Eating contaminated freshwater fish carries risks
PFAS compounds can enter bloodstream
Eating one locally caught freshwater fish in a year delivers as much potentially health-harming nonstick PFAS compounds to the blood as drinking PFAS-contaminated water for a month, newly published scientific research finds.
Eating these fish “is like drinking some of the most PFAS-contaminated water that you could find in any public water system in the country, if not worse,” said David Andrews, senior scientist with the nonprofit Environmental Working Group in Washington, which conducted the study with Duke University.
The researchers reviewed data from more than 500 fish fillet samples collected by the U.S. Environmental Protection Agency from 2013 to 2015 in two programs: nationwide in its National Rivers and Streams Assessment and for the Great Lakes Human Health Fish Fillet Tissue Study. More than 44 different fish species were sampled, including popular sport fish such as largemouth and smallmouth bass, rainbow trout, northern pike and more.
‘Now I see a fish and I think PFAS’
They found PFAS compounds in the fish were 280 times higher than those detected in some commercially caught and sold fish. Andrews speculated that the commercial fish could be raised on farms fed by groundwater that has relatively less exposure to industrial and commercial sources of contamination.
“I grew up fishing every week, and ate a lot of the fish that we caught,” he said. “Now I see a fish and I think PFAS . ... These are industrial chemicals that have really become ubiquitous contaminants in the environment.”
Per- and polyfluoroalkyl substances – PFAS – were compounds used throughout industry and in commercial products since the mid-20th century for their nonstick and water-resistant properties, including Teflon-coated pots and pans, Scotchgard carpet stain protection and Gore-Tex rain-resistant clothing. The compounds have been dubbed “forever chemicals” because they generally fail to break down in nature. In recent years, they’ve been found to contribute to a host of human health problems, including cancer.
PFAS compounds are now detected in the blood of 98% of Americans. It has even been found in polar bears in the Arctic Circle, as the chemicals have worked their way up the food chain from fish and seals.
One of the most commonly used PFAS compounds historically, perfluorooctane sulfonate, or PFOS, is the most commonly found nonstick compound in the fish studied, making up almost three-quarters of the total PFAS content detected.
The researchers calculated that eating one fish in a year equated to drinking water with PFOS at 48 parts per trillion for a month in terms of its impact on increased human blood levels. The EPA in June revised its nonenforceable drinking water health advisory for PFOA down to 0.004 parts per trillion, meaning anyone drinking water over a lifetime with PFOS levels above that advisory limit is exposed to more risk of adverse health effects.
The study underscores the importance of diet in PFAS exposure, said Tasha Stoiber, a senior scientist with Environmental Working Group and a co-author of the new study.
“We talk a lot about drinking water contamination, and that gets a lot of attention,” she said. “But paying attention to dietary sources, and your overall sources of exposure to PFAS is also really important.”
Health and economic risks
It’s an economic as well as public health concern. According to a 2019 study conducted by the Michigan United Conservation Clubs and Michigan State University, fishing contributes $2.3 billion to the state economy through gear and clothing, booking hotel rooms, buying meals and more.
According to the Centers for Disease Control and Prevention, exposure to high levels of PFAS can lead to health problems including kidney or testicular cancer, increased cholesterol levels, liver problems, high blood pressure or preeclampsia in pregnant women and decreased vaccine response in children.
Michigan issues Eat Safe Fish guidelines and recommendations on limiting fish consumption due to contamination with PFAS compounds, mercury, or PCBs. The recommendations are broken down by region and by river, lake, or other water body.
In some places – such as Belleville Lake in Wayne County, Portage Lake in Livingston County, or Ford Lake in Washtenaw County – the Michigan Department of Health and Human Services recommends no consumption of fish due to the levels of PFOS detected in fish there. But in other places, the guidelines are more species-specific, and eating some of the fish is considered acceptable. On Lake St. Clair for example, the Eat Safe Fish guidelines call for limiting sunfish and bluegill consumption to four servings per month.
Environmental justice questions
The guidelines are regularly updated based on new fish contaminant data, health department spokeswoman Lynn Sutfin said. “Since MDHHS can’t test every kind of fish from every lake and river in the state every year, the guidelines for every water body won’t necessarily change in every Eat Safe Fish Guide,” she said.
The program also regularly reviews the science behind its guidelines.
“This review can take some time, but ensures that Eat Safe Fish guidelines are based on the best available science to be health protective for people who eat fish caught in Michigan,” Sutfin said.
The PFAS contamination in locally caught freshwater fish, nationwide and in the Great Lakes region, has an environmental injustice component, Andrews said. Many people fish for sustenance, eating their catches in several meals per week.
“It’s an important food supply for many people, especially immigrant populations and disadvantaged populations. And that really is of particular concern,” he said.
Though fish can contain PFAS, mercury, or other contaminants, it also can be an important source of nutrients such as omega-3 fatty acids, Sutfin noted.
“Sport-caught fish can also be a lowcost source of lean protein,” she said. “People can use the Eat Safe Fish Guides to make informed choices when eating fish caught in Michigan waters.”
The most important mitigation that can occur is stopping PFAS pollution, Andrews said.
“Ultimately, this is a problem that needs to be controlled by not putting the contamination out there,” he said.
Eating these fish “is like drinking some of the most PFAS-contaminated water that you could find in any public water system in the country, if not worse.”
David Andrews
Senior scientist, Environmental Working Group