Short-chain Polyfluoroalkyl Substances Research Articles

Effect of short-term sample storage and preparatory conditions on losses of 18 per- and polyfluoroalkyl substances (PFAS) to container materials

There is a lack of agreement on a suitable container material for per- and polyfluoroalkyl substances (PFAS) analysis, particularly at trace levels. In this study, the losses of 18 short- and long-chain (C4–C10) PFAS to commonly used labware materials (high-density polyethylene (HDPE), polypropylene (PP), polystyrene (PS), polypropylene co-polymer (PPCO), polyethylene terephthalate (PET), polytetrafluoroethylene (PTFE), and glass were investigated. The influence of sample storage and preparation conditions, i.e., storage time, solvent composition, storage temperatures (4 °C and 20 °C), and sample agitation techniques (shaking and centrifugation) on PFAS losses to the container materials were investigated. The results showed higher losses for most of the considered PFAS (up to 50.9%) in 100% aqueous solutions after storage for 7 days regardless of the storage temperature compared to those after 3 days. Overall, the order of losses to different materials varied for individual PFAS, with the highest losses of long-chain PFAS observed to PP and HDPE after 7-day storage at room temperature. The addition of methanol to aqueous PFAS solutions reduced the losses of long-chain PFAS to all tested materials. The use of sample centrifugation and shaking did not influence the extent of losses for most of the PFAS in 80:20 water:methanol (%, v/v) to container materials except for 8:2 fluorotelomer sulfonic acid (8:2 FTS), 9-chlorohexadecafluoro-3-oxanone-1-sulfonic acid (9Cl-PF3ONS), perfluorodecanoic acid (PFDA) and 4:2 fluorotelomer sulfonic acid (4:2 FTS). This study demonstrates lower losses of both long- and short-chain PFAS to glass and PET. It also highlights the need for caution when deciding on sample preparatory steps and storage during the analysis of PFAS.

Evaluation of separation by high shear mixing for per- and poly-fluoroalkyl substances (PFAS) treatment in water

Widespread per- and poly-fluoroalkyl substances (PFAS) contamination in water, sediments and soils has driven demand for scalable and cost-effective treatments suitable for application across a range of ∑PFAS concentrations from ng/L to mg/L. One promising class of treatment technology is based on PFAS accumulation at the surface of air bubbles. In this study, hydrodynamic cavitation induced by high shear mixing generated colloidal gas aphrons (CGAs) made of different surfactants (cationic, anionic and non-ionic) to facilitate separation of PFAS differing in carbon–fluorine chain length, head group and charge. Separation efficiency was evaluated for a 600 µg/L ∑PFAS mixture of 6 PFAS each at 100 µg/L, and also for a solution spiked to 1 mg/L ∑PFAS with an aqueous film forming foam (AFFF) mixture. The choice of surfactant produced CGAs with different bubble sizes and surface properties; the non-ionic surfactant produced significantly smaller bubbles, while the cationic and anionic surfactant varied principally by charge. The ∑PFAS separation efficiency varied from < 30 % to 86 % using different surfactants after a 30 s process. The non-ionic surfactant was most effective overall, and the cationic surfactant was most efficient for short-chain PFAS, and those with the carboxylic head group due to surface charge compatibility. Zwitterionic precursor PFAS and perfluoroalkyl sulfonic acids species tested in this study were removed with > 90 % efficiency when anionic and non-ionic surfactants formed the CGAs, while short-chain perfluoroalkyl acids PFAA were removed similarly effectively by cationic surfactant-derived CGAs. While separation efficiencies were lower than the > 95 % ∑PFAS reductions reported elsewhere, the effect was achieved with a treatment time of 30 s, in contrast to the significantly longer treatment cycles applied in other studies.

Occurrence and fate of perfluoroalkyl and polyfluoroalkyl substances (PFAS) in an urban aquifer located at the Besòs River Delta (Spain)

Urban aquifers are at risk of contamination from persistent and mobile organic compounds (PMOCs), especially per- and polyfluoroalkyl substances (PFAS), which are artificial organic substances widely used across various industrial sectors. PFAS are considered toxic, mobile and persistent, and have therefore gained significant attention in environmental chemistry. Moreover, precursors could transform into more recalcitrant products under natural conditions. However, there is limited information about the processes which affect their behaviour in groundwater at the field-scale. In this context, the aim of this study is to assess the presence of PFAS in an urban aquifer in Barcelona, and identify processes that control their evolution along the groundwater flow. 21 groundwater and 6 river samples were collected revealing the presence of 16 PFAS products and 3 novel PFAS. Short and ultra-short chain PFAS were found to be ubiquitous, with the highest concentrations detected for perfluorobutanesulfonic acid (PFBS), trifluoroacetic acid (TFA) and trifluoromethanesulfonic acid (TFSA). Long chain PFAS and novel PFAS were found to be present in very low concentrations (<50 ng/L). It was observed that redox conditions influence the behaviour of a number of PFAS controlling their attenuation or recalcitrant behaviour. Most substances showed accumulation, possibly explained by sorption/desorption processes or transformation processes, highlighting the challenges associated with PFAS remediation. In addition, the removal processes of different intensities for three PFAS were revealed. Our results help to establish the principles of the evolution of PFAS along the groundwater flow, which are important for the development of conceptual models used to plan and adopt site specific groundwater management activities (e.g., Managed Aquifer Recharge).

An in silico insight on inhibitory potential of short-chain PFHxA and PFHxS against endogenous antioxidant enzymes

Per- and polyfluoroalkyl substances (PFAS) are a large group of synthetic chemicals that are globally used in various commercial products like cloths, carpets, cookware, firefighting foams, cosmetics, electronic products, etc. Inappropriate disposal of these consumer products could lead to environmental contamination with PFAS. Nowadays short-chain PFAS are substituting the long chain PFAS due to their short half-life. However, multiple studies have suggested that short-chain PFAS such as Perfluorohexanoic acid (PFHxA) and Perfluorohexanesulfonic acid (PFHxS) modulate antioxidant enzyme activities, induce Reactive Oxygen Species production, and contribute to oxidative stress in organisms. Notably, experimental set-ups aiming to investigate the mode of action of these compounds on antioxidants are entirely lacking. Hence in the present study, a ligand-docking approach was adopted to investigate the potential intermolecular interactions between short-chain PFAS and major antioxidants such as Glutathione peroxidase-4, Glutathione reductase, Glutathione S-Transferase, Catalase, and Superoxide dismutase-1. Three-dimensional structures of proteins were processed and docked individually with PFHxA and PFHxS using the AutoDock vina.. Results indicated significant binding affinities between various antioxidant proteins and PFAS. Interestingly, non-covalent interactions such as H-bonds, van der Waals, CH bonds, halogen bonds, and alkyl/pi-alkyl were apparent at protein-ligand interface. Hence, these results suggest that both PFHxA and PFHxS may potentially interact with the endogenous antioxidants and this outcome can be detrimental to the redox homeostasis of living organisms.

Comparative assessment of activated carbon and anion exchange resin for short- and long-chain per- and poly-fluoroalkyl substances sorption: Insight into performance and mechanism

Perfluoroalkyl and polyfluoroalkyl substances (PFAS) are ubiquitous and persistent environmental contaminants that have adverse effects on human health. Even though numerous studies have evaluated the performance and sorption mechanisms of activated carbon and anion exchange resins for PFAS removal, a comparative study of the sorbents has not been reported thus far. In this study, we compared the sorption performance, selectivity, reusability, and sorption mechanisms of pulverized activated carbon (PAC) and a commercial anion exchange resin, A520E, for the removal of two short-chain PFAS [perfluorobutanoic acid (PFBA) and potassium nonafluoro-1-butanesulfonate (PFBS)] and two long-chain PFAS [pentadecafluorooctanic acid (PFOA) and perfluorooctane sulfonate (PFOS)] from water samples. Both showed good removal efficiencies at environmentally relevant concentrations. However, at higher concentrations, A520E exhibited higher sorption than PAC. Moreover, PAC demonstrated faster sorption kinetics (<5 min) owing to its lower Biot number, indicating the influence of both intraparticle and external diffusion. In contrast, A520E primarily involves intraparticle diffusion, particularly for short-chain PFAS, resulting in a slower sorption rate (48 h). Notably, the PFAS sorption efficiencies of PAC and A520E decreased in real-field water, especially PFBA removal by PAC. A520E demonstrated higher regeneration ability than PAC. Our results highlight the importance of sorbent selection for the removal of PFAS compounds from contaminated water and could promote the development of effective and sustainable PFAS removal strategies.

Efficient adsorption of short-chain perfluoroalkyl substances by pristine and Fe/Cu-loaded reed straw biochars

As the substitutes of legacy long-chain per-/polyfluoroalkyl substances (PFASs), short-chain PFASs have been widely detected in the environment. Compared to long-chain PFASs, short-chain PFASs have smaller molecules and are more hydrophilic. Therefore, they are more likely to experience long-distance transport and pose lasting environmental impacts. In this study, Fe-doped (R-Fe) and Cu-doped biochars (R-Cu) were prepared using reed straw biochar (R). The results showed that the PFBA and PFPeA sorption capacities of R-Fe were 25.81 and 43.59 mg g−1, 1.65 and 1.55 times higher than those of R, respectively. The PFBA and PFPeA sorption capacities of R-Cu were 19.34 and 33.69 mg g−1, 1.24 and 1.20 times higher than those of R, respectively. In addition, R, R-Fe, and R-Cu exhibited higher PFBA and PFPeA sorption capacities than the biochars previously reported. The excellent PFAS sorption performances of the biochars were attributed to the highly porous structure of R, which provided rich adsorption sites. Ion-pair sorption, pore filling, electrostatic interaction between the Fe/Cu and cationic groups on biochar and the anionic groups of PFASs, and hydrophobic interaction between the hydrophobic surface of biochar and the fluorinated tails of PFASs were the underlying sorption mechanisms. The biochars presented high removal rates (>86 %) of multiple PFASs (∑PFAS: 350 μg L−1) from synthetic wastewaters, including legacy and emerging PFASs of different chain lengths and with different functional groups. The biochars reported in this study are promising candidate adsorbents for treating waters contaminated with short-chain PFASs.

Per- and polyfluoroalkyl substances in Chinese commercially available red swamp crayfish (Procambarus clarkii): Implications for human exposure and health risk assessment

The extensive utilization of per- and polyfluoroalkyl substances (PFASs) has led to their pervasive presence in the environment, resulting in contamination of aquatic products. Prolonged exposure to PFASs has been linked to direct hepatic and renal damage, along with the induction of oxidative stress, contributing to a spectrum of chronic ailments. Despite the recent surge in popularity of red swamp crayfish as a culinary delicacy in China, studies addressing PFASs' exposure and associated health risks from their consumption remain scarce. To address this gap, our study investigated the PFASs’ content in 85 paired edible tissue samples sourced from the five primary red swamp crayfish breeding provinces in China. The health risks associated with dietary exposure were also assessed. Our findings revealed widespread detection of PFASs in crayfish samples, with short-chain perfluoroalkyl carboxylic acids (PFCAs) exhibiting the highest concentrations. Notably, the total PFAS concentration in the hepatopancreas (median: 160 ng/g) significantly exceeded that in muscle tissue (5.95 ng/g), as did the concentration of every single substance. The hazard quotient of perfluorohexanesulfonic acid (PFHxS) via consuming crayfish during peak season exceeded 1. In this case, a potential total non-cancer health risk of PFASs, which is mainly from the hepatopancreas and associated with PFHxS, is also observed (hazard index>1). Thus, it is recommended to avoid consuming the hepatopancreas of red swamp crayfish. Greater attention should be paid to governance technology innovation and regulatory measure strengthening for short-chain PFASs.

Anionic covalent organic framework membranes for the removal of per- and polyfluoroalkyl substances with enhanced selectivity

Nanofiltration (NF) is an effective technology for removing per- and polyfluoroalkyl substances (PFAS), a group of emerging pollutants. However, conventional NF membranes often reject high levels of minerals, leading to low salt/PFAS selectivity. Herein, we introduce the use of continuous ionic covalent organic framework (COF) membranes as a novel approach to achieve effective PFAS removal with high selectivity. Thin TpPa-SO3H COF selective membrane layers were fabricated on polymer supports using a scalable counter-diffusion interfacial polymerization (IP) method to form thin film composite (TFC) membranes. These membranes feature a highly negative surface charge and ordered pore channels with suitable pore sizes, leading to impressive PFAS rejection rates, with over 99 % rejection for perfluorooctanesulfonic acid (PFOS) and 90–95 % rejection for perfluorooctanoic acid (PFOA) and two short-chain PFAS. Moreover, the TpPa-SO3H membranes allowed the passage of scale-forming salts, enabling selective PFAS removal with a high salt/PFAS selectivity. Furthermore, these continuous ionic COF membranes exhibited a high water permeance of 19.9–37.5 LMH/bar, outperforming commercial membranes like NF270 and other lab-made membranes.

Sources of per- and polyfluoroalkyl substances in an arid, urban, wastewater-dominated watershed

Per- and polyfluoroalkyl substances (PFAS) enter surface waters from various sources such as wastewater treatment plants, fire-fighting sites, and PFAS-producing and PFAS-using industries. The Las Vegas Wash in Southern Nevada of the United States (U.S.) conveys wastewater effluent from the Las Vegas metropolitan area to Lake Mead, a drinking water source for millions of people in the U.S. Southwest. PFAS have previously been detected in the Las Vegas Wash, but PFAS sources were not identified. In this study, upstream wash tributaries, wastewater treatment effluents, and shallow groundwater wells were sampled in multiple campaigns during dry-weather conditions to investigate possible PFAS sources. Out of 19 PFAS, two short-chain PFAS—perfluoropentanoic acid (48 % of the total molar concentration) and perfluorohexanoic acid (32 %)—comprised the majority of PFAS loading measured in the Las Vegas Wash, followed by perfluorooctanoic acid (9 %). On a mass loading basis, the majority of total measured PFAS (approximately 90 %) and at least 48 % of each specific PFAS in the Las Vegas Wash likely entered via municipal wastewater effluents, of which the main source was likely residential wastewater. One of the drainage areas with a major civilian airport was identified as a potential source of relatively enriched perfluorosulfonic acids to a small wash tributary and shallow groundwater samples. Nonetheless, that tributary contributed at most 15 % of any specific PFAS to the mainstem of the Las Vegas Wash. Total PFAS concentrations were relatively low for the small tributary associated with an urban smaller airport and the lack of flow in the tributary channel immediately downgradient of an Air Force base indicates the smaller airport and base were unlikely significant PFAS sources to the Las Vegas Wash. Overall, this study demonstrated effective PFAS source investigation methodology and the importance of wastewater effluent as a PFAS environmental pathway.

Determinants of per- and polyfluoroalkyl substances (PFAS) exposure among Wisconsin residents

BackgroundPer- and polyfluoroalkyl substances (PFAS) include thousands of manufactured compounds with growing public health concerns due to their potential for widespread human exposure and adverse health outcomes. While PFAS contamination remains a significant concern, especially from ingestion of contaminated food and water, determinants of the variability in PFAS exposure among regional and statewide populations in the United States remains unclear. ObjectivesThe objective of this study was to leverage The Survey of the Health of Wisconsin (SHOW), the only statewide representative cohort in the US, to assess and characterize the variability of PFAS exposure in a general population. MethodsThis study sample included a sub-sample of 605 adult participants from the 2014–2016 tri-annual statewide representative sample. Geometric means for PFOS, PFOA, PFNA, PFHxS, PFPeS, PFHpA, and a summed measure of 38 analyzed serum PFAS were presented by demographic, diet, behavioral, and residential characteristics. Multivariate linear regression was used to determine significant predictors of serum PFAS after adjustment. ResultsOverall, higher serum concentrations of long-chain PFAS were observed compared with short-chain PFAS. Older adults, males, and non-Hispanic White individuals had higher serum PFAS compared to younger adults, females, and non-White individuals. Eating caught fish in the past year was associated with elevated levels of several PFAS. DiscussionThis is among the first studies to characterize serum PFAS among a representative statewide sample in Wisconsin. Both short- and long-chain serum PFAS were detectable for six prominent PFAS. Age and consumption of great lakes fish were the most significant predictors of serum PFAS. State-level PFAS biomonitoring is important for identifying high risk populations and informing state public health standards and interventions, especially among those not living near known contamination sites.

Air-water interfacial properties of perfluorosulfonic acid salts with different chain lengths

Perfluorosulfonic acids (PFSA) are a class of per- and polyfluoroalkyl substances (PFAS), which have been extensively used in numerous applications. The toxicity and bioaccumulation of PFAS have become a serious worldwide problem. Foam fractionation has been suggested as a promising remediation method for PFAS removal owing to the amphiphilic nature of most of the currently existing PFAS in the environment, allowing them to migrate to the air-water interface during the foaming process. Nevertheless, the current challenge for widespread utilization of foam fractionation is its low removal efficiency, especially for short-chain PFAS. Foam fractionation performance depends on the air-water interfacial properties as well as the ability for PFAS to adsorb at the air-water interface. In the present study, therefore, we investigate surface tensions of PFSA with long and short chain lengths. Different adsorption models are studied to estimate maximum surface excess concentrations for various PFSA. Our results indicate that long-chain PFSA have lower surface tensions, higher surface activities, and form more rigid air-water interfaces. This study marks the first investigation of dilatational interfacial rheology of PFAS, as well as addressing the gap in understanding PFAS interfacial rheology by focusing on the quantification the storage and loss interfacial moduli, which are known to play a significant role in the foaming process.

Variable PFAS removal by adsorbent media with sufficient prediction of breakthrough despite reduced contact time at pilot scale.

One alternative adsorbent (AA) and five ion exchange (IX) resins were tested for the removal of per- and polyfluoroalkyl substances (PFAS) from groundwater in pilot-scale columns for up to 19 months using empty bed contact times (EBCTs) representative of full-scale treatment. For the six detected PFAS in the pilot feed water, the long-chain PFAS (perfluorooctanoic acid [PFOA], perfluorooctanesulfonic acid [PFOS], and perfluorohexanesulfonic acid [PFHxS]) were well removed with only PFOA, which is a perfluoroalkyl carboxylic acid (PFCA) eventually breaking through as the media became exhausted. Perfluorobutanesulfonic acid (PFBS), a short-chain perfluorosulfonic acid (PFSA), was also well removed, whereas short-chain PFCAs (perfluoropentanoic acid [PFPeA] and perfluorobutanoic acid [PFBA]) were not removed (i.e., immediate breakthrough). Overall, IX and AA demonstrated superior removal of PFSAs compared to PFCAs (i.e., later breakthrough of PFSAs translating to longer media life). Media life varied, ranging from 6 to 15 months before adsorbents reached a significant PFOA breakthrough. The performance of the two adsorbents piloted at shorter EBCT reasonably predicted the longer (representative) pilot EBCT results (within ±20-30%) for the same adsorbents following data scaling. This suggests that pilot-scale testing may be conducted at a faster pace and therefore more economically. PRACTITIONER POINTS: Long-chain PFAS (PFOA, PFOS, and PFHxS) were well removed by five ion exchange and one alternative adsorbent tested herein. One short-chain PFAS (PFBS) was well removed with no removal of two other short-chain PFAS (PFBA and PFPeA). Performance of the two adsorbents piloted at shorter EBCT reasonably predicted the longer (representative) pilot EBCT results for the same adsorbents following data scaling.

Spatial distribution, source, and fate of per- and polyfluoroalkyl substances in the surrounding environment of closed and converted fluorochemical factories in Fujian, China

Following the closure of perfluorooctanesulfonic acid (PFOS) production to comply with the Stockholm Convention regulations or restrictions, manufacturers have shifted to developing short-chain alternatives like perfluorobutane sulfonic acid (PFBS). However, limited research has been conducted to evaluate the impact of this transition on the surrounding environment. This study focused on the spatial distribution, source, and fate of 18 per- and polyfluoroalkyl substances (PFAS) in the surrounding environment of the closure and transformation of two PFAS manufacturing plants in Fujian, China. The total concentrations of PFAS in surface water, sediment, and fish were within the range of 48.9–72,400 ng/L, 0.930–57.6 ng/g dw, and 3.33–1245 ng/g dw, respectively. The predominant compounds were PFBS, PFOS, and perfluorooctanoic acid (PFOA) among the three matrices. Principal component analysis highlighted significant differences in PFAS profiles across different regions of the Futun River, suggesting diverse sources of PFAS. Source apportionment indicated that despite being closed or converted for almost three years, the two factories still significantly impacted the surrounding environment. The shutdown factory mainly released PFAS characterized by perfluoroalkyl sulfonic acids. In contrast, the PFAS were released from conversion plant with the fingerprint being PFBS and perfluoroalkyl carboxylic acids. The conversion of the factories has resulted in the coexistence of long-chain and short-chain PFAS, which has complicated the composition of PFAS in the environment. As sewage treatment plant could not effectively remove PFBS and perfluorobutanoic acid (PFBA) in wastewater, and due to their strong migration ability, these chemicals had a wider impact range, increasing the difficulty of environmental restoration and management. Risk assessment showed that PFAS downstream of the two factories posed high or moderate ecological risks. Specifically, PFBS, PFOS, and PFOA displayed the highest risk quotients and should be paid further attention.

Remove legacy perfluoroalkyl acids and emerging per- and polyfluoroalkyl ether acids by single-use and regenerable anion exchange resins: Rapid small-scale column tests and model fits

Rapid small-scale column tests (RSSCT) are used to study the removal of per- and polyfluoroalkyl substances (PFAS) for drinking water treatment by ion exchange. Breakthroughs of 15 emerging per- and perfluoroalkyl ether acids and six legacy perfluoroalkyl acid analogs are studied using a single-use PFAS-selective anion exchange resin (AER1) and a regenerable, generic anion exchange resin (AER2). The Bohart-Adams model was used to describe and predict breakthrough, with the modeled results reasonably aligned with RSSCT results in most cases, enabling shorter RSSCT duration for future applications. AER1 exhibited high uptake capacity with no breakthrough for 11 of the 21 tested PFAS during the 144,175 BV continuous operation, allowing compliance with the new National Primary Drinking Water Regulation in many application scenarios. AER2 exhibited much faster breakthroughs for most PFAS and is not a promising option for drinking water treatment. However, the summed PFAS capacity via model fit and total PFAS adsorbed via measurement were only <0.01 % of both resin capacities at full breakthrough, suggesting PFAS could only occupy a tiny portion of the ion exchange sites even for the PFAS-selective AER1. Ether group insertion in the PFAS group leads to later breakthrough, and linear isomers were better captured by the resins than the branched isomers. Overall, PFAS uptake capacity increases and kinetics decrease when the PFAS molecular volume increases. Regeneration using 10 % NaCl solutions partially released PFAS from AER2 but not from AER1, with more short-chain PFAS released than long-chain ones. Ether group insertion decreased the PFAS recoveries during the regeneration of AER2. The regenerated resins showed much faster breakthroughs than the pristine resins, making them unfavorable for drinking water treatment applications. Adsorption displacement of short-chain PFAS by long-chain PFAS was observed in pristine AER1, and post-regeneration leaching occurred for both resins, both phenomena making the resins a possible PFAS source in long-term use.

Treatment of aqueous per- and poly-fluoroalkyl substances: A review of biochar adsorbent preparation methods

Per- and poly-fluoroalkyl substances (PFAS) are synthetic chemicals widely used in everyday products, causing elevated concentrations in drinking water and posing a global challenge. While adsorption methods are commonly employed for PFAS removal, the substantial cost and environmental footprint of commercial adsorbents highlight the need for more cost-effective alternatives. Additionally, existing adsorbents exhibit limited effectiveness, particularly against diverse PFAS types, such as short-chain PFAS, necessitating modifications to enhance adsorption capacity. Biochar can be considered a cost-effective and eco-friendly alternative to conventional adsorbents. With abundant feedstocks and favorable physicochemical properties, biochar shows significant potential to be applied as an adsorbent for removing contaminants from water. Despite its effectiveness in adsorbing different inorganic and organic contaminants from water environments, some factors restrict its effective application for PFAS adsorption. These factors are related to the biochar properties, and characteristics of PFAS, as well as water chemistry. Therefore, some modifications have been introduced to overcome these limitations and improve biochar's adsorption capacity. This review explores the preparation conditions, including the pyrolysis process, activation, and modification techniques applied to biochar to enhance its adsorption capacity for different types of PFAS. It addresses critical questions about the adsorption performance of biochar and its composites, mechanisms governing PFAS adsorption, challenges, and future perspectives in this field. The surge in research on biochar for PFAS adsorption indicates a growing interest, making this timely review a valuable resource for future research and an in-depth exploration of biochar's potential in PFAS remediation.

Exposure to per- and polyfluoroalkyl substances in lung cancer patients and their associations with clinical health indicators

Per- and polyfluoroalkyl substances (PFASs) have potential carcinogenicity, immunotoxicity, and hepatotoxicity. Research has been conducted on PFAS exposure in people to discuss their potential health effects, excluding lung cancer. In this study, we recruited participants (n = 282) with lung cancer from Heilongjiang Province, northeast China. The PFAS concentrations were measured in their serum to fill the data gap of exposure, and relationships were explored in levels between PFASs and clinical indicators of tumor, immune and liver function. Ten PFASs were found in over 80 % of samples and their total concentrations were 5.27–152 ng/mL, with the highest level for perfluorooctanesulfonate (median: 12.4 ng/mL). Long-chain PFASs were the main congeners and their median concentration (20.5 ng/mL) was nearly three times to that of short-chain PFASs (7.61 ng/mL). Significantly higher concentrations of perfluorobutanoic acid, perfluorononanoic acid and perfluorohexanesulfonate were found in males than in females (p < 0.05). Serum levels of neuro-specific enolase were positively associated with perfluoropentanoic acid in all participants and were negatively associated with perfluorononanesulfonate in females (p < 0.05, multiple linear regression models). Exposure to PFAS mixture was significantly positively associated with the lymphocytic absolute value (difference: 0.224, 95% CI: 0.018, 0.470; p < 0.05, quantile g-computation models) and serum total bilirubin (difference: 2.177, 95% CI: 0.0335, 4.33; p < 0.05). Moreover, PFAS exposure can affect γ-glutamyl transpeptidase through several immune markers (p < 0.05, mediating test). Our results suggest that exposure to certain PFASs could interfere with clinical indicators in lung cancer patients. To our knowledge, this is the first study to detect serum PFAS occurrence and check their associations with clinical indicators in lung cancer patients.

Commercial compost amendments inhibit the bioavailability and plant uptake of per- and polyfluoroalkyl substances in soil-porewater-lettuce systems

Compost is widely used in agriculture as fertilizer while providing a practical option for solid municipal waste disposal. However, compost may also contain per- and polyfluoroalkyl substances (PFAS), potentially impacting soils and leading to PFAS entry into food chains and ultimately human exposure risks via dietary intake. This study examined how compost affects the bioavailability and uptake of eight PFAS (two ethers, three fluorotelomer sulfonates, and three perfluorosulfonates) by lettuce (Lactuca sativa) grown in commercial organic compost-amended, PFAS spiked soils. After 50 days of greenhouse experiment, PFAS uptake by lettuce decreased (by up to 90.5 %) with the increasing compost amendment ratios (0–20 %, w/w), consistent with their decreased porewater concentrations (by 30.7–86.3 %) in compost-amended soils. Decreased bioavailability of PFAS was evidenced by the increased in-situ soil-porewater distribution coefficients (Kd) (by factors of 1.5–7.0) with increasing compost additions. Significant negative (or positive) correlations (R2 ≥ 0.55) were observed between plant bioaccumulation (or Kd) and soil organic carbon content, suggesting that compost amendment inhibited plant uptake of PFAS mainly by increasing soil organic carbon and enhancing PFAS sorption. However, short-chain PFAS alternatives (e.g., perfluoro-2-methoxyacetic acid (PFMOAA)) were effectively translocated to shoots with translocation factors > 2.9, increasing their risks of contamination in leafy vegetables. Our findings underscore the necessity for comprehensive risk assessment of compost-borne PFAS when using commercial compost products in agricultural lands.

Occurrence of forever chemicals in Chennai waters, India

BackgroundPer- and polyfluoroalkyl substances (PFAS) are considered ‘contaminants of emerging concern’ due to their environmental persistence, bio-accumulative potential, and adverse effects on human health. They are widely employed in producing various goods used in daily life, such as non-stick cookware, cleaning agents, and many industrial applications in aerospace, automotive, construction, electronics, and military, all of which ultimately end up in different environmental matrices. India’s rapid economic growth necessitates a comprehensive understanding of its PFAS contamination levels and potential human and ecological exposure.ResultsThe present study reports the quantification of one long-chain and two short-chain perfluoroalkyl acids and three long-chain and two short-chain perfluorosulfonic acids and qualitative analysis using suspect screening in the waters of Chennai, Tamil Nadu, India. Samples were collected from surface and groundwater sources, including the Adyar river, Buckingham canal, Chembarambakkam lake, and the water treatment plant. The concentrations analyzed in all the samples ranged from 0.10 ng/L to 136.27 ng/L. Groundwater had some of the highest concentrations of PFAS. L-PFBS (up to 136.27 ng/L) and PFOA (up to 77.61 ng/L) are present in all the samples. The concentrations of all the target PFAS increased in the 5 to 103% range in the final treated water compared to the raw water of the water treatment plant. This treated water is distributed as a source of drinking water for the residents of Chennai. Additionally, the dominance of short-chain compounds (4–7 carbons) over long-chain compounds (> 7 carbons) was observed. Suspect screening revealed numerous precursors and other fluorinated compounds abundantly present in the samples.ConclusionsOur study revealed PFAS levels up to 136.27 ng/L in both surface and groundwater samples from Chennai. These findings raise concerns about potential risks to ecosystems and human well-being. The dominance of short-chain PFAS coupled with abundant precursors and unidentified fluorinated compounds indicates an ongoing shift toward alternatives. Conventional water treatment is ineffective in eliminating these chemicals from the water system; rather, increasing the PFAS concentrations from raw water to treated water necessitates advanced polishing steps. Industrial emissions, untreated domestic wastewater discharge, and open dump sites have been suspected as the significant sources of contamination, highlighting the need for further investigation to fully assess the extent of PFAS contamination in Chennai.Graphical

Using the benzenepolycarboxylic acid (BPCA) method to assess activated biochars and their PFAS sorption abilities

Activated carbon (AC) has important industrial and environmental applications as it has excellent abilities to sorb contaminants such as per- and polyfluoroalkyl substances (PFAS). Current research aims to develop activated biochars (AB) from renewable biomass to replace AC that is produced from fossil feedstock. Both AC and AB are primarily comprised of condensed aromatic carbon (ConAC), the component that is the focus of this study. ConAC is characterized to determine its relationship with biochar activation conditions and PFAS sorption, which are understudied at present.Benzenepolycarboxylic acid (BPCA) markers for ConAC were quantified in steam-activated biochars (AB-Steam) and carbon dioxide-activated biochars (AB-CO2) prepared from waste timber at different temperatures (800, 850, 900 °C) and molar ratios of feedstock-carbon:steam (0.50 – 1.25). A non-activated biochar was also included as a reference. ConAC relative to total organic carbon content was higher in AB-Steam than in AB-CO2 (92 ± 2 % vs. 81 ± 11%). The ratio of benzenehexa- (B6CA) to benzenepentacarboxylic (B5CA) acids revealed that AB-Steam also had larger ConAC clusters than AB-CO2. These findings provide novel evidence that steam activation is more effective than CO2 activation in creating ConAC.To assess how ConAC impacts AB sorption abilities, AB-Steam were used to remediate PFAS from contaminated soils. The observed strong correlations between ConAC content and sorption of long-chain PFAS suggest the importance of hydrophobic interactions between PFAS tails and ConAC. Poor correlations for short-chain PFAS, on the other hand, indicated the existence of electrostatic repulsion interactions between PFAS head groups and ConAC. Collectively, these results explain the great ability of AB-Steam to sorb PFAS from contaminated soils (up to 100% remediation). More broadly, this work demonstrates that the BPCA method can be a valuable tool to assess the quality of biochars and other carbonaceous sorbents in relation to their production conditions or contaminant sorption abilities.

Roles of varying carbon chains and functional groups of legacy and emerging per-/polyfluoroalkyl substances in adsorption on metal-organic framework: Insights into mechanism and adsorption prediction

Metal-organic frameworks (MOFs) are promising adsorbents for legacy per-/polyfluoroalkyl substances (PFASs), but they are being replaced by emerging PFASs. The effects of varying carbon chains and functional groups of emerging PFASs on their adsorption behavior on MOFs require attention. This study systematically revealed the structure-adsorption relationships and interaction mechanisms of legacy and emerging PFASs on a typical MOF MIL-101(Cr). It also presented an approach reflecting the average electronegativity of PFAS moieties for adsorption prediction. We demonstrated that short-chain or sulfonate PFASs showed higher adsorption capacities (μmol/g) on MIL-101(Cr) than their long-chain or carboxylate counterparts, respectively. Compared with linear PFASs, their branched isomers were found to exhibit a higher adsorption potential on MIL-101(Cr). In addition, the introduction of ether bond into PFAS molecule (e.g., hexafluoropropylene oxide dimeric acid, GenX) increased the adsorption capacity, while the replacement of CF2 moieties in PFAS molecule with CH2 moieties (e.g., 6:2 fluorotelomer sulfonate, 6:2 FTS) caused a decrease in adsorption. Divalent ions (such as Ca2+ and SO42−) and solution pH have a greater effect on the adsorption of PFASs containing ether bonds or more CF2 moieties. PFAS adsorption on MIL-101(Cr) was governed by electrostatic interaction, complexation, hydrogen bonding, π-CF interaction, and π-anion interaction as well as steric effects, which were associated with the molecular electronegativity and chain length of each PFAS. The average electronegativity of individual moieties (named Me) for each PFAS was estimated and found to show a significantly positive correlation with the corresponding adsorption capacity on MIL-101(Cr). The removal rates of major PFASs in contaminated groundwater by MIL-101(Cr) were also correlated with the corresponding Me values. These findings will assist with the adsorption prediction for a wide range of PFASs and contribute to tailoring efficient MOF materials.