Administration is responsible for food labeling, and doesn’t have regulations in place for adding safety recommendations to labels, though it did release general advisories for children and pregnant women. Bruneau suggested following basic consumption guidelines is the best way to go in these cases. Bhavsar said local health agencies take the lead on purchased fish, like Toronto’s, but generally the province recommends people cut back one meal of wild-caught Ontario fish for every two meals of store-bought fish.
The concentrations of some of these chemicals are shrinking, but others remain problems. Bruneau said PCBs and dioxins have been regulated for years and are slowly dropping in concentrations throughout much of the Great Lakes, particularly thanks to work cleaning up Areas of Concern. Mercury – which is transported through the air into the water system via sources such as coal-fired power plants - and newly emerging chemicals such as PBDEs will most likely drive guidelines into the future, however. The costs for chemical testing can quickly add up when all the potential contaminants, locations and fish species are being accounted for, becoming prohibitively expensive.
Fish consumption guidelines for provinces and states in the region are linked below:
Kevin Bunch is a writer-communications specialist at the IJC’s US Section office in Washington, D.C.
