Polyfluorinated Alkyl Substances Research Articles

Life Cycle Fluoropolymer Management in Proton Exchange Membrane Electrolysis

Concerns over the life cycle impacts of fluoropolymers have led to their inclusion in broad product restriction proposals for per- and poly-fluorinated alkyl substances (PFAS), despite their non-bioavailable properties and low exposure potential in complex, durable goods such as non-consumer electrical products. Based on the hypothesis that manufacturers are most able to manage the environmental impacts of their products, practical engineering approaches to implementing life cycle fluoropolymer stewardship are evaluated to bridge the ongoing debate between precautionary and risk-based approaches to PFAS management. A life cycle thinking approach is followed that considers product design and alternatives, as well as the product life cycle stages of material sourcing, manufacturing, field deployment, and end-of-life. Over the product life cycle, the material sourcing and end-of-life stages are most impactful in minimizing potential life cycle PFAS emissions. Sourcing fluoropolymers from suppliers with fluorosurfactant emissions control and replacement minimizes the potential emissions of bio-available PFAS substances. A stack-as-service approach to electrolyzer operations ensures a takeback mechanism for the recycling of end-of-life fluoropolymer materials. Retaining electrolytic hydrogen’s license to operate results in over USD 2 of environmental and health benefits per kilogram of hydrogen produced from reduced greenhouse gas and air pollutant emissions compared to conventional hydrogen production via steam methane reforming.

Tackling toxins: Case studies of industrial pollutants and implications for climate policy

AbstractAs scholars race to address the climate crisis, they have often treated the problem as sui generis and have only rarely sought to learn from prior efforts to make industrial operations greener. In this paper, we consider what can be learned from other shifts away from polluting substances. Drawing on literatures on corporate regulatory strategies and evolving regulatory interactions, we argue for a focus on configurations of regulatory scrutiny and industrial reform, which we then consider through case studies of several major industrial pollutants. We consider the phaseout of ozone‐depleting substances, which has often been cited as a model for mitigating climate change, plus three other cases: per‐ and polyfluorinated alkyl substances (PFAS), leaded fuel, and mercury. We highlight four configurations of regulatory scrutiny and industrial reform: (1) progressive substitution (of ozone‐depleting substances); (2) regrettable substitution (in the first waves of PFAS regulation); (3) knock‐on substitution (in the phaseout of leaded fuel); and (4) narrow substitution (in the case of mercury). These configurations, and the processes that generated them, provide novel lenses for understanding climate mitigation and confronting obstructionism. They point to the diversity of positions that corporate actors may take in the face of potential or actual public regulation, and the possibility of notable divides across and within given industries, which can facilitate meaningful reforms.

Perfluorodecanoic acid induces the increase of innate cells in zebrafish embryos by upregulating oxidative stress levels

Several studies reported that the widespread use of perfluoroalkyl and polyfluoroalkyl substances (PFASs) causes increased environmental pollution, subsequently impacting aquatic organisms. Perfluoroalkyl substances such as perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) reportedly cause cardiotoxicity, neurotoxicity, and developmental toxicity in different organisms. However, whether perfluorodecanoic acid (PFDA), a widely used perfluoroalkyl substance, induces animal embryos developmental toxicity remain unknown. Here, we explored the immunotoxicity and associated mechanisms of PFDA in zebrafish embryos via RNA sequencing, morphological assessment and behavioral alteration detection following exposure to 0.5, 1 and 2 mg/L of PFDA. Interestingly, We found that with the increase of PFDA to drug concentration, including neutrophils and macrophages, significantly increased the number of inherent cells, immune related genes expression. Furthermore, oxidative stress increased in the PFDA-treated embryos in a dose-dependent manner and inhibition of oxidative stress levels effectively rescued the number of neutrophils. Changes in embryonic behavior were observed after exposure to PFDA. Overall, our results suggest that PFDA may induce innate immune response by accumulation of oxidative stress in zebrafish at early developmental stages, and concern is needed about its environmental exposure risks for animals embryos development. Environmental implicationPerfluorinated and polyfluorinated alkyl substances (PFASs) are a class of synthetic organic compounds containing fluorine widely used as lubricants, surfactants, insecticides, etc. The PFDA, a typical perfluorinated compound, is often used as a wetting agent and flame retardant in industries.Several studies showed that PFASs can cause serious environmental pollution, leading to developmental toxicity to various animals, including reproductive toxicity, liver toxicity, heart toxicity, neurotoxicity, and immunotoxicity.However, there are still limited studies on the effects and mechanisms of PFDA on aquatic organisms. Therefore, there is a need to evaluate the ecological risks of PFDA in animals.

Breast cancer risk and prevention in 2024: An overview from the Breast Cancer UK - Breast Cancer Prevention Conference.

The Breast Cancer UK-Breast Cancer Prevention Conference addressed risk from environmental pollutants and health behaviour-related breast-cancer risk. Epidemiological studies examining individual chemicals and breast cancer risk have produced inconclusive results including endocrine disrupting chemicals (EDCs) Bisphenol A, per- and polyfluorinated alkyl substances as well as aluminium. However, laboratory studies have shown that multiple EDCs, can work together to exhibit effects, even when combined at levels that alone are ineffective. The TEXB-α/β assay measures total estrogenic load, and studies have provided evidence of a link between multiple-chemical exposures and breast cancer. However, prospective studies using TEXB-α/β are needed to establish a causative link. There is also a need to assess real-life exposure to environmental-chemical mixtures during pregnancy, and their potential involvement in programming adverse foetal health outcomes in later life. Higher rates of breast cancer have occurred alongside increases in potentially-modifiable risk factors such as obesity. Increasing body-mass index is associated with increased risk of developing postmenopausal breast cancer, but with decreased risk of premenopausal breast cancer. In contrast, lower rates of breast cancer in Asian compared to Western populations have been linked to soya/isoflavone consumption. Risk is decreased by breastfeeding, which is in addition to the decrease in risk observed for each birth and a young first-birth. Risk is lower in those with higher levels of self-reported physical activity. Current evidence suggests breast-cancer survivors should also avoid weight gain, be physically active, and eat a healthy diet for overall health. A broad scientific perspective on breast cancer risk requires focus on both environmental exposure to chemicals and health behaviour-related risk. Research into chemical exposure needs to focus on chemical mixtures and prospective epidemiological studies in order to test the effects on breast cancer risk. Behaviour-related research needs to focus on implementation as well as deeper understanding of the mechanisms of cancer prevention.

Research and Development Practices within PEM Water Electrolyzer Manufacturing to Support a Circular Economy

Nel Hydrogen has in the last decades substantially invested in R&D efforts to consolidate next-generation PEM stacks and systems towards a commercial pathway for these devices at scale. These innovative tasks have allowed the company to reach much lower values for levelized costs of hydrogen (LCOHs) supported by devices that are much more efficient and lower costs; but that still holds robustness and long-life characteristics. However, to truly represent a sustainable pathway, the production lifecycle needs to be considered, especially related to critical materials such as catalysts and polyfluorinated alkyl substances (PFAS) used for instance in the membranes. PFAS are beginning to be regulated globally, with a goal of for responsible manufacturing and hence zero disposal to the environment. Recycling programs for the polymers used in electrolyzers can assist in keeping them exempt from PFAS regulations, due to the minimized environmental impact and lack of related emissions. In addition, PEM electrolyzers use a significant amount of platinum group metals (PGMs), including iridium, one of the scarcest naturally occurring elements. Addressing these issues through recycling and a healthy circular economy of these key components is an important part of large-scale commercialization and deployment.Recent customers have already raised questions about supplier philosophy and documentation of environmental practices. In other words, these large-scale market players are looking for instance to be ISO14001 certified; designed to minimize a company’s negative impact on the environment. While recycling of any chemicals is not specifically required by ISO14001, the standards include lifecycle assessments, integration of environmental aspects into product design, reduction of greenhouse gas emissions, and related topics where recycling would have positive impact on the metrics.At the last 244th ECS meeting in Gothenburg 2023, we have shown how recycling (or PGM thrifting) is ultimately required to meet the IEA projected capacity demands for electrolyzers by 2050, or around 2500 GW globally. Our analysis has demonstrated that above 40% market share can be reached by 2050 for PEM electrolysis, proven that: 1)20% annual Iridium production (ca. 8 tons/year) is allocated for PEM electrolyzer manufacturing; 2) significant PGM thrifting (above 80%) is demonstrated for these devices; 3) life-time and robustness of these new low loading electrodes are maintained; and 4) a circular economy (responsible recycling) is stablished. Repurposing other components such as titanium, stainless steel, and fluoropolymers provides some additional value stream from reclamation as well. For maximum benefit, material collection methods need to be set up within the manufacturing facility, to capture waste materials and scrap, as well as through the field population, so that systems no longer being operated can be reclaimed for materials. This talk will cover some of the business considerations for effective recycling, as well as current practices.

An automated and high-throughput data processing workflow for PFAS identification in biota by direct infusion ultra-high resolution mass spectrometry

The increasing recognition of the health impacts from human exposure to per- and polyfluorinated alkyl substances (PFAS) has surged the need for sophisticated analytical techniques and advanced data analyses, especially for assessing exposure by food of animal origin. Despite the existence of nearly 15,000 PFAS listed in the CompTox chemicals dashboard by the US Environmental Protection Agency, conventional monitoring and suspect screening methods often fall short, covering only a fraction of these substances. This study introduces an innovative automated data processing workflow, named PFlow, for identifying PFAS in environmental samples using direct infusion Fourier transform ion cyclotron resonance mass spectrometry (DI-FT-ICR MS). PFlow’s validation on a bream liver sample, representative of low-concentration biota, involves data pre-processing, annotation of PFAS based on their precursor masses, and verification through isotopologues. Notably, PFlow annotated 17 PFAS absent in the comprehensive targeted approach and tentatively identified an additional 53 compounds, thereby demonstrating its efficiency in enhancing PFAS detection coverage. From an initial dataset of 30,332 distinct m/z values, PFlow thoroughly narrowed down the candidates to 84 potential PFAS compounds, utilizing precise mass measurements and chemical logic criteria, underscoring its potential in advancing our understanding of PFAS prevalence and of human exposure.Graphical abstract

PFAS distribution in cascade derived foam at wastewater treatment plants: The role of non-linear drainage, collapse induced enrichment, and implications for removal

Per- and polyfluorinated alkyl substances (PFAS) enrichment in foam was investigated for the first time at a wastewater treatment plant cascade. A novel sampling device was utilized to allow spatial and temporal heterogeneity in PFAS concentrations and liquid content to be characterized. Concentrations of 8 PFAS compounds were normalized to liquid content and fit to a power law model revealing strong correlation (R2 = 0.91) between drainage induced enrichment and PFAS molar volume. Short chain PFAS such as perfluorobutanoate (PFBA) exhibited minor to no enrichment factors in foam (0.24–5.9) compared to effluent concentrations across the range of foam liquid contents (0.28–6.24 %), while long chain compounds such as perfluorooctane sulfonate (PFOS) became highly enriched with factors of 295–143,000. A conceptual model is proposed to explain higher than expected enrichment of more surface-active PFAS relative to liquid content, which combines continuous partitioning of PFAS to air bubbles during foam formation with additional partitioning during non-linear drainage and foam collapse, both controlled by their affinity for the air-water interface. Scoping calculations suggest the majority of PFOS and other long chain PFAS may be removed if foam is continuously collected with potential to reduce waste volume under economic barriers for current destructive technologies.

Ecological risk of per-and polyfluorinated alkyl substances in the phytoremediation process: a case study for ecologically keystone species across two generations

The potential ecological risk of per- and polyfluorinated alkyl substances (PFASs) in phytoremediation has raised social concerns, promoting a need to better understand their distribution and risks in the recovery process of aquatic plants. Herein, we aim to fill this knowledge gap by investigating the distribution and ecotoxicological effects of PFASs on the structure and function of water-macrophyte-sediment microcosm systems. Among the entire system, 63.0 %–73.1 % PFOA was found in sediments and submerged plants, however, 52.5 %–53.0 % of PFPeA and 47.0 %–47.5 % of PFBS remained in the water under different treatments. PFOA was more bioavailable than the other substances, as demonstrated by the bioaccumulation factors (BAF) with ranges exposed to PFPeA and PFBS. Bioaccumulation PFASs induced plant oxidative stress which generates enzymes to suppress superoxide, and disturbed the processes of lysine biosynthesis, in which allysine, meso-2,6-diaminoheptanedioate, and Nsuccinyl-2-amino-6-ketopimelate were downregulated. PFASs were detected in the propagator (turions) of an ecological restoration species, where short-chain PFASs (70.1 % and 45.7 % for 2 or 20 μg/L PFAS exposure, respectively) were found to spread further into new individuals and profoundly influence ecological processes shaping populations. PFASs significantly enhanced the number of microbial species in the sediment, but the degree of differentiation in the microbial community structure was not significantly different. This study enhances our understanding of the ecological mechanisms of PFASs in the water-macrophyte-sediment systems and potential threats to the recovery process of macrophytes.

Occurrence of 80 per and polyfluorinated alkyl substances (PFAS) in muscle and liver tissues of marine mammals of the St. Lawrence Estuary and Gulf, Quebec, Canada

Occurrence of 80 per and polyfluorinated alkyl substances (PFAS) in muscle and liver tissues of marine mammals of the St. Lawrence Estuary and Gulf, Quebec, Canada

Identification and quantification of per- and polyfluorinated alkyl substances (PFAS) migrating from food contact materials (FCM)

Per- and polyfluorinated alkyl substances (PFAS) can be added to food contact materials (FCM) to increase their water and/or grease repellent properties. Some well-known PFAS are perfluoroalkyl carboxylic acids (PFCA), perfluoroalkyl sulfonic acids (PFSA), and polyfluorinated telomer alcohols (FTOH). Due to the strength of the carbon-fluorine bond, PFAS are chemically very stable and highly resistant to biological degradation, posing a risk to human health and the environment.To examine the presence of PFAS in paper-based FCM, various samples were collected, including popcorn bags, muffin cups, and pizza boxes with high total organic fluorine (TOF) content from the Danish and Spanish markets. The FCM composition was characterised by FTIR. Quantification of some well-known PFAS such as PFCA, PFSA, and FTOH was performed in food simulants using LC-MS/MS, and in addition a non-targeted screening approach was performed by LC-Orbitrap-HRMS.Among analysed samples, the highest concentrations of PFAS were found in a muffin cup made of cellulose (PFCA ∼ 1.41 μg kg−1 food, FTOH ∼ 11.5 μg kg−1 food), and the results were used to estimate dietary exposures to PFAS migrated from this FCM. Compared to measured TOF value in this sample, the fluorine from all quantified PFAS accounted for only 0.6%. Thus, a more powerful analytical approach was used to further investigate PFAS occurrence in this sample. Using non-targeted screening, an additional twenty compounds were identified, among them five with confidence level 1 and ten with confidence level 2. Many of them were either fluorotelomer carboxylic acids or sulfonic acids or ether-containing compounds.

Comparison of transcriptomic profiles between HFPO-DA and prototypical PPARα, PPARγ, and cytotoxic agents in mouse, rat, and pooled human hepatocytes.

Like many per- or polyfluorinated alkyl substances (PFAS), toxicity studies with HFPO-DA (ammonium, 2,3,3,3-tetrafluoro-2-(heptafluoropropoxy)-propanoate), a short-chain PFAS used in the manufacture of some types of fluorinated polymers, indicate that the liver is the primary target of toxicity in rodents following oral exposure. Although the current weight of evidence supports the PPARα mode of action (MOA) for liver effects in HFPO-DA-exposed mice, alternate MOAs have also been hypothesized including PPARγ or cytotoxicity. To further evaluate the MOA for HFPO-DA in rodent liver, transcriptomic analyses were conducted on samples from primary mouse, rat, and pooled human hepatocytes treated for 12, 24, or 72 h with various concentrations of HFPO-DA, or agonists of PPARα (GW7647), PPARγ (rosiglitazone), or cytotoxic agents (ie, acetaminophen or d-galactosamine). Concordance analyses of enriched pathways across chemicals within each species demonstrated the greatest concordance between HFPO-DA and PPARα agonist GW7647-treated hepatocytes compared with the other chemicals evaluated. These findings were supported by benchmark concentration modeling and predicted upstream regulator results. In addition, transcriptomic analyses across species demonstrated a greater transcriptomic response in rodent hepatocytes treated with HFPO-DA or agonists of PPARα or PPARγ, indicating rodent hepatocytes are more sensitive to HFPO-DA or PPARα/γ agonist treatment. These results are consistent with previously published transcriptomic analyses and further support that liver effects in HFPO-DA-exposed rodents are mediated through rodent-specific PPARα signaling mechanisms as part of the MOA for PPARα activator-induced rodent hepatocarcinogenesis. Thus, effects observed in mouse liver are not appropriate endpoints for toxicity value development for HFPO-DA in human health risk assessment.

There's Something in What We Eat: An Overview on the Extraction Techniques and Chromatographic Analysis for PFAS Identification in Agri-Food Products.

Per- and polyfluorinated alkyl substances (PFASs) are a group of anthropogenic chemicals used in a range of industrial processes and consumer products. Recently, their ubiquitous presence in the environment as well as their toxicological effects in humans have gained relevant attention. Although the occurrence of PFASs is widely investigated in scientific community, the standardization of analytical method for all matrices still remains an important issue. In this review, we discussed extraction and detection methods in depth to evaluate the best procedures of PFAS identification in terms of analytical parameters (e.g., limits of detection (LODs), limits of quantification (LOQs), recoveries). Extraction approaches based on liquid-liquid extraction (LLE), alkaline digestion, and solid phase extraction (SPE), followed by liquid chromatography-mass spectrometry (LC-MS) and gas chromatography-mass spectrometry (GC-MS) analysis are the main analytical methods applied in the literature. The results showed detectable recoveries of PFOA and PFOS in meat, milk, vegetables, eggs products (90.6-101.2% and of 89.2-98.4%), and fish (96-108%). Furthermore, the low LOD and LOQ values obtained for meat (0.00592-0.01907 ng g-1; 0.050 ng g-1), milk (0.003-0.009 ng g-1; 0.010-0.027 ng g-1), fruit (0.002-0.009 ng g-1; 0.006-0.024 ng g-1), and fish (0.00369-0.017.33 ng g-1; 0.05 ng g-1) also confirmed the effectiveness of the recent quick, easy, cheap, effective, rugged, and safe method (QuEChERS) for simple, speedy, and sensitive ultra-trace PFAS analysis.

Review of Recent Computational Research on the Adsorption of PFASs with a Variety of Substrates.

The widespread use and impervious nature of per- and polyfluorinated alkyl substances (PFASs) is leading to potentially harmful exposure in numerous environments. One avenue to explore remediation of PFAS-contaminated environments involves investigating how well PFASs adsorb onto various substrates. In the current review, we focus on summarizing recent computational research, largely involving density functional theory (DFT) and molecular dynamics (MD), into the adsorption and interaction of PFASs with a variety of substrates with an aim to provide insight and inspire further research that may lead to solutions to this critical problem that impacts the environment and human health.

Alternatives to Fluoropolymers for Motion-Based Energy Harvesting: Perspectives on Piezoelectricity, Triboelectricity, Ferroelectrets, and Flexoelectricity.

Fluoropolymers, including polytetrafluoroethylene (PTFE, Teflon), polyvinylidene difluoride (PVDF), and fluorine kautschuk materials (FKMs, Viton) are critical polymers for applications ranging from non-stick coatings, corrosion resistant seals, semiconductor manufacturing, membranes, and energy harvesting technologies. However, the synthesis of these fluoropolymers requires the use of per- and polyfluorinated alkyl substances (PFAS) known colloquially as "forever chemicals," and as such there is a pressing need to develop alternative technologies that can serve the end-use of fluoropolymers without the environmental cost of using PFAS. Further, fluoropolymers themselves fall under the PFAS umbrella. Here, alternative mechanical-to-electrical energy harvesting polymers are reviewed and benchmarked against the leading fluoropolymer energy harvesters. These alternative technologies include nonfluoropolymer piezoelectric polymers, triboelectric nanogenerators (TENGs), ferroelectric elastomers, and flexoelectric polymers. A vision towards sustainable, non-fluoropolymer-based energy harvesting is provided.

Environmental impact of PFAS: Filling data gaps using theoretical quantum chemistry and QSPR modeling

Per- and polyfluorinated alkyl substances (PFAS), known for their widespread environmental presence and slow degradation, pose significant concerns. Of the approximately 10,000 known PFAS, only a few have undergone comprehensive testing, resulting in limited experimental data. In this study, we employed a combination of physics-based methods and data-driven models to address gaps in PFAS bioaccumulation potential. Using the COnductor-like Screening MOdel for Realistic Solvents (COSMO-RS) method, we predicted n-octanol/water partition coefficients (logKOW), crucial for PFAS bioaccumulation. Our developed Quantitative Structure-Property Relationship (QSPR) model exhibited high accuracy (R2 = 0.95, RMSEC = 0.75) and strong predictive ability (Q2LOO = 0.93, RMSECV = 0.83). Leveraging the extensive NORMAN, we predicted logKOW for over 4,000 compounds, identifying 244 outliers out of 4519. Further categorizing the database into eight Organisation for Economic Co-operation and Development (OECD) categories, we confirmed fluorine atoms role in enhanced bioaccumulation. Utilizing predicted logKOW, water solubility logSW, and vapor pressure logVP values, we calculated additional physicochemical properties that are responsible for the transport and dispersion of PFAS in the environment. Parameters such as Henry’s Law (kH), air–water partition coefficient (KAW), octanol–air coefficient (KOA), and soil adsorption coefficient (KOC) exhibited favorable correlations with literature data (R2 > 0.66). Our study successfully filled data gaps, contributing to the understanding of ubiquitous PFAS in the environment and estimating missing physicochemical data for these compounds.

Fate and effects of a new generation fluorosurfactant (cC6O4) in freshwater mesocosms

Per- and polyfluorinated alkyl substances (PFAS) have raised international concerns due to their widespread use, environmental persistence and potential bioaccumulative and ecotoxicological effects. Therefore, the chemical industry has been dedicated to develop new generation fluorosurfactants which are aimed to replace the most concerning PFAS. Here we investigated the fate and effects of cyclic C6O4 (cC6O4), a compound used as alternative to long-chain perfluorocarboxylic acids, in freshwater mesocosms located in the Mediterranean region (Spain) over a period of 90 days. cC6O4 was applied as ammonium salt once at the following nominal concentrations: 0 µg/L (control), 1 µg/L, 20 µg/L, 400 µg/L, and 8,000 µg/L. The study shows that cC6O4 is relatively persistent in water (dissipation: 34–37 % after 90 days), has very low sorption capacity to sediments (sediment-water partition coefficient: 0.18–0.32 L/kg) and very limited bioconcentration (BCF: 0.09–0.94), bioaccumulation (BAF: 0.09–4.06) and biomagnification (BMF: 0.05–0.28) potential. cC6O4 did not result in significant adverse effects on aquatic populations and communities of phytoplankton and zooplankton at the tested concentrations. As for the macroinvertebrate community, the ephemeropteran Cloeon sp. showed a population decline at the highest test concentration on day 60 onwards, and a significant effect on the macroinvertebrate community was identified on the last sampling day at the same exposure level. Therefore, the calculated NOEC for cC6O4 in freshwater mesocosms exposed over a period of 90 days was 400 µg/L, which corresponded to a time weighted average concentration of 611 µg/L, given the water evaporation in the test systems. This concentration is about an order of magnitude higher than the highest exposure concentration monitored in freshwater ecosystems. Therefore, it can be concluded that cC6O4 poses insignificant ecological risks for freshwater plankton and macroinvertebrate communities given the current environmental exposure levels.

Influence of Area, Age and Sex on Per- and Polyfluorinated Alkyl Substances Detected in Roe Deer Muscle and Liver from Selected Areas of Northern Italy.

Due to their physicochemical properties, per- and polyfluorinated alkyl substances (PFASs) persist and bioaccumulate in living organisms, causing adverse health effects. Since exposure to xenobiotics is influenced by factors related to both the living organism and the considered compounds, biomonitoring PFASs' presence in the environment is of crucial importance. This study aimed to detect and quantify 15 PFASs in the muscle and liver of 40 roe deer from a specific area in Northern Italy by UPLC-HRMS. In the roe deer, liver PFAS concentrations were higher than those seen in muscle (p < 0.05). Although PFAS content in animals from urbanized areas was higher than those found in deer from rural areas, this difference was not statistically significant. In female roe deer, the concentration was higher than in males (p < 0.05); moreover, older animals showed higher concentrations of PFASs in the liver than younger animals (p < 0.05). In conclusion, the amount of PFASs was higher in tissues from roe deer belonging to urbanized areas, showing that this species might serve as a good bioindicator due to its territorial behavior. PFAS content was significantly higher in female roe deer, although the reason is not fully known. Finally, PFAS concentration was higher in the liver of older animals, probably due to compromised hepatic function.

Aquatic macroinvertebrate community responses to pollution of perfluoroalkyl substances (PFAS): Can we define threshold body burdens?

The pollution of per- and polyfluorinated alkyl substances (PFAS) in aquatic environments is a worldwide concern of which the ecological impact is still not well understood. Especially field-based effect studies in aquatic ecosystems are generally lacking, creating a knowledge gap that goes along with monitoring and regulatory challenges. Therefore, this study examined if bioaccumulated PFAS concentrations could be related to ecological responses assessed by changes in the macroinvertebrate community structure. In addition, threshold body burdens that are protective of ecological damage were estimated. Aquatic macroinvertebrates were sampled in 30 streams across Flanders (Belgium) and 28 PFAS target analytes were measured in three resident taxa (Gammarus sp., Asellus sp. and Chironomus sp.) and translocated zebra mussels (Dreissena polymorpha). The macroinvertebrate community structure was assessed by calculating the Multimetric Macroinvertebrate Index Flanders (MMIF). Primarily long-chain perfluorinated carboxylic acids (PFCAs) were detected in both resident taxa (passive biomonitoring) and zebra mussels (active biomonitoring). Based on a 90th quantile regression model, safe threshold body burdens could be calculated for PFTeDA (7.1 ng/g ww) and ΣPFAS (2264 ng/g ww) in Gammarus sp. and for PFOA (5.5 ng/g ww), PFDoDA (1.7 ng/g ww), PFTrDA (0.51 ng/g ww), PFTeDA (2.4 ng/g ww), PFOS (644 ng/g ww) and ΣPFAS (133 ng/g ww) in zebra mussel. An additional threshold value was calculated for most compounds and species using the 95th percentile method. However, although these estimated thresholds are pertinent and indicative, regulatory applicability requires further lines of evidence and validation. Nevertheless, this study offers first-time evidence of associations between accumulated PFAS concentrations in invertebrates and a reduced ecological water quality in terms of macroinvertebrate community structure and highlights the potential of Gammarus sp. and zebra mussels to serve as reliable PFAS biomonitoring species.

Determination of Perfluorinated and Polyfluorinated Alkyl Substances (PFASs) in PM10 Samples: Analytical Method, Seasonal Trends, and Implications for Urban Air Quality in the City of Terni (Central Italy)

A quantitative analytical method for PFAS determination in airborne particulate matter (PM) has been developed using liquid chromatography coupled with high-resolution mass spectrometry (LC-HRMS), allowing for the determination of 33 compounds. The procedure was applied to ambient PM10 with limits of quantification for PFAS in the fg m−3 range. PM10 samples collected during a year-long campaign conducted in an urban site in Umbria (Central Italy) have been characterized for their PFAS content. Among the seven detected PFASs, perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) were the most abundant compounds. Furthermore, this work allowed us to obtain the first seasonal trend of airborne PFASs in Central Italy. Seasonal trend analysis shows that PFAS concentration in the atmosphere peaks in summertime. A comparison with trends of other relevant primary and secondary air pollutants determined at the sampling site suggests a secondary nature of the observed PFAS, which are formed in the atmosphere directly from gaseous precursors and can contribute to worsen the urban air quality in summertime.

In vitro evaluation of the carcinogenic potential of perfluorinated chemicals.

Perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) are the major components of long-chain per- and polyfluorinated alkyl substances (PFAS), known for their chemical stability and environmental persistence. Even if PFOA and PFOS have been phased out or are limited in use, they still represent a concern for human and environmental health. Several studies have been per­formed to highlight the toxicological behavior of these chemicals and their mode of action (MoA). Data have suggested a causal association between PFOA or PFOS exposure and carcinogenicity in humans, but the outcomes of epidemiological studies showed some inconsistency. Moreover, the hypothesized MoA based on animal studies is considered not relevant for human cancer. To improve the knowledge on PFAS toxicology and contribute to the weight of evidence for the regu­latory classification of PFAS, we used the BALB/c 3T3 cell transformation assay (CTA), an in vitro model under consideration to be included in an integrated approach to testing and assessment for non-genotoxic carcinogens (NGTxCs). PFOS and PFOA were tested at several concentrations using a validated experimental protocol. Our results demonstrate that PFOA does not induce cell transformation, whereas PFOS exposure induced a concentration-related increase of type III foci. Malignant foci formation was triggered at PFOS concentrations equal to or higher than 50 ppm and was not directly associated with cytotoxicity or proliferation induction. The divergent CTA outcomes suggest that different molecular events could be responsible for the toxicological profiles of PFOS and PFOA, which were not fully captured in our study.