Perfluoroalkyl and polyfluoroalkyl substances (PFAS) are a broad class of fluorine-rich specialty chemicals. More than 4,700 PFAS are used in consumer, commercial and industrial applications, including food packaging materials, waterproof textiles, stain-resistant carpets and furniture, fire-suppression foams, processing aids for the production of fluoropolymers like Teflon, mist suppressants in metal-plating, and hydraulic aviation fluids. Perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) have been shown to be highly toxic and have been phased out of production in the US. Use is shifting to alternatives to PFOS and PFOA, including shorter-chain perfluoroalkyl chemicals and polyfluoroalkyl chemicals; however, very little is known about the fate of these compounds in the environment or their potential to cause ecological harm.
The RMP has monitored PFAS in the San Francisco Bay for over a decade. PFAS are widely detected in Bay matrices including water and sediment. These contaminants are also ubiquitous in Bay biota including fish, bird eggs, and harbor seals. A detailed synthesis of the RMP PFAS work can be found here.
Concentrations of PFOS in Bay harbor seals and bird eggs in 2004 and 2006 were some of the highest detected globally (additional information can be found here and here). The RMP has continued to monitor PFOS concentrations in bird eggs on a triennial basis. Current PFOS concentrations in South Bay bird eggs, while lower than those observed in the mid-2000s, may still pose a risk to hatching success.
In addition, the RMP monitors sport fish for PFAS on a recurring five-year basis. Current sport fish PFOS concentrations may pose risks to humans eating high-fish diets, according to consumption guidelines from the State of Michigan. Much lower fish consumption guidelines have been proposed by the New Jersey Department of Environmental Protection. A summary of the most recent PFAS concentrations in Bay sport fish can be found here. The SFEI has also examined sport fish from the Russian River and have found some samples to be above the State of Michigan's guidelines for frequent consumption of fish.
PFOS, PFOA and other long-chain perfluorocarboxylates have been identified as a moderate concern for San Francisco Bay, according to the RMP’s tiered, risk-based framework that guides monitoring and management actions on emerging contaminants in the Bay.
Stormwater and wastewater are two potential pathways by which PFAS enter the Bay. Studies of Bay Area stormwater and wastewater also suggest that a significant fraction of the PFAS discharged are of unknown chemical composition. Analysis of wastewater data over multiple years is consistent with manufacturing and use trends including decreasing average levels of PFOS and PFOA (not statistically significant) and statistically significant increasing levels of short-chain perfluoroalkyl substances. Additional information regarding stormwater and wastewater studies can be found here and here.
For more information, please contact Meg Sedlak at [email protected].
- Environmental Working Group – Interactive map showing concentrations of PFAS in tap water and at industrial or military sites
- Agency for Toxic Substances & Disease Registry has developed toxicological profiles for perfluoroalkyls
- Interstate Technology and Regulatory Council has summarized regulatory thresholds for PFAS established around the world
- Per and Polyfluoroalkyl Substances (PFAS) in San Francisco Bay: Synthesis and Strategy
- Perfluoroalkyl compounds (PFCs) in wildlife from an urban estuary
- Per- and polyfluoroalkyl substances (PFAS) in San Francisco Bay wildlife: Temporal trends, exposure pathways, and notable presence of precursor compounds
- Contaminant Concentrations in Sport Fish from San Francisco Bay, 2014
- Pilot Study of Contaminants of Emerging Concern (CECs) in the Russian River Watershed: Lessons Learned
- Contaminants of Emerging Concern in San Francisco Bay: A Strategy for Future Investigations. 2017 Revision
- Oxidative Conversion as a Means of Detecting Precursors to Perfluoroalkyl Acids in Urban Runoff
- Poly- and perfluoroalkyl substances in wastewater: Significance of unknown precursors, manufacturing shifts, and likely AFFF impacts
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Perfluoroalkyl and polyfluoroalkyl substances (PFAS) are a broad class of fluorine-rich specialty chemicals. More than 4,700 PFAS are used in consumer, commercial and industrial applications. Well-studied members of the perfluoroalkyl family, including perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA), have been shown to be highly toxic. Use is shifting to alternatives to PFOS and PFOA, including shorter-chain perfluoroalkyl chemicals and polyfluoroalkyl chemicals.
The San Francisco Chronicle published an article featuring research conducted by Meg Sedlak and other RMP scientists, which has found elevated concentrations of PFOS, a persistent fluorine-containing chemical, in San Francisco Bay apex predators. Once the prime ingredient in Scotchgard, PFOS has remained elevated in harbor seals even though it has declined in sea birds that share their fish diet.