Chemistry:Per- and polyfluoroalkyl substances

From HandWiki
Short description: Class of perfluorinated chemical compounds


Per- and polyfluoroalkyl substances (PFAS[1] or PFASs[2]) are a group of synthetic organofluorine chemical compounds that have multiple fluorine atoms attached to an alkyl chain. An early definition, from 2011, required that they contain at least one perfluoroalkyl moiety, –CnF2n+1–.[3][4] Beginning in 2021, the Organisation for Economic Co-operation and Development (OECD) expanded their terminology, stating that "PFASs are defined as fluorinated substances that contain at least one fully fluorinated methyl or methylene carbon atom (without any H/Cl/Br/I atom attached to it), i.e., with a few noted exceptions, any chemical with at least a perfluorinated methyl group (–CF3) or a perfluorinated methylene group (–CF2–) is a PFAS."[2][5]

According to the OECD, at least 4,730 distinct PFASs that contain at least three perfluorinated carbon atoms are known.[6] The United States Environmental Protection Agency's (EPA) toxicity database, DSSTox, lists 14,735 unique PFAS chemical compounds,[7] while PubChem lists more than 6 million.[8] The fluorinated surfactants or fluorosurfactants subgroup has a fluorinated "tail" and a hydrophilic "head" and are thus considered surfactants. These are more effective at reducing the surface tension of water than comparable hydrocarbon surfactants. They include the perfluorosulfonic acids, such as perfluorooctanesulfonic acid (PFOS), and the perfluorocarboxylic acids like perfluorooctanoic acid (PFOA).

Many PFASs were used in the mid-20th century in products and on materials due to their enhanced water-resistant properties, such as within Teflon or aqueous film forming foam. Only since the start of the 21st century has the environmental impact and toxicity to human and mammalian life been studied in depth. PFOS, PFOA and other PFASs are commonly described as persistent organic pollutants or "forever chemicals" because they do not break down via natural processes.[9] Residues have been detected in humans and wildlife, prompting concern about impacts on health.[10][11][12] According to the National Academies of Sciences, Engineering, and Medicine, PFAS exposure is linked to increased risk of dyslipidemia (abnormally high cholesterol), suboptimal antibody response, reduced infant and fetal growth, and higher rates of kidney cancer.[13]

Health concerns related to PFASs have resulted in numerous litigations (see Timeline of events related to per- and polyfluoroalkyl substances). PFAS producers such as 3M, Chemours, DuPont and Corteva have reached billion dollar agreements to settle claims against them. The use of PFAS is regulated in several parts of the world, with some plans to phase them out entirely from products.

Skeletal structure of PFOS, an effective, persistent and bioaccumulative fluorosurfactant
Space filling model of PFOS

Fluorosurfactants

A shiny spherical drop of water on blue cloth
Fluorine-containing durable water repellent makes a fabric water-resistant.

Fluorosurfactants are surfactants containing fluorocarbon chains such as those in PFASs. Their hydrophobic nature can reduce the surface tension of water below what is attainable by using hydrocarbon surfactants,[14] so fluorosurfactants tend to concentrate at the liquid-air interface.[15] Fluorocarbons are both lipophobic and hydrophobic, which allows them to repel both oil and water. Their lipophobicity results from the relative lack of London dispersion forces when compared to hydrocarbons, a consequence of fluorine's large electronegativity and small bond length, which reduce the polarizability of the surfactants' fluorinated molecular surface. Fluorosurfactants are more stable and fit for harsher conditions than hydrocarbon surfactants because of the stability of the carbon–fluorine bond. Perfluorinated surfactants persist in the environment for the same reason.[10]

Economic role

PFASs play a key economic role for companies such as DuPont, 3M, and W. L. Gore & Associates because they are used in emulsion polymerization to produce fluoropolymers. They have two main markets: a $1 billion annual market for use in stain repellents, and a $100 million annual market for use in polishes, paints, and coatings.[16] In 2022, 3M announced that it would end PFAS production by 2025.[17][18]

Health and environmental effects

On their introduction in the 1940s, PFASs were considered inert.[19][20] Early occupational studies revealed elevated levels of fluorochemicals, including perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA, C8), in the blood of exposed industrial workers, but cited no ill health effects.[21][22] These results were consistent with the measured serum concentrations of PFOS and PFOA in 3M plant workers ranging from 0.04 to 10.06 ppm and 0.01 to 12.70 ppm, respectively, well below toxic and carcinogenic levels cited in animal studies.[22] Given, however, the "forever chemical" property of PFASs (serum elimination half-life of 4–5 years) and widespread environmental contamination, molecules have been shown to accumulate in humans to such a degree that adverse health outcomes have resulted.[19]

Effects of exposure to PFASs on human health[23][24][25]

Hormone-disrupting chemicals, including PFASs, are linked with rapid declines in human fertility.[26] In a meta-analysis for associations between PFASs and human clinical biomarkers for liver injury, authors considered both PFAS effects on liver biomarkers and histological data from rodent experimental studies and concluded that evidence exists showing that PFOA, perfluorohexanesulfonic acid (PFHxS), and perfluorononanoic acid (PFNA) are hepatotoxic to humans.[27]

Many comprehensive epidemiological studies linking adverse human health effects to PFASs, particularly PFOA, come from the C8 Science Panel.[28] The panel was formed as part of a contingency to a class action lawsuit brought by communities in the Ohio River Valley against DuPont in response to landfill and wastewater dumping of PFAS-laden material from DuPont's West Virginia Washington Works Plant.[28] The panel measured PFOA (also known as C8) serum concentrations in 69,000 individuals from around DuPont's Washington Works Plant and found a mean concentration of 83.0 ng/mL, compared to 4 ng/mL in a standard population of Americans.[29] This panel reported probable links between elevated PFOA blood concentration and hypercholesterolemia, ulcerative colitis, thyroid disease, testicular cancer, kidney cancer as well as pregnancy-induced hypertension and preeclampsia.[30][31][32][33][34]

Pregnancy

Exposure to PFAS is a risk factor for various hypertensive disorders in pregnancy, including preeclampsia and high blood pressure. It is not clear whether PFAS exposure is associated with wider cardiovascular disorders during pregnancy.[35]

Cancer

As of November 2023, the International Agency for Research on Cancer (IARC) has classified PFOA as carcinogenic to humans (Group 1) based on “sufficient” evidence for cancer in animals and “strong” mechanistic evidence in exposed humans. IARC also classified PFOS as possibly carcinogenic to humans (Group 2b) based on “strong” mechanistic evidence.[36] There is a lack of high-quality epidemiological data on the associations between many specific PFAS chemicals and specific cancer types, and research is ongoing.[37]

Prevalence in rainwater

In 2022, it was found that levels of at least four perfluoroalkyl acids (PFAAs) in rainwater worldwide ubiquitously and often greatly exceeded the EPA's lifetime drinking water health advisories as well as comparable Danish, Dutch, and European Union safety standards, leading to the conclusion that "the global spread of these four PFAAs in the atmosphere has led to the planetary boundary for chemical pollution being exceeded".[38] There are some moves to restrict and replace their use.[39]

Estimated contemporary costs

Chemical corporations that produce PFAS generate approximately US$4 billion in annual profits from the production of this chemical, but it is estimated that they impose much larger costs on taxpayers and the health of the planet's population (i.e. as external costs). Of these costs, remediation efforts fighting PFAS soil and water contamination are the most expensive, followed by the healthcare costs of treating people who develop cancer, thyroid disease, kidney dysfunction, birth defects, and other major medical conditions that have been linked to even low levels of exposure to PFAS, and the costs of monitoring of PFAS pollution in human and other life forms. Such costs to society have been estimated to amount to approximately US$17.5 trillion annually (which would be almost one fifth of the US$96 trillion global GDP in 2021[40]), according to a press release by The International Chemical Secretariat (ChemSec), a Sweden-based NGO that works with industry and policymakers to limit the use of toxic chemicals.[41]

Costs by region

In a report by the Nordic Council of Ministers, the total annual health-related costs associated with human exposure to PFASs were estimated to be at least €52–84 billion in the European Economic Area (EEA) countries.[42] Aggregated annual costs covering environmental screening, monitoring where contamination is found, water treatment, soil remediation and health assessment total €821 million – 170 billion in the EEA plus Switzerland.[42]

In the United States, estimated PFAS-attributable disease costs amount to 6–62 billion US$.[43] Studies have estimated the annual healthcare costs in the United States of each of some of the major diseases attributed to PFAS.[44]

Proposed mechanisms of PFAS-related adverse health outcomes

Hypercholesterolemia

A response is observed in humans where elevated PFOS levels were significantly associated with[vague] elevated total cholesterol and LDL cholesterol, highlighting significantly reduced PPAR expression and alluding to PPAR independent pathways predominating over lipid metabolism in humans compared to rodents.[45]

Ulcerative colitis

PFOA and PFOS have been shown to significantly alter immune and inflammatory responses in human and animal species. In particular, IgA, IgE (in females only) and C-reactive protein have been shown to decrease whereas antinuclear antibodies increase as PFOA serum concentrations increase.[46] These cytokine variations allude to immune response aberrations resulting in autoimmunity. One proposed mechanism is a shift towards anti-inflammatory M2 macrophages and/or T-helper (TH2) response in intestinal epithelial tissue which allows sulfate-reducing bacteria to flourish. Elevated levels of hydrogen sulfide result, which reduce beta-oxidation and nutrient production, leading to a breakdown of the colonic epithelial barrier.[47]

Thyroid disease

Hypothyroidism is the most common thyroid abnormality associated with PFAS exposure.[48] PFASs have been shown to decrease thyroid peroxidase, resulting in decreased production and activation of thyroid hormones in vivo.[49] Other proposed mechanisms include alterations in thyroid hormone signaling, metabolism and excretion as well as function of nuclear hormone receptor.[48]

Washington Post 2018 op-ed

Fluorosurfactants such as PFOS, PFOA, and PFNA have caught the attention of regulatory agencies because of their persistence, toxicity, and widespread occurrence in the blood of general populations[50][51] and wildlife. In 2009, PFOS, its salts, and perfluorooctanesulfonyl fluoride were listed as persistent organic pollutants under the Stockholm Convention due to their ubiquitous, persistent, bioaccumulative, and toxic nature.[52][53] PFAS chemicals were dubbed "forever chemicals" in a 2018 op-ed in the Washington Post.[54] The nickname was derived by combining the two dominant attributes of this class of chemicals: PFAS chemicals are characterized by a carbon-fluorine backbone (the "F-C" in "forever chemicals"), and the carbon-fluorine bond is one of the strongest bonds in organic chemistry, which gives these chemicals an extremely long environmental half-life. The term forever chemicals is commonly used in media outlets in addition to the more technical name of per- and polyfluorinated alkyl substances.[55][56][57] Their production has been regulated or phased out by manufacturers, such as 3M, DuPont, Daikin, and Miteni in the U.S., Japan, and Europe. In 2006 3M replaced PFOS and PFOA with short-chain PFASs,[16] such as perfluorohexanoic acid (PFHxA) and perfluorobutanesulfonic acid (PFBS). Shorter fluorosurfactants may be less prone to accumulating in mammals;[16] there is still some concern that they may be harmful to both humans[58][59][60] and the environment,[61] though the EPA states, "...research is still ongoing to determine how different levels of exposure to different PFAS can lead to a variety of health effects."[62] Many PFASs are either not covered by European legislation or are excluded from registration obligations under the EU REACH chemical regulation.[63] Several PFASs have been detected in drinking water,[64] municipal wastewater,[65] and landfill leachates[66] worldwide.

It had been thought that PFAAs would eventually end up in the oceans, where they would be diluted over decades, but a field study published in 2021 by researchers at Stockholm University found that they are significantly transferred from water to air when waves break on land, and are a significant source of air pollution, and eventually get into the rain. The researchers concluded that pollution "may impact large areas of inland Europe and other continents, in addition to coastal areas".[67][68]

Bioaccumulation and biomagnification

Bioaccumulation of PFAS: PFASs from sediments and water can accumulate in marine organisms. Animals higher up the food chain accumulate more PFAS because they absorb PFAS in prey they consume.
In marine species of the food web

Bioaccumulation controls internal concentrations of pollutants, including PFAS, in individual organisms. When bioaccumulation is looked at in the perspective of the entire food web, it is called biomagnification, which is incredibly important to track because lower concentrations of pollutants in environmental matrices such as seawater or sediments, can very quickly grow to harmful concentrations in organisms at higher trophic levels, including humans. Notably, concentrations in biota can even by >5000 times those present in water for PFOS and C10-C14 PFCAs.[69] PFAS can enter an organism by ingestion of sediment, through the water, or directly via their diet. It accumulates namely in areas with high protein content, in the blood and liver, but its also found to a lesser extent in tissues.[70]

Biomagnification can be described using the estimation of the trophic magnification factor (TMF), this describes the relationship between the contamination levels in a species and their trophic level in the food web. TMFs are determined by graphing the log transformed concentrations of PFAS against the assigned trophic level, and taking the antilog of the regression slope (10slope).[10]

In a study done on a macrotidal estuary in Gironde, SW France, TMFs were >1 for nearly all 19 PFAS compounds considered in the study and were particularly high for PFOA and PFNA (6.0 and 3.1 respectively).[10] A TMF> 1 means that accumulation in the organism is greater than that of the medium, in this case the medium being sea water.

PFOS, a long chain sulfonic acid, was found at the highest concentrations relative to other PFASs measured in fish and birds in Northern seas such as the Barents Sea and the Canadian Arctic.[71] A study and an interactive map by the EWG using its results showed freshwater fish in the U.S.Template:Globalize inline ubiquitously contain high levels of harmful PFAS, with a single serving typically significantly increasing the blood PFOS level.[72][73]

Bioaccumulation and biomagnification of PFASs in marine species throughout the food web, particularly frequently consumed fish and shellfish, can have important impacts on human populations.[74] PFASs have been frequently documented in both fish and shellfish that are commonly consumed by human populations,[75] which poses health risks to humans and studies on the bioaccumulation in certain species are important to determine daily tolerable limits for human consumption, and where those limits may be exceeded causing potential health risks.[76] This has particular implications for populations that consume larger numbers of wild fish and shellfish species.[75] In addition to health risks, populations may be impacted by advisories, limits of fishing closures for certain species that are put in place to help mitigate health risks from potential consumption of species with higher levels of accumulated PFASs, but result in a loss of food sources and important subsistence species depended on by local communities. There is research being done in this area, including into spatial patterns of PFAS bioaccumulation in fish and crustaceans.[77]

Corporate and federal government suppression of information

Since the 1970s, forty years before the public health community, DuPont and 3M were aware that PFAS was “highly toxic when inhaled and moderately toxic when ingested.”[78] Producers used several strategies to influence science and regulation – most notably, suppressing unfavorable research and distorting public discourse.[78]

In 2018 White House staff and the EPA pressured the U.S. Agency for Toxic Substances and Disease Registry to suppress a study that showed PFASs to be even more dangerous than previously thought.[79][80]

Concerns, litigation and regulations in specific countries and regions

Australia

In 2017, the ABC's current affairs program Four Corners reported that the storage and use of firefighting foams containing perfluorinated surfactants at Australian Defence Force facilities around Australia had contaminated nearby water resources.[81] In 2019, remediation efforts at RAAF Base Tindal and the adjacent town of Katherine were ongoing.[82] In the 2022 Australian federal budget $428 million was allocated for works at HMAS Albatross, RAAF Base Amberley, RAAF Base Pearce and RAAF Base Richmond including funding to remediate PFAS contamination.[83]

Canada

Although PFASs are not manufactured in Canada, they may be present in imported goods and products. In 2008, Canada prohibited the import, sale, or use of PFOS or PFOS-containing products, with some exceptions for products used in firefighting, the military, and some forms of ink and photo media.[84]

Health Canada has published drinking water guidelines for maximum concentrations of PFOS and PFOA to protect the health of Canadians, including children, over a lifetime's exposure to these substances. The maximum allowable concentration for PFOS under the guidelines is 0.0002 milligrams per litre. The maximum allowable concentration for PFOA is 0.0006 milligrams per litre.[85]

United Kingdom

The environmental consequences of PFAS, especially from firefighting activities, has been recognized since the mid-1990s and came to prominence after the Buncefield explosion on 11 December 2005. In recent years the Environment Agency has undertaken a series of projects to understand the scale and nature of PFAS in the environment. The Drinking Water Inspectorate requires water companies to report concentrations of 47 PFAS.[86]

European Union

In 2019, the European Council requested the European Commission to develop an action plan to eliminate all non-essential uses of PFAS due to the growing evidence of adverse effects caused by exposure to these substances; the evidence for the widespread occurrence of PFAS in water, soil, articles, and waste; and the threat it can pose to drinking water.[87] Germany, the Netherlands, Denmark, Norway, and Sweden submitted a so-called restriction proposal based on the REACH regulation to achieve a European ban on the production, use, sale and import of PFAS.[88] The proposal states that a ban is necessary for all use of PFAS, with different periods for different applications when the ban takes effect (immediately after the restriction comes into force, 5 years afterwards, or 12 years afterwards), depending on the function and the availability of alternatives. The proposal has not assessed the use of PFAS in medicines, plant protection products and biocides because specific regulations apply to those substances (Biocidal Products Regulation, Plant Protection Products Regulation, Medicinal Products Regulation) that have an explicit authorization procedure that focuses on risk for health and the environment.

The proposal was submitted on 13 January 2023 and published by the European Chemicals Agency (ECHA) on 7 February. From 22 March to 21 September, citizens, companies and other organizations can comment on the proposal during a public consultation.[89] Based on the information in the restriction proposal and the consultation, two committees from ECHA formulate an opinion on the risk and socio-economic aspects of the proposed restriction. Within a year of publication, the opinions are sent to the European Commission, which makes a final proposal that is submitted to the EU Member States for discussion and decision.[90] Eighteen months after the publication of the restriction decision (which may differ from the original proposal), it will enter the ban.[89]

Italy

Over 350,000 residents in the Veneto region are estimated to have been exposed to contamination through tap water, and it is thought to be Europe's biggest PFAS-related environmental disaster.[who?] While Italy's National Health Institute (ISS, Istituto Superiore di Sanità) set the threshold limit of PFOA in the bloodstream at 8 nanograms per milliliter (ng/mL), some residents had reached 262 and some industrial employees reach 91,900 ng/mL. In 2021 some data was disclosed by Greenpeace and local citizens after a long legal battle against the Veneto Region and ISS, which for years has denied access to data, despite values known since or even before 2017. The Veneto region has not carried out further monitoring or taken resolutive actions to eliminate pollution and reduce, at least gradually, the contamination of non-potable water. Although in 2020 the European Food Safety Agency (EFSA) has reduced by more than four times the maximum tolerable limit of PSAS that can be taken through the diet, the region has not carried out new assessments or implemented concrete actions to protect the population and the agri-food and livestock sectors. Some limits were added to monitoring the geographical area, which does not include the orange zone and other areas affected by contamination, as well as the insufficiency of analysis on important productions widespread in the areas concerned: eggs (up to 37,100 ng/kg), fish (18,600 ng/kg) spinach and radicchio (only one sampling carried out), kiwis, melons, watermelons, cereals (only one sample was analyzed), soy, wines and apples.[91]

Sweden

Highly contaminated drinking water has been detected at several locations in Sweden. Such locations include Arvidsjaur, Lulnäset, Uppsala and Visby.[92][93] In 2013, PFAS were detected at high concentrations in one of the two municipality drinking water treatment plants in the town of Ronneby, in southern Sweden. Concentrations of PFHxS and PFOS were found at 1700 ng/L and 8000 ng/L, respectively.[94] The source of contamination was later found to be a military fire-fighting exercise site in which PFAS containing fire-fighting foam had been used since the mid-1980s.[95]

Additionally, low-level contaminated drinking water has also been shown to be a significant exposure source of PFOA, PFNA, PFHxS and PFOS for Swedish adolescents (ages 10–21). Even though the median concentrations in the municipality drinking water were below <1 ng individual PFAS/L, positive associations were found between adolescent serum PFAS concentrations and PFAS concentrations in drinking water.[96]

United States

In products

Certain PFASs are no longer manufactured in the United States as a result of phase-outs including the PFOA Stewardship Program (2010-2015), in which eight major chemical manufacturers agreed to eliminate the use of PFOA and PFOA-related chemicals in their products and emissions from their facilities.[97] Although PFOA and PFOS are no longer manufactured in the United States, they are still produced internationally and are imported into the U.S. in consumer goods such as carpet, leather and apparel, textiles, paper and packaging, coatings, rubber, and plastics.[98]

In 2020, manufacturers and the Food and Drug Administration announced an agreement to phase out some types of PFAS that are used in food packaging by 2024.[99]

PFASs are also used by major companies of the cosmetics industry in a wide range of cosmetics, including lipstick, eye liner, mascara, foundation, concealer, lip balm, blush, and nail polish. A 2021 study tested 231 makeup and personal care products and found organic fluorine, an indicator of PFASs, in more than half of the samples. High levels of fluorine were most commonly identified in waterproof mascara (82% of brands tested), foundations (63%), and liquid lipstick (62%).[100][101] As many as 13 types of individual PFAS compounds were found in each product.[100] Since PFAS compounds are highly mobile, they are readily absorbed through human skin and through tear ducts, and such products on lips are often unwittingly ingested. Manufacturers often fail to label their products as containing PFASs, which makes it difficult for cosmetics consumers to avoid products containing PFASs.[102] In response, Senators Susan Collins of Maine and Richard Blumenthal of Connecticut proposed the No PFAS in Cosmetics Act in the United States Senate.[103] It was also introduced in the United States House of Representatives by Michigan Representative Debbie Dingell,[104] but the U.S. chemical industry lobby has killed efforts to regulate this.[105]

In 2021, Maine became the first U.S. state to ban these compounds in all products by 2030, except for instances deemed "currently unavoidable".[106][107]

Contaminated sites, drinking water and wastewater

An estimated 26,000 U.S. sites are contaminated with PFASs. At least six million Americans are estimated to have drinking water containing PFASs above the safe limit published prior to 2022 by the U.S. Environmental Protection Agency (EPA).[108][109] More than 200 million Americans are estimated to live in places where the tap water PFAS level (a combination of PFOA and PFOS levels) exceeds the 1 ppt (part per trillion) limit set in 2022 by the EPA.[110]

(As of October 2020), the states of California, Connecticut, Massachusetts, Michigan, Minnesota, New Hampshire, New Jersey, New York, Vermont, and Wisconsin had enforceable drinking water standards for between two and six types of PFAS. The six chemicals (termed by the Massachusetts Department of Environmental Protection as PFAS6) are measured either individually or summed as a group depending on the standard; they are:[111]

EPA published non-enforceable drinking water health advisories for PFOA and PFOS in 2016.[112][113] In March 2021 EPA announced that it would develop national drinking water standards for PFOA and PFOS.[114] On December 27, 2021, EPA published a regulation requiring drinking water utilities to conduct monitoring for 29 compounds. The data are to be collected during 2023 to 2025. EPA will pay for the monitoring costs for small drinking water systems (those serving a population of 10,000 or fewer). The agency may use the monitoring data to develop additional regulations.[115][116]

In mid-2021 EPA announced plans to revise federal wastewater regulations (effluent guidelines) for several industries that manufacture PFASs or use PFASs in fabricating various products.[117][118]

In October 2021 EPA announced the PFAS Strategic Roadmap. It is a "whole-of-EPA" strategy and considers the full lifecycle of PFAS—including drinking water monitoring and risk assessment for PFOA and PFOS in biosolids (processed wastewater sludge used as fertilizer).[119][120]

The EPA issued health advisories for four specific PFASs in June 2022, significantly lowering their safe threshold levels for drinking water. PFOA was reduced from 70 ppt to 0.004 ppt, while PFOS was reduced from 70 ppt to 0.02 ppt. GenX's safe levels were set at 10 ppt, while PFBS were set to 2000 ppt. While not enforceable, these health advisories are intended to be acted on by states in setting their own drinking water standards.[121]

A formal EPA rule to add PFOA and PFAS as hazardous chemicals was first issued for comment on 26 August 2022, which would require anyone discharging waste to monitor and restrict the release of these PFAS to set levels, and report when the wastewater exceeds it. It would also make grounds affected by high levels of PFIA or PFAS to be considered Superfund cleanup sites.[122]

EPA has listed recommended steps that consumers may take to reduce possible exposure to PFAS chemicals.[123]

This USGS map shows the number of PFAS detections in tap water samples from select sites across the US.

On 14 March 2023, EPA announced the proposed National Primary Drinking Water Regulation (NPDWR). This proposal includes new maximum contaminant levels (MCLs) in drinking water for six well-known PFAS: PFOA, PFOS, GenX, PFBS, PFNA, and PFHxS. While the proposal does not require any actions until its finalization, the EPA believes it will be implemented by late 2023. If these new restrictions are put into place, the EPA expects that they will prevent thousands of deaths and tens of thousands of PFAS-attributable illnesses. Along with legally enforceable MCLs, the EPA proposal will also require public water systems to actively monitor for the 6 PFAS, notify the public about the level of PFAS in the water supply, and take measures to reduce the level of PFAS in drinking water if they exceed the MCLs.[124]

Between 2016 and 2021 the U.S. Geological Survey (USGS) tested tap water from 716 locations across the United States, and reported in 2023 that the PFAS levels exceeded the EPA advisories in approximately 75% of the samples from urban areas and in approximately 25% of the rural area samples.[125]

In 2023, the American multinational 3M reached a US$10.3 billion settlement with a host of US public water systems to resolve water pollution claims tied to PFAS.[126] Three other major chemicals companies – Chemours, DuPont and Corteva – have reached an agreement in principle for US$1.19 bn to settle claims they contaminated US public water systems with PFAS.[126]

Water contamination by U.S. military bases

The water in and around at least 126 U.S. military bases has been contaminated by high levels of PFASs because of their use of firefighting foams since the 1970s, according to a study by the U.S. Department of Defense. Of these, 90 bases reported PFAS contamination that had spread to drinking water or groundwater off the base.[127][128] A 2022 Pentagon report acknowledged that approximately 175,000 U.S. military personnel at two dozen American military facilities drank water contaminated by PFAS that exceeded the U.S. EPA limit. However, according to an analysis of the Pentagon report by the non-partisan Environmental Working Group, the Pentagon report downplayed the number of people exposed to PFAS, which was much higher, probably in excess of 640,000 at 116 military facilities, than the number advanced by the Pentagon report. The EWG found that the Pentagon also omitted from its report some types of diseases that are likely to be caused by PFAS exposure, such as testicular cancer, kidney disease, and fetal abnormalities.[129]

Class action lawsuits

In February 2017, DuPont and Chemours (a DuPont spin-off) agreed to pay $671 million to settle lawsuits arising from 3,550 personal injury claims related to releasing of PFASs from their Parkersburg, West Virginia, plant into the drinking water of several thousand residents.[130] This was after a court-created independent scientific panel—the C8 Science Panel—found a "probable link" between C8 exposure and six illnesses: kidney and testicular cancer, ulcerative colitis, thyroid disease, pregnancy-induced hypertension and high cholesterol.[28][131]

In October 2018, a class action suit was filed by an Ohio firefighter against several producers of fluorosurfactants, including the 3M and DuPont corporations, on behalf of all U.S. residents who may have adverse health effects from exposure to PFASs.[132] The story is told in the film Dark Waters.[133]

EPA ongoing research

The EPA has stated that while some companies have reached certain conclusions related to PFASs, the EPA research is still ongoing and as of 2023, remains inconclusive as it relates to the certainty of detrimental effects on humans, according to the EPA:

Current scientific research suggests that exposure to certain PFAS may lead to adverse health outcomes. However, research is still ongoing to determine how different levels of exposure to different PFAS can lead to a variety of health effects. Research is also underway to better understand the health effects associated with low levels of exposure to PFAS over long periods of time, especially in children.[62]

California

In 2021 California banned PFASs for use in food packaging and from infant and children's products and also required PFAS cookware in the state to carry a warning label.[134]

Maine

A program licensed and promoted by the Maine Department of Environmental Protection that provided free municipal wastewater sludge (biosolids) to farmers as fertilizer has resulted in PFAS contamination of local drinking water and farm-grown produce.[135][136]

Michigan

The Michigan PFAS Action Response Team (MPART) was launched in 2017 and is the first multi-agency action team of its kind in the nation. Agencies representing health, environment, and other branches of state government have joined together to investigate sources and locations of PFAS contamination in the state, take action to protect people's drinking water, and keep the public informed.[137]

Groundwater is tested at locations throughout the state by various parties to ensure safety, compliance with regulations, and proactively detect and remedy potential problems. In 2010, the Michigan Department of Environmental Quality (MDEQ) discovered levels of PFASs in groundwater monitoring wells at the former Wurtsmith Air Force Base . As additional information became available from other national testing, Michigan expanded its investigations into other locations where PFAS compounds were potentially used.[137]

In 2018, the MDEQ's Remediation and Redevelopment Division (RRD) established cleanup criteria for groundwater used as drinking water of 70 ppt of PFOA and PFOS, individually or combined. The RRD staff are responsible for implementing these criteria as part of their ongoing efforts to clean up sites of environmental contamination. The RRD staff are the lead investigators at most of the PFAS sites on the MPART website and also conduct interim response activities, such as coordinating bottled water or filter installations with local health departments at sites under investigation or with known PFAS concerns. Most of the groundwater sampling at PFAS sites under RRD's lead is conducted by contractors familiar with PFAS sampling techniques. The RRD also has a Geologic Services Unit, with staff who install monitoring wells and are also well versed with PFAS sampling techniques.[137]

The MDEQ has been conducting environmental clean-up of regulated contaminants for decades. Due to the evolving nature of PFAS regulations as new science becomes available, the RRD is evaluating the need for regular PFAS sampling at Superfund sites and is including an evaluation of PFAS sampling needs as part of a Baseline Environmental Assessment review.[137]

Earlier in 2018, the RRD purchased lab equipment that will allow the MDEQ Environmental Lab to conduct analyses of certain PFAS samples. (Currently, most samples are shipped to one of the few labs in the country that conduct PFAS analysis, in California, although private labs in other parts of the country, including Michigan, are starting to offer these services.) As of August 2018, RRD has hired additional staff to work on developing the methodology and conducting PFAS analyses.[137]

In 2020 Michigan Attorney General Dana Nessel filed a lawsuit against 17 companies, including 3M, Chemours, and DuPont, for hiding known health and environmental risks from the state and its residents. Nessel's complaint identifies 37 sites with known contamination.[138] The Michigan Department of Environment, Great Lakes, and Energy introduced some of the strictest drinking water standards in the country for PFAS, setting maximum contaminant levels (MCLs) for PFOA and PFOS to 8 and 16 ppt respectively (down from previous existing groundwater cleanup standards of 70 ppt for both), and introducing MCLs for 5 other previously unregulated PFAS compounds, limiting PFNA to 6 ppt, PFHxA to 400,000 ppt, PFHxS to 51 ppt, PFBS to 420 ppt and HFPO-DA to 370 ppt.[139] The change adds 38 additional sites to the state's list of known PFAS contaminated areas, bringing the total number of known sites to 137. About half of these sites are landfills and 13 are former plating facilities.[140]

In 2022 PFOS was found in beef produced at a Michigan farm: the cattle had been fed crops fertilized with contaminated biosolids. State agencies issued a consumption advisory, but did not order a recall, because there currently is no PFOS contamination in beef government standards.[141]

Minnesota

In February 2018, 3M settled a lawsuit for $850 million related to contaminated drinking water in Minnesota.[142]

New Jersey

In 2018 the New Jersey Department of Environmental Protection (NJDEP) published a drinking water standard for PFNA. Public water systems in New Jersey are required to meet an MCL standard of 13 ppt.[143][144] In 2020 the state set a PFOA standard at 14 ppt and a PFOS standard at 13 ppt.[145]

In 2019 NJDEP filed lawsuits against the owners of two plants that had manufactured PFASs, and two plants that were cited for water pollution from other chemicals. The companies cited are DuPont, Chemours and 3M.[146] NJDEP also declared five companies to be financially responsible for statewide remediation of the chemicals. Among the companies accused were Arkema and Solvay regarding a West Deptford Facility in Gloucester County, where Arkema manufactured PFASs, but Solvay claims to have never manufactured but only handled PFASs.[147] The companies denied liability and contested the directive.[148] In June 2020, the U.S. Environmental Protection Agency and NJ Department of Environmental Protection published a paper reporting that a unique family of PFAS used by Solvay, chloroperfluoropolyether carboxylates (ClPFPECAs), were contaminating the soils of New Jersey as far from the Solvay facility as 150 km.[149] and the ClPFPECAs were found in water as well.[150]

Later in 2020, the New Jersey state attorney general filed suit in the New Jersey Superior Court against Solvay regarding PFAS contamination of the state's environment.[151] In May 2021, Solvay issued a press release that the company is "discontinuing the use of fluorosurfactants in the U.S.".[152]

New York

In 2016, New York, along with Vermont and New Hampshire, acknowledged PFOA contamination by requesting the EPA to release water quality guidance measures. Contamination has been observed by the New York State Department of Environmental Conservation in Hoosick Falls, Newburgh, Petersburgh, Poestenkill, Mahopac, and Armonk.[153]

The village of Hoosick Falls has received a $65.25 million dollar settlement from Saint-Gobain Performance Plastics, Honeywell, 3M, and DuPont companies through a class action lawsuit in 2021, due to the disposal of PFAS chemicals into the groundwater of the local water treatment plant.[154]

Washington

Five military installations in Washington State have been identified by the U.S. Senate Committee on Environment and Public Works as having PFAS contamination. Toward environmental and consumer protections, the Washington State Department of Ecology published a Chemical Action Plan in November 2021, and in June 2022 the governor tasked the Washington State Department of Ecology with phasing out manufacture and import of products containing PFASs. Initial steps taken by the Washington State Department of Health to protect the public from exposure through drinking water have included setting State Action Levels for five PFASs (PFOA, PFOS, PFNA, PFHxS, and PFBS), which were implemented in November 2021.[155][156][157]

Occupational exposure

Occupational exposure to PFASs occurs in numerous industries due to the widespread use of the chemicals in products and as an element of industrial process streams.[158] PFASs are used in more than 200 different ways in industries as diverse as electronics and equipment manufacturing, plastic and rubber production, food and textile production, and building and construction.[159] Occupational exposure to PFASs can occur at fluorochemical facilities that produce them and other manufacturing facilities that use them for industrial processing like the chrome plating industry.[158] Workers who handle PFAS-containing products can also be exposed during their work, such as people who install PFAS-containing carpets and leather furniture with PFAS coatings, professional ski-waxers using PFAS-based waxes, and fire-fighters using PFAS-containing foam and wear flame-resistant protective gear made with PFASs.[158][160][161]

Exposure pathways

People who are exposed to PFASs through their jobs typically have higher levels of PFASs in their blood than the general population.[158][162][163] While the general population is exposed to PFASs through ingested food and water, occupational exposure includes accidental ingestion, inhalation exposure, and skin contact in settings where PFAS become volatile.[164][3] The severity of PFAS-associated health effects can vary based on the length of exposure, level of exposure, and health status.[158]

Professional ski wax technicians

Compared to the general public exposed to contaminated drinking water, professional ski wax technicians are more strongly exposed to PFASs (PFOA, PFNA, PFDA, PFHpA, PFDoDA) from the glide wax used to coat the bottom of skis to reduce the friction between the skis and snow.[165] During the coating process, the wax is heated, which releases fumes and airborne particles.[165] Compared to all other reported occupational and residential exposures, ski waxing had the highest total PFAS air concentrations.[166]

Manufacturing workers

People who work at fluorochemical production plants and in manufacturing industries that use PFASs in the industrial process can be exposed to PFASs in the workplace. Much of what we know about PFASs exposure and health effects began with medical surveillance studies of workers exposed to PFASs at fluorochemical production facilities. These studies began in the 1940s and were conducted primarily at U.S. and European manufacturing sites. Between the 1940s and 2000s, thousands of workers exposed to PFASs participated in research studies that advanced scientific understanding of exposure pathways, toxicokinetic properties, and adverse health effects associated with exposure.[21][167][168]

The first research study to report elevated organic fluorine levels in the blood of fluorochemical workers was published in 1980.[21] It established inhalation as a potential route of occupational PFAS exposure by reporting measurable levels of organic fluorine in air samples at the facility.[21] Workers at fluorochemical production facilities have higher levels of PFOA and PFOS in their blood than the general population. Serum PFOA levels in fluorochemical workers are generally below 20,000 ng/mL but have been reported as high as 100,000 ng/mL, whereas the mean PFOA concentration among non-occupationally exposed cohorts in the same time frame was 4.9 ng/mL.[169][22] Among fluorochemical workers, those with direct contact with PFASs have higher PFAS concentrations in their blood than those with intermittent contact or no direct PFAS contact.[167][169] Blood PFAS levels have been shown to decline when direct contact ceases.[169][170] PFOA and PFOS levels have declined in U.S. and European fluorochemical workers due to improved facilities, increased usage of personal protective equipment, and the discontinuation of these chemicals from production.[167][171] Occupational exposure to PFASs in manufacturing continues to be an active area of study in China with numerous investigations linking worker exposure to various PFASs.[172][173][174]

Firefighters

Firefighters using aqueous film forming foam (AFFF)

PFASs are commonly used in Class B firefighting foams due to their hydrophobic and lipophobic properties, as well as the stability of the chemicals when exposed to high heat.[175]

Research into occupational exposure for firefighters is emergent, though frequently limited by underpowered study designs. A 2011 cross-sectional analysis of the C8 Health Studies found higher levels of PFHxS in firefighters compared to the sample group of the region, with other PFASs at elevated levels, without reaching statistical significance.[176] A 2014 study in Finland studying eight firefighters over three training sessions observed select PFASs (PFHxS and PFNA) increase in blood samples following each training event.[175] Due to this small sample size, a test of significance was not conducted. A 2015 cross-sectional study conducted in Australia found that PFOS and PFHxS accumulation was positively associated with years of occupational AFFF exposure through firefighting.[162]

Due to their use in training and testing, recent studies indicate occupational risk for military members and firefighters, as higher levels of PFASs in exposure were indicated in military members and firefighters when compared to the general population.[177] PFAS exposure is prevalent among firefighters not only due to its use in emergencies, but also because it is used in personal protective equipment. In support of these findings, states like Washington and Colorado have moved to restrict and penalize the use of Class B firefighting foam for firefighter training and testing.[178][179]

Exposure after World Trade Center terrorist attacks

The 11 September 2001 collapse of the World Trade Center buildings in New York City resulted in the release of chemicals from the destruction of construction and electrical material and long-term chemical fires. This collapse caused the release of several toxic chemicals, including fluorinated surfactants used as soil- and stain-resistant coatings on various materials.[180] First responders to this incident were exposed to PFOA, PFNA, and PFHxS through inhalation of dust and smoke released during and after the collapse of the World Trade Center.[180]

Fire responders who were working at or near ground zero were assessed for respiratory and other health effects from exposure to emissions at the World Trade Center. Early clinical testing showed a high prevalence of respiratory health effects. Early symptoms of exposure often presented with persistent coughing and wheezing. PFOA and PFHxS levels were present in both smoke and dust exposure, but first responders exposed to smoke had higher concentrations of PFOA and PFHxS than those exposed to dust.[180]

Mitigation measures

Several strategies have been proposed as a way to protect those who are at greatest risk of occupational exposure to PFAS, including exposure monitoring, regular blood testing, and the use of PFAS-free alternatives. For example, fluorine-free firefighting foam and plant-based ski wax contain no PFAS and greatly reduce the occupational hazards associated with certain professions.[181]

Remediation solutions

Water treatment

Several technologies are currently available for remediating PFASs in liquids. These technologies can be applied to drinking water supplies, groundwater, industrial wastewater, surface water, and other applications such as landfill leachate. Influent concentrations of PFASs can vary by orders of magnitude for specific media or applications. These influent values, along with other general water quality parameters (for example, pH) can influence the performance and operating costs of the treatment technologies. The technologies are:

Private and public sector applications of one or more of these methodologies above are being applied to remediation sites throughout the United States and other international locations.[184] Most solutions involve on-site treatment systems, while others are leveraging off-site infrastructure and facilities, such as a centralized waste treatment facility, to treat and dispose of the PFAS pool of compounds.

Most recently, a 2022 study published in the Journal of Environmental Engineering found that a heat-and pressure-based technique known as supercritical water oxidation destroyed 99% of the PFASs present in a water sample. During this process, oxidizing substances are added to PFAS-contaminated water and then the liquid is heated above its critical temperature of 374 degrees Celsius at a pressure of more than 220 bars. The water becomes supercritical, and, in this state, water-repellent substances such as PFASs dissolve much more readily.[183]

Theoretical and early-stage solutions

A possible solution for PFAS-contaminated wastewater treatment has been developed by the Michigan State University-Fraunhofer team. Boron-doped diamond electrodes are used for the electrochemical oxidation system where it is capable of breaking PFAS molecular bonds which essentially el,inaites the contaminates, leaving fresh water.[185] Cory Rusinek, an electrochemist at MSU-Fraunhofer stated:

"EO, or electrochemical oxidation, is a simple, clean, and effective method for destruction of PFASs and other co-contaminants as a complementary procedure to other wastewater treatment processes. If we can remove it from wastewater, we can reduce its occurrence in surface waters.[185]

Acidimicrobium sp. strain A6 has been shown to be a PFAS and PFOS remediator.[186] PFAS with unsaturated bonds are easier to break down: the commercial dechlorination culture KB1 (contains Dehalococcoides) is capable of breaking down such substances, but not saturated PFAS. When alternative, easier-to-digest substrates are present, microbes may prefer them over PFAS.[187]

Chemical treatment

A study published in Science in August 2022 indicated that perfluoroalkyl carboxylic acids (PFCAs) can be mineralized via heating in a polar aprotic solvent such as dimethyl sulfoxide. It reported that heating PFCAs in an 8 to 1 mixture of dimethyl sulfoxide and water at 80–120 °C (176–248 °F) in the presence of sodium hydroxide caused the removal of the carboxylic acid group at the end of the carbon chain, creating a perfluoroanion that mineralizes into sodium fluoride and other salts such as sodium trifluoroacetate, formate, carbonate, oxalate, and glycolate. The process does not work on perfluorosulfonic acids such as PFOS.[188] A more recent study published in Chemical Science shows breakdown of C-F bonds and their mineralization as YF3 or YF6 clusters.[189] Another study in the Journal of the American Chemical Society described the PFAs breakdown using metal-organic frameworks (MOFs).[190]

Sample chemicals

Some common per- and polyfluoroalkyl substances include:[191][192]

Name Abbreviation Structural formula Molecular weight (g/mol) CAS No.
Perfluorobutane sulfonamide H-FBSA C4F9SO2NH2 299.12 30334-69-1
Perfluoropentanesulfonamide PFPSA C5F11SO2NH2 349.12 82765-76-2
Perfluorohexanesulfonamide PFHxSA C6F13SO2NH2 399.13 41997-13-1
Perfluoroheptanesulfonamide PFHpSA C7F15SO2NH2 449.14 82765-77-3
Perfluorooctanesulfonamide PFOSA C8F17SO2NH2 499.14 754-91-6
Perfluorobutanesulfonyl fluoride PFBSF C4F9SO2F 302.09 375-72-4
Perfluorooctanesulfonyl fluoride PFOSF C8F17SO2F 502.12 307-35-7

Films

  • The Devil We Know (2018)
  • Dark Waters (2019)

See also

  • Timeline of events related to per- and polyfluoroalkyl substances
  • Entegris, formerly Fluoroware, of Chaska, MN, manufacturer of teflon components for health and semiconductor Fabs
  • FSI International, now TEL FSI
  • Polytetrafluoroethylene (PTFE)
  • Fluoropolymer, subclass of per- and polyfluoroalkyl substances

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  182. ↑ "Treatment Technologies". Washington, DC: Interstate Technology & Regulatory Council (ITRC). September 2020. https://pfas-1.itrcweb.org/12-treatment-technologies/. 
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Further reading

External links



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