Per- and polyfluoroalkyl substances and fluorine mass balance in cosmetic products from the Swedish market: implications for environmental emissions and human exposure

Perfluoroalkyl substances in the meat of Polish farm animals and game - Occurrence, profiles and dietary intake

Meat from farm animals (pigs, cattle and poultry) and game (wild boar and deer) was analysed in terms of thirteen perfluoroalkyl substances (PFASs). Wild boar muscle tissue was statistically significantly more contaminated than muscle tissue from other animals, and the species order of the lower-bound (LB) sum of four (∑4) PFAS (perfluorooctanesulfonic acid (PFOS), perfluorooctanoic acid, perfluorononanoic acid and perfluorohexanesulfonic acid) concentrations was wild boar > cattle > deer > pigs > poultry. None of the samples exceeded the maximum levels set by Commission Regulation (EU) 2023/915. Linear PFOS was the most frequently detected compound (in 21 % of all samples analysed and 100 % of wild boar samples), reaching its highest concentration of 1.87 μg/kg wet weight in wild boar. Dietary intake was estimated on the basis of the average per-serving consumption of pork, beef and poultry, and in the absence of such data for game, a 100 g portion was used for the calculation. Mean LB∑4 PFAS concentrations led to intakes between 0.000 and 1.75 ng/kg body weight (BW) for children and 0.000 and 0.91 ng/kg BW for adults. The potential risk to consumers was assessed in relation to the tolerable weekly intake (TWI) of 4.4 ng/kg BW established by the European Food Safety Authority in 2020. Exposure associated with the consumption of poultry, pork, beef and venison was negligible, being only <1 % of the TWI for children and adults; higher exposure was found to associate with the consumption of wild boar, being 63 % and 21 % of the TWI for children and adults, respectively. The findings of this research suggest that the intake of PFASs through the consumption of meat from Polish livestock and deer is unlikely to be a health concern. However, frequent consumption of wild boar meat could be a significant source of PFASs.

Contribution of Continued Dermal Exposure of PFAS-Containing Sunscreens to Internal Exposure: Extrapolation from In Vitro and In Vivo Tests to Physiologically Based Toxicokinetic Models

Per- and polyfluoroalkyl substances (PFASs) are widely present in sunscreen products as either active ingredients or impurities. They may penetrate the human skin barrier and then pose potential health risks. Herein, we aimed to develop a physiologically based toxicokinetic (PBTK) model capable of predicting the body loading of PFASs after repeated, long-term dermal application of commercial sunscreens. Ten laboratory-prepared sunscreens, generally falling into two categories of water-in-oil (W/O) and oil-in-water (O/W) sunscreens, were subject to in vitro percutaneous penetration test to assess the impacts of four sunscreen ingredients on PFAS penetration. According to the results, two sunscreen formulas representing W/O and O/W types that mostly enhanced PFAS dermal absorption were then selected for a subsequent 30 day in vivo exposure experiment in mice. PBTK models were successfully established based on the time-dependent PFAS concentrations in mouse tissues (R2 = 0.885-0.947) and validated through another 30 day repeated exposure experiment in mice using two commercially available sunscreens containing PFASs (R2 = 0.809-0.835). The PBTK model results suggest that applying sunscreen of the same amount on a larger skin area is more conducive to PFAS permeation, thus enhancing the exposure risk. This emphasizes the need for caution in practical sunscreen application scenarios, particularly during the summer months.

Concentration and health risk assessment of per- and polyfluoroalkyl substances in cosmetic and personal care products

Per and polyfluoroalkyl substances (PFAS) are toxicologically concerning because of their potential to bioaccumulate and their persistence in the environment and the human body. We determined PFAS levels in cosmetic and personal care products and assessed their health risks. We investigated the trends in concentrations and types of PFAS contaminants in cosmetic and personal care products before and after perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) were added to the list of persistent organic pollutants. The total PFAS concentration ranged from 1.98 to 706.75 ng g-1. The hazard quotients (HQs) for PFOA, PFOS and perfluorobutanesulfonic acid (PFBS) were lower than 1, indicating no appreciable risk to consumers. Assuming the simultaneous use of all product types and the worst-case scenario for calculations, perfluoroalkyl carboxylic acids and perfluoroalkane sulfonic acids (PFSAs) also had hazard indices lower than 1. We found that adverse effects are unlikely to occur when each type of cosmetic is used separately, or even when all product types are used together. Nevertheless, the persistence and bioaccumulation characteristics of additional PFAS present in cosmetics continue to be a cause for concern. Further research is necessary to investigate the long-term impacts of using such cosmetics and the associated risks to human health.

Comprehensive assessment of per and polyfluoroalkyl substances (PFAS) contamination in groundwater of Kamrup, Assam, India: occurrence, health risks, and metabolomic insights

Per-and polyfluoroalkyl substances (PFAS) are synthetic chemicals that are known for their environmental persistence and adverse health effects. This study comprehensively assessed PFAS contamination in the Kamrup region of Assam, India, focusing on its presence in groundwater and associated health risks. The analysis detected 12 PFAS in groundwater samples from both the Kamrup Metro and Rural regions. In Kamrup Rural, Perfluorohexanoic acid (PFHxA), perfluorononanoic acid (PFNA), and perfluorooctanesulfonic acid (PFOS) were prevalent, whereas in Kamrup Metro, PFNA and PFOS were dominant, based on detection frequencies. These findings are noteworthy, as they demonstrate the widespread presence of PFAS in groundwater, a vital source of drinking water in the region. The assessment of PFAS health risks in India involved hazard quotient calculations for different age groups. Perfluorobutanesulfonic acid (PFBS) posed the highest risk, ranking children > boys > men > girls > women. Overall, ∑PFAS had low hazard (HQ: 0.27-0.41). Further, this study assessed PFBS and PFOS toxicity in human kidney epithelial cell lines (HEK293T) cells, revealing that PFBS was more cytotoxic than PFOS. The study examined the metabolomics of HEK293T cells after PFBS exposure, revealing significant alterations in lipid metabolism, particularly glycerophospholipids, potentially affecting cellular function and health. These findings underscore the importance of monitoring PFAS contamination in drinking water sources, especially in regions such as Kamrup, where groundwater is a primary source. Our metabolomics results show significant health effects at the cellular level, raising concerns about the impact of PFAS exposure on human health. This study highlights PFAS contamination in Kamrup, Assam's groundwater and its health risks, providing valuable insights for policymakers and public health management.

A multi-platform approach for the comprehensive analysis of per- and polyfluoroalkyl substances (PFAS) and fluorine mass balance in commercial ski wax products

The unique properties of per- and polyfluoroalkyl substances (PFAS) have led to their extensive use in consumer products, including ski wax. Based on the risks associated with PFAS, and to align with PFAS regulations, the international ski federation (FIS) implemented a ban on products containing "C8 fluorocarbons/perfluorooctanoate (PFOA)" at all FIS events from the 2021/2022 season, leading manufactures to shift their formulations towards short-chain PFAS chemistries. To date, most studies characterising PFAS in ski waxes have measured a suite of individual substances using targeted analytical approaches. However, the fraction of total fluorine (TF) in the wax accounted for by these substances remains unclear. In this study, we sought to address this question by applying a multi-platform, fluorine mass balance approach to a total of 10 commercially available ski wax products. Analysis of TF by combustion ion chromatography (CIC) revealed concentrations of 1040-51700 μg F g-1 for the different fluorinated waxes. In comparison, extractable organic fluorine (EOF) determined in methanol extracts by CIC (and later confirmed by inductively-coupled plasma-mass spectrometry and 19F- nuclear magnetic resonance spectroscopy) ranged from 92 to 3160 μg g-1, accounting for only 3-8.8 % of total fluorine (TF). Further characterisation of extracts by cyclic ion mobility-mass spectrometry (IMS) revealed 15 individual PFAS with perfluoroalkyl carboxylic acid concentrations up to 33 μg F g-1, and 3 products exceeding the regulatory limit for PFOA (0.025 μg g-1) by a factor of up to 100. The sum of all PFAS accounted for only 0.01-1.0 % of EOF, implying a high percentage of unidentified PFAS, thus, pyrolysis gas chromatography-mass spectrometry was used to provide evidence of the nature of the non-extractable fluorine present in the ski wax products.

The Total Mass of Per- and Polyfluoroalkyl Substances (PFASs) in California Cosmetics

Cosmetics make up one of the consumer product categories most widely known to contain perfluoroalkyl and polyfluoroalkyl substances (PFASs), including precursors to perfluorooctanoic acid (PFOA) and other perfluoroalkyl acids (PFAAs). Because of the way cosmetics are used, most of the PFASs present in these products are likely to reach wastewater treatment plants (WWTPs), which suggests that cosmetics may contribute significantly to the load of PFOA and other PFASs at WWTPs. However, the majority of PFASs present as intentional ingredients in cosmetics cannot be quantified with the available analytical methods. To address this issue, we developed a methodology to estimate the total PFAS mass in cosmetics as well as the corresponding mass of total organic fluorine and of fluorinated side chains associated with PFAA precursors, using various ingredient databases and ingredient concentrations reported by manufacturers. Our results indicate that the cosmetics sold in California during a one-year period cumulatively contain 650-56 000 kg of total PFASs, 370-37 000 kg of organic fluorine, and 330-20 000 kg of fluorinated side chains associated with PFAA precursors. Among the 16 product subcategories considered, >90% of the PFAS mass came from shaving creams and gels, hair care products, facial cleansers, sun care products, and lotions and moisturizers, while the sum of all nine makeup subcategories accounted for <3%. Comparing our estimates to available WWTP influent data from the San Francisco Bay Area suggests that cosmetics may account for at least 4% of the precursor-derived PFAAs measured in wastewater. As the first study ever to estimate the total mass of PFASs contained in cosmetics sold in California, our results shed light on the significance of certain cosmetics as a source of PFASs to WWTPs and can inform effective source reduction efforts.

Penetration pathways, influencing factors and predictive models for dermal absorption of exobiotic molecules: A critical review

This review provides a comprehensive summary of the skin penetration pathways of xenobiotics, including metals, organic pollutants, and nanoparticles (NPs), with a particular focus on the methodologies employed to elucidate these penetration routes. The impacts of the physicochemical properties of exogenous substances and the properties of solvent carriers on the penetration efficiencies were discussed. Furthermore, the review outlines the steady-state and transient models for predicting the skin permeability of xenobiotics, emphasizing the models which enable realistic visualization of pharmaco-kinetic phenomena via detailed geometric representations of the skin microstructure, such as stratum corneum (SC) (bricks and mortar) and skin appendages (hair follicles and sebaceous gland units). Limitations of published research, gaps in current knowledge, and recommendations for future research are highlighted, providing insight for a better understanding of the skin penetration behavior of xenobiotics and associated health risks in practical application contexts.

Identifying PFAS hotspots in surface waters of South Carolina using a new optimized total organic fluorine method and target LC-MS/MS

Per- and polyfluoroalkyl substances (PFAS) are environmental contaminants of concern due to their long persistence in the environment, toxicity, and widespread presence in humans and wildlife. Knowledge regarding the extent of PFAS contamination in the environment is limited due to the need for analytical methods that can reliably quantify all PFAS, since traditional target methods using liquid chromatography (LC)-mass spectrometry (MS) fail to capture many. For a more comprehensive analysis, a total organic fluorine (TOF) method can be used as a screening tool. We combined TOF analysis with target LC-MS/MS analysis to create a statewide PFAS hotspot map for surface waters throughout South Carolina. Thirty-eight of 40 locations sampled contained detectable concentrations of organic fluorine (above 100 ng/L). Of the 33 target PFAS analyzed using LC-MS/MS, the most prevalent were perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), perfluoroheptanoic acid (PFHpA), and perfluorohexanesulfonate (PFHxS). On average, LC-MS/MS only accounted for 2 % of the TOF measured. Locations with high TOF did not necessarily correlate to high total quantified PFAS concentrations and vice-versa, demonstrating the limitations of target PFAS analysis and indicating that LC-MS may miss highly contaminated sites. Results suggest that future surveys should utilize TOF to more comprehensively capture PFAS in water bodies.

Evaluation of per- and polyfluoroalkyl substances (PFAS) in landfill liquids from Pennsylvania, Colorado, and Wisconsin

PER: and polyfluoroalkyl substances (PFAS) have been measured in aqueous components within landfills. To date, the majority of these studies have been conducted in Florida. This current study aimed to evaluate PFAS concentrations in aqueous components (leachate, gas condensate, stormwater, and groundwater) from four landfills located outside of Florida, in Pennsylvania, Colorado, and Wisconsin (2 landfills). The Pennsylvania landfill also provided the opportunity to assess a leachate treatment system. Sample analyses were consistent across studies including the measurements of 26 PFAS and physical-chemical parameters. For the four target landfills, average PFAS concentrations were 6,900, 22,000, 280, and 260 ng L-1 in the leachate, gas condensate, stormwater, and groundwater, respectively. These results were not significantly different than those observed for landfills in Florida except for the significantly higher PFAS concentrations in gas condensate compared to leachate. For on-site treatment at the Pennsylvania landfill, results suggest that the membrane biological bioreactor (MBBR) system performed similarly as aeration-based leachate treatment systems at Florida landfills resulting in no significant decreases in ∑26PFAS. Overall, results suggest a general consistency across US regions in PFAS concentrations within different landfill liquid types, with the few differences observed likely influenced by landfill design and local climate. Results confirm that leachate exposed to open air (e.g., in trenches or in treatment systems) have lower proportions of perfluoroalkyl acid precursors relative to leachate collected in enclosed pipe systems. Results also confirm that landfills without bottom liner systems may have relatively higher PFAS levels in adjacent groundwater and that landfills in wetter climates tend to have higher PFAS concentrations in leachate.

Per- and polyfluoroalkyls used as cosmetic ingredients - Qualitative study of 765 cosmetic products

Per- and polyfluoroalkyl substances (PFAS) form a vast family comprising more than 4700 synthetic compounds. Their molecules contain a terminal functional group and a hydrophobic carbon tail (alkyl group) at which the hydrogen atoms are totally (in the case of perfluorinated compounds) or partially (in the case of polyfluorinated compounds) replaced by fluorine atoms. Due to the very specific properties of their structure, they have been used in a vast range of applications over the last 70 years. These substances are considered to be of concern for the environment. Their effects on human health are still poorly understood because studies are still too rare, but the cutaneous route could be a significant pathway of penetration. In this context, we made a qualitative study to assess the presence of PFAS in various cosmetics such as hygiene products, skin care products, make-up and perfumes. Among the 765 products studied, we found 11 different PFAS. Polytetrafluoroethylene (PTFE) and perfluorodecalin, present in 25.9% and 22.2% of products containing it, respectively, were the most frequent. Although the presence of this type of ingredient seems to be limited in Europe, make-up appears to be the type of product most likely to contain PFAS.

Evaluation of per- and polyfluoroalkyl substances (PFAS) released from two Florida landfills based on mass balance analyses

Per- and polyfluoroalkyl substances (PFAS) have been found at high levels within landfill environments. To assess PFAS distributions, this study aimed to evaluate PFAS mass flux leached from disposed solid waste and within landfill reservoirs by mass balance analyses for two full-scale operational Florida landfills. PFAS mass flux in different aqueous components within landfills were estimated based on PFAS concentrations and water flow rates. For PFAS concentration, 26 PFAS, including 18 perfluoroalkyl acids (PFAAs) and 8 PFAA-precursors, were measured in samples collected from the landfills or estimated based on previous studies. Flow rates of aqueous components (rainfall, evapotranspiration, runoff, stormwater, groundwater, leakage, gas condensate, and leachate) were evaluated through the Hydrologic Evaluation of Landfill Performance model, water balance, and Darcy's Law. Results showed that the average PFAS mass flux leached from the solid waste standardized by area was estimated as 36.8 g/ha-yr, which was approximately 1 % to 3 % of the total amount of PFAS within the solid waste. The majority of PFAS leached from the solid waste (95 % to 97 %) is captured by the leachate collection system, with other aqueous components representing much smaller fractions (stormwater system at 3 % to 5 %, and gas condensate and groundwater at < 1 %). Also, based on the results, we estimate that PFAS releases will likely occur at least over 40 years. Overall, these results can help prioritize components for waste management and PFAS treatment during the anticipated landfill release periods.

Toxic Ingredients in Personal Care Products: A Dermatological Perspective

Environmental dermatology is the study of how environmental factors affect the integumentary system. The environment includes natural and built habitats, encompassing ambient exposure, occupational exposures, and lifestyle exposures secondary to dietary and personal care choices. This review explores common toxins found in personal care products and packaging, such as bisphenols, parabens, phthalates, per- and poly-fluoroalkyl substances, p-phenylenediamine, and formaldehyde. Exposure to these toxins has been associated with carcinogenic, obesogenic, or proinflammatory effects that can potentiate disease. In addition, these compounds have been implicated as endocrine-disrupting chemicals that can worsen dermatological conditions such as acne vulgaris, or dermatitis. Certain pollutants found in personal care products are not biodegradable and have the potential to bioaccumulate in humans. Therefore, even short-term exposure can cause long-lasting issues for communities. The skin is often the first point of contact for environmental exposures and serves as the conduit between environmental toxins and the human body. Therefore, it is important for dermatologists to understand common pollutants and their acute, subacute, and chronic impact on dermatological conditions to better diagnose and manage disease.

Polyfluoroalkyl phosphate esters (PAPs) as PFAS substitutes and precursors: An overview

Polyfluoroalkyl phosphate esters (PAPs) are emerging substitutes for legacy per- and polyfluoroalkyl substances (PFAS), which are widely applied in consumer products and closely related to people's daily lives. Increasing concern has been raised about the safety of PAPs due to their metabolism into perfluorooctanoic acid (PFOA) and other perfluorinated carboxylates (PFCAs) in vivo. This review summarizes the current knowledge on PAPs and highlights the knowledge gaps. PAPs dominated the PFAS profiles in wastewater, sludge, household dust, food-contact materials, paper products, paints, and cosmetics. They exhibit biomagnification due to their higher levels in top predators. PAPs have been detected in human blood worldwide, with the highest mean levels being found in the United States (1.9 ng/mL) and China (0.4 ng/mL). 6:2 diPAP is the predominant PAP among all identified matrices, followed by 8:2 diPAP. Toxicokinetic studies suggest that after entering the body, most PAPs undergo biotransformation, generating phase Ⅰ (i.e., PFCAs), phase II, and intermediate products with toxicity to be verified. Several epidemiological and toxicological studies have reported the antiandrogenic effect, estrogenic effect, thyroid disruption, oxidative damage, and reproductive toxicity of PAPs. More research is urgently needed on the source and fate of PAPs, human exposure pathways, toxicity other than reproductive and endocrine systems, toxic effects of metabolites, and mixed exposure effects.

Closing the Organofluorine Mass Balance in Marine Mammals Using Suspect Screening and Machine Learning-Based Quantification

High-resolution mass spectrometry (HRMS)-based suspect and nontarget screening has identified a growing number of novel per- and polyfluoroalkyl substances (PFASs) in the environment. However, without analytical standards, the fraction of overall PFAS exposure accounted for by these suspects remains ambiguous. Fortunately, recent developments in ionization efficiency (IE) prediction using machine learning offer the possibility to quantify suspects lacking analytical standards. In the present work, a gradient boosted tree-based model for predicting log IE in negative mode was trained and then validated using 33 PFAS standards. The root-mean-square errors were 0.79 (for the entire test set) and 0.29 (for the 7 PFASs in the test set) log IE units. Thereafter, the model was applied to samples of liver from pilot whales (n = 5; East Greenland) and white beaked dolphins (n = 5, West Greenland; n = 3, Sweden) which contained a significant fraction (up to 70%) of unidentified organofluorine and 35 unquantified suspect PFASs (confidence level 2-4). IE-based quantification reduced the fraction of unidentified extractable organofluorine to 0-27%, demonstrating the utility of the method for closing the fluorine mass balance in the absence of analytical standards.

Fluoroether Double-Chain Phosphate Surfactants: An Exploration of Alternatives to Fluorotelomer Surfactants

While legacy fluorosurfactants have already been categorized as persistent organic pollutants, there appeared to be many strategies to develop alternatives. In this work, fluoroether double-chain phosphate surfactants (C72 diPAP-Na and C72 diPAP-NH4) were designed and synthesized with the initial intention of exploring the creation of new fluorosurfactants containing oxygen heteroatoms in the fluorocarbon chain segments to provide an alternative to the legacy long-chain fluorosurfactants. Furthermore, it was expected that they would even exceed the existing 6:2 fluorotelomer surfactants (6:2 diPAP-Na and 6:2 diPAP-NH4). Compared with characterizations of surface activity, foam performance, and wettability, the results showed that each of them has its own distinctive performance. Although the C72 series as new fluoroether surfactants cannot fully replace the 6:2 series of fluorosurfactants in terms of performance, there is a possibility of substitution in some aspects, which is of positive significance for further exploration to improve alternatives to legacy fluorosurfactants.

Determination of Perfluorooctanoic Acid (PFOA) in the Indoor Dust Matter of the Sicily (Italy) Area: Analysis and Exposure Evaluations

Perfluorooctanoic acid (PFOA) in environmental matrices is increasingly being studied due to its environmental persistence, global occurrence, bioaccumulation, and associated human health risks. Some indoor environments can significantly impact the health of occupants due to pollutants in indoor air and household dust. To investigate the potential exposure of individuals to PFOA in specific confined environments, this study reports an analytical method and results concerning the determination of PFOA in household dust, used as a passive sampler. To the best of our knowledge, this paper represents one of the first studies concerning PFOA concentrations in indoor dust collected in the south of Italy, within the European region. A total of twenty-three dust samples were collected from two different areas of Sicily (Palermo and Milena), extracted, and analyzed by an UHPLC-QTOF-MS/MS system. Finally, PFOA exposure was estimated using a new index (Indoor PFOA Exposure Index, IPEX) that incorporates the PFOA levels in dust, exposure time, and the correlation between the PFOA in dust and blood. It was then compared across four different exposure groups, revealing that PFOA exposure for people working in chemistry laboratories was evaluated to be ten times higher than the exposure for homemakers.

Comparison of aggregated exposure to perfluorooctanoic acid (PFOA) from diet and personal care products with concentrations in blood using a PBPK model - Results from the Norwegian biomonitoring study in EuroMix

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) constitute a large group of compounds that are water, stain, and oil repellent. Numerous sources contribute to the blood levels of PFAS in the European population. The main contributor for perfluorooctanoic acid (PFOA) is food, house dust, consumer products and personal care products (PCPs).

OBJECTIVES

The purpose of the present work is to calculate the dietary and dermal external exposure to PFOA, estimate the aggregated internal exposure from diet and PCPs using a PBPK model, and compare estimates with measured concentrations.

METHODS

Detailed information on diet and PCP use from the EuroMix study is combined with concentration data of PFOA in food and PCPs in a probabilistic exposure assessment. A physiologically based pharmacokinetic model (PBPK) was further refined by incorporating a dermal exposure pathway, and changes in the kidney and faecal excretion.

RESULTS

The aggregated internal exposure using the PBPK model shows that the major contributor to the internal exposure is diet for both males and females. The estimated internal exposure of PFOA for the EuroMix population was in the same range but lower than the measured blood concentrations using the lower bound (LB) external exposure estimates, showing that the LB estimates are underestimations. For seven females the internal exposure of PFOA were higher from PCPs than from diet.

CONCLUSION

PCPs and diet contributed in the same range to the internal PFOA exposure for several women participating in EuroMix. This calls for additional studies on exposure to PFOA and possibly other PFAS from PCPs, especially for women. Overall, PBPK modelling was shown as valuable tool in understanding the sources of PFOA exposure and in guiding risk assessments and regulatory decisions.

Determination of polyfluoroalkyl substances in cosmetic products using dispersed liquid-liquid extraction coupled with UHPLC-MS/MS

Human exposure to polyfluoroalkyl substances (PFASs) via cosmetics has been of increasing concern due to the tremendous detrimental health impacts of PFASs. Developing an effective method for extracting and determining PFASs in cosmetics is crucial in accurately assessing their corresponding human exposure risk. Herein, this study developed a new sample pre-treatment method to address the challenges posed by the variety and complexity of cosmetic matrices. Seventeen PFASs in cosmetic products, including 9 perfluoro carboxylic acids and 8 perfluorosulfonic acids, were simultaneously determined using ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). The whole pre-treatment process can be divided into three steps. In step 1, cosmetics with diverse matrix types can be effectively dispersed during extraction by using saturated sodium chloride-acetonitrile and saturated sodium chloride-tetrahydrofuran as extraction solvents. In step 2, the pre-purification step employs a potassium ferrocyanide-zinc acetate co-precipitant to remove high molecular weight interferents from the extraction solution, thereby enhancing the efficiency of solid-phase extraction (SPE). In step 3, WAX-SPE is utilized to further eliminate interferents from the extraction solution while concentrating the analytes, meeting the trace analysis requirements for PFASs in cosmetics. The method detection limits were 0.09-0.26 ng g-1. The recoveries ranged from 70.1% to 114.7%, with relative standard deviations in the range of 2.0-19.1%. The method was applied to cosmetic samples in the Guangzhou market, and the total concentration of PFASs ranged from 0 to 10.8 ng g-1. This method has strong anti-interference ability, good applicability, high sensitivity, and good reproducibility, making it suitable for the analysis and detection of perfluorinated acids in cosmetic samples. It provides technical support for cosmetics safety regulation.

Interlaboratory Comparison of Extractable Organofluorine Measurements in Groundwater and Eel (Anguilla rostrata): Recommendations for Methods Standardization

Research on per- and polyfluoroalkyl substances (PFAS) frequently incorporates organofluorine measurements, particularly because they could support a class-based approach to regulation. However, standardized methods for organofluorine analysis in a broad suite of matrices are currently unavailable, including a method for extractable organofluorine (EOF) measured using combustion ion chromatography (CIC). Here, we report the results of an international interlaboratory comparison. Seven laboratories representing academia, government, and the private sector measured paired EOF and PFAS concentrations in groundwater and eel (Anguilla rostrata) from a site contaminated by aqueous film-forming foam. Among all laboratories, targeted PFAS could not explain all EOF in groundwater but accounted for most EOF in eel. EOF results from all laboratories for at least one replicate extract fell within one standard deviation of the interlaboratory mean for groundwater and five out of seven laboratories for eel. PFAS spike mixture recoveries for EOF measurements in groundwater and eel were close to the criterion (±30%) for standardized targeted PFAS methods. Instrumental operation of the CIC such as replicate sample injections was a major source of measurement uncertainty. Blank contamination and incomplete inorganic fluorine removal may introduce additional uncertainties. To elucidate the presence of unknown organofluorine using paired EOF and PFAS measurements, we recommend that analysts carefully consider confounding methodological uncertainties such as differences in precision between measurements, data processing steps such as blank subtraction and replicate analyses, and the relative recoveries of PFAS and other fluorine compounds.

Elevated Levels of Ultrashort- and Short-Chain Perfluoroalkyl Acids in US Homes and People

Per- and polyfluoroalkyl substances (PFAS) make up a large group of fluorinated organic compounds extensively used in consumer products and industrial applications. Perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA), the two perfluoroalkyl acids (PFAAs) with 8 carbons in their structure, have been phased out on a global scale because of their high environmental persistence and toxicity. As a result, shorter-chain PFAAs with less than 8 carbons in their structure are being used as their replacements and are now widely detected in the environment, raising concerns about their effects on human health. In this study, 47 PFAAs and their precursors were measured in paired samples of dust and drinking water collected from residential homes in Indiana, United States, and in blood and urine samples collected from the residents of these homes. Ultrashort- (with 2 or 3 carbons [C2-C3]) and short-chain (with 4-7 carbons [C4-C7]) PFAAs were the most abundant in all four matrices and constituted on average 69-100% of the total PFAA concentrations. Specifically, trifluoroacetic acid (TFA, C2) and perfluoropropanoic acid (PFPrA, C3) were the predominant PFAAs in most of the samples. Significant positive correlations (n = 81; r = 0.23-0.42; p < 0.05) were found between TFA, perfluorobutanoic acid (PFBA, C4), and perfluoroheptanoic acid (PFHpA, C7) concentrations in dust or water and those in serum, suggesting dust ingestion and/or drinking water consumption as important exposure pathways for these compounds. This study demonstrates that ultrashort- and short-chain PFAAs are now abundant in the indoor environment and in humans and warrants further research on potential adverse health effects of these exposures.

Fluorine Mass Balance, including Total Fluorine, Extractable Organic Fluorine, Oxidizable Precursors, and Target Per- and Polyfluoroalkyl Substances, in Pooled Human Serum from the Tromsø Population in 1986, 2007, and 2015

Of the thousands of per- and polyfluoroalkyl substances (PFAS) known to exist, only a small fraction (≤1%) are commonly monitored in humans. This discrepancy has led to concerns that human exposure may be underestimated. Here, we address this problem by applying a comprehensive fluorine mass balance (FMB) approach, including total fluorine (TF), extractable organic fluorine (EOF), total oxidizable precursors (TOP), and selected target PFAS, to human serum samples collected over a period of 28 years (1986, 2007, and 2015) in Tromsø, Norway. While concentrations of TF did not change between sampling years, EOF was significantly higher in 1986 compared to 2007 and 2015. The ∑12PFAS concentrations were highest in 2007 compared to 1986 and 2015, and unidentified EOF (UEOF) decreased from 1986 (46%) to 2007 (10%) and then increased in 2015 (37%). While TF and EOF were not influenced by sex, women had higher UEOF compared to men, opposite to target PFAS. This is the first FMB in human serum to include TOP, and it suggests that precursors with >4 perfluorinated carbon atoms make a minor contribution to EOF (0-4%). Additional tools are therefore needed to identify substances contributing to the UEOF in human serum.

The wide presence of fluorinated compounds in common chemical products and the environment: a review

The C-F bonds, due to their many unique features, have been incorporated into numerous compounds in countless products and applications. These fluorinated compounds eventually are disposed of and released into the environment through different pathways. In this review, we analyzed the occurrence of these fluorinated compounds in seven types of products (i.e., refrigerants/propellants, aqueous film-forming foam, cosmetics, food packaging, agrochemicals, pharmaceuticals, coating materials) and discussed their fate in the environment. This is followed by describing the quantity of fluorinated compounds from each source based on available data. Total on- and off-site disposal or other releases of 536 fluorinated compounds in 2021 were analyzed using the data sourced from the U.S. EPA Toxics Release Inventory (TRI). Among the chemicals examined, chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) were the primary contributors in terms of total mass. Upon examining the seven sources of fluorinated compounds, it became evident that additional contributors are also responsible for the presence of organofluorine compounds in the environment. Although various toxic degradation products of fluorinated compounds could form in the environment, trifluoroacetic acid (TFA) was specifically highlighted in this review given the fact that it is a common dead-end degradation product of > 1 million chemicals. This paper ended with a discussion of several questions raised from this study. The path forward was elaborated as well for the purpose of protecting the environment and human health.

Revealing the factors resulting in incomplete recovery of perfluoroalkyl acids (PFAAs) when implementing the adsorbable and extractable organic fluorine methods

Per- and polyfluoroalkyl substances (PFASs) are environmental contaminants of concern. Techniques that quantify total organic fluorine (TOF) such as the adsorbable organic fluorine (AOF) and extractable organic fluorine (EOF) methods are important for PFAS risk assessments. The objective of this study was to systematically evaluate each step of the AOF (loading, washing, combustion) and EOF (loading, washing, elution, combustion) methods for the recovery of ten ultrashort-, short-, and long-chain unsubstituted perfluoroalkyl acids (PFAAs). We measured the overall recovery of fluoride for each method for each PFAA, and the recovery of each PFAA around the loading, washing, and elution steps. We also measured the combustion efficiency of each PFAA by direct combustion. The overall AOF and EOF recovery ranged from 9.3%-103.3% to 21.0%-108.1%, respectively, with higher recoveries measured for PFAAs with increasing chain length in both methods. The three ultrashort-chain PFAAs (trifluoroacetic acid, perfluoropropionic acid, and perfluoropropanesulfonic acid) exhibited the lowest overall recoveries from 9.3-25.2% for AOF and 21.0-51.5% for EOF. We found that decreases in the overall recovery are the result of losses of ultrashort- and short-chain PFAAs during the washing step and the incomplete mineralization of perfluoroalkyl sulfonic acids during combustion for AOF and incomplete elution of short- and long-chain PFAAs and the loss of ultrashort-chain PFAAs during the washing step for EOF. Our data suggest that the EOF method is more appropriate than the AOF method for measuring TOF in samples containing ultrashort- and short-chain PFAAs and that methodological improvements are possible with a focus on the washing, elution, and combustion steps.

Finding a way out? Comprehensive biotransformation study of novel fluorinated surfactants

In this study the environmental fate of two novel trifluoromethoxy-substituted surfactants with respectively an ether or thioether linkage were investigated, of which the design aimed for less persistency and complete mineralization. Long-term microbial transformation studies under aerobic conditions in activated sludge-wastewater medium were performed for 126 days. A semi-closed experimental system with a trapping sorbent was selected to avoid losses of possible volatile transformation products (TPs). The changes in the concentration of the surfactants and their expected TPs were monitored by target analysis using liquid chromatography-tandem mass spectrometry. Significant decrease in the concentration of the surfactants was observed over the incubation period. The main detected TPs were short-chained carboxylic acids (CAs), including a CA with two fluorinated carbon atoms representing the last product prior to mineralization. High stability of these CAs and lack in the formation of inorganic fluoride over the incubation time was however observed. Consequently, unequivocal final mineralization of the investigated surfactants could not be confirmed. Regarding the mass balance, the total amount of detected substances achieved only 30-37% of the expected concentration at the end of the incubation time. The reason of the incomplete mass balance should be further investigated.

Exploring the Evolution of Organofluorine-Containing Compounds during Simulated Photolithography Experiments

One potential source of per- and polyfluoroalkyl substances (PFASs) in electronics fabrication wastewater are the organofluorine-containing compounds used in photolithography materials such as photoresists and top antireflective coatings (TARCs). However, the exact identities of these constituents are unknown and transformation reactions that may occur during photolithography may result in the formation of unknown or unexpected PFASs. To address this knowledge gap, we acquired five commercially relevant photolithography materials, characterized the occurrence of organofluorine-containing compounds in each material, and performed simulated photolithography experiments to stimulate any potential transformation reactions. We found that photoresists and TARCs have total fluorine (TF) concentrations in the g L-1 range, similar to the levels of other industrial and commercial products. However, the target and suspect PFASs present in these materials can only explain up to 20% of the TF in a material. We evaluated wastewater samples collected after simulated photolithography experiments and used a mass balance approach to assess the extent of transformations. Although a number of target, suspect, and nontarget PFASs were identified in the wastewater samples, the extent of transformation was limited and the fluorine contained in the PFASs could not explain more than an additional 1% of the TF in the photolithography materials.

Trace analysis of per- and polyfluorinated alkyl substances (PFAS) in dried blood spots - Demonstration of reproducibility and comparability to venous blood samples

Per- and polyfluoroalkyl substances (PFAS) are a group of man-made chemicals that have been widely used in consumer, personal care, and household products for their stain- and water-repellent properties. PFAS exposure has been linked to various adverse health outcomes. Such exposure has commonly been evaluated in venous blood samples. While this sample type can be obtained from healthy adults, a less invasive method of blood collection is required when evaluating vulnerable populations. Dried blood spots (DBS) have gained attention as a biomatrix for exposure assessment given the relative ease of collection, transport, and storage. The objective of this study was to develop and validate an analytical method to measure PFAS in DBS. A workflow is presented for extracting PFAS from DBS, chemical analysis by liquid chromatography-high resolution mass spectrometry, normalization for blood mass, and blank correction to account for potential contamination. Over 80 % recovery was achieved for the 22 PFAS measured with an average coefficient of variation of 14 %. Comparison of PFAS concentrations detected in DBS and paired whole blood samples from six healthy adults was correlated (R2 > 0.9). Findings demonstrate trace levels of a broad range of PFAS in DBS can be reproducibly measured and are comparable to liquid whole blood samples. DBS can offer novel insights to environmental exposures, including during critical windows of susceptibility (i.e., in utero, early life), which have been largely uncharacterized.

Deciphering the Mechanistic Basis for Perfluoroalkyl-Protein Interactions

Although rarely used in nature, fluorine has emerged as an important elemental ingredient in the design of proteins with altered folding, stability, oligomerization propensities, and bioactivity. Adding to the molecular modification toolbox, here we report the ability of privileged perfluorinated amphiphiles to noncovalently decorate proteins to alter their conformational plasticity and potentiate their dispersion into fluorous phases. Employing a complementary suite of biophysical, in-silico and in-vitro approaches, we establish structure-activity relationships defining these phenomena and investigate their impact on protein structural dynamics and intracellular trafficking. Notably, we show that the lead compound, perfluorononanoic acid, is 106 times more potent in inducing non-native protein secondary structure in select proteins than is the well-known helix inducer trifluoroethanol, and also significantly enhances the cellular uptake of complexed proteins. These findings could advance the rational design of fluorinated proteins, inform on potential modes of toxicity for perfluoroalkyl substances, and guide the development of fluorine-modified biologics with desirable functional properties for drug discovery and delivery applications.

Improved total organic fluorine methods for more comprehensive measurement of PFAS in industrial wastewater, river water, and air

Per- and polyfluoroalkyl substances (PFAS) are high-profile environmental contaminants, many having long persistence in the environment and widespread presence in humans and wildlife. Following phase-out of perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) in North America and restrictions in Europe, PFAS replacements are now widely found in the environment. While liquid chromatography (LC)-mass spectrometry (MS) is typically used for measurement, much of the PFAS is missed. To more comprehensively capture organic fluorine, we developed sensitive and robust methods using activated carbon adsorption, solid phase extraction, and combustion ion chromatography (CIC) to measure total organic fluorine (TOF) in industrial wastewaters, river water, and air. Two extraction techniques, adsorbable organic fluorine (AOF) and extractable organic fluorine (EOF), were optimized and compared using 39 different PFAS, including replacements, such as GenX and perfluorobutanesulfonate. Our AOF method achieves 46-112% and 87% recovery for individual PFAS and PFAS mixtures, respectively, with 0.5 µg/L limit of detection (LOD) for a 50 mL sample volume and a 0.3 μg/L LOD for a 500 mL sample volume . Our EOF method achieves 72-99% and 91% recovery for individual PFAS and PFAS mixtures, respectively, with 0.2 µg/L LOD for a 500 mL sample volume and 0.1 μg/L LOD for 1200 mL. In addition to 39 anionic PFAS, two zwitterionic PFAS and two neutral PFAS were evaluated using the optimized TOF methods. Substantially higher TOF values were measured in industrial wastewater, river water, and air samples compared to LC-MS/MS, demonstrating how TOF methods provided a more comprehensive measurement of the total PFAS present, capturing known and unknown organic fluorine.

Unknown Organofluorine Mixtures in U.S. Adult Serum:Contribution from Pharmaceuticals?

Organofluorines occur in human serum as complex mixtures of known and unidentified compounds. Human biomonitoring traditionally uses targeted analysis to measure the presence of known and quantifiable per- and polyfluoroalkyl substances (PFAS) in serum, yet characterization of exposure to and quantification of PFAS are limited by the availability of methods and analytical standards. Studies comparing extractable organofluorine (EOF) in serum to measured PFAS using organofluorine mass balance show that measurable PFAS only explain a fraction of EOF in human serum and that other sources of organofluorine may exist. The gap in fluorine mass balance has important implications for human biomonitoring because the total body burden of PFAS cannot be characterized and the chemical species that make up unidentified EOF are unknown. Many highly prescribed pharmaceuticals contain organofluorine (e.g., Lipitor, Prozac) and are prescribed with dosing regimens designed to maintain a therapeutic range of concentrations in serum. Therefore, we hypothesize organofluorine pharmaceuticals contribute to EOF in serum. We use combustion ion chromatography to measure EOF in commercial serum from U.S. blood donors. Using fluorine mass balance, we assess differences in unexplained organofluorine (UOF) associated with pharmaceutical use and compare them with concentrations of organofluorine predicted based on the pharmacokinetic properties of each drug. Pharmacokinetic estimates of organofluorine attributable to pharmaceuticals ranged from 0.1 to 55.6 ng F/mL. Analysis of 44 target PFAS and EOF in samples of commercial serum (n = 20) shows the fraction of EOF not explained by Σ₄₄ PFAS ranged from 15% to 86%. Self-reported use of organofluorine pharmaceuticals is associated with a 0.36 ng F/mL (95% CL: -1.26 to 1.97) increase in UOF, on average, compared to those who report not taking organofluorine pharmaceuticals. Our study is the first to assess sources of UOF in U.S. serum and examine whether organofluorine pharmaceuticals contribute to EOF. Discrepancies between pharmacokinetic estimates and EOF may be partly explained by differences in analytical measurements. Future analyses using EOF should consider multiple extraction methods to include cations and zwitterions. Whether organofluorine pharmaceuticals are classified as PFAS depends on the definition of PFAS.

Thermal Decomposition of Two Gaseous Perfluorocarboxylic Acids: Products and Mechanisms

The thermal decomposition products and mechanisms of per- and polyfluoroalkyl substances (PFASs) are poorly understood despite the use of thermal treatment to remediate PFAS-contaminated media. To identify the thermal decomposition products and mechanisms of perfluorocarboxylic acids (PFCAs), gaseous perfluoropropionic acid (PFPrA) and perfluorobutyric acid (PFBA) were decomposed in nitrogen and oxygen at temperatures from 200 to 780 °C. In nitrogen (i.e., pyrolysis), the primary products of PFPrA were CF₂═CF₂, CF₃CF₂H, and CF₃COF. CF₃CF═CF₂ was the dominant product of PFBA. These products are produced by HF elimination (detected as low as 200 °C). CF₄ and C₂F₆ were observed from both PFCAs, suggesting formation of perfluorocarbon radical intermediates. Pyrolysis products were highly thermally stable, resulting in poor defluorination. In oxygen (i.e., combustion), the primary product of both PFPrA and PFBA below 400 °C was COF₂, but the primary product was SiF₄ above 600 °C due to reactions with the quartz reactor. Oxygen facilitated thermal defluorination by reacting with PFCAs and with pyrolysis products (i.e., fluoroolefins and fluorocarbon radicals). Platinum improved combustion of PFCAs to COF₂ at temperatures as low as 200 °C, while quartz promoted the combustion of PFCAs into SiF₄ at higher temperatures (>600 °C), highlighting the importance of surface reactions that are not typically incorporated into computational approaches.

Electrochemical Oxidation for Treatment of PFAS in Contaminated Water and Fractionated Foam-A Pilot-Scale Study

Per- and polyfluoroalkyl substances (PFAS) are persistent synthetic contaminants that are present globally in water and are exceptionally difficult to remove during conventional water treatment processes. Here, we demonstrate a practical treatment train that combines foam fractionation to concentrate PFAS from groundwater and landfill leachate, followed by an electrochemical oxidation (EO) step to degrade the PFAS. The study combined an up-scaled experimental approach with thorough characterization strategies, including target analysis, PFAS sum parameters, and toxicity testing. Additionally, the EO kinetics were successfully reproduced by a newly developed coupled numerical model. The mean total PFAS degradation over the designed treatment train reached 50%, with long- and short-chain PFAS degrading up to 86 and 31%, respectively. The treatment resulted in a decrease in the toxic potency of the water, as assessed by transthyretin binding and bacterial bioluminescence bioassays. Moreover, the extractable organofluorine concentration of the water decreased by up to 44%. Together, these findings provide an improved understanding of a promising and practical approach for on-site remediation of PFAS-contaminated water.

Quantitation of Total PFAS Including Trifluoroacetic Acid with Fluorine Nuclear Magnetic Resonance Spectroscopy

Fluorine nuclear magnetic resonance (19F-NMR) spectroscopy has been shown to be a powerful tool capable of quantifying the total per- and polyfluoroalkyl substances (PFAS) in a complex sample. The technique relies on the characteristic terminal -CF3 shift (-82.4 ppm) in the alkyl chain for quantification and does not introduce bias due to sample preparation or matrix effects. Traditional quantitative analytical techniques for PFAS, such as liquid chromatography-mass spectrometry (LC-MS) and combustion ion chromatography (CIC), contain inherent limitations that make total fluorine analysis challenging. Here, we report a sensitive 19F-NMR method for the analysis of total PFAS, with a limit of detection of 99.97 nM, or 50 μg/L perfluorosulfonic acid. To demonstrate the capabilities of 19F-NMR, the technique was compared to two commonly used methods for PFAS analysis: total oxidizable precursor (TOP) assay and LC-high resolution MS analysis for targeted quantification and suspect screening. In both cases, the 19F-NMR analyses detected higher total PFAS quantities than either the TOP assay (63%) or LC-MS analyses (65%), suggesting that LC-MS and TOP assays can lead to underreporting of PFAS. Importantly, the 19F-NMR detected trifluoroacetic acid at a concentration more than five times the total PFAS concentration quantified using LC-MS in the wastewater sample. Therefore, the use of 19F-NMR to quantify the total PFAS in highly complex samples can be used to complement classic TOP or LC-MS approaches for more accurate reporting of PFAS contamination in the environment.

New insights into the oxidative damage and antioxidant defense mechanism in Manila clams (Ruditapes philippinarum) exposed to 8:2 polyfluoroalkyl phosphate diester stress

8:2 perfluoroalkyl phosphate diester (8:2 diPAP) is the main precursor of perfluoroalkyl carboxylic acids, and it has been detected in a wide range of environments. In this study, conventional biochemical and histopathological analyses and transcriptome methods were used to investigate the accumulation and oxidative stress of 8:2 diPAP in Manila clams (Ruditapes philippinarum) as well as the clam's defense mechanisms for the first time. The hepatopancreas was the main target organ for 8:2 diPAP accumulation; the concentration reached 484.0 ± 15.5 ng/g after 7 days of exposure to 10 μg/L of 8:2 diPAP, which was 2-100 times higher than that found in other organs. 8:2 diPAP accumulation resulted in significant lipid peroxidation, and the change in malondialdehyde content was highly correlated with 8:2 diPAP accumulation (r > 0.8). The antioxidant enzymes catalase and peroxidase were significantly activated at 7 days of exposure. Although the levels subsequently returned to normal, this restoration was unable to prevent damage. Histopathological analysis showed that 8:2 diPAP exposure resulted in inflammatory damage to the hepatopancreas, which failed to resolve during the recovery period. Transcriptomic analyses showed that the expression of differentially expressed genes had different degrees of positive/negative correlation with antioxidant indicators, and they were significantly enriched in cell death regulatory pathways such as autophagy, apoptosis, and necrosis. The core factor expression results indicated that 8:2 diPAP exposure induced activation of the organismal autophagy factor followed by a shift towards apoptosis. In addition, pathways related to amino acid metabolism and energy metabolism were involved in determining the cell fate of Manila clams. Overall, these results indicated that 8:2 diPAP induced peroxidation of membrane lipids, disturbed physiological processes, and ultimately initiated programmed cell death in Manila clams. The findings of this study provide new insights into the mechanism of toxicity of 8:2 diPAP exposure in marine bivalves.

Evaluation of per- and polyfluoroalkyl substances (PFAS) in leachate, gas condensate, stormwater and groundwater at landfills

Per- and polyfluoroalkyl substances (PFAS), found in many consumer products, are commonly disposed of in landfills at the end of their service lives. To identify landfill liquids that should be prioritized for treatment, this study aimed to evaluate PFAS levels in different aqueous samples from landfills and identify relationships between PFAS and landfill characteristics. Twenty-six PFAS including 11 perfluoroalkyl carboxylic acids (PFCAs), 7 perfluoroalkyl sulfonates (PFSAs), and 8 perfluoroalkyl acid precursors (PFAA-precursors) were measured in municipal solid waste (MSW) leachate, construction and demolition debris (CDD) leachate, municipal solid waste incineration (MSWI) ash leachate, gas condensate, stormwater, and groundwater from landfills. Based on the median, results show that PFAS levels in MSW leachate were the highest (10,000 ng L-1), CDD leachate were intermediate (6200 ng L-1), and MSWI ash leachate were the lowest (1300 ng L-1) among the leachates evaluated. PFAS levels in gas condensate (7000 ng L-1) were similar to MSW leachate. PFAS in stormwater and groundwater were low (medians were less than 500 ng L-1). Dominant subgroups included PFCAs and PFAA-precursors in all leachates. PFSAs were also found in CDD leachate, PFAA-precursors in gas condensate, and PFCAs in stormwater and groundwater. Landfill characteristics significantly correlated with ∑26PFAS included waste proportions (percentage of MSWI ash in landfill, |rs| = 0.22), operational status (active or not, |rs| = 0.27) and rainfall (30-d cumulative rainfall, |rs| = 0.39). The results from this study can be used to prioritize which landfills and which reservoir of liquids (and corresponding subgroup of PFAS) to target for PFAS management.

Transport and transformation of perfluoroalkyl acids, isomer profiles, novel alternatives and unknown precursors from factories to dinner plates in China: New insights into crop bioaccumulation prediction and risk assessment

Perfluoroalkyl acids (PFAAs) are contaminants of global concern, and the inadvertent consumption of PFAA-contaminated crops may pose a threat to public health. Therefore, systematically studying their source tracing, bioaccumulation prediction and risk assessments in crops is an urgent priority. This study investigated the source apportionment and transport of PFAAs and novel fluorinated alternatives (collectively as per- and polyfluoroalkyl substances, PFASs) from factories to agricultural fields in a fluorochemical industrial region of China. Furthermore, bioaccumulation specificities and prediction of these chemicals in different vegetables were explored, followed by a comprehensive risk assessment from agricultural fields to dinner plates which considered precursor degradation. A positive matrix factorization model revealed that approximately 70 % of PFASs in agricultural soils were derived from fluorochemical manufacturing and metal processing. Alarming levels of ∑PFASs ranged 8.28-84.3 ng/g in soils and 163-7176 ng/g in vegetables. PFAS with short carbon chain or carboxylic acid group as well as branched isomers exhibited higher environmental transport potentials and bioaccumulation factors (BAFs) across a range of vegetables. The BAFs of different isomers of perfluorooctanoic acid (PFOA) decreased as the perfluoromethyl group moved further from the acid functional group. Hexafluoropropylene oxide dimer acid (GenX) showed relatively low BAFs, probably related to its ether bond with a high affinity to soil. Vegetables with fewer Casparian strips (e.g., carrot and radish), or more protein, possessed larger BAFs of PFASs. A bioaccumulation equation integrating critical parameters of PFASs, vegetables and soils, was built and corroborated with a good contamination prediction. After a total oxidizable precursors (TOP) assay, incremental perfluoroalkyl carboxylic acids (PFCAs) were massively found (325-5940 ng/g) in edible vegetable parts. Besides, precursor degradation and volatilization loss of PFASs was firstly confirmed during vegetable cooking. A risk assessment based on the TOP assay was developed to assist the protection of vegetable consumers.

Per- and polyfluoroalkyl substances exposure and its influence on the intestinal barrier: An overview on the advances

Per- and polyfluoroalkyl substances (PFAS) are a class of artificially synthetic organic compounds that are hardly degraded in the natural environment. PFAS have been widely used for many decades, and the persistence and potential toxicity of PFAS are an emerging concern in the world. PFAS exposed via diet can be readily absorbed by the intestine and enter the circulatory system or accumulate directly at intestinal sites, which could interact with the intestine and cause the destruction of intestinal barrier. This review summarizes current relationships between PFAS exposure and intestinal barrier damage with a focus on more recent toxicological studies. Exposure to PFAS could cause inflammation in the gut, destruction of the gut epithelium and tight junction structure, reduction of the mucus layer, and induction of the toxicity of immune cells. PFAS accumulation could also induce microbial disorders and metabolic products changes. In addition, there are limited studies currently, and most available studies converge on the health risk of PFAS exposure for human intestinal disease. Therefore, more efforts are deserved to further understand potential associations between PFAS exposure and intestinal dysfunction and enable better assessment of exposomic toxicology and health risks for humans in the future.

Insights into the Dermal Absorption, Deposition, and Elimination of Poly- and Perfluoroalkyl Substances in Rats: The Importance of Skin Exposure

Humans are frequently exposed to poly- and perfluoroalkyl substances (PFASs) via direct skin contact with personal care and consumer products containing them. Here, we used a rat model to estimate the dermal penetration efficiency of 15 representative PFASs. After 144 h post-dosing, 4.1-18.0 and 5.3-15.1% of the applied PFASs in the low (L) and high (H) groups, respectively, were absorbed into the rats. PFAS absorption and permeation were parabolically associated with the perfluorinated carbon chain length (C_F), peaking for perfluoroheptanoic acid (PFHpA). The lipid-rich stratum corneum of the skin barrier substantially suppressed the penetration of less hydrophobic short-chain PFASs, whereas the water-rich viable epidermis and dermis served as obstacles to hydrophobic long-chain PFAS permeation. However, the renal clearance (CL_renal) of the target PFAS decreased with increasing C_F, suggesting that urinary excretion is crucial to eliminate less hydrophobic short-chain PFASs. Notably, the peak times of PFASs in the systemic circulation of rats (8-72 h) were remarkably longer than those after oral administration (1-24 h). These results suggest that dermal penetration can be long-lasting and contribute considerably to the body burden of PFASs, especially for those with moderate hydrophobicity due to their favorable skin permeation and unfavorable urinary excretion.

Organic Fluorine as an Indicator of Per- and Polyfluoroalkyl Substances in Dust from Buildings with Healthier versus Conventional Materials

Per- and polyfluoroalkyl substances (PFAS) are a class of thousands of persistent, organic fluorinated chemicals added to materials and products mainly to repel stains and water. PFAS have been associated with many adverse human health effects. We aimed to determine whether buildings with "healthier" materials─defined here as reportedly free of all PFAS─exhibit lower PFAS in dust. In addition to analyzing targeted PFAS with available commercial standards, we measured extractable organic fluorine (EOF) as a novel proxy that includes both known and unknown types of PFAS. We measured at least 15 targeted PFAS (n = 24), EOF (n = 24), and total fluorine (TF; n = 14) in dust collected from university common spaces and classrooms, half of which had "healthier" furniture and carpet. We observed lower PFAS contamination in buildings with "healthier" materials: "healthier" rooms had a 66% lower median summed PFAS and a 49% lower Kaplan-Meier estimated mean EOF level in dust in comparison to conventional rooms. The summed targeted PFAS were significantly correlated with EOF but accounted for up to only 9% of EOF, indicating the likely presence of unidentified PFAS. EOF levels explained less than 1% of TF in dust. We emphasize the need to use chemical class-based methods (e.g., EOF) for evaluating class-based solutions and to expand non-PFAS solutions for other building materials.

The Need for Testing Isomer Profiles of Perfluoroalkyl Substances to Evaluate Treatment Processes

Many environmentally relevant poly-/perfluoroalkyl substances (PFASs) including perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) exist in different isomeric (branched and linear) forms in the natural environment. The isomeric distribution of PFASs in the environment and source waters is largely controlled by the source of contamination and varying physicochemical properties imparted by their structural differences. For example, branched isomers of PFOS are relatively more reactive and less sorptive compared to the linear analogue. As a result, the removal of branched and linear PFASs during water treatment can vary, and thus the isomeric distribution in source waters can influence the overall efficiency of the treatment process. In this paper, we highlight the need to consider the isomeric distribution of PFASs in contaminated matrices while designing appropriate remediation strategies. We additionally summarize the known occurrence and variation in the physicochemical properties of PFAS isomers influencing their detection, fate, toxicokinetics, and treatment efficiency.

Transdermal absorption of 13C4-perfluorooctanoic acid (13C4-PFOA) from a sunscreen in a male volunteer - What could be the contribution of cosmetics to the internal exposure of perfluoroalkyl substances (PFAS)?

Per- and polyfluoroalkyl substances (PFAS) are a complex group of man-made chemicals with high stability and mobility leading to ubiquitous environmental contamination and accumulation especially of some long-chain perfluoroalkyl acids (PFAA) in humans. While dietary intake is the main route of exposure, transdermal uptake from cosmetic products usually is considered negligible. However, PFAS are present in a part of these products, and recent epidemiological studies have provided evidence for relevant uptake via this route. The crucial question is whether PFAA in cosmetic products can cross the human skin barrier. A defined amount (110 µg) of ¹³C₄-perfluorooctanoic acid (¹³C₄-PFOA) was mixed into a sunscreen (30 g) which was applied on the whole skin of a volunteer. The plasma concentrations of ¹³C₄-PFOA were determined in serial blood samples taken over 115 days using UHPLC-MS/MS and ¹³C₂-PFOA as internal standard. After application, ¹³C₄-PFOA plasma levels increased continuously, reaching levels of 3, 56 and 118 ng/L after 6 h, 3 days and 10 days, respectively. A maximum level of 132 ng/L was measured 22 days after application, representing 9.4 % of the PFOA level resulting from the volunteer's background exposure (1400 ng/L, equivalent to 1.4 ng/mL). In the following weeks, the levels slightly decreased with an estimated half-life of 1.8 years. The best estimate for the fraction absorbed may be 1.6 % of the dose, using a volume of distribution of 0.17 L/kg body weight. For PFOA mixed into a sunscreen, this experimental approach demonstrates a significant uptake of a PFAA via transdermal absorption in humans. In the past, some cosmetic products contained relevant PFAA levels as contaminants/impurities of PFAS added as active ingredients. Depending on these levels and the use (frequency, skin area involved), it is plausible that this route of exposure has contributed to the internal exposure to PFAA, as already suggested by epidemiological observations.

Concentrations of perfluoroalkyl and polyfluoroalkyl substances before and after full-scale landfill leachate treatment

Many consumer and industrial products, industrial wastes and dewatered sludge from municipal wastewater treatment plants containing per- and polyfluoroalkyl substances (PFAS) are disposed of in landfills at the end of their usage, with PFAS in these products leached into landfill leachates. On-site leachate treatment is one possible method to reduce PFAS in leachates. Many landfills are equipped with on-site leachate treatment systems, but few full-scale facilities have been systematically evaluated for PFAS concentration changes. The objective of this study was to evaluate a cross-section of full-scale on-site landfill treatment systems to measure changes in PFAS concentrations. Leachate samples were collected before and after treatment from 15 facilities and were evaluated for 26 PFAS, including 11 perfluoroalkyl carboxylic acids (PFCAs), 7 perfluoroalkyl sulfonic acids (PFSAs), and 8 perfluoroalkyl acid precursors (PFAA-precursors). Transformation of precursors was evaluated by the total oxidizable precursor (TOP) assay. Results showed no obvious reductions in total measured PFAS (∑26PFAS) for on-site treatment systems including ponds, aeration tanks, powdered activated carbon (PAC), and sand filtration. Among evaluated on-site treatment systems, only systems fitted with reverse osmosis (RO) showed significant reductions (98-99 %) of ∑26PFAS in the permeate. Results from the TOP assay showed that untargeted PFAA-precursors converted into targeted short-chain PFCAs increasing ∑26PFAS in oxidized samples by 30 %, on average. Overall, results of this study confirm the efficacy of RO systems and suggest the presence of additional precursors beyond those measured in this study.

Targeted and Suspect Screening of Per- and Polyfluoroalkyl Substances in Cosmetics and Personal Care Products

Per- and polyfluoroalkyl substances (PFAS) are anthropogenic chemicals reported in cosmetics and personal care products as ingredients, possible impurities in the raw material manufacturing process, or degradation products. The purpose of this study was to further delineate contributions of these varying PFAS sources to these products. Thirty-eight cosmetics and personal care products were selected and analyzed for polyfluoroalkyl phosphates (PAPs), perfluoroalkyl carboxylic acids (PFCAs), fluorotelomer sulfonic acids (FTSAs), and perfluoroalkyl sulfonic acids (PFSAs) using targeted liquid chromatography tandem mass spectrometry (LC-MS/MS). A subset of products was also subjected to suspect screening using LC-high resolution mass spectrometry (HRMS) for >200 compounds. Results of LC-MS/MS and LC-HRMS indicated a predominant and ubiquitous presence of PAPs (detection frequency 99.7%, mean and median ΣPAPs 1 080 000 and 299 ng/g). Total median PFCA and PFSA concentrations were 3 and 38 times lower, respectively. There were significant correlations (Spearman's correlation coefficients = 0.60-0.81, p < 0.05) between 6:2 PAPs and their biotransformation products. Low levels of other PFAS classes were detected, including those previously measured in wastewater and human blood (e.g., hydrido-PFCAs), and five compounds associated with aqueous film-forming foams. Overall, these data highlight that cosmetics and personal care products can contain a breadth of PFAS at extremely high levels, leading to human and environmental exposure.

Long-distance transport of per- and polyfluoroalkyl substances (PFAS) in a Swedish drinking water aquifer

Use of per- and polyfluoroalkyl substance (PFAS)-containing aqueous film-forming foams (AFFF) at firefighting training sites (FFTS) has been linked to PFAS contamination of drinking water. This study investigated PFAS transport and distribution in an urban groundwater aquifer used for drinking water production that has been affected by PFAS-containing AFFF. Soil, sediment, surface water and drinking water were sampled. In soil (n = 12) at a FFTS with high perfluorooctane sulfonate (PFOS) content (87% of ∑PFAS), the ∑PFAS concentration (n = 26) ranged from below detection limit to 560 ng g^-1 dry weight. In groundwater (n = 28), the ∑PFAS concentration near a military airbase FFTS reached 1000 ng L^-1. Principal component analysis (PCA) identified the military FFTS as the main source of PFAS contamination in drinking water wellfields >10 km down-gradient. Groundwater samples taken close to the military FFTS site showed no ∑PFAS concentration change between 2013 and 2021, while a location further down-gradient showed a transitory 99.6% decrease. Correlation analysis on PFAS composition profile indicated that this decrease was likely caused by dilution from an adjacent conflating aquifer. ∑PFAS concentration reached 15 ng L^-1 (PFOS 47% and PFHxS 41% of ∑PFAS) in surface river water (n = 6) and ranged between 1 ng L^-1 and 8 ng L^-1 (PFHxS 73% and PFBS 17% of ∑PFAS) in drinking water (n = 4). Drinking water had lower PFAS concentrations than the wellfields due to PFAS removal at the water treatment plant. This demonstrates the importance of monitoring PFAS concentrations throughout a groundwater aquifer, to better understand variations in transport from contamination sources and resulting impacts on PFAS concentrations in drinking water extraction areas.

Use of a horizontal ball mill to remediate per- and polyfluoroalkyl substances in soil

There is a need for destructive technologies for per- and polyfluoroalkyl substances (PFAS) in soil. While planetary ball mill have been shown successful degradation of PFAS, there are issues surrounding scale up (maximum size is typically 0.5 L cylinders). While having lower energy outputs, horizontal ball mills, for which scale up is not a limiting factor, already exist at commercial/industrial sizes from the mining, metallurgic and agricultural industries, which could be re-purposed. This study evaluated the effectiveness of horizontal ball mills in degrading perfluorooctanesulfonate (PFOS), 6:2 fluorotelomer sulfonate (6:2 FTSA), and aqueous film forming foam (AFFF) spiked on nepheline syenite sand. Horizontal ball milling was also applied to two different soil types (sand dominant and clay dominant) collected from a firefighting training area (FFTA). Liquid chromatography tandem mass spectrometry was used to track 21 target PFAS throughout the milling process. High-resolution accurate mass spectrometry was also used to identify the presence and degradation of 19 non-target fluorotelomer substances, including 6:2 fluorotelomer sulfonamido betaine (FtSaB), 7:3 fluorotelomer betaine (FtB), and 6:2 fluorotelomer thioether amido sulfonate (FtTAoS). In the presence of potassium hydroxide (KOH), used as a co-milling reagent, PFOS, 6:2 FTSA, and the non-target fluorotelomer substances in the AFFF were found to undergo upwards of 81%, 97%, and 100% degradation, respectively. Despite the inherent added complexity associated with field soils, better PFAS degradation was observed on the FFTA soils over the spiked NSS, and more specifically, on the FFTA clay over the FFTA sand. These results held through scale-up, going from the 1 L to the 25 L cylinders. The results of this study support further scale-up in preparation for on-site pilot tests.

Widespread Occurrence of Non-Extractable Fluorine in Artificial Turfs from Stockholm, Sweden

Per- and polyfluoroalkyl substances (PFAS) are frequently used in the production of rubber and plastic, but little is known about the identity, concentration, or prevalence of PFAS in these products. In this study, a representative sample of plastic- and rubber-containing artificial turf (AT) fields from Stockholm, Sweden, was subjected to total fluorine (TF), extractable organic fluorine (EOF), and target PFAS analysis. TF was observed in all 51 AT samples (ranges of 16-313, 12-310, and 24-661 μg of F/g in backing, filling, and blades, respectively), while EOF and target PFAS occurred in <42% of all samples (<200 and <1 ng of F/g, respectively). A subset of samples extracted with water confirmed the absence of fluoride. Moreover, application of the total oxidizable precursor assay revealed negligible perfluoroalkyl acid (PFAA) formation across all three sample types, indicating that the fluorinated substances in AT are not low-molecular weight PFAA precursors. Collectively, these results point toward polymeric organofluorine (e.g., fluoroelastomer, polytetrafluoroethylene, and polyvinylidene fluoride), consistent with patent literature. The combination of poor extractability and recalcitrance toward advanced oxidation suggests that the fluorine in AT does not pose an imminent risk to users. However, concerns surrounding the production and end of life of AT, as well as the contribution of filling and blades to environmental microplastic contamination, remain.

Elucidating degradation mechanisms for a range of per- and polyfluoroalkyl substances (PFAS) via controlled irradiation studies

Per- and polyfluoroalkyl substances (PFAS) are a challenging class of environmental pollutants due to a lack of available destructive remediation technologies. Understanding the fundamental mechanisms for degradation of PFAS is key for the development of field scalable and in-situ destructive based remediation technologies. This study aimed to elucidate and refine the current understanding of PFAS degradation mechanisms in water through a series of controlled gamma irradiation studies. Gamma irradiation of PFAS was performed using a cobalt-60 source in a batch irradiation up to 80 kGy at the Australian Nuclear Science and Technology Organisation. Perfluorooctanoic acid (PFOA), perfluorooctanesulfonic acid (PFOS), 6:2 fluorotelomer sulfonate (6:2 FTS), and a suite of thirteen different PFAS (including C4-C12 PFCAs, C4, C6, C8 PFSAs, and FOSA) were irradiated to investigate degradation, influence of pH, chain length, and transformation. High resolution mass spectrometry was used to identify more than 80 fluorinated transformation products throughout the degradation experiments. These included the -F/+H, -F/+OH, -F/CH₂OH exchanged PFAS and n - 1 PFCA, amongst others. Given the reactive species present (hydroxyl radicals (·OH), hydrogen radicals (·H) and aqueous electrons (e^-_aq)), and the degradation products formed it was shown that aqueous electrons were the key reactive species responsible for initial PFAS degradation. Most importantly, based on degradation product formation, we found that the initial -F/+H does not have to occur at the α-fluoride (nearest the functional head group), rather occurring throughout the chain length leading to more complex degradation pathways than previously postulated. While our results support some of the reaction steps postulated in the literature, we have developed a unified 16 step and 3 pathway schematic of degradation supported by experimental observations.

Internal Relative Potency Factors for the Risk Assessment of Mixtures of Per- and Polyfluoroalkyl Substances (PFAS) in Human Biomonitoring

BACKGROUND

In human biomonitoring, blood is often used as a matrix to measure exposure to per- and polyfluoroalkyl substances (PFAS). Because the toxicokinetics of a substance (determining the steady-state blood concentration) may affect the toxic potency, the difference in toxicokinetics among PFAS has to be accounted for when blood concentrations are used in mixture risk assessment.

OBJECTIVES

This research focuses on deriving relative potency factors (RPFs) at the blood serum level. These RPFs can be applied to PFAS concentrations in human blood, thereby facilitating mixture risk assessment with primary input from human biomonitoring studies.

METHODS

Toxicokinetic models are generated for 10 PFAS to estimate the internal exposure in the male rat at the blood serum level over time. By applying dose-response modeling, these internal exposures are used to derive quantitative internal RPFs based on liver effects.

RESULTS

Internal RPFs were successfully obtained for nine PFAS. Perfluorobutanoic acid (PFBA), perfluorohexanoic acid (PFHxA), perfluorononanoic acid (PFNA), perfluorododecanoic acid (PFDoDA), perfluorooctane sulfonic acid (PFOS), and hexafluoropropylene oxide-dimer acid (HFPO-DA, or GenX) were found to be more potent than perfluorooctanoic acid (PFOA) at the blood serum level in terms of relative liver weight increase, whereas perfluorobutane sulfonic acid (PFBS) and perfluorohexane sulfonic acid (PFHxS) were found to be less potent. The practical implementation of these internal RPFs is illustrated using the National Health and Nutrition Examination Survey (NHANES) biomonitoring data of 2017-2018.

DISCUSSION

It is recommended to assess the health risk resulting from exposure to PFAS as combined, aggregate exposure to the extent feasible. https://doi.org/10.1289/EHP10009.

Developing innovative treatment technologies for PFAS-containing wastes

The release of persistent per- and polyfluoroalkyl substances (PFAS) into the environment is a major concern for the United States Environmental Protection Agency (U.S. EPA). To complement its ongoing research efforts addressing PFAS contamination, the U.S. EPA's Office of Research and Development (ORD) commissioned the PFAS Innovative Treatment Team (PITT) to provide new perspectives on treatment and disposal of high priority PFAS-containing wastes. During its six-month tenure, the team was charged with identifying and developing promising solutions to destroy PFAS. The PITT examined emerging technologies for PFAS waste treatment and selected four technologies for further investigation. These technologies included mechanochemical treatment, electrochemical oxidation, gasification and pyrolysis, and supercritical water oxidation. This paper highlights these four technologies and discusses their prospects and the development needed before potentially becoming available solutions to address PFAS-contaminated waste.Implications: This paper examines four novel, non-combustion technologies or applications for the treatment of persistent per- and polyfluoroalkyl substances (PFAS) wastes. These technologies are introduced to the reader along with their current state of development and areas for further development. This information will be useful for developers, policy makers, and facility managers that are facing increasing issues with disposal of PFAS wastes.

Exposure of Preconception Couples to Legacy and Emerging Per- and Polyfluoroalkyl Substances: Variations Within and Between Couples

Exploration of the exposure of preconception couples to per- and polyfluoroalkyl substances (PFAS), as well as the most important influencing factors, promotes the understanding of the joint effects of parental exposure on reproductive health. In the present study, a total of 938 preconception couples recruited through the Shanghai Birth Cohort were investigated for the variations of PFAS exposure and contributing factors within and between couples. While linear perfluorooctanoic acid (n-PFOA, median 20.4 ng/mL) and linear perfluorooctanesulfonic acid (n-PFOS, 12.1 ng/mL) remained dominant in plasma, emerging PFAS, particularly 6:2 chlorinated polyfluorinated ether sulfonate (10.5 ng/mL), 6:2 polyfluoroalkyl phosphate diester (0.41 ng/mL), and branched PFOS or PFOA isomers, were also frequently detected. Although individual PFAS were generally correlated within couples, gender differences significantly existed in the concentrations of most individual PFAS and isomer profiles of PFOS and PFOA. Men generally exhibited higher plasma concentrations than their partners, likely reflecting gender-specific elimination pathway and kinetics. Couple-based PFAS exposure also varied greatly. After adjustment for individual factors, several household factors, including annual household income, dwelling floor type, drinking water source, and living near farmlands, were found to be associated with couple-based PFAS exposure. Our study constitutes one of the few studies addressing couple-based exposure to PFAS and lays a solid ground for further assessment of the impacts of parental exposure on reproductive health.