Toxic Catch: Bay Area Communities at Risk from PFAS in Local Fish

People have always fished in the San Francisco Bay. But they may also unknowingly consume unhealthy levels of persistent, dangerous chemicals with their catch.

A study published on Tuesday from researchers at the San Francisco Estuary Institute found that 10 species of commonly consumed fish from the Bay frequently contain high levels of “forever chemicals,” which can take hundreds to thousands of years to break down and accumulate in the people and animals that eat them. The South Bay, the study found, is especially polluted.

Study author Rebecca Sutton said she and colleagues have been worried about perfluoroalkyl and polyfluoroalkyl substances, or PFAS, in local fish for decades. The study examined the prevalence of PFAS in shiner surfperch, striped bass, white croaker and seven other sport fish from the Bay over the last ten years.

“Our concern is that there are a lot of fishing communities who eat a significant amount of fish from the Bay, and they could be more exposed to these highly toxic chemicals,” Sutton said. “With this study, we’re trying to assess the level of risk.”

The findings were staggering: In sampling nearly 100 fish between 2009 and 2019, effectively every sample contained PFAS. More than 80% of fish from the South Bay,  which has less tidal “flushing” than other communities and more runoff from highly urbanized areas,  had more PFAS than some state standards consider safe to eat once a week. The southern waterways tested were Coyote Creek, Redwood Creek and Artesian Slough.

While fish caught in the northern and central Bay — around Berkeley, the Carquinez Strait, Oakland and Suisun Bay — were less contaminated, about a third of all fish were found to be above the one meal per week threshold, based on a serving size of 8 ounces of fillet meat with the skin off.

California does not currently have a safety recommendation for PFAS in fish. Researchers used Massachusetts’ advisory threshold, which is currently the most stringent in the U.S., Sutton said.

PFAS refers to a broad class of thousands of chemicals made for use in consumer, commercial and industrial products — many used to make products stain-resistant or nonstick. They’re stable, repel water and oil and effectively never break down. They’re also bad for us, even in tiny amounts.

“Trace exposures, like very low concentrations, are associated with all kinds of human health impacts,” Sutton said.

PFAS have been shown to increase the risk for several types of cancers, thyroid disease and other hormone-disruption issues, including fertility problems and developmental delays in children and immune system impacts.

“So, there’s a lot of actually really good epidemiological and animal studies showing major impacts, multi-system impacts in humans.”

The researchers detected elevated levels of one PFAS — the uncharismatically named “7:3 FTCA,” — not previously detected in marine fish. Sutton said this was their first time testing for it, using methods only recently standardized. Sutton and colleagues believe that these chemicals find their way into the Bay primarily from consumer products. That includes food packaging, waterproof fabrics, stain-resistant carpets and furniture, fire-suppression foams and nonstick pans.

In other bodies of water across the U.S., especially in places like the East Coast, Midwest and South, chemical manufacturing plants and industry can be key sources of PFAS pollution. Past SFEI studies have shown that treated wastewater and stormwater runoff from towns and cities are both PFAS routes to the Bay.

The California Department of Public Health declined a phone interview but shared a statement by email confirming that this research “provides evidence that parallels efforts at CDPH to understand PFAS exposures in Californians … This work will help address PFAS contamination in local food supplies, such as culturally inclusive fish consumption advisories.”

Indigenous and tribal communities, as well as Asian Americans and Pacific Islanders, frequently eat fish from the Bay and may be disproportionately affected by exposure to these dangerous chemicals. SFEI is collaborating with community groups such as All Positives Possible to mitigate the impact on those whose culture is tied to the Bay’s fish and marine life.

*Correction: A previous version of this story described Rebecca Sutton as a lead author the study, when she is the corresponding author.  Miguel Méndez is the lead author.