What are per- and polyfluoroalkyl substances (PFASs)?
PFASs (perfluoroalkyl and polyfluoroalkyl substances) are a wide class of anthropogenic compounds that contain the perfluoroalkyl moiety CnF2n+1.
Water, heat and stain resistance is achieved using synthetic compounds.
Only a functional group (e.g. COOH, SO3H) is directly connected to the CnF2n+1 moiety in perfluoroalkyl compounds.
Polyfluoroalkyl compounds (e.g., CnF2n+1C2H4SO3H, CnF2n+1SO2NHC2H4OH) have the CnF2n+1 moiety, a functional group and at least one C-H bond in their chemical formula.
Perfluoroalkyl substances have been demonstrated to degrade into perfluoroalkyl compounds under both biotic and abiotic settings, whereas polyfluoroalkyl chemicals have been shown to break down into perfluoroalkyl substances.
Since the 1950s, perfluoroalkyl and polyfluoroalkyl substances (PFAS) have been widely produced and consumed around the world and their use has grown significantly since then.
They are used in aqueous film-forming foams, semiconductors, electronics, stain-resistant coatings, oil-repellents and industrial product additives because of their amphiphilic characteristics.
PFASs are ubiquitous in aquatic habitats, sediments, air, biota and people due to their widespread manufacture and application, as well as their high persistence and mobility.
As a result, they are classified as high-risk and emerging environmental pollutants.
Concerns about the presence of PFASs in drinking water have grown in recent years due to their potential for harmful consequences and direct human exposure.
Because of their ability to resist both oil and water, as well as their durability, they are widely used compounds.
Conventional drinking water treatment often results in equivalent or even higher PFAS concentrations in finished drinking water compared to raw water due to inadequate treatment processes or PFAS precursor change by destructive technologies.
Why it’s a problem?
Clothing, food packaging, cookware, cosmetics and carpet, as well as a fire-fighting foam known as aqueous film-forming foam, include PFAS (AFFF).
People are exposed to PFAS through contaminated water and food, breathing PFAS-contaminated dust and coming into contact with PFAS-containing consumer items.
Airports, military bases, chemical plants and above-ground petroleum storage tanks, among other places, have employed PFAS AFFF-based firefighting foam.
Because they are developed for long-term stability, PFAS are resistant to decomposition and destruction.
Incineration factories may release PFAS into the atmosphere and polluted biosolids generated by wastewater treatment plants have been linked to PFAS in vegetables cultivated in agricultural areas where it was utilized.
Cancer, high cholesterol and preeclampsia during pregnancy have all been linked to trace amounts of many of the most investigated substances.
According to research, PFAS affects the immune, endocrine and metabolic systems.
However, little is known about the majority of PFAS, such as how long they remain in our systems (half-life), their toxicity and how different PFAs interact in our bodies.
Perfluorooctanoic acid (PFOA), one of the most well-studied PFAS, has been linked to kidney and testicular cancer, lower antibody responses to immunizations, liver damage, higher cholesterol levels, increased risk of thyroid illness, decreased fertility, decreased birth weight and an increased risk of pregnancy-induced hypertension and preeclampsia.
PFOA and perfluoro octane sulfonic acid (PFOS) were phased out in the United States due to evidence of negative health effects.
The majority of Americans have one or more PFAS, primarily PFOA and PFOS, in their blood.
There is, however, no cure for PFAS exposure and blood testing cannot provide a clinical diagnosis or indicate if a person’s health has been or will be harmed.
Shorter-chain PFAS, such as GenX, which were used to replace phased-out chemicals, are surviving in the environment and bioaccumulating in persons, potentially creating health concerns.
Federal authorities are funding and researching to learn more about PFAS contamination.
PFAS in water supplies
PFAS can be detected in both drinking water and wastewater.
The Environmental Working Group (EWG) has created an interactive map that shows the extent of PFAS contamination in water systems, including drinking water.
The EPA announced proposals to regulate wastewater contamination in September 2021, including concentration limits for PFAS released in wastewater.
Because it is required to define wastewater limitations for the amount of PFAS that can be present in wastewater.
Bottled water also contains PFAS.
A study published by John Hopkins University and Stantec in Washington, D.C. discovered PFAS in bottled water but did not identify the brands.
How are PFAS controlled?
In the United States, there are no legally enforceable rules for PFAS in drinking water, but the US Environmental Protection Agency (EPA) is working on a national primary drinking water standard for PFOA and PFOS and is evaluating how to examine other PFAS.
In 2016, the Environmental Protection Agency set a health advisory level of 70 parts per trillion in drinking water for two PFAS, PFOA and PFOS.
In the lack of mention of a federal drinking water standard, several nations have enacted PFAS limits in drinking water, surface water and groundwater based on a variety of health hazards, including fetal and infant growth delays, thyroid dysfunction, infertility, changes in liver function and/or impaired immune function.
Producers are now obliged to provide extensive information on some PFAS to the EPA to guide possible regulatory action and are barred from using some long-chain PFAS without prior assessment and clearance under the Toxic Substances Control Act.
PFAS have not yet been classified as dangerous compounds.
States have controlled the presence of PFAS in drinking water, food packaging and consumer items in recent years, as well as banned the use of PFAS firefighting foam, earmarked funding for cleaning and remediation and sued PFAS chemical producers.
Some scientists and environmentalists propose regulating PFAS as a class rather than trying to control each chemical separately, such as by setting a single drinking water quality standard for the whole PFAS class.
Other possible solutions include controlling PFAS subclasses that have comparable chemical features or regulating PFAS based on common adverse health consequences, co-occurrence with other PFAS, or a combination of these factors.
Remove PFAS
From water
Activated charcoal filtration, reverse osmosis (RO) and anion exchange treatment are examples of water treatment technologies that have been independently evaluated to indicate that they are effective in eliminating PFAS from drinking water in your house.
From wastewater
Wastewater contains various compounds that are known to affect the efficiency of treatment technologies; consequently, rather than individual technologies, a suite of technologies is required for the removal of PFAS from wastewater.
Some water and wastewater treatment solution providers suggest ion exchange as an additional technology to GAC, RO and NF, while others add PFAS destructive technology to this list.
References
[1] Dauchy, X. (2019). Per-and poly-fluoroalkyl substances (PFASs) in drinking water: current state of the science. Current Opinion in Environmental Science & Health, 7, 8-12. (online) available at: https://www.sciencedirect.com/science/article/abs/pii/S2468584418300370
[2] per- and polyfluoroalkyl substances (PFASs) in drinking water (online) available at: https://www.aaas.org/epi-center/pfas
[3] Liu, L., Qu, Y., Huang, J., & Weber, R. (2021). Per-and poly-fluoroalkyl substances (PFASs) in Chinese drinking water: risk assessment and geographical distribution. Environmental Sciences Europe, 33(1), 1-12. (online) available at: https://enveurope.springeropen.com/articles/10.1186/s12302-020-00425-3
[4] What are Per- and Polyfluoroalkyl Substances (PFAS)? (online) available at: https://www.wwdmag.com/editorial-topical/what-is-articles/article/10940589/what-are-per-and-polyfluoroalkyl-substances-pfas.
