PFAS: A Look at Alternatives and Environmental Pollution

Per- and polyfluoroalkyl substances (PFAS) are a class of anthropogenic chemicals that have extensive applications in industry and daily life. Once released into the environment, PFAS are highly persistent; some are also bio-accumulative and toxic.

PFAS are a class of more than 9,000 compounds, many of which are used in industrial and commercial applications, including firefighting foams, paints, food packaging, cookware, textiles, and electronic and medical devices.1 PFAS owe their properties to the carbon–fluorine bond, which is one of the shortest and strongest known. This also makes them highly resistant to breakdown in the environment. While some are considered chemically inert, others have reactive sites, including sulfonic and carboxylic acid groups.

Acid, salts, and related compounds of perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA) have been marked for restricted use, with voluntary phase-out initiatives. However, the enduring environmental legacy of PFAS will remain long after they are discontinued.2 An ACS Publications Special Issue in Environmental Science & Technology brings together 23 papers covering a broad range of topics, including fluorinated alternatives to legacy PFAS; methodologies to characterize the structural diversity of PFAS alternatives; environmental distribution, bioaccumulation, transfer, and ecological impacts; and strategies for PFAS control.3

Environmental and Health Impacts

Well-known legacy PFAS have been subject to scrutiny due to their ubiquitous presence in the environment and biological species,2 with evidence for prenatal exposure in humans and adverse birth outcomes such as preeclampsia or low birth weight.1,4 One common route of exposure is dust—both in the home and outdoors—with data from China suggesting daily PFOA-equivalent intakes in toddlers of at least twice the recommended threshold from the European Food Safety Authority.5 Research suggests PFAS are in our drinking water, and they have been detected in over 99% of blood samples from people in the US.1

Emerging PFAS Alternatives: What Do We Know?

Increased restrictions and public attention on PFAS have resulted in a number of emerging alternatives as replacements—but some novel alternatives, such as perfluoroalkyl ether carboxylic acids (PFECAs), have been widely detected in the environment, with a potential health risk identified related to the consumption of polluted seafoods.6 Results from case-control studies also suggest that both legacy PFAS and novel alternatives could interfere with thyroid function, with exposure inversely associated with the risk of thyroid cancer.7 While some PFAS have also shown a tendency to accumulate in the liver and cause hepatotoxicity, certain alternatives have even longer half-lives in humans than PFOS and may also contribute to liver damage.8 However, researchers agree that information on emerging PFAS alternatives is often limited or lacking, and more studies are needed to better understand their effects on humans and the environment.9

A Need for Greater Transparency

Understanding PFAS ecotoxicity and its impact on public health paves the way for treatment, resource recovery, and agreement on sustainable systems that limit PFAS to essential uses where they are critical for health, safety, or the functioning of society—and for which no alternatives are available.9 However, the current uses of PFAS are highly diverse—although PFAS in consumer products are often relatively easy to replace, those in industrial processes can be highly complex, and a thorough evaluation of the technical function is needed.9 Ultimately, there is a need for more coordination between manufacturers, users, government authorities, and other stakeholders in order to make the process of phasing out PFAS and evaluating alternatives more transparent and coherent.9

References

1. Rodgers K, et al. How Well Do Product Labels Indicate the Presence of PFAS in Consumer Items Used by Children and Adolescents? Environ Sci Technol 2022;56(10):6294–6304.
2. Ruan T, et al. Emerging Contaminants: Fluorinated Alternatives to Existing PFAS (editorial). Environ Sci Technol 2022;56(10):6001–6003.
3. Emerging Contaminants: Fluorinated Alternatives to Existing PFAS Compound (Special Issue). Environ Sci Technol 2022.
4. Ma D, et al. A Critical Review on Transplacental Transfer of Per- and Polyfluoroalkyl Substances: Prenatal Exposure Levels, Characteristics, and Mechanisms. Environ Sci Technol 2022;56(10):6014–6026.
5. Wang B, et al. Per- and Polyfluoroalkyl Substances in Outdoor and Indoor Dust from Mainland China: Contributions of Unknown Precursors and Implications for Human Exposure. Environ Sci Technol 2022;56(10):6036–6045.
6. Li Y, et al. First Report on the Bioaccumulation and Trophic Transfer of Perfluoroalkyl Ether Carboxylic Acids in Estuarine Food Web. Environ Sci Technol 2022;56(10):6046–6055.
7. Liu M, et al. Associations between Novel and Legacy Per- and Polyfluoroalkyl Substances in Human Serum and Thyroid Cancer: A Case and Healthy Population in Shandong Province, East China. Environ Sci Technol 2022;56(10):6144–6151.
8. Jia Y, et al. Insights into the Competitive Mechanisms of Per- and Polyfluoroalkyl Substances Partition in Liver and Blood. Environ Sci Technol 2022;56(10):6192–6200.
9. Glüge J, et al. Information Requirements under the Essential-Use Concept: PFAS Case Studies. Environ Sci Technol 2022;56(10):6232–6242.

Explore the special issue on PFAS in Environmental Science & Technology

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