To Örebro University

The global ubiquity of perfluoroalkyl and polyfluoroalkyl substances (PFAS) highlights the important role of atmospheric transport. This study monitored 47 PFAS, including perfluoroalkyl acids (PFAAs), emerging PFAS, and precursors of PFAAs (pre-PFAAs), in seasonal ambient air in Japan between 2022 and 2023, quantifying 38 of them in collected samples. The profiles were dominated by 6:2 fluorotelomer alcohol, perfluorobutanesulfonic acid, and perfluorobutanoic acid, with median levels of 245, 117, and 78.0 pg m-3, respectively. Pre-PFAS and perfluoroalkyl carboxylic acids (PFCAs) exhibited relatively higher concentrations in the warm seasons, whereas perfluoroalkyl sulfonic acids (PFSAs) were more abundant in the cold seasons. Particle-bound fractions of PFCAs with carbon number (Cn) ≤ 13 and PFSAs with Cn ≤ 8 were found at lower levels than in previous reports. Additionally, an odd-even pattern in the gas-particle distribution ratio was observed for PFCAs, with relatively higher values for odd-numbered compounds than for their even-numbered counterparts. Using positive matrix factorization analysis, aqueous film-forming foam-related activities, waste stream emissions, and fluoropolymer manufacturing were proposed as potential major sources in the studied areas, with their relative contribution quantified. These findings enhance our understanding of the atmospheric behavior of PFAS and facilitate the development of tailored PFAS mitigation strategies.

Per- and polyfluoroalkyl substances (PFAS)-containing firefighting foam have been used in stationary fire suppression systems for several decades. However, there is a lack of research on how to decontaminate PFAS-contaminated infrastructure and evaluate treatment efficiency. This study assessed the removal of PFAS from stainless steel pipe surfaces using different cleaning agents (tap water, methanol, and aqueous solutions containing 10 and 20 wt % of butyl carbitol (BC)) at different temperatures (20 °C, 40 °C, and 70 °C). The content of the remaining fluorine (F)-containing compounds on the pipe surfaces was evaluated for the first time using time-of-flight elastic recoil detection (ToF-ERD). The results showed that a 20% BC aqueous solution heated to 70 °C removed up to 40 μg/cm2 ∑PFAS from surfaces via soaking (targeted analysis). Treatment with 20% BC was 2- to 8-fold more effective than tap water at 70 °C and 10- to 20-fold more effective than tap water at 20 °C. Total fluorine analysis determined by combustion ion chromatography showed a 2- to 8-fold higher F-equivalent compared to targeted analysis in the cleaning solution after treatment, indicating the presence of a significant amount of polyfluoroalkyl PFAS. Surface analysis with ToF-ERD confirmed partial F removal from pipe surfaces throughout consecutive soaking intervals, with residual F remaining on pipe surfaces after treatment, leaving the risk of PFAS rebound into F-free firefighting foams. Furthermore, supramolecular assemblies of PFAS with at least 70 PFOS molecules/nm2 were identified by ToF-ERD on pipe interior surfaces.

Despite advancements in high-resolution screening techniques, the identification of novel perfluoroalkyl and polyfluoroalkyl substances (PFAS) remains challenging without prior structural information. In view of this, we proposed and implemented a new data-driven algorithm to calculate spectral similarity among PFAS, facilitating the generation of molecular networks to screen for unknown compounds. Using this approach, 81 PFAS across 12 distinct classes were identified in soil samples collected near an industrial park in Shandong Province, China, including the first reported occurrence of 12 iodine-substituted PFAS. Among them, the standards of four iodine-substituted polyfluorinated ether sulfonates (I-PFESA) were successfully synthesized, enabling structural confirmation and subsequent quantitative analysis. Although the median concentration of ∑I-PFESA (0.74 ng/g dw) in soil samples was lower than that of ∑H-PFESA (hydrogen-substituted, 61.96 ng/g dw) and ∑Cl-PFESA (chlorine-substituted, 2.98 ng/g dw), embryotoxicity assays in zebrafish revealed that 6:2 I-PFESA exhibited greater toxicity compared to 6:2 Cl-PFESA of the same chain length. This highlights the need for a closer examination of the toxic effects of I-PFESA. Notably, the proposed algorithm, based on novel PFAS spectral similarity, provides new perspectives on the environmental behavior and transformation of I-PFESA, although further investigation is required to elucidate the underlying mechanisms of their toxicity.

Per- and polyfluoroalkyl substances (PFAS) are anthropogenic contaminants commonly found in drainage water from waste management facilities. Within the European Union, these facilities either treat the water locally or transfer it to wastewater treatment plants to reduce harmful emissions. However, PFAS are a broad class of compounds with varying physicochemical properties, leading to different removal efficiencies for adsorbents. Activated carbon and ion exchange resins are effective but costly, and they can become saturated with other contaminants. Therefore, this study aims to explore inexpensive, abundant alternatives for reducing PFAS concentrations in the environment. In Sweden, bark is a by-product of forestry activities, primarily used as fuel in heat and power plants. This study evaluates the ability of pine and spruce bark to remove PFAS from contaminated drainage water. Initial laboratory experiments employed liquid-to-solid ratios of 10 and 20 to assess the performance of both materials. Results indicated that pine bark exhibited better removal efficiencies, particularly when a layered column with pine bark followed by spruce bark was utilized. The overall removal efficiencies for short-chain PFAS (perfluorinated carbons: PFCA C3-C6 and PFSA C4-C5) and long-chain PFAS (PFCA > C7 and PFSA > C6) were below 20%, except for perfluorooctane sulfonic acid (PFOS), which showed reductions of 40% to 80%. The pH of the treated water decreased from 7 to 4 (pine bark) and 5 (spruce bark) after treatment. In a larger-scale trial, a combination of 50% pine bark and 50% spruce bark was tested, achieving similar reductions for PFOS. Although the removal efficiencies were insufficient for exclusive treatment, these materials may be useful in specific applications targeting long-chain PFAS or in conjunction with other treatment methods.

Generally, activated carbons demonstrated a notable ability to capture long-chain PFAS, but exhibited relatively lower effectiveness for short-chain PFAS. Thirteen commercially available activated carbons in Japan underwent testing for their adsorption capacity of PFAS in water. The activated carbon derived from rice husk, Triporous™-PFAS, exhibited the highest adsorption capacity (over 95%) for PFAS from ultrashort-chain (perfluorocarbon chain: C1 for perfluorocarboxylic acid (PFCA) and C2 for perfluoroalkane sulfonic acid (PFSA)) to long-chain PFAS (C13 for PFCA and C10 for PFSA). An earlier lysimeter study highlighted Andosol, representative soil in Japan, as a potential medium for removing PFAS from irrigation water. Considering cultivating rice on Andosol fields and producing biochar from rice husks and rice straw, a new rice cultivation system is proposed. This system aims to facilitate continuous removal of PFAS from the environment in Asia. Japanese rice cultivation system produces not only rice but also biochar to remove PFAS from water circulation system. The total fluorine content in the tested activated carbon materials ranged from 0.18 to 38 μg g-1 F. Based on the results from background F blank and adsorption capacity, TriporousTM-PFAS-F was shown to be an option to lower the method detection limit for a proposed international standard method for measuring total PFAS.

Per- and polyfluoroalkyl substances (PFASs) are a large group of anthropogenic fluorinated chemicals. Ultrashort-chain perfluoroalkyl acids (PFAAs) have recently gained attention due to their prevalence in the environment and increasing environmental concerns. In this review, we established a literature database from 1990 to 2024, encompassing environmental and biological concentrations (>3,500 concentration records) of five historically overlooked ultrashort-chain PFAAs (perfluoroalkyl carboxylic and sulfonic acids with less than 4 carbons): trifluoroacetic acid (TFA), perfluoropropanoic acid (PFPrA), trifluoromethanesulfonic acid (TFMS), perfluoroethanesulfonate (PFEtS), and perfluoropropanesulfonate (PFPrS). Our data mining and analysis reveal that (1) ultrashort-chain PFAAs are globally distributed in various environments including water bodies, solid matrices, and air, with concentrations usually higher than those of longer-chain compounds; (2) TFA, the most extensively studied ultrashort-chain PFAA, shows a consistent upward trend in concentrations in surface water, rainwater, and air over the past three decades; and (3) ultrashort-chain PFAAs are present in various organisms, including plants, wildlife, and human blood, serum, and urine, with concentrations sometimes similar to those of longer-chain compounds. The current state of knowledge regarding the sources and fate of TFA and other ultrashort-chain PFAAs is also reviewed. Amid the global urgency to regulate PFASs, particularly as countries worldwide have intensified such efforts, this critical review will inform scientific research and regulatory policies.

To date, considerable knowledge and data gaps regarding the occurrence, environmental levels, and fate of polymeric perfluoroalkyl and polyfluoroalkyl substances (PFAS) exist. In the present study availability, accumulation, and transformation of C4- and C8-fluoroalkylsulfonamide (FASA)-based copolymers were assessed in laboratory-grown earthworms (Eisenia fetida, triplicate of exposure tests and control). Further, a field study on earthworms (18 pooled samples) in sludge-amended soil was conducted to assess the environmental impact of sludge-amended soil with regard to the FASA-based copolymers, together with the applied sludge (n = 3), and the field soils during the period (n = 4). In the laboratory study, the FASA-based copolymers were taken up by the earthworms in concentrations between 19 and 33 ng/g of dw for the C8- and between 767 and 1735 ng/g of dw for the C4-FASA-based copolymer. Higher biota soil accumulation factors (BAFs) were observed for the copolymer with a longer perfluorinated side-chain length (C8, average BAF value of 0.7) compared to the copolymer with a shorter side-chain length (C4, average BAF value of 0.02). Perfluorooctane sulfonamidoacetates (FOSAAs) and perfluorooctane sulfonamide (FOSA), including both branched and linear isomers, were detected after exposure to the C8-FASA-based copolymer. Two metabolites were detected in the earthworms exposed to the C4-FASA-based copolymer: perfluorobutanesulfonamide (FBSA) and perfluorobutanesulfonic acid (PFBS). Although the presence of other monomers or impurities in the copolymer formulation cannot be ruled out, the present laboratory study suggests that the FASA-based copolymers may be an indirect source of lower molecular weight PFAS in the environment through transformation. Elevated levels of C8-FASA-based copolymer were found in the field sludge-amended soil compared to nontreated soil (32 versus 11 ng/g d.w.), and higher concentrations of PFAS in earthworms living in sludge-amended soil compared to nontreated soil (566 versus 103 ng/g d.w.) were observed. These findings imply that the application of sludge is a potential pathway of PFAS to the environment.

Background and aim: Diet and drinking water have been identified as major sources of PFAS exposure in humans. To accurately estimate exposure in the Swedish population, knowledge of background levels in foods are crucial. The study aims to increase knowledge of levels of PFOA, PFNA, PFHxS, and PFOS (PFAS4) in foods commonly consumed by the majority of Swedish consumers, to enable updated exposure estimations in small children, adolescents, and adults.

Material and methods: Food samples from the Swedish Market Basket 2022, including 16 food groups, were analysed for PFAS. Exposuree stimations in the Swedish population were performed using consumption data from three Swedish dietary surveys: Riksmaten adults (2010–11), Riksmaten adolescents (2016–17), and Riksmaten small children (2021–2023). Exposure scenarios for drinking water (4 ng PFAS4/L) and fish consumption (2–3 portions/week) were used. A drinking water consumption of 2 (adults, adolescents), 1.6 (4-year-olds), and 1.2 (1.5-year-olds) L per day was used, and a portion size of 150 (adults), 100 (adolescents), and 50 (small children) g for fish. All results are presented as lower bound.

Results: Detectable levels of PFAS4 were found in 3 of the 16 food groups, in lean fish (PFOA, PFNA, PFOS), fatty fish (PFOS), and eggs (PFOS). The mean PFAS4 concentration was 0.30 ng/g in lean fish, 0.08 ng/g in fatty fish, and 0.05 ng/g in eggs. The median exposure of PFAS4 from food in adult women and men was 0.12 and 0.10 ng/kg body weight (BW)/day (75 th percentile (p75), 0.22, 0.21), respectively. In 4-year-olds and adolescents, it was lower, medians 0.03–0.08 ng/kgBW/day (p75, 0.13–0.42), and in 1.5-year-olds, slightly higher, median 0.11 ng/kg BW/day (p75, 0.46). The proportion exceeding the TDI by EFSA (0.63 ng/kg BW/day) was decreasing by increasing age. In the small children 16–19% exceeded the TDI, whereas 1–4% of the adults and adolescents. When drinking water was added, the median exposure rose to 0.24 and 0.20 ng/kg BW/day for women and men, respectively, and to 0.16–0.27 ng/kg BW/day for adolescents. In 1.5-year-olds, median exposure was 0.55 ng/kg BW/day and in 4-year-olds 0.47 ng/kg BW/day. TDI exceeded in 3–11% of adults and adolescents and 33–41% of small children. Consuming fish 2–3 times/week, including drinking water, raised median exposure to 0.31 and 0.26 ng/kg BW/day for women and men, respectively, and to 0.25–0.39 ng/kg BW/day in adolescents. The median exposure was 0.83 and 0.64 ng/kg BW/day in 1.5- and 4-year-olds, in turn.

Conclusion: The highest exposure to PFAS4 was seen in 1.5-year-olds, and the lowest in adolescents. The median exposure in the scenario of fish consumption 2–3 times/week and drinking water included was below the TDI, except for the small children. The results stress thei mportance of updating levels in food in order to obtain accurate exposure estimations, as background exposure to PFAS4 is decreasing.

Per- and polyfluoroalkyl substances (PFAS) have been used for decades in a broad range of consumer products and industrial applications. A variety of waste and products containing PFAS inevitably end up at waste management facilities when they are no longer considered useful. Drainage water samples (n = 157) were collected from eight subsections at a waste management facility in Sweden and analyzed for 23 PFAS and extractable organofluorine (EOF). Two different sampling methods were used, grab sampling (n = 32, without filtration) and composite sampling (n = 8, produced by pooling 16 filtered samples taken at the same subsection). Although PFAS have been studied at waste sites, the information is scarce regarding how the concentrations and homologue profiles could differ within the sites. In this study, we investigated if composite sampling could be an alternative to grab sampling for PFAS monitoring purposes. Herein, the PFAS concentrations ranged from <1 to 22 μg/L; the grab samples showed systematic higher concentrations than their corresponding composite sample. Short-chain perfluoroalkyl sulfonic acids (C4 and C5) were the largest contributing sub-class, followed by short-chain perfluoroalkyl carboxylic acids (C4 to C6). EOF was measured up to approximately 140 μg/L F with 99% being unexplained by the fluorine mass balance analysis. The results from this study showed that both sampling methods were comparable for target analysis and that 11 compounds represented most of the PFAS concentrations. However, the discrepancy between the sampling methods was greater for EOF analysis and may be due to the preparation of composite samples and/or due to fluctuating discharges during the sampling period. Composite sampling was observed to be comparable to grab sampling for target analysis.

Per- and polyfluoroalkyl substances (PFAS) are persistent anthropogenic contaminants, some of which are toxic and bioaccumulative. Perfluoroalkyl carboxylic acids (PFCAs) and perfluoroalkyl sulfonic acids (PFSAs) can form during the atmospheric degradation of precursors such as fluorotelomer alcohols (FTOHs), N-alkylated perfluoroalkane sulfonamides (FASAs), and hydrofluorocarbons (HFCs). Since PFCAs and PFSAs will readily undergo wet deposition, snow and ice cores are useful for studying PFAS in the Arctic atmosphere. In this study, 36 PFAS were detected in surface snow around the Arctic island of Spitsbergen during January-August 2019 (i.e., 24 h darkness to 24 h daylight), indicating widespread and chemically diverse contamination, including at remote high elevation sites. Local sources meant some PFAS had concentrations in snow up to 54 times higher in Longyearbyen, compared to remote locations. At a remote high elevation ice cap, where PFAS input was from long-range atmospheric processes, the median deposition fluxes of C2-C11 PFCAs, PFOS and HFPO-DA (GenX) were 7.6-71 times higher during 24 h daylight. These PFAS all positively correlated with solar flux. Together this suggests seasonal light is important to enable photochemistry for their atmospheric formation and subsequent deposition in the Arctic. This study provides the first evidence for the possible atmospheric formation of PFOS and GenX from precursors.