Emerging PFAS

Recently, mounting concerns over the effect per and polyfluoroalkyl substances (PFAS) might have on the environment and on human health have led to increased regulation and efforts to phase out the use of these compounds. In this infographic, we will explore what While the most common “legacy” PFAS have been emerging PFAS are, subject to restriction from global organizations and their sources and how other national regulatory agencies, newer “alternative” they can be detected. or “emerging” PFAS remain a major concern. What are PFAS are a broad class of man-made compounds characterized by their highly fluorinated carbon chain. As a general rule, all PFAS contain at least one perfluoroalkyl moiety – CnF2n. Fluorine C C C Oxygen C C C Perfluoroalky C substances have a C Carbon e a carbon chain Polyfluoroalky Hydrogen substances have a partially fluorinate The chemical structure of perfluorooctanoi carbon chain acid (PFOA), a common PFAS. This structure gives PFAS many For decades, PFAS were used in desirable physical and chemical industry for firefighting foams and in properties, such as very high thermal more domestic settings, as a coating and chemical stability. for water-proof, grease-proof and stain-resistant products. Why are a problem? Several international organizations and national-level regulatory bodies have moved to introduce policies that ban or significantly restrict the manufacture, import and export of select PFAS compounds. Ecnonvitraomnimneatnitoanl Heeffaeclttsh The extreme chemical and physical Scientists are still determining stability of PFAS is key to their the exact health effects of PFAS appeal as an ingredient in consumer exposure. However, it is known that products. This also makes the the compounds can bioaccumulate in compounds extremely slow to human and animal body tissues. degrade once they have entered the Epidemiological studies have suggested environment, which is why PFAS are links between exposure to specific PFAS also called “forever chemicals”. and negative health effects, including altered immune and thyroid function, insulin dysregulation, kidney disease, cancer and adverse reproductive and developmental outcomes PFAS exposure can happen through consuming contaminated water or foodstuffs, breathing in airborne PFAS, or working in occupations that are more likely to use PFAS-containing products, such as firefighting or chemicals manufacturing. Legacy and emerging The term “legacy PFAS” is used to refer to the long-chain perfluoroalkyl acids (PFAAs) that have been studied most extensively. These compounds have tended to be the focus of regulatory restrictions, having been largely phased out of production in several nations. Emerging PFAS are part of a new class called persistent organic pollutants (POPs). This category includes short-chain PFAAs, as well as other previously unreported and unknown PFAS that are being discovered in the environment. Legianccylu PdFeAS Emeringicnlugd Pe FAS Perfluorooctanoi Hexafluoropropylene oxide dimer acid acid (PFOA) (HFPO-DA), also known as GenX. It is a popular PFOA alternative Perfluorooctanesulfoni acid (PFOS) Cyclic PFAS, such as perfluoroethylcy clohexanesulfonate (PFECHS) Perfluorohexane sulfonate (PFHxS) Fluorotelomer sulfonic acids (FTSA), such as 6:2 fluorotelomer sulfonate (6:2 FTS) Some emerging PFAS are compounds that have been intentionally produced to act as replacements for banned legacy PFAS. Others are industrial by-products or other substances that have been degraded to form new highly-fluorinated compounds. Sources of emerging There have been relatively few studies investigating the sources of emerging PFAS. Direct emissions from Degredation of Long-range transport local fluorochemica other fluorinate production substances The few studies that have been done suggest that their presence in the environment is primarily the result of direct emissions from fluorochemica manufacturing. Short-chain PFAS compounds generally have a shorter half-life in the environment than long-chain legacy PFAS. Still, HFPO-DA has been detected alongside other legacy PFAS in Arctic seawaters, suggesting that emerging PFAS also have the potential to travel long distances and become global contaminants if left unaddressed. A 2017 study of river and drinking A 2015 study of surface water water in the Netherlands found in the US found traces of HFPO HFPO-DA and other emerging DA, a PFOA substitute, and PFAS downstream from a other new PFAS in geographic fluorochemical production plant, egions with historic legacy PFAS suggesting the plant was the contamination. source of the compound. analysis Given the structural similarities of the legacy PFAS compared to many of the known emerging PFAS, the emerging compounds can generally be studied using the same techniques used for legacy PFAS. HFPO-DA PFOA However, emerging PFAS analysis may be further complicated by the unavailability of reference standards, low recoveries and poor sensitivity due to in-source fragmentation for some compounds. PFAS analysis/detection can be done using targeted or non-targeted techniques Non-targeted analysis techniques are used to detect/identify unknown Targeted analysis is used to detect or suspected compounds in a sample. specific known compounds. This is This approach is useful for detecting useful where scientists wish to study previously undiscovered PFAS that only certain PFAS that might be might be missed in targeted analysis. present in a sample. Targeted analysis Non-targeted analysis generally is also generally less demanding in requires more time and resources to terms of data analysis. analyze the datasets produced. Used in multiple PFAS analytical standard methods issued by the US Environmental Protection Agency. These methods include the detection of HFPO-DA and other short-chain emerging PFAS in water. LC-MS/MS is a popular technique due to its excellent sensitivity and low limit of detection. It is often paired with other methods, such as isotope dilution anion exchange solid-phase extraction or multiple reaction monitoring (MRM), to suit the requirements of the analysis. C-MS/M LC-MS/MS C-MS/MS Total organic TOF SENSOR-BASED TOF OR-B Total organic fluorine (TOF) analysis Sensor-based technologies are a is a popular non-targeted screening highly targeted form of analysis. These method, which can be applied to sensors are normally specialized to environmental samples and human detect only one compound, or a very blood samples to broadly assess the narrow range of PFAS compounds, in burden of PFAS contamination. a certain environment. Examples of such sensors have been developed for several emerging PFAS, including HFPO-DA and 6:2FTS. Although significant research progress has been made with respect to both legacy and emerging PFAS, the current scientific understanding of these compounds is likely just the tip of the iceberg. Developing suitable analysis techniques and procedures for emerging PFAS, in addition to continuing investigations into the potential health and environmental impacts of PFAS as a class, will be key to addressing the issue of PFAS contamination. Sponsored by