home textiles3.8 to 438 treated non-woven medical garments46 to 369 industrial floor wax and wax removers7.5 to 44.8 stone, tile, and wood sealants477 to 3720 membranes for apparel0.1 to 2.5 ng/cm2 food contact papernd (<1.5) to 4640 dental floss/tapend (<1.5) to 96.7 thread sealant tapend (<1.5) to 3490 ptfe cookwarend (<1.5) to 4.3 global occurrence and sources pfoa contaminates every continent. two of the most common types (pfos and pfoa) were phased out of production in the united states (us) in 2002 and 2015 respectively, but are still present in some imported products. pfoa and pfos are found in every american person's blood stream in the parts per billion range, though those concentrations have decreased by 70% for pfoa and 84% for pfos between 1999 and 2014, which coincides with the end of the production and phase out of pfoa and pfos in the us. pfoa has been detected in the central pacific ocean at low parts per quadrillion ranges, and at low parts per trillion (ppt) levels in coastal waters. due to the surfactant nature of pfoa, it has been found to concentrate in the top layers of ocean water. pfoa is detected widely in surface waters, and is present in numerous mammals, fish, and bird species. pfoa is in the blood or vital organs of atlantic salmon, swordfish, striped mullet, gray seals, common cormorants, alaskan polar bears, brown pelicans, sea turtles, sea eagles, midwestern bald eagles, california sea lions and laysan albatrosses on sand island, a wildlife refuge on midway atoll, in the middle of the north pacific ocean, about halfway between north america and asia. because pfas are ubiquitous in households, consumer products, food, and the environment generally, some trace levels reflecting this ubiquitous broad use of these compounds will make their way into the wastewater and solid waste streams. however, wildlife has much less pfoa than humans, unlike pfos and other longer perfluorinated carboxylic acids; in wildlife, pfoa is not as bioaccumulative as longer perfluorinated carboxylic acids. municipal wastewater and landfill leachates are considered as important sources of pfoa to the environment, most industrialized nations have average pfoa blood serum levels ranging from 2 to 8 parts per billion; the highest consumer sub-population identified was in korea—with about 60 parts per billion. in peru, vietnam, and afghanistan blood serum levels have been recorded to be below one part per billion. in 2003–2004 99.7% of americans had detectable pfoa in their serum with an average of about 4 parts per billion, and concentrations of pfoa in us serum have declined by 25% in recent years. despite a decrease in pfoa, the longer perfluorinated carboxylic acid pfna is increasing in the blood of us consumers. pfas are also found in paper mill residuals, digestates, composts, and soils. given the ubiquity of pfas, and the comparative background levels which may be found in wastewater, biosolids, and leachates, setting requirements near analytical detection limits on these sources may not provide a discernable benefit to protecting public health. industrial sources pfoa is released directly from industrial sites. for example, the estimate for the dupont washington works facility is a total pfoa emissions of 80,000 pounds (lbs) in 2000 and 1,700 pounds in 2004. a 2006 study, with two of four authors being dupont employees, estimated about 80% of historical perfluorocarboxylate emissions were released to the environment from fluoropolymer manufacture and use. pfoa can be measured in water from industrial sites other than fluorochemical plants. pfoa has also been detected in emissions from the carpet industry, paper and electronics industries. the most important emission sources are carpet and textile protection products, as well as fire-fighting foams. precursors 8:2 fluorotelomer alcohol, (8:2 ftoh), degrades environmentally to pfoa pfoa can form as a breakdown product from a variety of precursor molecules. in fact, the main products of the fluorotelomer industry, fluorotelomer-based polymers, have been shown to degrade to form pfoa and related compounds, with half-lives of decades, both biotically and by simple abiotic reaction with water. it has been argued that fluorotelomer-based polymers already produced might be major sources of pfoa globally for decades to come. other precursors that degrade to pfoa include 8:2 fluorotelomer alcohol (f(cf2)8ch2ch2oh), polyfluoroalkyl phosphate surfactants (paps), and possibly n-etfose alcohol (f(cf2)8so2n(et)ch2ch2oh). when ptfe (teflon) is degraded by heat (pyrolysis) it can form pfoa as a minor product. the organisation for economic co-operation and development (oecd) has compiled a list of 615 chemicals that have the potential to break down into perfluorocarboxylic acids (pfca) including pfoa. however, not all 615 have the potential to break down to form pfoa. a majority of waste water treatment plants (wwtps) that have been tested output more pfoa than is input, and this increased output has been attributed to the biodegradation of fluorotelomer alcohols. a current pfoa precursor concern are fluorotelomer-based polymers; fluorotelomer alcohols attached to hydrocarbon backbones via ester linkages may detach and be free to biodegrade to pfoa. sources to people food, drinking water, outdoor air, indoor air, dust, and food packagings are all implicated as sources of pfoa to people. however, it is unclear which exposure routes dominate because of data gaps. when water is a source, blood levels are approximately 100 times higher than drinking water levels. people who lived in the pfoa-contaminated area around dupont's washington works facility were found to have higher levels of pfoa in their blood from drinking water. the highest pfoa levels in drinking water were found in the little hocking water system, with an average concentration of 3.55 parts per billion during 2002–2005. individuals who drank more tap water, ate locally grown fruits and vegetables, or ate local meat, were all associated with having higher pfoa levels. residents who used water carbon filter systems had lower pfoa levels. food contact surfaces microwave popcorn bags can contain residual pfoa from fluorotelomers. pfoa is also formed as an unintended byproduct in the production of fluorotelomers and is present in finished goods treated with fluorotelomers, including those intended for food contact. fluorotelomers are applied to food contact papers because they are lipophobic: they prevent oil from soaking into the paper from fatty foods. also, fluorotelomers can be metabolized into pfoa. in a u.s. food and drug administration (usfda) study, lipophobic fluorotelomer-based paper coatings (which can be applied to food contact paper in the concentration range of 0.4%) were found to contain 88,000–160,000 parts per billion pfoa before application, while the oil from microwave popcorn bags contained 6–290 parts per billion pfoa after heating. toxicologists estimate that microwave popcorn could account for about 20% of the pfoa levels measured in an individual consuming 10 bags a year if 1% of the fluorotelomers are metabolized to pfoa. in 2008 as news stories began to raise concerns about pfoa in microwaved popcorn, dan turner, dupont's global public relations chief, said, "i serve microwave popcorn to my three-year-old." five years later, journalist peter laufer wrote to turner to ask if his child was still eating microwave popcorn. "i am not going to comment on such a personal inquiry", turner replied. fluorotelomer coatings are used in fast food wrappers, candy wrappers, and pizza box liners. paps, a type of paper fluorotelomer coating, and pfoa precursor, is also used in food contact papers. despite dupont's asserting that "cookware coated with dupont teflon non-stick coatings does not contain pfoa", residual pfoa was also detected in finished ptfe products including ptfe cookware (4–75 parts per billion). however, pfoa levels ranged from undetectable (<1.5) to 4.3 parts per billion in a more recent study. also, non-stick cookware is heated—which should volatilize pfoa; ptfe products that are not heated, such as ptfe sealant tape, had higher (1800 parts per billion) levels detected. overall, ptfe cookware is considered an insignificant exposure pathway to pfoa. potential path: sludge to food pfoa and pfos were detected in "very high" (low parts per million) levels in agricultural fields for grazing beef cattle and crops around decatur, alabama. the approximately 5000 acres of land were fertilized with "treated municipal sewage sludge, or biosolids". pfoa was also detected in fodder grass grown in these soils and the blood of the cattle feeding on this grass. the water treatment plant received process wastewater from a nearby perfluorochemical manufacturing plant. 3m says they managed their own wastes, but daikin america "discharged process wastewater to the municipal waste treatment plant". if traced to meat, it would be the first time perfluorochemicals were traced from sludge to food. however, the usda reported—with a detection limits of 20 parts per billion—non-detectable levels for both pfoa and pfos in cattle muscle tissue. household dust pfoa is frequently found in household dust, making it an important exposure route for adults, but more substantially, children. children have higher exposures to pfoa through dust compared to adults. hand-to-mouth contact and proximity to high concentrations of dust make them more susceptible to ingestion, and increases pfoa exposure. one study showed significant positive associations were recognized between dust ingestion and pfoa serum concentrations. however, an alternate study found exposure due to dust ingestion was associated with minimal risk. regulatory status drinking water and products in the united states there are no federal drinking water standards for pfoa or pfos as of early 2021. epa began requiring public water systems to monitor for pfoa and pfos in 2012, and published drinking water health advisories, which are non-regulatory technical documents, in 2016. the lifetime health advisories and health effects support documents assist federal, state, tribal, and local officials and managers of drinking water systems in protecting public health when these chemicals are present in drinking water. the levels of pfos and pfoa concentrations under which adverse health effects are not anticipated to occur over a lifetime of exposure are 0.07 ppb (70 ppt). in march 2021 epa announced that it would develop a national primary drinking water regulation for these contaminants. the state of new jersey published drinking water standards for pfoa and pfos in 2020. a standard for pfna was published in 2018. this was the first state to publish pfas standards in the absence of federal regulations. see u.s. state government actions. in 2018 the state of new york adopted drinking water standards of 10 ppt for pfoa and 10 ppt for pfos, the most stringent such standards in the united states. the standards apply to public water systems and took effect in 2019 after a public comment period. using information gained through a freedom of information act request, in may 2018 it was learned that january 2018 emails between the epa, the office of management and budget, the department of defense, and the department of health and human services showed an effort to suppress the release of a draft report on the toxicology of pfos and pfoa done by the agency for toxic substances and disease registry. the report found that these chemicals endanger human health at a far lower level than epa has previously called safe. after media accounts of the effort surfaced, the regional epa administrator for colorado denied that epa had anything to do with suppressing the report. the report was finally released on june 21, 2018. the new atsdr analysis derives provisional minimal risk levels (mrls) of 3x10−6 mg/kg/day for pfoa and 2x10−6 mg/kg/day for pfos during intermediate exposure. the european food safety authority opinion sets a provisional tolerable weekly intake (twi) of 6 x10−6 mg/kg body weight per week for pfoa. california and food packaging an attempt to regulate pfoa in food packaging occurred in the us state of california in 2008. a bill, sponsored by state senator ellen corbett and the environmental working group, was passed in the house and senate that would have banned pfoa, pfos, and seven or more related fluorinated carbon compounds in food packaging starting in 2010, but the bill was vetoed by governor schwarzenegger. the bill would have affected fluorochemical manufacturers outside of the state. schwarzenegger said the compound should be reviewed by the newly established, and more comprehensive, state program. fluorotelomers fluorotelomer-based products have been shown to degrade to pfoa over periods of decades; these studies could lead epa to require dupont and others to reformulate products with a value over $1 billion. health concerns toxicology data pfoa is a possible carcinogen, a possible liver toxicant, a possible developmental toxicant, and a possible immune system toxicant, and also exerts