per- and polyfluoroalkyl substance
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What are per- and polyfluoroalkyl substances (PFAS)?
Per- and polyfluoroalkyl substances (PFAS) are synthetic chemical compounds with fluorine atoms attached to carbon atom chains. Their ability to resist degradation has earned them the nickname "forever chemicals". PFAS provide useful properties to surfaces, making them nonstick, waterproof, and stain-repellent. They have a variety of practical applications in consumer products.
PFAS are synthesized through electrochemical fluorination or fluorotelomerization. They are used in grease-resistant paper, stain-resistant coatings, water-resistant clothing, cleaning products, cosmetics, and firefighting foams.
However, PFAS resist degradation and persist in the environment. Extensive use has resulted in air, water, and soil contamination, impacting human and animal health. Exposure is linked to endocrine disruption, decreased fertility, obesity, asthma, and cancer.
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What are some common uses of PFAS in everyday products?
Per- and polyfluoroalkyl substances (PFAS) are a group of synthetic chemical compounds containing fluorine atoms attached to carbon atom chains. PFAS have properties that make surfaces nonstick, waterproof, and stain-repellent, leading to their use in consumer products.
PFAS are used in various products, such as grease-resistant paper for food packaging, stain-resistant coatings for carpets and upholstery, and water-resistant clothing. They are also found in cleaning products, paints, varnishes, cosmetics, personal-care items, and firefighting foams.
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What chemical features make PFAS different from other substances?
Per- and polyfluoroalkyl substances (PFAS) are synthetic chemical compounds characterized by fluorine atoms attached to chains of carbon atoms. A key feature of PFAS is their resistance to degradation, leading to their nickname, "forever chemicals".
The Organisation for Economic Co-operation and Development defines a PFAS as a fluorinated chemical with at least one fully fluorinated methyl or methylene carbon atom. The Swiss Federal Institute of Technology specifies at least one perfluorinated methyl group (-CF_3) or a perfluorinated methylene group (-CF_2-). This unique chemical makeup gives PFAS useful properties, such as rendering surfaces nonstick, waterproof, and stain repellent, leading to their widespread use in consumer products.
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How do PFAS interact with water and oil, and why is this important?
Per- and polyfluoroalkyl substances (PFAS) are synthetic chemicals containing fluorine atoms attached to carbon atom chains. PFAS resist degradation, earning them the nickname "forever chemicals".
PFAS have the ability to repel both water and oil, as well as resist heat, which makes them useful in consumer products. They are used to manufacture grease-resistant paper, stain-resistant coatings, water-resistant clothing, and firefighting foam.
Their widespread use has led to extensive contamination of the environment and has affected the health of humans and animals.
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Why are PFAS sometimes called 'forever chemicals'?
PFAS, or per- and polyfluoroalkyl substances, are called "forever chemicals" because of their ability to resist degradation. PFAS contain fluorine atoms attached to carbon atom chains, a structure that gives them the ability to resist breakdown.
Due to their resistance to degradation, PFAS persist and accumulate in the environment, affecting the health of humans and animals. Exposure to PFAS has been associated with health conditions such as cancer, hormone disruption, and immune dysfunction.
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What environmental and health concerns are associated with PFAS?
PFAS, or per- and polyfluoroalkyl substances, are synthetic chemicals used in consumer and industrial products for their water, stain, and fire resistance. Their resistance to degradation has led to the nickname "forever chemicals".
PFAS accumulate in the environment, contaminating water, soil, and animals, including humans. Water contamination is a particular concern because these chemicals are difficult to remove through conventional water treatment. Exposure to PFAS is associated with various health conditions, including cancer, hormone disruption, immune dysfunction, reduced fertility, and thyroid disease. Children are especially vulnerable to physical and neurological development impacts.
Increased awareness of the dangers of PFAS has led to regulations and bans in some countries.
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per- and polyfluoroalkyl substance (PFAS), any of a group of synthetic chemical compounds that contain fluorine atoms attached to chains of carbon atoms. Numerous different per- and polyfluoroalkyl substances (PFASs) have been synthesized, many of which possess highly useful properties when applied to surfaces—such as rendering surfaces nonstick, waterproof, and stain repellent—giving them a great variety of practical applications in consumer products.
All PFASs share in common an ability to resist degradation, which underlies their nickname, “forever chemicals.” Many years of heavy and widespread use of PFASs has resulted in extensive contamination of air, water, and soil and has affected the health of humans and other animals. Exposure to PFASs is ubiquitous, and in humans the harmful effects range from endocrine disruption, decreased fertility, and obesity to increased risk of asthma and certain types of cancer.
Definition and examples
PFASs are defined in multiple ways. According to the Organisation for Economic Co-operation and Development, for example, a PFAS is a fluorinated chemical consisting of at least one fully fluorinated methyl or methylene carbon atom. The Swiss Federal Institute of Technology considers a PFAS to be any chemical with at least one perfluorinated methyl group (–CF3) or a perfluorinated methylene group (–CF2–). The lack of consensus regarding their definition simply reflects the great diversity in the chemical makeup of PFASs.
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One of the first PFASs was polytetrafluoroethylene (PTFE), which was discovered in the late 1930s by Roy J. Plunkett, a chemist who at the time was working for DuPont de Nemours, Inc. In 1945, having been patented several years earlier, PTFE was registered by the trademarked name Teflon; DuPont later began mass-producing the chemical for use in nonstick coatings applied to various types of surfaces. In the 1950s the American corporation 3M also began manufacturing PFASs, specifically perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS), which possess many useful properties, including the ability to repel water and resist heat. In the decades that followed, many other PFASs were developed; examples include perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), 2-(N-methyl-perfluorooctane sulfonamido) acetic acid, and perfluoroheptanoic acid (PFHpA).
Synthesis and uses
PFASs are synthesized in one of two ways: electrochemical fluorination (ECF), in which fluorine atoms are introduced into organic molecules using electrolysis in the presence of anhydrous hydrogen fluoride, and fluorotelomerization, in which the chemicals are synthesized from reactions involving perfluoroalkyl iodide and tetrafluoroethylene. In ECF, all hydrogen atoms in the organic substrate are replaced by fluorine atoms, and the rearrangement of carbon chains within the original molecule results in a mixture of both linear and branching perfluorinated structures. Fluorotelomerization produces linear perfluoroalkyl iodide chemicals; in some cases, the product is further reacted with ethylene to generate fluorotelomer-based chemicals, including polymers and surfactants.
PFASs are employed in the manufacture and production of an astonishing array of consumer and industrial products. For instance, they are used in the manufacture of grease-resistant paper, such as packaging for baked goods, candy, fast food, and microwave popcorn; stain-resistant coatings, such as spray-on coatings applied to carpets and upholstery; water-resistant clothing, particularly outerwear and footwear; cleaning products, paints, sealants, and varnishes; and cosmetics and personal-care products, including dental floss, menstrual products, nail polish, and shampoo. PFASs also are used in the manufacture of fire-fighting aqueous film-forming foams.
Environmental and health impacts
PFASs, owing to their chemical constitution and persistence, accumulate in water, soil, and animals, such as fish and other wildlife, as well as humans. Water contamination is of particular concern, because the chemicals are difficult to extract through conventional water treatment methods. PFAS water pollution spreads through waterways, leading to contaminated food sources for animals and contaminated crops and drinking water for humans. PFASs spread through water channels further add to soil contamination. Moreover, PFASs were created first through substances derived from coal and later through petrochemicals, making the production of PFASs a concern for climate change mitigation.
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Owing to extensive contamination of sources of drinking water, many of which have been found to contain a mixture of PFASs, as well as daily exposure from contact with PFAS-containing products, PFASs can be detected in the blood of most humans and animals worldwide. Individuals who work in certain industries, such as firefighting and agriculture, are at increased risk of more extensive PFAS exposure. In such cases, inhalation, ingestion, and absorption through the skin are common exposure pathways.
Exposure to PFASs is associated with a variety of health conditions, including cancer (particularly lymphoma, kidney cancer, and prostate cancer), hormone disruption, immune dysfunction, preeclampsia, reduced fertility, and thyroid disease. PFAS exposure also is linked to low birth weight among infants. In children, risks from PFAS exposure are especially heightened, resulting in potentially significant impacts on physical and neurological development.
Regulation
Increased awareness of the dangers of PFASs has led to the introduction of regulations and bans on specific chemicals in some countries and regions worldwide, including Australia, Canada, Japan, the United Kingdom, and the European Union (EU). In July 2020, for example, the EU banned the use of PFOA and placed restrictions on applications of PFOS; most countries worldwide have placed similar bans on PFOA. In the United States, some states have placed legal maximums on PFAS levels in drinking water, introduced regulations on the use of PFASs in food packaging and other products, and set aside funds for remediation of PFASs in the environment.