Study: U.S. freshwater fish 'significant' source of 'forever chemicals' in blood

Eating just one bass or other wild-caught freshwater fish a year adds a significant increase in “forever chemicals” in our blood, equivalent to a month's worth of drinking water laden with fire-proofing compounds that have been linked to certain cancers and increased lifetime health risks, according to a new study.

But the risks of so-called PFAS compounds are so poorly understood, and the science so new, that health and food safety officials say there's not enough proof yet that consumers should be alarmed enough to forego the overall health benefits of eating freshwater fish, altogether.

The study deals with fish caught in the wild. Researchers haven't found similar levels of the chemicals in store-bought fish, much of which are farm-raised.

The study by researchers at Duke University and a D.C.-based nonprofit group echoes similar findings regarding so-called PFAS compounds in recent years. The researchers say their study also bolsters the case for the U.S. Environmental Protection Agency to regulate industrial producers of so-called PFAS compounds more aggressively. Key among those compounds is this study is one called PFOS (perfluorooctanoic acid).

"Fish is an important source of protein and part of a healthy diet, but government testing has found that wild caught freshwater fish are incredibly contaminated with PFOS and grocery store fish are not," David Andrews, a senior scientist at Environmental Working Group and lead author of the study said via email in response to FLORIDA TODAY's questions. "These test results, finding high levels of PFOS widespread across the country call into question whether wild caught freshwater fish should be consumed and in many locations the answer is likely 'No.' "

PFAS, sometimes called “perfluorinated compounds,” are a class of manufactured chemicals that have been detected nearly everywhere scientists sample for them worldwide, including sites with no nearby manufacturing or use of PFAS. They have a variety of uses such as in manufacturing firefighting foam or non-stick cookware.

The main compound in the EWG/Duke researchers found in fish was PFOA, a chemical used to make coatings and products that resist water, heat, oil, stains and grease.

The researchers examined PFAS levels in blood serum from consumption of locally caught freshwater fish from more than 500 composite samples of fish fillets gathered nationwide from 2013 to 2015 under EPA monitoring programs.

A large-mouth bass caught in the Kissimmee River in 2014 had more than twice the upper-limit of PFAS seen in most fish. Fifty samples nationwide had more than five times the typical amounts.

Little is known about PFAS, but science is emerging to show no amount of the chemicals is healthy.

The EWG/Duke researchers found more so-called PFAS chemicals in the human blood of those who ate just one freshwater fish than a month’s worth of drinking water contaminated at the usual levels with the same compounds.

Again, scientists don't know how much is a significant lifetime health risk. But some are worried.

"What was most surprising was how freshwater fish around the U.S. is contaminated at levels hundreds to thousands of times higher than drinking water that would be considered unsafe to drink," Tasha Stoiber, a senior scientist at the nonprofit Environmental Working Group (EWG) and a coauthor of the paper, said via email.

Last year EPA dramatically lowered recommended lifetime limits for certain PFAS chemicals in drinking water citing the an increased risk of harm to the immune system.

EWG created an interactive map to search how high PFAS levels tested in local freshwater fish.

Their study, published in the journal Environmental Research. was supported by a grant from Yahoo cofounder David Filo's Yellow Chair Foundation.

The chemicals can remain in the body for decades. These fluorinated compounds forge some of the strongest chemical bonds in nature, thus the name, "forever chemicals." Thousands of PFAS compounds aren't even yet measured, so the combined long-term toxic effects also remain unclear. University of Florida researchers hope to narrow those knowledge gaps with ongoing studies, some of which also might yield clues as to what's killing so many manatees in Florida, lately, and risking human health.

Other studies in recent years have linked PFAS to testicular cancer, kidney cancer, high cholesterol, ulcerative colitis, thyroid disease and pregnancy-induced hypertension. The association with other diseases is less certain.

More: Indian River Lagoon PFAS resultsUF to announce Brevard 'forever chemicals' results from soil and water tests

The EWG/Duke study arrives as regulators and activists have been focusing for years on zeroing out PFAS in drinking water, while food ― especially seafood ― harbors the cancer-causing compounds at several orders of magnitude higher levels than drinking water. It also comes as Congress balked at dozens of bills to regulate PFAS. Last session, the then Democratic-controlled Congress failed to pass proposed bans on PFAS in cosmetics, food packaging and textiles, and measures that would have set stricter cleanup standards. The bills stalled under lobbying pressure from the American Chemistry Council trade group, which represents chemical makers, Dupont and other industry interests..

Proposals to speed up PFAS cleanups on military bases were included in the National Defense Authorization Act, however.

Patrick Space Force Base had used firefighting foam containing PFAS for decades, until discontinuing their use a few years ago. Some of the highest levels in groundwater nationwide have been detected on Patrick, with PFAS exceeding 4.3 million parts per trillion. Those levels rekindled concerns in the Satellite Beach area that the compounds may have contributed to rare cancer outbreaks over the years.

PFAS also has been turning up in blood and tissues of alligators, manatees, dolphins and other wildlife at and near NASA's Kennedy Space Center. A 2017 study found the blood of alligators caught between 2012 and 2015 at the space center had the highest levels of toxic fluorinated chemicals ever measured in the species.

As a result, Brevard now is part of a three-year pilot study of PFAS in Brevard's groundwater and the Indian River Lagoon, conducted by the University of Florida under an almost $800,000 EPA grant. The study is examining how flooding caused by hurricanes influences distribution of PFAS, and how societal factors can exacerbate health impacts from exposure.

More:UF to announce Brevard 'forever chemicals' results from soil and water tests

More: Researchers find PFAS everywhere‘Forever chemicals’ lurk everywhere Florida looks for them in the Indian River Lagoon

For recreationally caught fish or other seafood, FDA recommends consumers check their state fish and shellfish consumption advisories. A searchable list of fish advisory websites maintained by states, territories, and tribes is available on the U.S. Environmental Protection Agency’s website.

Jim Waymer is an environment reporter at FLORIDA TODAY. Contact Waymer at 321-261-5903 or jwaymer@floridatoday.com. Or find him on Twitter: @JWayEnviro or on Facebook: www.facebook.com/jim.waymer

This article originally appeared on Florida Today: Study: Local freshwater fish in U.S. 'significant' source of 'forever chemicals' in human blood