Scientific Overview of PFAS and Drinking Water | AAAS EPI Center
Table 1 - Known and Unknown PFAS Human Health Implications
KNOWNS
UNKNOWNS
• Most people in the U.S. have been exposed to PFAS and as of 2004, 98% of Americans had PFAS in their blood 8 . • Exposure to certain PFAS may lead to liver damage, thyroid issues, testicular and kidney cancer, immune deficiencies, developmental effects, reproductive issues, and cardiovascular effects. • Long-chain PFAS have longer half-lives in humans (> 1 year) than short-chain PFAS (days to months), meaning long-chain PFAS take longer to exit the body after consumption.
• There is minimal information about a majority of individual PFAS, including half-life, toxicity, and bioaccumulation data. • Short-chain vs. long-chain PFAS toxicity is still under investigation and largely uncertain 6 . • Carcinogenicity studies are only available for four PFAS (PFOS, PFOA, PFHxS, and GenX). • Comprehensive epidemiological studies of communities with a known PFAS source, with the exception of PFOA, are generally lacking. Some small sample size studies have investigated community effects, such as the C8 Science Panel and Faroe Islands Exposure Study 17,19 . • Toxicological data for PFAS mixtures are unavailable but currently under investigation and noted by several as an important data gap for future research 20,21 . • Biomonitoring data are somewhat limited for a majority of PFAS.
PFAS in the Environment PFAS are used in consumer products, industrial applications, and firefighting foam . PFAS have been found in everyday items such as nonstick cookware, stain-resistant upholstered furniture, waterproof clothing, pizza boxes, dental floss, fast food wrappers, microwave popcorn bags, waxes, and paints. Industrial applications of PFAS include uses such as chrome plating, electronics manufacturing, and oil and mining operations. PFAS-based firefighting foams, known as Class B aqueous film-forming foams (AFFF), are designed to extinguish high-risk fires involving flammable liquids (e.g., gasoline, alcohol). The Department of Defense (DoD) and the Federal Aviation Administration (FAA) currently require use of AFFF at military airfields and many civilian airfields, but this is being phased out in the next several years (by 2023) following congressional action 22 . The DoD is currently researching effective alternative foams. PFAS Can Enter the Environment from Several Sources There are multiple ways for PFAS to enter the environment, which can be classified as primary and secondary sources. Primary sources produce PFAS contamination, whereas secondary sources convey contamination produced by primary sources. Figure 2 presents examples of primary and secondary sources of PFAS that contribute to accumulation in the environment and, specifically, drinking water. Due to their strong carbon-fluorine bonds, PFAS do not significantly biodegrade, which makes them persistent in the environment and enables them to impact groundwater, surface water, and ecosystems.
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