Multiple pathways of human exposure to poly- and perfluoroalkyl substances (PFASs): From external exposure to human blood

Per- and polyfluoroalkyl substances alter innate immune function: evidence and data gaps

Per- and polyfluoroalkyl substances (PFASs) are a large class of compounds used in a variety of processes and consumer products. Their unique chemical properties make them ubiquitous and persistent environmental contaminants while also making them economically viable and socially convenient. To date, several reviews have been published to synthesize information regarding the immunotoxic effects of PFASs on the adaptive immune system. However, these reviews often do not include data on the impact of these compounds on innate immunity. Here, current literature is reviewed to identify and incorporate data regarding the effects of PFASs on innate immunity in humans, experimental models, and wildlife. Known mechanisms by which PFASs modulate innate immune function are also reviewed, including disruption of cell signaling, metabolism, and tissue-level effects. For PFASs where innate immune data are available, results are equivocal, raising additional questions about common mechanisms or pathways of toxicity, but highlighting that the innate immune system within several species can be perturbed by exposure to PFASs. Recommendations are provided for future research to inform hazard identification, risk assessment, and risk management practices for PFASs to protect the immune systems of exposed organisms as well as environmental health.

Systemic and immunotoxicity induced by topical application of perfluoroheptane sulfonic acid (PFHpS) or perfluorooctane sulfonic acid (PFOS) in a murine model

Per- and polyfluoroalkyl substances (PFAS) are a large group of synthetic surfactants of over 12,000 compounds that are incorporated into numerous products for their chemical and physical properties. Studies have associated PFAS with adverse health effects. Although there is a high potential for dermal exposure, these studies are lacking. The present study evaluated the systemic and immunotoxicity of subchronic 28- or 10-days of dermal exposure, respectively, to PFHpS (0.3125-2.5% or 7.82-62.5 mg/kg/dose) or PFOS (0.5% or 12.5 mg/kg/dose) in a murine model. Elevated levels of PFHpS were detected in the serum and urine, suggesting that absorption is occurring through the dermal route. PFHpS induced significantly increased relative liver weight, significantly decreased relative spleen and thymus weight, altered serum chemistries, and altered histopathology. Additionally, PFHpS significantly reduced the humoral immune response and altered immune subsets in the spleen, suggesting immunosuppression. Gene expression changes were observed in the liver, skin, and spleen of genes involved in fatty acid metabolism, necrosis, and inflammation. Immune-cell phenotyping identified significant decreases in B-cells and CD11b+ monocyte and/or macrophages in the spleen along with decreases in eosinophils and dendritic cells in the skin. These findings support PFHpS absorption through the skin leading to liver damage and immune suppression.

Infants exposure to chemicals in diapers: A review and perspective

Diapers are a staple care product for infants, yet concerns persist regarding the potential risks posed by dermal exposure to chemicals through their usage. This review provides a comprehensive summary of reported chemicals, highlighting the frequent detection of polychlorodibenzo-p-dioxins (PCDDs), phthalates (PAEs), volatile organic compounds (VOCs), polycyclic aromatic hydrocarbons (PAHs), bisphenols (BPs), organotins, and heavy metals. Disposable diapers commonly exhibit higher concentrations of VOCs, PAEs, BPs, and heavy metals than other chemicals. Our estimation reveals formaldehyde as posing the highest dermal exposure dose, reaching up to 0.018 mg/kg bw/day. Conversely, perfluorooctanoic acid (PFOA) exhibits lower exposure, but its non-cancer hazard quotient (0.062) is the highest. In most scenarios, the risk of chemical exposure through diapers for infants is deemed acceptable, while the risk is higher under some extreme exposure scenarios. Using the cancer slope factor recently suggested by U.S. EPA, the cancer risk in diapers raised by PFOA is 5.5 × 10-5. It should be noted that our estimation is approximately 1000-10,000 folds lower than some previous estimations. The high uncertainties associated with exposure and risk estimations are primarily raised by unclear parameters related to chemical migration coefficients, absorption factors, concentrations, and toxicity data for skin exposure, which requires research attention in future. Besides that, future research endeavors should prioritize the identification of potential toxic chemicals and the development of hygiene guidelines and standards.

Differential uptake and translocation of perfluoroalkyl substances by vegetable roots and leaves: Insight into critical influencing factors

Crop contamination of perfluoroalkyl substances (PFASs) may threaten human health, with root and leaves representing the primary uptake pathways of PFASs in crops. Therefore, it is imperative to elucidate the uptake characteristics of PFASs by crop roots and leaves as well as the critical influencing factors. In this study, the uptake and translocation of PFASs by roots and leaves of pak choi and radish were systematically explored based on perfluorobutanoic acid (PFBA), perfluorohexanoic acid (PFHxA), perfluorooctanoic acid (PFOA), and perfluorooctane sulfonate (PFOS). Additionally, the roles of root Casparian strips, leaf stomata, and PFAS structures in the aforementioned processes were elucidated. Compared with pak choi, PFASs are more easily transferred to leaves after root uptake in radish, resulting from the lack of root Casparian strips. In pak choi root, the bioaccumulation of C4-C8 perfluoroalkyl carboxylic acids (PFCAs) showed a U-shaped trend with the increase of their carbon chain lengths, and the translocation potentials of individual PFASs from root to leaves negatively correlated with their chain lengths. The leaf uptake of PFOA in pak choi and radish mainly depended on cuticle sorption, with the evidence of a slight decrease in the concentrations of PFOA in exposed leaves after stomatal closure induced by abscisic acid. The leaf bioaccumulation of C4-C8 PFCAs in pak choi exhibited an inverted U-shaped trend as their carbon chain lengths increased. PFASs in exposed leaves can be translocated to the root and then re-transferred to unexposed leaves in vegetables. The longer-chain PFASs showed higher translocation potentials from exposed leaves to root. PFOS demonstrated a higher bioaccumulation than PFOA in crop roots and leaves, mainly due to the greater hydrophobicity of PFOS. Planting root vegetables lacking Casparian strips is inadvisable in PFAS-contaminated environments, in view of their higher PFAS bioaccumulation and considerable human intake.

An in-depth examination of Per- and Polyfluoroalkyl (PFAS) effects on transporters, with emphasis on the ABC superfamily: A critical review

Per- and polyfluoroalkyl (PFAS) substances are a type of chemical compound unique for their multiple carbon-fluorine bonds, imbuing them with strength and environmental permanence. While legacy substances have been phased out due to human health risks, short-chain and alternative PFAS remain omnipresent. However, a detailed explanation for the pathways through which PFAS interact on a cellular and molecular level is still largely unknown, and the human health effects remain mechanistically unexplained. Of particular interest when focusing on this topic are the interactions between these exogenous chemicals and plasma and membrane proteins. Such proteins include serum albumin which can transport PFAS throughout the body, solute carrier proteins (SLC) and ATP binding cassette (ABC) transporters which are able to move PFAS into and out of cells, and proteins and nuclear receptors which interact with PFAS intracellularly. ABC transporters as a family have little available human data despite being responsible for the export of endogenous substances and drugs throughout the body. The multifactorial regulation of these crucial transporters is affected directly and indirectly by PFAS. Changes, which can include alterations to membrane transport activity and differences in protein expression, vary greatly depending on the specific PFAS and protein of interest. Together, the myriad of changes caused by understudied PFAS exposure to a class of understudied proteins crucial to cellular function and drug treatments has not been fully explored regarding human health and presents room for further exploration. This critical work aims to provide a novel framework of existing human data on PFAS and ABC transporters, allowing for future advancement and investigation into human transporter activity, mechanisms of regulation, and interactions with emerging contaminants.

Partitioning of Neutral PFAS in Homes and Release to the Outdoor Environment: Results from the IPA Campaign

The distribution and fate of per- and polyfluoroalkyl substances (PFAS) in homes are not well understood. To address this, we measured nine neutral PFAS in dust, airborne particles, dryer lint, and on heating and air conditioning (HAC) filters in 11 homes in North Carolina as part of the Indoor PFAS Assessment (IPA) Campaign and compared them with concurrently collected gas and cloth measurements. Fluorotelomer alcohols (FTOHs) contributed most (≥75%) to total (∑) measured neutral PFAS concentrations in dust, HAC filter, and dryer lint samples, with mean ∑(FTOH) concentrations of 207 ng/g, 549 ng/g, and 84 ng/g, respectively. In particles, perfluorooctane sulfonamidoethanols (FOSEs) dominated, with a mean ∑(FOSE) concentration of 0.28 ng/m3 or 75,467 ng/g. For FTOHs and FOSEs, resulting mean dust-air, HAC filter-air, dryer lint-air and particle-air partition coefficients in units of log(m3/μg) ranged (across species) from -5.1 to -3.6, -4.9 to -3.5, -5.4 to -4.1, and -3.2 to -0.78, respectively. We estimate that cloth, gas phase, and HAC filters are the largest reservoirs for FTOHs, while cloth, HAC filters, and dust are the largest reservoirs for FOSEs. Release rates of neutral PFAS from homes to the outdoor environment are reported.

Effects of per- and polyfluoroalkyl substances on the liver: Human-relevant mechanisms of toxicity

Per- and polyfluoroalkyl substances (PFAS) are abundantly used in a plethora of products with applications in daily life. As a result, PFAS are widely distributed in the environment, thus providing a source of exposure to humans. The majority of human exposure to PFAS is attributed to the human diet, which encompasses drinking water. Their chemical nature grants persistent, accumulative and toxic properties, which are currently raising concerns. Over the past few years, adverse effects of PFAS on different organs have been repeatedly documented. Numerous epidemiological studies established a clear link between PFAS exposure and liver toxicity. Likewise, effects of PFAS on liver homeostasis, lipid metabolism, bile acid metabolism and hepatocarcinogenesis have been reported in various in vitro and in vivo studies. This review discusses the role of PFAS in liver toxicity with special attention paid to human relevance as well as to the mechanisms underlying the hepatotoxic effects of PFAS. Future perspectives and remaining knowledge gaps were identified to enhance future PFAS risk assessment.

Cross-cutting studies of per- and polyfluorinated alkyl substances (PFAS) in Arctic wildlife and humans

This cross-cutting review focuses on the presence and impacts of per- and polyfluoroalkyl substances (PFAS) in the Arctic. Several PFAS undergo long-range transport via atmospheric (volatile polyfluorinated compounds) and oceanic pathways (perfluorinated alkyl acids, PFAAs), causing widespread contamination of the Arctic. Beyond targeting a few well-known PFAS, applying sum parameters, suspect and non-targeted screening are promising approaches to elucidate predominant sources, transport, and pathways of PFAS in the Arctic environment, wildlife, and humans, and establish their time-trends. Across wildlife species, concentrations were dominated by perfluorooctane sulfonic acid (PFOS), followed by perfluorononanoic acid (PFNA); highest concentrations were present in mammalian livers and bird eggs. Time trends were similar for East Greenland ringed seals (Pusa hispida) and polar bears (Ursus maritimus). In polar bears, PFOS concentrations increased from the 1980s to 2006, with a secondary peak in 2014-2021, while PFNA increased regularly in the Canadian and Greenlandic ringed seals and polar bear livers. Human time trends vary regionally (though lacking for the Russian Arctic), and to the extent local Arctic human populations rely on traditional wildlife diets, such as marine mammals. Arctic human cohort studies implied that several PFAAs are immunotoxic, carcinogenic or contribute to carcinogenicity, and affect the reproductive, endocrine and cardiometabolic systems. Physiological, endocrine, and reproductive effects linked to PFAS exposure were largely similar among humans, polar bears, and Arctic seabirds. For most polar bear subpopulations across the Arctic, modeled serum concentrations exceeded PFOS levels in human populations, several of which already exceeded the established immunotoxic thresholds for the most severe risk category. Data is typically limited to the western Arctic region and populations. Monitoring of legacy and novel PFAS across the entire Arctic region, combined with proactive community engagement and international restrictions on PFAS production remain critical to mitigate PFAS exposure and its health impacts in the Arctic.

Exposure to Per- and Polyfluoroalkyl Substances and Timing of Puberty in Norwegian Boys: Data from the Bergen Growth Study 2

Per- and polyfluoroalkyl substances (PFAS) are widespread environmental contaminants with endocrine-disruptive properties. Their impact on puberty in boys is unclear. In this cross-sectional study, we investigated the association between PFAS exposure and pubertal timing in 300 Norwegian boys (9-16 years), enrolled in the Bergen Growth Study 2 during 2016. We measured 19 PFAS in serum samples and used objective pubertal markers, including ultrasound-measured testicular volume (USTV), Tanner staging of pubic hair development, and serum levels of testosterone, luteinizing hormone, and follicle-stimulating hormone. In addition to logistic regression of single pollutants and the sum of PFAS, Bayesian and elastic net regression were used to estimate the contribution of the individual PFAS. Higher levels of the sum of perfluorooctanesulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), and perfluorohexanesulfonic acid (PFHxS) were associated with later pubertal onset according to USTV (age-adjusted odds ratio (AOR): 2.20, 95% confidence interval (CI): 1.29, 3.93) and testosterone level (AOR: 2.35, 95% CI: 1.34, 4.36). Bayesian modeling showed that higher levels of PFNA and PFHxS were associated with later pubertal onset by USTV, while higher levels of PFNA and perfluoroundecanoic acid (PFUnDA) were associated with later pubertal onset by testosterone level. Our findings indicate that certain PFAS were associated with delay in male pubertal onset.

Sex-specific associations of per- and polyfluoroalkyl substances with brain-derived neurotrophic factors (BDNF) in cord serum

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) is perceived as an emerging environmental endocrine disruptor, which have been linked to children neurodevelopment. However, the potential mechanisms are not clear. Brain-derived neurotrophic factor (BDNF) is a vital protein in neurodevelopment, and the associations between PFAS exposure and BDNF require exploration.

OBJECTIVE

We aimed to explore the relationships between PFAS exposure and the levels of BDNF in cord serum.

METHODS

A total of 1,189 mother-infant dyads from the Sheyang Mini Birth Cohort Study (SMBCS) were enrolled. The levels of 12 PFAS and BDNF were measured in cord serum. We utilized generalized linear models (GLMs), quantile-based g-computation (QGC) models, and Bayesian Kernel Machine Regression (BKMR) models to explore the relationships between single and mixed PFAS exposure and BDNF concentration. Additionally, the potential sex differences were explored by sex-stratified analysis.

RESULTS

Median concentrations of the included 10 PFAS ranged from 0.04 to 3.97 μg/L. In the single chemical models, four PFAS congeners, namely perfluorononanoic acid (PFNA), perfluorooctane sulfonic acid (PFOS), perfluorodecanoic acid (PFDA), perfluoroundecanoic acid (PFUnDA), were negatively associated with BDNF levels in cord serum among females only (β: -0.116 to -0.062, p < 0.05). In the BKMR models of total mother-infant dyads and female fetuses, the significant negative relationships between PFAS mixtures and BDNF were observed, and PFUnDA was identified as an important contributor (Posterior inclusion probability, PIP = 0.8584 for the total subjects; PIP = 0.8488 for the females). PFOS was another important driver based on the mixture approaches.

CONCLUSIONS

We found that PFNA, PFOS, PFDA, and PFUnDA were associated with decreased BDNF concentration in the females, although the causal inference might be limited. PFAS mixtures were also negatively linked with BDNF levels in the total mother-infant pairs and female fetuses. The adverse effect of PFAS exposure on fetal BDNF levels might be sex-specific.

Perinatal Exposure to Phenols and Poly- and Perfluoroalkyl Substances and Gut Microbiota in One-Year-Old Children

The role of the gut microbiota in human health calls for a better understanding of its determinants. In particular, the possible effects of chemicals with widespread exposure other than pharmaceuticals are little known. Our aim was to characterize the sensitivity of the early-life gut microbiota to specific chemicals with possible antimicrobial action. Within the SEPAGES French couple-child cohort, we assessed 12 phenols in repeated urine samples from 356 pregnant women and their offspring and 19 poly- and perfluoroalkyl substances (PFASs) in serum from the pregnant women. We collected stool samples from the children at one year of age, in which the V3-V4 region of the 16S rRNA gene was sequenced, allowing for gut bacterial profiling. Associations of each chemical with α- and β-diversity indices of the gut microbiota and with the relative abundance of the most abundant taxa were assessed using single-pollutant and mixture (BKMR) models. Perinatal exposure to certain parabens was associated with gut microbiota α- and β-diversity and with Firmicutes and Proteobacteria. Suggestive associations of certain phenols with genera of the Lachnospiraceae and Enterobacteriaceae families were observed, but these were not maintained after correction for multiple testing. Parabens, which have known antimicrobial properties, might disrupt the child gut microbiota, but larger studies are required to confirm these findings.

Early-life exposure to per- and polyfluoroalkyl substances: Analysis of levels, health risk and binding abilities to transport proteins

Per- and polyfluoroalkyl substances (PFAS) can pass through the placenta and adversely affect fetal development. However, there is a lack of comparison of legacy and emerging PFAS levels among different biosamples in pregnant women and their offspring. This study, based on the Shanghai Maternal-Child Pairs Cohort, analyzed the concentrations of 16 PFAS in the maternal serum, cord serum, and breast milk samples from 1,076 mother-child pairs. The placental and breastfeeding transfer efficiencies of PFAS were determined in maternal-cord and maternal-milk pairs, respectively. The binding affinities of PFAS to five transporters were simulated using molecular docking. The results suggested that PFAS were frequently detected in different biosamples. The median concentration of perfluorooctane sulfonate (PFOS) was the highest at 8.85 ng/mL, followed by perfluorooctanoic acid (PFOA) at 7.13 ng/mL and 6:2 chlorinated polyfluorinated ether sulfonate at 5.59 ng/mL in maternal serum. The median concentrations of PFOA were highest in cord serum (4.23 ng/mL) and breast milk (1.08 ng/mL). PFAS demonstrated higher placental than breastfeeding transfer efficiencies. The transfer efficiencies and the binding affinities of most PFAS to proteins exhibited alkyl chain length-dependent patterns. Furthermore, we comprehensively assessed the estimated daily intakes (EDIs) of PFAS in breastfeeding infants of different age groups and used the hazard quotient (HQ) to characterize the potential health risk. EDIs decreased with infant age, and PFOS had higher HQs than PFOA. These findings highlight the significance of considering PFAS exposure, transfer mechanism, and health risks resulting from breast milk intake in early life.

Occurrence and health risk assessment of PFAS and possible precursors: a case study in a drinking water treatment plant and bottled water (south Catalonia, Spain)

The presence of PFAS in drinking water may pose a serious threat to human health. This study aims to determine the levels of these compounds and their precursors in water samples from a drinking water treatment plant (DWTP) located in l'Ampolla (Spain) and to assess their fate. Additionally, ten Spanish bottled waters were analyzed to compare the occurrence of PFAS in the mentioned matrices and in drinking water. Off-line solid phase extraction (SPE) followed by liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was applied to determine 26 PFAS and PFAS precursors after a total oxidizable precursor assay. The analytical method presents low quantification limits (0.25-5 ng/L). A total PFAS concentration of up to 16 ng/L in all the DWTP samples was obtained, and 6:2 FTS was the only precursor detected. Results are close to the quantification limits, resulting in a high degree of uncertainty, and for this, it is difficult to evaluate the DWTP PFAS removal efficiency. Regarding bottled water, total PFAS concentration found was up to 12 ng/L in one of ten samples, with no precursors detected. Exposure assessment revealed that there is no risk associated with the ingestion of the samples analyzed. Moreover, there were no differences in terms of risk between drinking water from l'Ampolla DWTP and bottled water.

Transport of perfluoroalkyl substances across human induced pluripotent stem cell-derived intestinal epithelial cells in comparison with primary human intestinal epithelial cells and Caco-2 cells

Humans can be exposed to per- and polyfluoroalkyl substances (PFASs) via many exposure routes, including diet, which may lead to several adverse health effects. So far, little is known about PFAS transport across the human intestinal barrier. In the current study, we aimed to assess the transport of 5 PFASs (PFOS, PFOA, PFNA, PFHxS and HFPO-DA) in a human induced pluripotent stem cell (hiPSC)-derived intestinal epithelial cell (IEC) model. This model was extensively characterized and compared with the widely applied human colonic adenocarcinoma cell line Caco-2 and a human primary IEC-based model, described to most closely resemble in vivo tissue. The hiPSC-derived IEC layers demonstrated polarized monolayers with tight junctions and a mucus layer. The monolayers consisted of enterocytes, stem cells, goblet cells, enteroendocrine cells, and Paneth cells that are also present in native tissue. Transcriptomics analysis revealed distinct differences in gene expression profiles, where the hiPSC-derived IECs showed the highest expression of intestinal tissue-specific genes relative to the primary IEC-based model and the Caco-2 cells clustered closer to the primary IEC-based model than the hiPSC-derived IECs. The order of PFAS transport was largely similar between the models and the apparent permeability (Papp) values of PFAS in apical to basolateral direction in the hiPSC-derived IEC model were in the following order: PFHxS > PFOA > HFPO-DA > PFNA > PFOS. In conclusion, the hiPSC-derived IEC model highly resembles human intestinal physiology and is therefore a promising novel in vitro model to study transport of chemicals across the intestinal barrier for risk assessment of chemicals.

Concentrations of per- and polyfluoroalkyl substances in vegetables from Sydney and Newcastle, Australia

BACKGROUND

This study investigated per- and polyfluoroalkyl substances (PFASs) in 53 fruit and vegetable samples collected from a local wholesale and retail market in Sydney and a local supermarket in Newcastle. As there is limited information about PFAS levels in vegetables on the market, this study aimed to fill this gap and assess potential risks for humans through consumption of these vegetables.

METHODS

QuEChERS extraction - a solid-phase extraction method, a portmanteau word formed from 'quick, easy, cheap, effective, rugged and safe' - followed by enhanced matrix removal-lipid cleaning and liquid chromatography-tandem mass spectrometry analysis were used to detect 30 PFASs in vegetables.

RESULTS

PFOA was detected in 7 out of the 53 samples, with concentrations of 0.038-1.996 ng g-1 fresh weight; PFOS was detected in 2 samples only, with concentrations ranging from 0.132 to 0.911 ng g-1 fresh weight. PFHxS was not detected in any sample in this study. PFOA and PFOS concentrations measured in vegetables in this study constituted daily intake of 2.03 ng kg-1 body weight (BW) and 1.98 ng kg-1 BW, respectively, according to recommended daily vegetable intake and BW data from the Australian Bureau of Statistics. The most sensitive population group is girls of 4-8 years of age. These estimated exposure levels represent up to 1.3% of the tolerable daily intake for PFOA (160 ng kg-1 BW) and 9.9% for PFOS (20 ng kg-1 BW) according to Food Standards Australia New Zealand. Consumption of the vegetables from the study locations poses a marginal risk to human health. © 2024 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Development and validation of the UHPLC-MS/MS method for the quantitative determination of 25 PFAS in dried blood spots

Per- and polyfluoroalkyl substances (PFAS) are anthropogenic fluorine-containing compounds largely used in industrial and consumer applications. They tend to bioaccumulate in the human body after intake from various sources in daily life. Following repeated exposure to PFAS, a broad range of adverse health outcomes has been reported. Consequently, monitoring PFAS levels in human blood is of paramount importance for public health policies. In contrast with traditional venipuncture, dried blood spots (DBS) constitute a reliable, cheap, and less invasive technique to allow microsampling by capillary blood collected on a specific device. This work aimed to develop and validate an innovative analytical method, combining quantitative DBS with UHPLC-MS/MS instrumentation to identify and quantify 25 PFAS. The extraction procedure was developed and optimized within the range 2-100 ng/mL. Specifically, fortified blood was applied on Capitainer®B devices providing 10 μL of blood volume through a microfluidic channel. After 3 h of drying, the extraction was performed by methanol under sonication, followed by centrifugation. Then, the extraction solvent was evaporated; the residue was reconstituted with the mobile phase solution. The validated method evidenced good sensitivity, with limits of detection ranging from 0.4 ng/mL (PFODA, PFOS) to 1.0 ng/mL (PFOA, 3,6-OPFHpA). The ± 20% acceptability criteria established for intra- and inter-day precision and accuracy were fulfilled for all analytes. High recovery-above 80%-was recorded, whereas significant matrix effect resulted in ion enhancement (> 50%) for 13 analytes. In conclusion, the proposed workflow proved to be reliable, fit for purpose, and easily adaptable in the laboratory routine.

Chemical mixture effects on the simplified human intestinal microbiota: Assessing xenobiotics at environmentally realistic concentrations

The microbial community present in our intestines is pivotal for converting indigestible substances into vital nutrients and signaling molecules such as short-chain fatty acids (SCFAs). These compounds have considerable influence over our immune system and the development of diverse human diseases. However, ingested environmental contaminants, known as xenobiotics, can upset the delicate balance of the microbial gut community and enzymatic processes, consequently affecting the host organism. In our study, we employed an in vitro bioreactor model system based on the simplified human microbiome model (SIHUMIx) to investigate the direct effects of specific xenobiotics, such as perfluorooctanoic acid (PFOA), perfluorohexanoic acid (PFHxA) and perfluorobutanoic acid (PFBA) or bisphenol S (BPS) and bisphenol F (BPF), either individually or in combination, on the microbiota. We observed increased SCFA production, particularly acetate and butyrate, with PFAS exposure. Metaproteomics revealed pathway alterations across treatments, including changes in vitamin synthesis and fatty acid metabolism with BPX. This study underscores the necessity of assessing the combined effects of xenobiotics to better safeguard public health. It emphasizes the significance of considering adverse effects on the microbiome in the risk assessment of environmental chemicals.

Machine learning predicts the serum PFOA and PFOS levels in pregnant women: Enhancement of fatty acid status on model performance

Human exposure to per- and polyfluoroalkyl substances (PFASs) has received considerable attention, particularly in pregnant women because of their dramatic changes in physiological status and dietary patterns. Predicting internal PFAS exposure in pregnant women, based on external and relevant parameters, has not been investigated. Here, machine learning (ML) models were developed to predict the serum concentrations of PFOA and PFOS in a large population of 588 pregnant participants. Dietary exposure characteristics, demographic parameters, and in particular, serum fatty acid (FA) data were used for the model development. The fitting results showed that the inclusion of FAs as covariates significantly improved the performance of the ML models, with the random forest (RF) model having the best predictive performance for PFOA (R2 = 0.33, MAE = 1.51 ng/mL, and RMSE = 1.89 ng/mL) and PFOS (R2 = 0.12, MAE = 2.65 ng/mL, and RMSE = 3.37 ng/mL). The feature importance analysis revealed that serum FAs greatly affected PFOA concentration in the pregnant women, with saturated FAs being associated with decreased PFOA levels and unsaturated FAs with increased levels. Comparison with one-compartment pharmacokinetic model further demonstrated the advantage of the ML models in predicting PFAS exposure in pregnant women. Our models correlate for the first time blood chemical concentrations with human FA status using ML, introducing a novel perspective on predicting PFAS levels in pregnant women. This study provides valuable insights concerning internal exposure of PFASs generated from external exposure, and contributes to risk assessment and management in pregnant populations.

Impacts of PFOS, PFOA and their alternatives on the gut, intestinal barriers and gut-organ axis

With the restricted use of perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA), a number of alternatives to PFOS and PFOA have attracted great interest. Most of the alternatives are still characterized by persistence, bioaccumulation, and a variety of toxicity. Due to the production and use of these substances, they can be detected in the atmosphere, soil and water body. They affect human health through several exposure pathways and especially enter the gut by drinking water and eating food, which results in gut toxicity. In this review, we summarized the effects of PFOS, PFOA and 9 alternatives on pathological changes in the gut, the disruption of physical, chemical, biological and immune barriers of the intestine, and the gut-organ axis. This review provides a valuable understanding of the gut toxicity of PFOS, PFOA and their alternatives as well as the human health risks of emerging contaminants.

Gene expression patterns associated with PFOA exposure in Czech young men and women

Perfluorooctanoic acid (PFOA), a member of per- and polyfluoroalkyl substances (PFASs), has been widely used in manufacturing for decades. Currently, PFOA is strictly regulated, but due to its high stability and persistence, it is detected in both environmental as well as in human matrices. To elucidate mechanisms of PFOA toxicity in humans, we determined the genome-wide transcriptomic changes of peripheral blood mononuclear cells (PBMC) responding to PFOA exposure in a sex-stratified analysis. This work employed samples from 145 female and 143 male participants of the CELSPAC: YA study to characterize PFOA-associated transcripts in a broader context using computational analysis. PFOA-associated gene expression differed significantly between men and women, as only 2 % of mapped genes were expressed in both sexes. Disease-specific enrichment analysis revealed cancer and immune-related disease terms as those most enriched in male and female populations. Patterns of enriched terms within the gene set enrichment analysis indicated three main targets of PFOA toxicity: i) lipid metabolism for women; ii) cell cycle regulation for men; and iii) immune system response for both sexes. In summary, our genome-wide transcriptomics analysis described sex-specific differences in PFOA-associated gene expression and provided evidence about biological pathways underlying PFOA toxicity in humans.

Limitations of wastewater treatment plants in removing trace anthropogenic biomarkers and future directions: A review

This review highlights the limitations faced by conventional wastewater treatment plants (WWTPs) in effectively removing contaminants of emerging concern (CECs), heavy metals (HMs), and Escherichia coli (E. coli). This emphasises the limitations of current treatment methods and advocates for innovative approaches to enhance the removal efficiency. By following the PRISMA guidelines, the study systematically reviewed relevant literature on detecting and remedying these pollutants in wastewater treatment facilities. Conventional wastewater treatment plants struggle to eliminate CECs, HMs, and E. coli owing to their small size, persistence, and complex nature. The review suggests upgrading WWTPs with advanced tertiary processes to significantly improve contaminant removal. This calls for cost-effective treatment parameters and standardised assessment techniques to enhance the fate of MPs in WWTPs and WRRFs. It recommends integrating insights from mass-balance model studies on MPs in WWTP to overcome modelling challenges and ensure model reliability. In conclusion, this review underscores the urgent need for advancements in wastewater treatment processes to mitigate the environmental impact of trace anthropogenic biomarkers. Future efforts should focus on conducting comprehensive studies, implementing advanced treatment methods, and optimising management practices in WWTPs and WRRFs.

Rapidly enrichment and detection of per-and polyfluoroalkyl substances in foods using a novel bifunctional covalent organic framework

Per- and polyfluoroalkyl substances (PFASs) are extensively found in foods, posing potential toxicity to humans. Therefore, rapid analysis and monitoring of PFASs in foods are crucial for public health and also a challenge. To detect trace PFASs in foods, construction of sorbents with multiple interactions could be an effective approach. Herein, a cationic-fluorinated covalent organic framework (CF-COF) was prepared by post-modification and used as a magnetic solid-phase extraction adsorbent for adsorption of PFASs. By combining magnetic solid-phase extraction based on CF-COF with liquid chromatography-tandem mass spectrometry (LC - MS/MS), a novel method was developed for determination of eight long-chain PFASs in foods. Under optimized conditions, the method exhibited low detection limits (0.003-0.019 ng/g) and satisfactory recovery rates (73.5-118%) for PFASs. This study introduces a novel idea for the development of adsorbents targeting PFASs, along with a new analytical method for monitoring of PFASs in foods.

Per- and poly-fluoroalkyl substances (PFAS) effects on lung health: a perspective on the current literature and future recommendations

Per- and poly-fluoroalkyl substances (PFAS) are a broad class of synthetic compounds widely used in commercial applications. The persistent nature of PFAS in the environment has earned them the epithet "forever chemicals." Concerns arise from widespread exposure to PFAS from occupational, household, and environmental sources. This widespread use of PFAS is particularly concerning, as emerging epidemiological evidence highlights their adverse effects on lung health. Such adverse impacts include impaired fetal lung development, reduced immune function in children, and potential links to lung cancer. Both in vivo and in vitro studies illuminate potential mechanisms underlying such adverse health outcomes subsequent to PFAS inhalation exposure, which may include immunomodulation, oxidative stress, and disruptions to epithelial barriers. However, evidence-based information focusing on the mechanisms of PFAS-mediated lung injury is lacking. Additionally, the discrepancies between data collected from animal and epidemiological studies highlight the need for improved approaches to better understand the toxicity results of PFAS exposure. To address these gaps, we recommend leveraging route-to-route extrapolation for risk assessment, prioritizing research on understudied PFAS, and adopting physiologically relevant, high-throughput approaches. These strategies are aimed at enhancing our understanding of PFAS inhalation effects, aiding in more informed risk management decisions. In this review, we summarize the current literature on PFAS exposure, emphasizing its adverse effects on lung health, particularly through inhalation. We then discuss the current knowledge on mechanisms underlying tissue- and cellular-level adverse outcomes caused by PFAS.

Polybrominated diphenyl ethers in indoor dust from Brazil: assessing demographic differences and human health exposure

Indoor house dust is considered an important human exposure route to polybrominated diphenyl ethers (PBDEs), which has raised concern about their environmental persistence and toxicity properties. In this study, eight PBDEs (BDE-28, -47, -99, -100, -153, -154, -183, and -209) were determined in house dust from two cities with different socio-demographic characteristics from Brazil, examining possible relationships with factors that potentially influence contamination (population density, economic activities, presence of electronic equipment, and so on) and also estimating the risk of human exposure through oral ingestion and dermal contact. The Σ8PBDE concentration in Sorocaba city ranged between 380 and 4269 ng/g dw, while in Itapetininga city ranged from 106 to 1000 ng/g dw. In both regions, BDE-209 was the most abundantly found congener, followed by BDE-99. House dust from Sorocaba presented significantly greater concentrations of BDE-183 and BDE-209 than Itapetininga. Regarding risk exposure assessment, the estimated daily intake (EDI) of PBDEs was much lower than their respective reference doses (RfDs) in all pathways estimated (non-dietary ingestion and dermal contact). This study provided valuable data to improve the knowledge about the presence and exposure to PBDEs in Brazilian house dust in comparison to other developing countries and the need to control environmental pollution and protect human health.

Prenatal exposure to per- and polyfluoroalkyl substances and child behavioral problems

BACKGROUND

Prenatal exposure to per- and polyfluoroalkyl substances (PFAS) may adversely affect child behaviors; however, findings of epidemiologic studies are inconsistent. We examined prenatal PFAS exposure in association with child behavioral problems.

METHODS

Participants were 177 mother-child pairs from MARBLES (Markers of Autism Risk in Babies - Learning Early Signs), a cohort with elevated familial likelihood of autism spectrum disorder (ASD). We quantified nine PFAS in maternal serum (1-3 samples per mother) collected from the 1st to 3rd trimesters of pregnancy. Child behavioral problems were assessed at 3 years of age using the Child Behavior Checklist (CBCL), developed to test for various behavioral problems of children. We examined associations of the CBCL scores with individual PFAS concentrations and with their mixture using negative binomial regression and weighted quantile sum regression models.

RESULTS

Higher prenatal perfluorononanoate (PFNA) concentrations were associated with higher scores of externalizing problems [β = 0.16, 95% CI (0.01, 0.32)] and aggressive behavior [β = 0.17 (0.01, 0.32)]. Higher PFNA, perfluorooctane sulfonate (PFOS), and perfluorodecanoate (PFDA) were associated with higher scores of sleep problems [β = 0.34 (0.15, 0.54) for PFNA, β = 0.20 (0.02, 0.37) for PFOS, and β = 0.19 (0.00, 0.37) for PFDA]. No significant associations observed for typically developing children, whereas PFOS, PFNA, and PFDA were associated with several behavioral problems among children diagnosed with ASD or other neurodevelopmental concerns. Exposure to a mixture of PFAS was associated with higher scores of sleep problems and aggressive behavior, mostly contributed by PFNA and PFDA.

CONCLUSIONS

Our study showed that prenatal exposure to some PFAS could increase child behavioral problems at 3 years of age. However, our results should be interpreted with caution because we relied on data from a cohort with increased familial likelihood of ASD and thereby had more behavioral problems.

Per- and polyfluoroalkyl substances (PFAS) in senior care facilities and older adult residents

Per- and polyfluoroalkyl substances (PFAS) are fluorinated organic compounds used in a variety of consumer products and industrial applications that persist in the environment, bioaccumulate in biological tissues, and can have adverse effects on human health, especially in vulnerable populations. In this study, we focused on PFAS exposures in residents of senior care facilities. To investigate relationships between indoor, personal, and internal PFAS exposures, we analyzed 19 PFAS in matched samples of dust collected from the residents' bedrooms, and wristbands and serum collected from the residents. The median ∑PFAS concentrations (the sum of all PFAS detected in the samples) measured in dust, wristbands, and serum were 120 ng/g, 0.05 ng/g, and 4.0 ng/mL, respectively. The most abundant compounds in serum were linear- and branched-perfluorooctane sulfonic acid (L-PFOS and B-PFOS, respectively) at medians of 1.7 ng/mL and 0.83 ng/mL, respectively, followed by the linear perfluorooctanoic acid (L-PFOA) found at a median concentration of 0.59 ng/mL. Overall, these three PFAS comprised 80 % of the serum ∑PFAS concentrations. A similar pattern was observed in dust with L-PFOS and L-PFOA found as the most abundant PFAS (median concentrations of 13 and 7.8 ng/g, respectively), with the overall contribution of 50 % to the ∑PFAS concentration. Only L-PFOA was found in wristbands at a median concentration of 0.02 ng/g. Significant correlations were found between the concentrations of several PFAS in dust and serum, and in dust and wristbands, suggesting that the indoor environment could be a significant contributor to the personal and internal PFAS exposures in seniors. Our findings demonstrate that residents of assisted living facilities are widely exposed to PFAS, with several PFAS found in blood of each study participant and in the assisted living environment.

Serum concentrations of legacy, alternative, and precursor per- and polyfluoroalkyl substances: a descriptive analysis of adult female participants in the MIREC-ENDO study

BACKGROUND

Several legacy and emerging per- and polyfluoroalkyl substances (PFAS) have been regulated around the world. There is growing concern over the proliferation of alternative PFAS, as well as PFAS precursors. Biomonitoring data for PFAS are critical for assessing exposure and human health risk.

METHODS

We collected serum samples from 289 adult female participants in a 2018-2021 follow-up study of the Maternal-Infant Research on Environmental Chemicals (MIREC) Canadian pregnancy cohort. Samples were analyzed for 40 PFAS using ultra-performance liquid chromatography-tandem mass spectrometry. For those compounds with > 50% detection, as well as the sum of these compounds, we describe serum concentrations and patterns of exposure according to sociodemographic and obstetrical history characteristics.

RESULTS

17 out of 40 PFAS were detected in > 50% of samples with 7 of these detected in > 97% of samples. Median [95th percentile] concentrations (µg/L) were highest for PFOS (1.62 [4.56]), PFOA (0.69 [1.52]), PFNA (0.38 [0.81]), and PFHxS (0.33 [0.92]). Geometric mean concentrations of PFOA and PFHxS were approximately 2-fold lower among those with more children (≥ 3 vs. 1), greater number of children breastfed (≥ 3 vs. ≤ 1), longer lifetime duration of breastfeeding (> 4 years vs. ≤ 9 months), and shorter time since last pregnancy (≤ 4 years vs. > 8 years). We observed similar patterns for PFOS, PFHpS, and the sum of 17 PFAS, though the differences between groups were smaller. Concentrations of PFOA were higher among "White" participants, while concentrations of N-MeFOSE, N-EtFOSE, 7:3 FTCA, and 4:2 FTS were slightly higher among participants reporting a race or ethnicity other than "White". Concentrations of legacy, alternative, and precursor PFAS were generally similar across levels of age, education, household income, body mass index, and menopausal status.

CONCLUSIONS

We report the first Canadian biomonitoring data for several alternative and precursor PFAS. Our findings suggest that exposure to PFAS, including several emerging alternatives, may be widespread. Our results are consistent with previous studies showing that pregnancy and breastfeeding are excretion pathways for PFAS.

The therapeutic potential of isosakuranetin against perfluorooctane sulfonate instigated cardiac toxicity via modulating Nrf-2/Keap-1 pathway, inflammatory, apoptotic, and histological profile

Perfluorooctane sulfonate (PFOS) is a pervasive organic toxicant that damages body organs, including heart. Isosakuranetin (ISN) is a plant-based flavonoid that exhibits a broad range of pharmacological potentials. The current investigation was conducted to evaluate the potential role of ISN to counteract PFOS-induced cardiac damage in rats. Twenty-four albino rats (Rattus norvegicus) were distributed into four groups, including control, PFOS (10 mg/kg) intoxicated, PFOS + ISN (10 mg/kg + 20 mg/kg) treated, and ISN (20 mg/kg) alone supplemented group. It was revealed that PFOS intoxication reduced the expressions of Nrf-2 and its antioxidant genes while escalating the expression of Keap-1. Furthermore, PFOS exposure reduced the activities of glutathione reductase (GSR), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione S-transferase (GST), Heme oxygenase-1 (HO-1) and glutathione (GSH) contents while upregulating the levels of reactive oxygen species (ROS) and malondialdehyde (MDA). Besides, PFOS administration upregulated the levels of creatine kinase-MB (CK-MB), troponin I, creatine phosphokinase (CPK), and lactate dehydrogenase (LDH). Moreover, the levels of tumor necrosis factor-alpha (TNF-α), nuclear factor kappa-B (NF-κB), interleukin-6 (IL-6), and interleukin-1β (IL-1β) were increased after PFOS intoxication. Additionally, PFOS exposure downregulated the expression of Bcl-2 while upregulating the expressions of Bax and Caspase-3. Furthermore, PFOS administration disrupted the normal architecture of cardiac tissues. Nonetheless, ISN treatment remarkably protected the cardiac tissues via regulating aforementioned dysregulations owing to its antioxidative, anti-inflammatory, and antiapoptotic properties.

Association between Combined Metals and PFAS Exposure with Dietary Patterns: A Preliminary Study

Background

The global burden of chronic diseases has been increasing, with evidence suggesting that diet and exposure to environmental pollutants, such as per- and polyfluoroalkyl substances (PFAS) and heavy metals, may contribute to their development. The Dietary Inflammatory Index (DII) assesses the inflammatory potential of an individual's diet. However, the complex interplay between PFAS, heavy metals, and DII remains largely unexplored.

Objective

The goal of this cross-sectional study was to investigate the associations between diet operationalized as the DII with individual and combined lead, cadmium, mercury, perfluorooctanoic acid (PFOA), and perfluorooctanesulfonic acid (PFOS) exposures using data from the National Health and Nutrition Examination Survey (NHANES) 2017-2018.

Methods

Descriptive statistics, a correlational analysis, and linear regression were initially used to assess the relationship between the variables of interest. We subsequently employed Bayesian kernel Machine regression (BKMR) to analyze the data to assess the non-linear, non-additive, exposure-response relationships and interactions between PFAS and metals with the DII.

Results

The multi-variable linear regression revealed significant associations between the DII and cadmium and mercury. Our BKMR analysis revealed a complex relationship between PFAS, metal exposures, and the DII. In our univariate exposure-response function plot, cadmium and mercury exhibited a positive and negative linear relationship, respectively, which indicated a positive and negative relationship across the spectrum of exposures with the DII. In addition, the bivariate exposure-response function between two exposures in a mixture revealed that cadmium had a robust positive relationship with the DII for different quantiles of lead, mercury, PFOA, and PFOS, indicating that increasing levels of cadmium are associated with the DII. Mercury's bivariate plot demonstrated a negative relationship across all quantiles for all pollutants. Furthermore, the posterior inclusion probability (PIP) results highlighted the consistent importance of cadmium and mercury with the inflammatory potential of an individual's diet, operationalized as the DII in our study, with both showing a PIP of 1.000. This was followed by PFOS with a PIP of 0.8524, PFOA at 0.5924, and lead, which had the lowest impact among the five environmental pollutants, with a PIP of 0.5596.

Conclusion

Our study suggests that exposures to environmental metals and PFAS, particularly mercury and cadmium, are associated with DII. These findings also provide evidence of the intricate relationships between PFAS, heavy metals, and the DII. The findings underscore the importance of considering the cumulative effects of multi-pollutant exposures. Future research should focus on elucidating the mechanistic pathways and dose-response relationships underlying these associations in a study that examines causality, which will enable a deeper understanding of the dietary risks associated with environmental pollutants.

Linking exposure to per- and polyfluoroalkyl substances (PFAS) in house dust and biomonitoring data in eight impacted communities

Per- and polyfluoroalkyl substances (PFAS) are widely used in industry and have been linked to various adverse health effects. Communities adjacent to sites where PFAS are manufactured, stored, or used may be at elevated risk. In these impacted communities, significant exposure often occurs through contaminated drinking water, yet less is known about the role of other pathways such as residential exposure through house dust. We analyzed a paired serum and house dust dataset from the Agency for Toxic Substances and Disease Registry's PFAS Exposure Assessments, which sampled eight United States communities with a history of drinking water contamination due to aqueous film forming foam (AFFF) use at nearby military bases. We found that serum PFAS levels of residents were significantly positively associated with the dust PFAS levels in their homes, for three of seven PFAS analyzed, when accounting for site and participant age. We also found that increased dust PFAS levels were associated with a shift in the relative abundance of PFAS in serum towards those chemicals not strongly linked to AFFF contamination, which may suggest household sources. Additionally, we analyzed participant responses to exposure questionnaires to identify factors associated with dust PFAS levels. Dust PFAS levels for some analytes were significantly elevated in households where participants were older and had lived at the home longer, cleaned less frequently, used stain resistant products, and had carpeted living rooms. Our results suggest that residential exposure to PFAS via dust or other indoor pathways may contribute to overall exposure and body burden, even in communities impacted by AFFF contamination of drinking water, and the magnitude of this exposure may also be influenced by demographic, behavioral, and housing factors.

Non-Targeted PFAS Suspect Screening and Quantification of Drinking Water Samples Collected through Community Engaged Research in North Carolina's Cape Fear River Basin

A community engaged research (CER) approach was used to provide an exposure assessment of poly- and perfluorinated (PFAS) compounds in North Carolina residential drinking water. Working in concert with community partners, who acted as liaisons to local residents, samples were collected by North Carolina residents from three different locations along the Cape Fear River basin: upper, middle, and lower areas of the river. Residents collected either drinking water samples from their homes or recreational water samples from near their residence that were then submitted by the community partners for PFAS analysis. All samples were processed using weak anion exchange (WAX) solid phase extraction and analyzed using a non-targeted suspect screening approach as well as a quantitative approach that included a panel of 45 PFAS analytes, several of which are specific to chemical industries near the collection site locations. The non-targeted approach, which utilized a suspect screening list (obtained from EPA CompTox database) identified several PFAS compounds at a level two confidence rating (Schymanski scale); compounds identified included a fluorinated insecticide, a fluorinated herbicide, a PFAS used in polymer chemistry, and another that is used in battery production. Notably, at several locations, PFOA (39.8 ng/L) and PFOS (205.3 ng/L) were at levels that exceeded the mandatory EPA maximum contaminant level (MCL) of 4 ng/L. Additionally, several sites had detectable levels of PFAS that are unique to a local chemical manufacturer. These findings were communicated back to the community partners who then disseminated this information to the local residents to help empower and aid in making decisions for reducing their PFAS exposure.

Insights into PFAS environmental fate through computational chemistry: A review

Per- and polyfluoroalkyl substances (PFAS) are widely used chemicals that exhibit exceptional chemical and thermal stability. However, their resistance to degradation has led to their widespread environmental contamination. PFAS also negatively affect the environment and other organisms, highlighting the need for effective remediation methods to mitigate their presence and prevent further contamination. Computational chemistry methods, such as Density Functional Theory (DFT) and Molecular Dynamics (MD) offer valuable tools for studying PFAS and simulating their interactions with other molecules. This review explores how computational chemistry methods contribute to understanding and tackling PFAS in the environment. PFAS have been extensively studied using DFT and MD, each method offering unique advantages and computational limitations. MD simulates large macromolecules systems however it lacks the ability model chemical reactions, while DFT provides molecular insights however at a high computational cost. The integration of DFT with MD shows promise in predicting PFAS behavior in different environments. This work summarizes reported studies on PFAS compounds, focusing on adsorption, destruction, and bioaccumulation, highlighting contributions of computational methods while discussing the need for continued research. The findings emphasize the importance of computational chemistry in addressing PFAS contamination, guiding risk assessments, and informing future research and innovations in this field.

Associations between serum per- and polyfluoroalkyl substances as mixtures and lipid levels: A cross-sectional study in Jinan

Per- and polyfluoroalkyl substances (PFASs) are known to be linked with dyslipidemia. Between March and June 2022, we collected 575 fasting serum samples from individuals without occupational exposure in Jinan, China. Eighteen PFASs were analyzed using UHPLC-Orbitrap MS. Multiple linear regression (MLR), Bayesian kernel machine regression (BKMR), and Quantile g-computation (QGC) models were utilized to assess the effects of both individual PFAS and PFAS mixtures on serum lipid levels, including triglycerides (TG), cholesterol (CHO), high-density lipoprotein (HDL), and low-density lipoprotein (LDL). The PFAS mixture, composed of perfluoroheptanoic acid (PFHpA), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), perfluoroundecanoic acid (PFUnDA), perfluorododecanoic acid (PFDoDA), perfluorotridecanoic acid (PFTrDA), perfluorohexane sulfonate (PFHxS), perfluoroheptane sulfonic acid (PFHpS), perfluorooctane sulfonate (PFOS), and 6:2 chlorinated polyfluoroalkyl ether sulfonate (6:2 Cl-PFESA), showed a positive association with CHO and LDL levels, while no distinct trend was noted in HDL and TG levels about changes in PFAS mixtures levels in BKMR and QGC models, adjusted for gender, age, BMI, occupation, and educational level. The effects of individual PFASs on lipid levels were in general consistent across MLR, BKMR and QGC models. PFUnDA and PFTrDA demonstrated greater impacts on blood lipid levels compared to other PFAS, albeit with varied directional effects. Age-stratified analysis revealed PFAS mixture effect was more pronounced in participants aged higher than 40. No obvious trend in lipid levels with changes in PFAS mixture levels in participants with age ranged from 18 to 40, while positive association between PFAS mixture and CHO and LDL was detected in participants aged higher than 40.

Threats of per- and poly-fluoroalkyl pollutants to susceptible populations

Environmental exposure to per- and poly-fluoroalkyl substances (PFAS) has raised significant global health concerns due to potential hazards in healthy adults. However, the impact of PFAS on susceptible populations, including pregnant individuals, newborns, the older people, and those with underlying health conditions, has been overlooked. These susceptible groups often have physiological changes that make them less resilient to the same exposures. Consequently, there is an urgent need for a comprehensive understanding of the health risks posed by PFAS exposure to these populations. In this review, we delve into the potential health risks of PFAS exposure in these susceptible populations. Equally important, we also examine and discuss the molecular mechanisms that underlie this susceptibility. These mechanisms include the induction of oxidative stress, disruption of the immune system, impairment of cellular metabolism, and alterations in gut microbiota, all of which contribute to the enhanced toxicity of PFAS in susceptible populations. Finally, we address the primary research challenges and unresolved issues that require further investigation. This discussion aims to foster research for a better understanding of how PFAS affect susceptible populations and to pave the way for strategies to minimize their adverse effects.

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.

Nationwide distribution of perfluoroalkyl ether carboxylic acids in Chinese diets: An emerging concern

With the phase-out of perfluorooctanoic acid (PFOA) and its replacement by perfluoroalkyl ether carboxylic acids (PFECAs), there is a potential for increased exposure to various new PFECAs among the general population in China. While there are existing studies on dietary exposure to legacy perfluoroalkyl and polyfluoroalkyl substances (PFASs), research on dietary exposure to PFECAs, especially among the general Chinese populace, remains scarce. In the present study, we investigated the distribution of PFECAs in dietary sources from 33 cities across five major regions in China, along with the associated dietary intake. Analysis indicated that aquatic animal samples contained higher concentrations of legacy PFASs compared to those from terrestrial animals and plants. In contrast, PFECAs were found in higher concentrations in plant and terrestrial animal samples. Notably, hexafluoropropylene oxide dimer (HFPO-DA) was identified as the dominant compound in vegetables, cereals, pork, and mutton across the five regions, suggesting widespread dietary exposure. PFECAs constituted the majority of PFAS intake (57 %), with the estimated daily intake (EDI) of HFPO-DA ranging from 2.33 to 3.96 ng/kg bw/day, which corresponds to 0.78-1.32 times the reference dose (RfD) (3.0 ng/kg bw/day) set by the United States Environmental Protection Agency. Given the ubiquity of HFPO-DA and many other PFECAs in the nationwide diet of China, there is an urgent need for further research into these chemicals to establish relevant safety benchmarks or consumption advisory values for the diet.

Estimating the dynamic early life exposure to PFOA and PFOS of the HELIX children: Emerging profiles via prenatal exposure, breastfeeding, and diet

In utero and children's exposure to per- and polyfluoroalkyl substances (PFAS) is a major concern in health risk assessment as early life exposures are suspected to induce adverse health effects. Our work aims to estimate children's exposure (from birth to 12 years old) to PFOA and PFOS, using a Physiologically-Based Pharmacokinetic (PBPK) modelling approach. A model for PFAS was updated to simulate the internal PFAS exposures during the in utero life and childhood, and including individual characteristics and exposure scenarios (e.g., duration of breastfeeding, weight at birth, etc.). Our approach was applied to the HELIX cohort, involving 1,239 mother-child pairs with measured PFOA and PFOS plasma concentrations at two sampling times: maternal and child plasma concentrations (6 to 12 y.o). Our model predicted an increase in plasma concentrations during fetal development and childhood until 2 y.o when the maximum concentrations were reached. Higher plasma concentrations of PFOA than PFOS were predicted until 2 y.o, and then PFOS concentrations gradually became higher than PFOA concentrations. From 2 to 8 y.o, mean concentrations decreased from 3.1 to 1.88 µg/L or ng/mL (PFOA) and from 4.77 to 3.56 µg/L (PFOS). The concentration-time profiles vary with the age and were mostly influenced by in utero exposure (on the first 4 months after birth), breastfeeding (from 5 months to 2 (PFOA) or 5 (PFOS) y.o of the children), and food intake (after 3 (PFOA) or 6 (PFOS) y.o of the children). Similar measured biomarker levels can correspond to large differences in the simulated internal exposures, highlighting the importance to investigate the children's exposure over the early life to improve exposure classification. Our approach demonstrates the possibility to simulate individual internal exposures using PBPK models when measured biomarkers are scarce, helping risk assessors in gaining insight into internal exposure during critical windows, such as early life.

Profile of per- and polyfluoroalkyl substances, source appointment, and determinants in Argentinean postpartum women

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) are a group of synthetic chemicals with potential adverse health effects. Information concerning PFAS concentrations in relation to pregnancy is scarce in South America and non-existent in Argentina.

AIM

We aimed to investigate an extended maternal PFAS profile herein serum concentrations in a regional and global view, source appointment, and determinants in Argentinean women.

METHODS

A cross-sectional study with a sampling period from 2011 to 2012 included 689 women from Ushuaia and Salta in Argentina. Serum samples collected two days postpartum were analyzed by ultra-high pressure liquid chromatography coupled to electrospray negative ionisation tandem-quadrupole mass-spectrometry. Principal Component Analysis (PCA) following absolute principal component score-multiple linear regression (APCS-MLR) was used for PFAS source appointments. Determinants of PFAS were explored through a MLR approach. A review of previous studies within the same period was conducted to compare with present levels.

RESULTS

Argentinean PFAS concentrations were the lowest worldwide, with PFOS (0.74 ng/mL) and PFOA (0.11 ng/mL) as the dominant substances. Detection frequencies largely aligned with the compared studies, indicating the worldwide PFAS distribution considering the restrictions. The PCA revealed region-specific loading patterns of two component groups of PFAS, a mixture of replaced and legacy substances in Ushuaia and long-chain in Salta. This might relate to a mix of non-diet and diet exposure in Ushuaia and diet in Salta. Region, age, lactation, parity, household members, migration, bottled water, and freshwater fish were among the determinants of various PFAS.

CONCLUSION

This is the first study to monitor human PFAS exposure in Argentina. Maternal PFAS concentrations were the lowest observed worldwide in the same period. Exposure contributions are suggested to be affected by restrictions and substitutions. Given the limited population-based studies and the emergence of PFAS, it is essential to conduct further monitoring of PFAS in Argentina and South America.

A review of foam fractionation for the removal of per- and polyfluoroalkyl substances (PFAS) from aqueous matrices

The detection of per- and polyfluoroalkyl substances (PFAS) in aqueous matrices is an emerging environmental concern due to their persistent, bioaccumulative and toxic properties. Foam fractionation has emerged as a viable method for removing and concentrating PFAS from aqueous matrices. The method exploits the surface-active nature of the PFAS to adsorb at the air-liquid interfaces of rising air bubbles, resulting in foam formation at the top of a foam fractionator. The removal of PFAS is then achieved through foam harvesting. Foam fractionation has gained increasing attention owing to its inherent advantages, including simplicity and low operational costs. The coupling of foam fractionation with destructive technologies could potentially serve as a comprehensive treatment train for future PFAS management in aqueous matrices. The PFAS-enriched foam, which has a smaller volume, can be directed to subsequent destructive treatment technologies. In this review, we delve into previous experiences with foam fractionation for PFAS removal from various aqueous matrices and critically analyse their key findings. Then, the recent industry advancements and commercial projects that utilise this technology are identified. Finally, future research needs are suggested based on the current challenges.

Assessing potential human health and ecological implications of PFAS from leave-in dental products

Contaminated water and food are the main sources of documented per- and polyfluoroalkyl substances (PFAS) exposure in humans. However, other sources may contribute to the overall PFAS intake. While several studies documented the presence of PFAS in consumer products, PFAS evaluation in dental products has been limited to floss and tape to date. This study estimated PFAS exposures from a convenience sample of leave-in dental products (night guards and whitening trays), which remain in contact with the mouth for longer durations than previously evaluated dental products. This analysis evaluated whether consumer usage of these dental products meaningfully contributes to oral exposure of PFAS. Leaching of PFAS upon disposal of products was also considered. Out of 24 PFAS measured, perfluorobutanoic acid (PFBA; 3.24-4.17 ng/product or 0.67-0.83 ng/g) and perfluorooctanesulfonic acid (PFOS; 7.25-16.45 ng/product or 1.2-2.3 ng/g) were detected in night guards, and no PFAS were detected in whitening trays. Non-targeted analysis showed additional possible PFAS, which could not be characterized. The findings showed that PFOS and/or PFBA present in night guards were unlikely to pose a health concern. From an ecological perspective, the dental products examined were shown to constitute a negligible contribution to environmental PFAS. In conclusion, the examined dental products do not represent a significant source of exposure to PFAS for humans or the environment. The study demonstrates how risk assessment can be integrated by the industry into product stewardship programs to evaluate the potential health and environmental impacts of chemicals in consumer products.

Prenatal exposure to poly- and perfluoroalkyl substances and postpartum depression in women with twin pregnancies

BACKGROUND

Women with multiple pregnancies are vulnerable to experience postpartum depression (PPD). Emerging evidence indicates an association between poly- and perfluoroalkyl substances (PFAS) exposure and PPD in women delivering singletons. The health risks of PFAS may also be present in women delivering twins.

OBJECTIVE

To estimate the impacts of prenatal PFAS exposure on the risk of PPD in women with twin pregnancies.

METHODS

Our study included 150 mothers who gave birth to twins and were enrolled in the Wuhan Twin Birth Cohort. The concentrations of maternal plasma PFAS were measured in each trimester and averaged. Eight individual PFAS were included in analyses. We used Edinburgh Postnatal Depression Scale to evaluate maternal depression at early pregnancy and 1 and 6 months after childbirth. The outcome was dichotomized using a cutoff value of ≥10 for main analyses. Associations were examined using multiple informant models and modified Poisson regressions. PFAS mixture effects were estimated using quantile g-computation.

RESULTS

Using quantile g-computation models, a quartile increase in the PFAS mixture during the first, second, third, and average pregnancy was significantly associated with a relative risk (RR) of 1.73 (95% CI: 1.42, 2.12), 1.54 (95% CI: 1.27, 1.84), 1.75 (95% CI: 1.49, 2.08), and 1.63 (95% CI: 1.35, 1.97) for PPD at 6 months after childbirth, respectively. The results of the single-PFAS models also indicated significant positive associations between individual PFAS and PPD at both 1 and 6 months.

CONCLUSIONS

The first study of women with twin pregnancies suggests that prenatal exposure to PFAS increases PPD risk up to 6 months postpartum. Twin pregnant women should receive long-term follow-up after delivery and extensive social support.

Characterization and dermal bioaccessibility of residual- and listed PFAS ingredients in cosmetic products

As a large group of chemicals with diverse properties, per- and polyfluoroalkyl substances (PFAS) have found extensive application throughout consumer products, including cosmetics. Little is known about the importance of dermal uptake as a human exposure pathway for PFAS. Here we investigate a suite of listed-ingredient and residual PFAS in cosmetic products, along with their dermal bioaccessibility using in vitro incubations with artificial sweat. Concentrations of volatile listed ingredients (including cyclic perfluorinated alkanes, perfluorinated ethers, and polyfluorinated silanes) in three products ranged from 876-1323 μg g-1, while polar listed ingredients (i.e., polyfluoroalkyl phosphate esters [PAPs]) in a single product occurred at up to 2427 μg g-1 (6 : 2/6 : 2 diPAP)). Residual perfluoroalkyl carboxylic acids (PFCAs) were also measured at concentrations ranging from 0.02-29 μg g-1. When listed ingredients were included, our targeted analysis accounted for up to 103% of the total fluorine, while highlighting ambiguous and/or incorrect International Nomenclature of Cosmetic Ingredient (INCI) names used in several products. Bioaccessibility experiments revealed that residual PFCAs readily partitioned to artificial sweat (bioaccessible fractions ranging from 43-76% for detectable substances) while listed ingredients (i.e., PAPs and neutral/volatile PFAS) displayed negligible partitioning. This work provides new insight into the occurrence of PFAS in cosmetic products, while furthering our understanding on their mechanisms of dermal uptake.

Remediation of PFAS-impacted soils using magnetic activated carbon (MAC) and hydrothermal alkaline treatment (HALT)

Per- and polyfluoroalkyl substances (PFAS) are a group of synthetic pollutants that are bioaccumulative, toxic, and persistent. One long-term source for PFAS release is PFAS-contaminated soil. Addition of activated carbon (AC) to soil has shown the potential to immobilize PFAS and reduce PFAS bioavailability, but PFAS-loaded spent AC remaining in the treated soil could lead to remobilization. Here we report a novel approach to address this challenge. By applying magnetic activated carbon (MAC) to remediate PFAS-impacted soil, the PFAS-loaded MAC can be retrieved from the treated soil and sorbed PFAS in the spent MAC can be destroyed using hydrothermal alkaline treatment (HALT). Effective MAC recovery was observed when water/soil ratios (w/w) were either <0.07 or > 1. Soil organic content and pH affected PFAS adsorption by the MAC added to soil. After three months of incubation with MAC, high PFAS removals [PFOS (87.6 %), PFOA (83.8 %), and 6:2 FTSA (81.5 %)] were observed for acidic environmental sandy soils with low organic content. In contrast, PFAS removal by MAC was poor for garden soils with high organic matter content. MAC was also used to remediate aqueous film-forming foam (AFFF)-impacted and PFAS-contaminated aged soils with varying PFAS removal performance. HALT technology was able to destroy and defluorinate PFAS adsorbed to the spent MAC. Additionally, the HALT-treated MAC retained its magnetic properties and PFOS sorption capacity, suggesting the potential reusability of HALT-treated MAC. Considering the low energy footprint of HALT compared to conventional PFAS thermal destruction techniques, the combination of MAC and HALT could be a promising treatment train for PFAS-contaminated soils.

Effects of charge-assisted hydrogen bond on sorption and co-sorption of pharmaceutical contaminants on carbonaceous materials: Spectroscopic and theoretical studies

Charge-assisted hydrogen bond (CAHB) is a key mechanism that affects the environmental behavior of pharmaceutical pollutants (PCs). However, the strength and stability of various CAHBs, and their effects on the co-sorption behavior of PCs are still unclear. Herein, DFT calculation with different solvent models including two implicit solvent model (PCM and SMD), and one explicit solvent model (ESM) were applied in this study, to investigate the effects of different CAHBs on the sorption and co-sorption behavior of four PCs (e.g., clofibric acid, p-aminobenzoic acid, acetaminophen, and sulfamerazine) on three model carbonaceous materials. First, the appearance of new peaks in the very low field of 1H NMR, and the blue shift of OH and NH2 peaks in FTIR indicated that CAHBs were indeed formed between PCs and carbonaceous materials. Next, according to the principal component analysis and correlation analysis of parameters (e.g., ΔEads, bond length, bond angle, Egap, and ΔG) of these CAHBs calculated by the DFT with different solvent models, the results showed that SMD is the optimal model for calculating the strength and stability of CAHBs by DFT, and the strength and stability of CAHBs formed between PCs and carbonaceous materials in this study were in the order of homonuclear [O⋯H⋯O]- CAHB > heteronuclear [O⋯HN]-/[N⋯HO]+ type of CAHB > homonuclear [N⋯H⋯N]+. Also, the co-sorption behavior of different PCs co-existing in binary systems further confirmed that, all above types of CAHBs formed between PCs and carbonaceous materials can produce obvious competition effect on the co-existing PCs that only OHB formed between them. This study not only reveals the environmental behavior of co-existing PCs, but also provides a theoretical basis for the design of obligate sorption materials for PCs in the natural environment.

In utero exposures to perfluoroalkyl substances and the human fetal liver metabolome in Scotland: a cross-sectional study

BACKGROUND

Perfluoroalkyl and polyfluoroalkyl substances are classed as endocrine disrupting compounds but continue to be used in many products such as firefighting foams, flame retardants, utensil coatings, and waterproofing of food packaging. Perfluoroalkyl exposure aberrantly modulates lipid, metabolite, and bile acid levels, increasing susceptibility to onset and severity of metabolic diseases, such as diabetes and metabolic dysfunction-associated steatotic liver disease. To date, most studies in humans have focused on perfluoroalkyl-exposure effects in adults. In this study we aimed to show if perfluoroalkyls are present in the human fetal liver and if they have metabolic consequences for the human fetus.

METHODS

In this cross-sectional study, human fetal livers from elective termination of pregnancies at the Aberdeen Pregnancy Counselling Service, Aberdeen, UK, were analysed by both targeted (bile acids and perfluoroalkyl substances) and combined targeted and untargeted (lipids and polar metabolites) mass spectrometry based metabolomic analyses, as well as with RNA-Seq. Only fetuses from normally progressing pregnancies (determined at ultrasound scan before termination), terminated for non-medical reasons, from women older than 16 years, fluent in English, and between 11 and 21 weeks of gestation were collected. Women exhibiting considerable emotional distress or whose fetuses had anomalies identified at ultrasound scan were excluded. Stringent bioinformatic and statistical methods such as partial correlation network analysis, linear regression, and pathway analysis were applied to this data to investigate the association of perfluoroalkyl exposure with hepatic metabolic pathways.

FINDINGS

Fetuses included in this study were collected between Dec 2, 2004, and Oct 27, 2014. 78 fetuses were included in the study: all 78 fetuses were included in the metabolomics analysis (40 female and 38 male) and 57 fetuses were included in the RNA-Seq analysis (28 female and 29 male). Metabolites associated with perfluoroalkyl were identified in the fetal liver and these varied with gestational age. Conjugated bile acids were markedly positively associated with fetal age. 23 amino acids, fatty acids, and sugar derivatives in fetal livers were inversely associated with perfluoroalkyl exposure, and the bile acid glycolithocholic acid was markedly positively associated with all quantified perfluoroalkyl. Furthermore, 7α-hydroxy-4-cholesten-3-one, a marker of bile acid synthesis rate, was strongly positively associated with perfluoroalkyl levels and was detectable as early as gestational week 12.

INTERPRETATION

Our study shows direct evidence for the in utero effects of perfluoroalkyl exposure on specific key hepatic products. Our results provide evidence that perfluoroalkyl exposure, with potential future consequences, manifests in the human fetus as early as the first trimester of gestation. Furthermore, the profiles of metabolic changes resemble those observed in perinatal perfluoroalkyl exposures. Such exposures are already linked with susceptibility, initiation, progression, and exacerbation of a wide range of metabolic diseases.

FUNDING

UK Medical Research Council, Horizon Europe Program of the European Union, Seventh Framework Programme of the European Union, NHS Grampian Endowments grants, European Partnership for the Assessment of Risks from Chemicals, Swedish Research Council, Formas, Novo Nordisk Foundation, and the Academy of Finland.

US and international per- and polyfluoroalkyl substances surface water quality criteria: A review of the status, challenges, and implications for use in chemical management and risk assessment

Regulation of per- and polyfluorinated substances (PFAS) in surface water is a work-in-progress with relatively few criteria promulgated in the United States and internationally. Surface water quality criteria (SWQC) or screening values derived for perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) by Australia, Canada, the European Union (EU), and four US states (Florida, Michigan, Minnesota, and Wisconsin), and the San Francisco Bay Regional Water Quality Control Board (SFB RWQCB; California) were compared. Across these eight jurisdictions, promulgated numeric criteria for the same compound and receptor span over five orders of magnitude as a result of different approaches and data interpretations. Human health criteria for PFOS range from 0.0047 to 600 ng/L depending on route of exposure (e.g., fish consumption or drinking water) and are lower than most ecological criteria for protection of aquatic and wildlife receptors. Data gaps and uncertainty in chronic toxicity and bioaccumulation of PFOS and PFOA, as well as the use of conservative assumptions regarding intake and exposure, have resulted in some criteria falling at or below ambient background concentrations and current analytical detection limits (around 1 ng/L for commercial laboratories). Some jurisdictions (e.g., Australia, Canada) have deemed uncertainty in quantifying water-fish bioaccumulation too great and set fish tissue action levels in lieu of water criteria. Current dynamics associated with the emerging and evolving science of PFAS toxicity, exposure, and environmental fate (i.e., data gaps and uncertainty), as well as the continuous release of scientific updates, pose a challenge to setting regulatory limits. Integr Environ Assess Manag 2024;20:36-58. © 2023 AECOM Technical Services, Inc and The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

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.

Exploring Route-Specific Pharmacokinetics of PFAS in Mice by Coupling in Vivo Tests and Physiologically Based Toxicokinetic Models

BACKGROUND

Oral ingestion, inhalation, and skin contact are important exposure routes for humans to uptake per- and polyfluoroalkyl substances (PFAS). However, nasal and dermal exposure to PFAS remains unclear, and accurately predicting internal body burden of PFAS in humans via multiple exposure pathways is urgently required.

OBJECTIVES

We aimed to develop multiple physiologically based toxicokinetic (PBTK) models to unveil the route-specific pharmacokinetics and bioavailability of PFAS via respective oral, nasal, and dermal exposure pathways using a mouse model and sought to predict the internal concentrations in various tissues through multiple exposure routes and extrapolate it to humans.

METHODS

Mice were administered the mixed solution of perfluorohexane sulfonate, perfluorooctane sulfonate, and perfluorooctanoic acid through oral, nasal, and dermal exposure separately or jointly. The time-dependent concentrations of PFAS in plasma and tissues were determined to calibrate and validate the individual and combined PBTK models, which were applied in single- and repeated-dose scenarios.

RESULTS

The developed route-specific PBTK models successfully simulated the tissue concentrations of PFAS in mice following single or joint exposure routes as well as long-term repeated dose scenarios. The time to peak concentration of PFAS in plasma via dermal exposure was much longer (34.1-83.0 h) than that via nasal exposure (0.960 h). The bioavailability of PFAS via oral exposure was the highest (73.2%-98.0%), followed by nasal (33.9%-66.8%) and dermal exposure (4.59%-7.80%). This model was extrapolated to predict internal levels in human under real environment.

DISCUSSION

Based on these data, we predict the following: PFAS were absorbed quickly via nasal exposure, whereas a distinct hysteresis effect was observed for dermal exposure. Almost all the PFAS to which mice were exposed via gastrointestinal route were absorbed into plasma, which exhibited the highest bioavailability. Exhalation clearance greatly depressed the bioavailability of PFAS via nasal exposure, whereas the lowest bioavailability in dermal exposure was because of the interception of PFAS within the skin layers. https://doi.org/10.1289/EHP11969.

The stage-specific toxicity of per- and polyfluoroalkyl substances (PFAS) in nematode Caenorhabditis elegans

Per- and Polyfluoroalkyl Substances (PFAS) are a diverse class of industrial chemicals that have been used for decades in industrial and commercial applications. Due to their widespread usages, persistence in the environment, and bioaccumulation in animals and humans, great public health concerns have been raised on adverse health risks of PFAS. In this study, ten PFAS were selected according to their occurrence in different water bodies. The wild-type worms were exposed to individual PFAS at 0, 0.1, 1,10, 100, and 200 μM, and the toxic effects of PFAS on growth, development, fecundity, and behavior at different life stages were investigated using a high-throughput screening (HTS) platform. Our results showed that perfluorooctanesulfonic acid (PFOS), 1H,1H, 2H, 2H-perfluorooctanesulfonamidoacetic acid (NEtFOSAA), perfluorobutanesulfonic (PFBS), and perfluorohexanesulfonic acid (PFHxS) exhibited significant inhibitive effects on the growth in the L4 larva and later stages of worms with concentrations ranging from 0.1 to 200 μmol/L. PFOS and PFBS significantly decreased the brood size of worms across all tested concentrations (p < 0.05), and the most potent PFAS is PFOS with BMC of 0.02013 μM (BMCL, 1.6e-06 μM). During adulthood, all PFAS induced a significant reduction in motility (p < 0.01), while only PFOS can significantly induce behavior alteration at the early larvae stage. Furthermore, the adverse effects occurred in larval stages were found to be the most susceptible to the PFAS exposure. These findings provide valuable insights into the potential adverse effects associated with PFAS exposure and show the importance of considering developmental stages in toxicity assessments.