Scientific Overview of PFAS and Drinking Water | AAAS EPI Center
analytical limitations, as the most commonly used EPA-approved laboratory method (537.1) can only measure 24 PFAS that may be on the global market, according to a recent inventory 4 . National Attention Given to PFOA and PFOS The National Health and Nutrition Examination Survey (NHANES), conducted by the Centers for Disease Control and Prevention (CDC), detected 4 PFAS (PFOA, PFOS, PFHxS, and PFNA) in greater than 98% of 2,000 blood samples collected in 2003 and 2004 8 . Due to their decades of widespread use, PFOA and PFOS are the PFAS most prevalent in the environment and in humans, so the health effects of these two PFAS are the most widely studied. They have been linked to adverse health effects, such as developmental issues in fetuses, testicular cancer, kidney cancer, liver effects, immune system effects, preeclampsia, and elevated blood pressure during pregnancy, thyroid impacts, ulcerative colitis, and high cholesterol. Historically, the primary applications of PFOA included protective coatings and the production of nonstick surfaces, and those of PFOS included firefighting foam and water-repellent or stain-resistant products 9,10 . Because of research that revealed harmful health effects, PFOS was phased out of production in the United States from 2000 to 2002, and eight major companies agreed to phase out the production and use of PFOA and some PFOA-related chemicals in 2006 as part of the EPA’s PFOA Stewardship Program 11 . However, PFOA, PFOS, and other legacy PFAS may still be manufactured in other countries and may be present in materials imported into the U.S. 12 . Alternative PFAS developed as replacements, including several short- chain PFAS, are still in production today and may pose problems 13 . PFAS Toxicology: PFAS Can Lead to Health Implications Research has shown that some PFAS, such as PFOA and PFOS, can have adverse health effects at trace levels (ng/L or ppt) . While research into the potential health implications of these PFAS indicates reason for concern, there are still toxicological unknowns. Very little is known about a majority of PFAS, including half- life, toxicity, and bioaccumulation data. The Interstate Technical and Regulatory Council (ITRC) frequently updates its toxicological database as new health-related data become available 14 . Table 1 presents current knowns and unknowns related to PFAS impacts on human health 14–18 .
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