Human exposure pathways to poly- and perfluoroalkyl substances (PFAS) from indoor media: A systematic review

Review of scientific research on air quality and environmental health risk and impact for PICTS

Air quality (AQ) significantly impacts human health, influenced by both natural phenomena and human activities. In 2021, heightened awareness of AQ's health impacts prompted the revision of the World Health Organization (WHO) guidelines, advocating for stricter pollution standards. However, research on AQ has predominantly focused on high-income countries and densely populated cities, neglecting low- and middle-income countries, particularly Pacific Island Countries, Territories, and States (PICTS). This systematic review compiles existing peer-reviewed literature on AQ research in PICTS to assess the current state of knowledge and emphasize the need for further investigation. A systematic literature search yielded 40 papers from databases including Web of Science, Scopus, and Embase. Among the 26 PICTS, only 6 (Hawai'i, Fiji, Papua New Guinea, New Caledonia, Republic of Marshall Islands, and Pacific) have been subject to AQ-related research, with 4 considering the World Health Organization (WHO) parameters and 26 addressing non-WHO parameters. Analysis reveals AQ parameters often exceed 2021 WHO guidelines for PM2.5, PM10, SO2, and CO, raising concerns among regional governments. Studies primarily focused on urban, agricultural, rural, and open ocean areas, with 15 based on primary data and 14 on both primary and secondary sources. Research interests and funding sources dictated the methods used, with a predominant focus on environmental risks over social, economic, and technological impacts. Although some papers addressed health implications, further efforts are needed in this area. This review underscores the urgent need for ongoing AQ monitoring efforts in PICTS to generate spatially and temporally comparable data. By presenting the current state of AQ knowledge, this work lays the foundation for coordinated regional monitoring and informs national policy development.

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.

General toxicity and screening of reproductive and developmental toxicity following bioaccumulation of oral-dosed perfluorooctanoic acid: Loss of the Golgi apparatus

Despite its widespread use as a stabilizer across various industries over the past several decades, the health effects of chronic exposure to PFOA are still unclear. We administered PFOA by oral gavage (0, 12.5, 50, and 200 μg/day/mouse, eight groups) to male and female mice for six months. Body weight gain decreased with dose accompanied by increased liver weight, and PFOA altered liver damage-related-blood biochemical indicators and induced pathological lesions, including hepatocellular hypertrophy, cholangiofibrosis, and centrilobular hepatocellular vacuolation. Loss of the Golgi apparatus, formation of lamellar body-like structures, and lipid accumulation were observed in the liver of PFOA-treated mice. We also cohabited five pairs of male and female mice for the last ten days of administration, dosed PFOA to dam up to 28 days after birth, and investigated effects on reproduction and development. The survival rate of pups and the sex ratio of surviving mice decreased significantly at the highest dose. PFOA tissue concentration increased with the dose in the parent mice's liver and the pups' blood and brain. Taken together, we suggest that PFOA primarily affects the liver and reproduction system and that disturbance in lipid metabolism and Golgi's structural stability may be involved in PFOA-induced toxicity.

Immunotoxicity of legacy and alternative per- and polyfluoroalkyl substances on zebrafish larvae

Hexafluoropropylene oxide dimer acid (HFPO-DA) and perfluoroethylcyclohexane sulfonate (PFECHS) are increasingly used as alternatives for perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS). However, their immunotoxicity and underlying molecular mechanisms remain poorly understood. Here, to assess immunotoxic effects, zebrafish embryos were exposed to environmentally relevant concentrations of PFOA, PFOS, HFPO-DA, and PFECHS for four days. Results revealed that all four per- and polyfluoroalkyl substances (PFAS) resulted in decreased heart rate and spontaneous movement, and induced oxidative stress in zebrafish larvae. Notably, HFPO-DA exhibited more severe oxidative stress than PFOA. Immune dysfunction was observed, characterized by elevated cytokine, complement factor, nitric oxide, and neutrophil content, along with a significant decrease in lysozyme content. Transcriptomic analysis revealed the activation of Toll-like receptor (TLR)/NOD-like receptor (NLR)/RIG-I-like receptor (RLR) and associated downstream genes, indicating their pivotal role in PFAS-induced immunomodulation. Molecular docking simulations demonstrated stable interactions between PFAS and key receptors (TLR2, NOD2 and RIG-I). Overall, HFPO-DA and PFECHS exhibited immunotoxic effects in zebrafish larvae similar to legacy PFAS, providing important information for understanding the toxic mode of action of these emerging alternatives.

Impact of perfluorooctanoic acid (PFOA) and perfluorobutanoic acid (PFBA) on oxidative stress and metabolic biomarkers in human neuronal cells (SH-SY5Y)

Perfluorinated alkyl substances (PFAS) are pervasive environmental contaminants that have attracted considerable attention due to their widespread utilization, resilient characteristics, adverse health implications, and regulatory scrutiny. Despite documented toxicity in living organisms, the precise molecular mechanisms governing the induced adverse effects remain unclear. This study aims to elucidate mechanisms of toxic action by collecting empirical data sets along oxidative stress and metabolic disruption pathways. We investigated the impact of long-chain PFAS (perfluorooctanoic acid (PFOA)) and its short-chain analog (perfluorobutanoic acid (PFBA)) on human neuronal cells (SH-SY5Y). The functionalities of enzymes associated with oxidative stress (catalase and glutathione reductase) and cellular metabolism (lactate dehydrogenase and pyruvate dehydrogenase) were also characterized. Our results reveal that a 24-hour exposure to PFOA and PFBA generated significant levels of reactive oxygen species. Correspondingly, there was a notable decline in catalase and glutathione reductase activities, with PFBA demonstrating a more pronounced effect. High concentrations of PFOA and PFBA reduced metabolic activity. Lactate dehydrogenase activity was only impacted by a high concentration of PFBA, while pyruvate dehydrogenase activity was decreased with PFBA exposure and increased with PFOA exposure. The findings from this study contribute to the knowledge of PFAS and cell interactions and reveal the potential underlying mechanisms of PFAS-induced toxicity.

Per- and polyfluoroalkyl substances and bone mineral content in early adolescence: Modification by diet and physical activity

BACKGROUND

Per- and polyfluoroalkyl substance (PFAS) exposures may negatively impact bone mineral accrual, but little is known about potential mitigators of this relation. We assessed whether associations of PFAS and their mixture with bone mineral content (BMC) in adolescence were modified by diet and physical activity.

METHODS

We included 197 adolescents enrolled in a prospective pregnancy and birth cohort in Cincinnati, Ohio (2003-2006). At age 12 years, we collected serum for PFAS measurements and used dual-energy x-ray absorptiometry to measure BMC. We calculated dietary calcium intake and Health Eating Index (HEI) scores from repeated 24-h dietary recalls, physical activity scores using the Physical Activity Questionnaire for Older Children (PAQ-C), and average moderate to vigorous physical activity (MVPA) based on accelerometry. We estimated covariate-adjusted differences in BMC z-scores per interquartile range (IQR) increase of individual PFAS concentrations using linear regression and per simultaneous IQR increase in all four PFAS using g-computation. We evaluated effect measure modification (EMM) using interaction terms between each modifier and PFAS.

RESULTS

Higher serum perfluorooctanoic acid, perfluorooctanesulfonic acid, and perfluorononanoic acid concentrations and the PFAS mixture were associated with lower BMC z-scores. An IQR increase in all PFAS was associated with a 0.27 (-0.54, 0.01) lower distal radius BMC z-score. Associations with lower BMC were generally stronger among adolescents classified as < median for calcium intake, HEI scores, or MVPA compared to those ≥ median. The difference in distal radius BMC z-score per IQR increase in all PFAS was -0.38 (-0.72, -0.04) for those with

CONCLUSION

Healthy, calcium-rich diets and higher intensity physical activity may mitigate the adverse impact of PFAS on adolescent bone health.

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Key Words

• Adolescent health
• Bone mineral content
• Calcium
• Diet
• Perfluoroalkyl substances
• Physical activity

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MESH Headings

• Humans
• Female
• Fluorocarbons/blood
• Male
• Bone Density/drug effects
• Child
• Adolescent
• Diet
• Environmental Pollutants/blood
• Prospective Studies
• Ohio
• Alkanesulfonic Acids/blood
• Exercise
• Motor Activity/drug effects

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Grants

• R01 ES030078 NIEHS NIH HHS
• R01 ES033252 NIEHS NIH HHS
• R01 ES027224 NIEHS NIH HHS
• L40 ES032257 NIEHS NIH HHS
• P01 ES011261 NIEHS NIH HHS
• R01 ES032836 NIEHS NIH HHS
• R01 ES028277 NIEHS NIH HHS
• T32 ES007141 NIEHS NIH HHS
• R01 ES025214 NIEHS NIH HHS
• R01 ES020349 NIEHS NIH HHS

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Affiliation(s)

Jessie P Buckley Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
Junyi Zhou Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, USA
Katherine M Marquess Department of Environmental Health and Engineering, Johns Hopkins Bloomberg School of Public Health, Baltimore, USA
Bruce P Lanphear Faculty of Health Sciences, Simon Fraser University, Vancouver, Canada
Kim M Cecil Department of Radiology, Cincinnati Children's Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati, USA; Department of Pediatrics, Cincinnati Children's Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati, USA
Aimin Chen Department of Biostatistics, Epidemiology and Informatics, University of Pennsylvania Perelman School of Medicine, Philadelphia, USA
Clara G Sears Christina Lee Brown Envirome Institute, Department of Medicine, Division of Environmental Medicine, University of Louisville, KY, USA
Yingying Xu Department of Pediatrics, Cincinnati Children's Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati, USA
Kimberly Yolton Department of Pediatrics, Cincinnati Children's Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati, USA
Heidi J Kalkwarf Department of Pediatrics, Cincinnati Children's Hospital Medical Center, University of Cincinnati College of Medicine, Cincinnati, USA
Joseph M Braun Department of Epidemiology, Brown University, Providence, USA
Jordan R Kuiper Department of Environmental and Occupational Health, The George Washington University Milken Institute School of Public Health, Washington, D.C., USA

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Systematic evidence mapping of potential correlates of exposure for per- and poly-fluoroalkyl substances (PFAS) based on measured occurrence in biomatrices and surveys of dietary consumption and product use

Per- and poly-fluoroalkyl substances (PFAS) are widely observed in environmental media and often are found in indoor environments as well as personal-care and consumer products. Humans may be exposed through water, food, indoor dust, air, and the use of PFAS-containing products. Information about relationships between PFAS exposure sources and pathways and the amounts found in human biomatrices can inform source-contribution assessments and provide targets for exposure reduction. This work collected and collated evidence for correlates of PFAS human exposure as measured through sampling of biomatrices and surveys of dietary consumption and use of consumer products and articles. A systematic evidence mapping approach was applied to perform a literature search, conduct title-abstract and full-text screening, and to extract primary data into a comprehensive database for 16 PFAS. Parameters of interest included: sampling dates and locations, cohort descriptors, PFAS measured in a human biomatrix, information about food consumption in 11 categories, use of products/articles in 11 categories, and reported correlation values (and their statistical strength). The literature search and screening process yielded 103 studies with information for correlates of PFAS exposures. Detailed data were extracted and compiled on measures of PFAS correlations between biomatrix concentrations and dietary consumption and other product/article use. A majority of studies (61/103; 59%) were published after 2015 with few (8/103; 8%) prior to 2010. Studies were most abundant for dietary correlates (n = 94) with fewer publications reporting correlate assessments for product use (n = 56), while some examined both. PFOA and PFOS were assessed in almost all studies, followed by PFHxS, PFNA, and PFDA which were included in >50% of the studies. No relevant studies included PFNS or PFPeS. Among the 94 studies of dietary correlates, significant correlations were reported in 83% of the studies for one or more PFAS. The significant dietary correlations most commonly were for seafood, meats/eggs, and cereals/grains/pulses. Among the 56 studies of product/article correlates, significant correlations were reported in 70% of the studies. The significant product/article correlations most commonly were for smoking/tobacco, cosmetics/toiletries, non-stick cookware, and carpet/flooring/furniture and housing. Six of 11 product/article categories included five or fewer studies, including food containers and stain- and water-resistant products. Significant dietary and product/article correlations most commonly were positive. Some studies found a mix of positive and negative correlations depending on the PFAS, specific correlate, and specific response level, particularly for fats/oils, dairy consumption, food containers, and cosmetics/toiletries. Most of the significant findings for cereals/grains/pulses were negative correlations. Substantial evidence was found for correlations between dietary intake and biomatrix levels for several PFAS in multiple food groups. Studies examining product/article use relationships were relatively sparse, except for smoking/tobacco, and would benefit from additional research. The resulting database can inform further assessments of dietary and product use exposure relationships and can inform new research to better understand PFAS source-to-exposure relationships. The search strategy should be extended and implemented to support living evidence review in this rapidly advancing area.

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.

Epidemic-specific association of maternal exposure to per- and polyfluoroalkyl substances (PFAS) and their components with maternal glucose metabolism: A cross-sectional analysis in a birth cohort from Hong Kong

Per- and polyfluoroalkyl substances (PFAS) are persistent chemicals that have been linked to increased risk of gestational diabetes mellitus (GDM) and may affect glucose metabolisms during pregnancy. We examined the associations between maternal PFAS exposure and maternal glucose metabolisms and GDM risk among 1601 mothers who joined the Hyperglycaemia-and-Adverse-Pregnancy-Outcome (HAPO) Study in Hong Kong in 2001-2006. All mothers underwent a 75 g-oral-glucose-tolerance test at 24-32 weeks of gestation. We measured serum concentrations of six PFAS biomarkers using high-performance liquid-chromatography-coupled-with-tandem-mass-spectrometry (LC-MS-MS). We fitted conventional and advanced models (quantile-g-computation [qgcomp] and Bayesian-kernel machine regression [BKMR]) to assess the associations of individual and a mixture of PFAS with glycaemic traits. Subgroup analyses were performed based on the enrollment period by the severe-acute-respiratory-syndrome (SARS) epidemic periods in Hong Kong between March 2003 and May 2004. PFOS and PFOA were the main components of PFAS mixture among 1601 pregnant women in the Hong Kong HAPO study, with significantly higher median PFOS concentrations (19.09 ng/mL), compared to Chinese pregnant women (9.40 ng/mL) and US women (5.27 ng/mL). Maternal exposure to PFAS mixture was associated with higher HbA1c in the qgcomp (β = 0.04, 95 % CI: 0.01-0.06) model. We did not observe significant associations of PFAS mixture with fasting plasma glucose (PG), 1-h and 2-h PG in either model, except for 2-h PG in the qgcmop model (β = 0.074, 95 % CI: 0.01-0.15). PFOS was the primary contributor to the overall positive effects on HbA1c. Epidemic-specific analyses showed specific associations between PFAS exposure and the odds of GDM in the pre-SARS epidemic period. The median concentration of PFOS was highest during the peri-SARS epidemic (21.2 [14.5-43.6] ng/mL) compared with the pre-SARS (12.3 [9.2-19.9] ng/mL) and post-SARS (20.3 [14.2-46.3] ng/mL) epidemic periods. Potential interactions and exposure-response relationships between PFOA and PFNA with elevated HbA1c were observed in the peri-SARS period in BKMR model. Maternal exposure to PFAS mixture was associated with altered glucose metabolism during pregnancy. SARS epidemic-specific associations call for further studies on its long-term adverse health effects, especially potential modified associations by lifestyle changes during the COVID-19 pandemic.

Hazard and risk characterization of 56 structurally diverse PFAS using a targeted battery of broad coverage assays using six human cell types

Per- and poly-fluoroalkyl substances (PFAS) are extensively used in commerce leading to their prevalence in the environment. Due to their chemical stability, PFAS are considered to be persistent and bioaccumulative; they are frequently detected in both the environment and humans. Because of this, PFAS as a class (composed of hundreds to thousands of chemicals) are contaminants of very high concern. Little information is available for the vast majority of PFAS, and regulatory agencies lack safety data to determine whether exposure limits or restrictions are needed. Cell-based assays are a pragmatic approach to inform decision-makers on potential health hazards; therefore, we hypothesized that a targeted battery of human in vitro assays can be used to determine whether there are structure-bioactivity relationships for PFAS, and to characterize potential risks by comparing bioactivity (points of departure) to exposure estimates. We tested 56 PFAS from 8 structure-based subclasses in concentration response (0.1-100 μM) using six human cell types selected from target organs with suggested adverse effects of PFAS - human induced pluripotent stem cell (iPSC)-derived hepatocytes, neurons, and cardiomyocytes, primary human hepatocytes, endothelial and HepG2 cells. While many compounds were without effect; certain PFAS demonstrated cell-specific activity highlighting the necessity of using a compendium of in vitro models to identify potential hazards. No class-specific groupings were evident except for some chain length- and structure-related trends. In addition, margins of exposure (MOE) were derived using empirical and predicted exposure data. Conservative MOE calculations showed that most tested PFAS had a MOE in the 1-100 range; ∼20% of PFAS had MOE<1, providing tiered priorities for further studies. Overall, we show that a compendium of human cell-based models can be used to derive bioactivity estimates for a range of PFAS, enabling comparisons with human biomonitoring data. Furthermore, we emphasize that establishing structure-bioactivity relationships may be challenging for the tested PFAS.

Understanding the effects of per- and polyfluoroalkyl substances on early skin development: Role of ciliogenesis inhibition and altered microtubule dynamics

Per- and polyfluoroalkyl substances (PFAS) are a class of highly stable chemicals, widely used in everyday products, and widespread in the environment, even in pregnant women. While epidemiological studies have linked prenatal exposure to PFAS with atopic dermatitis in children, little is known about their toxic effects on skin development, especially during the embryonic stage. In this study, we utilized human embryonic stem cells to generate non-neural ectoderm (NNE) cells and exposed them to six PFAS (perfluorooctanoic acid (PFOA), undecafluorohexanoic acid (PFHxA), heptafluorobutyric acid (PFBA), perfluorooctane sulfonate (PFOS), perfluorohexane sulfonate (PFHxS) and perfluorobutyric acid (PFBS)) during the differentiation process to assess their toxicity to early skin development. Our results showed that PFOS altered the spindle-like morphology of NNE cells to a pebble-like morphology, and disrupted several NNE markers, including KRT16, SMYD1, and WISP1. The six PFAS had a high potential to cause hypohidrotic ectodermal dysplasia (HED) by disrupting the expression levels of HED-relevant genes. Transcriptomic analysis revealed that PFOS treatment produced the highest number (1156) of differentially expressed genes (DEGs) among the six PFAS, including the keratinocyte-related genes KRT6A, KRT17, KRT18, KRT24, KRT40, and KRT81. Additionally, we found that PFOS treatment disturbed several signaling pathways that are involved in regulating skin cell fate decisions and differentiation, including TGF-β, NOTCH, Hedgehog, and Hippo signaling pathways. Interestingly, we discovered that PFOS inhibited, by partially interfering with the expression of cytoskeleton-related genes, the ciliogenesis of NNE cells, which is crucial for the intercellular transduction of the above-mentioned signaling pathways. Overall, our study suggests that PFAS can inhibit ciliogenesis and hamper the transduction of important signaling pathways, leading potential congenital skin diseases. It sheds light on the underlying mechanisms of early embryonic skin developmental toxicity and provides an explanation for the epidemiological data on PFAS. ENVIRONMENTAL IMPLICATION: We employed a model based on human embryonic stem cells to demonstrate that PFOS has the potential to elevate the risk of hypohidrotic ectodermal dysplasia. This is achieved by targeting cilia, inhibiting ciliogenesis, and subsequently disrupting crucial signaling pathways like TGF-β, NOTCH, Hedgehog, and Hippo, during the early phases of embryonic skin development. Our study highlights the dangers and potential impacts of six PFAS pollutants on human skin development. Additionally, we emphasize the importance of closely considering PFHxA, PFBA, PFHxS, and PFBS, as they have shown the capacity to modify gene expression levels, albeit to a lesser degree.

The association between per- and polyfluoroalkyl substances (PFASs) and brain, esophageal, melanomatous skin, prostate, and lung cancer using the 2003-2018 US National Health and Nutrition Examination Survey (NHANES) datasets

Introduction

The purpose of this study was to use the US National Health and Nutrition Examination Survey (NHANES) datasets to examine potential relationships between four per- and polyfluoroalkyl substance (PFAS) exposures and each type of cancer, specifically perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS), perfluorohexane sulfonic acid (PFHxS), and perfluorononanoic acid (PFNA).

Methods

A logistic regression analysis was performed. A directed acyclic graph was plotted to adjust for the potential confounders.

Results

The odds ratio (OR) of brain cancer for a one-unit increase in ln (PFHxS) was 8.16 (95 % confidence interval [CI] 2.98-68.89). The OR of esophageal cancer for one unit increase of ln (PFOA) and ln (PFOS) was 5.10 (95 % CI 1.18-17.34) and 3.97 (95 % CI 1.24-11.42), respectively. The OR of melanoma for one unit increase of ln (PFOA) and ln (PFHxS) was 1.65 (95 % CI 1.07-2.58) and 1.55 (95 % CI 1.07-2.25), respectively. The OR of prostate cancer for one unit increase of ln (PFOS) and ln (PFNA) was 1.21 (95 % CI 1.00-1.48) and 1.27 (95 % CI 1.00-1.62), respectively. The OR of lung cancer for one unit increase of ln (PFOS) and ln (PFNA) was 2.62 (95 % CI 1.24-5.83) and 2.38 (95 % CI 1.00-5.52), respectively.

Discussion

Considering that brain, esophageal, and melanomatous skin cancers have not been targets of epidemiologic studies regarding PFAS exposure, future studies could target these cancers as outcomes of interest.

PFHxS Exposure and the Risk of Non-Alcoholic Fatty Liver Disease

Perfluorohexanesulfonic acid (PFHxS) is a highly prevalent environmental pollutant, often considered to be less toxic than other poly- and perfluoroalkyl substances (PFASs). Despite its relatively lower environmental impact compared to other PFASs, several studies have suggested that exposure to PFHxS may be associated with disruptions of liver function in humans. Nevertheless, the precise pathomechanisms underlying PFHxS-induced non-alcoholic fatty liver disease (NAFLD) remain relatively unclear. Therefore, this study applied our previously published transcriptome dataset to explore the effects of PFHxS exposure on the susceptibility to NAFLD and to identify potential mechanisms responsible for PFHxS-induced NAFLD through transcriptomic analysis conducted on zebrafish embryos. Results showed that exposure to PFHxS markedly aggravated hepatic symptoms resembling NAFLD and other metabolic syndromes (MetS) in fish. Transcriptomic analysis unveiled 17 genes consistently observed in both NAFLD and insulin resistance (IR), along with an additional 28 genes identified in both the adipocytokine signaling pathway and IR. These shared genes were also found within the NAFLD dataset, suggesting that hepatic IR may play a prominent role in the development of PFHxS-induced NAFLD. In conclusion, our study suggests that environmental exposure to PFHxS could be a potential risk factor for the development of NAFLD, challenging the earlier notion of PFHxS being safer as previously claimed.

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.

Serum per- and polyfluoroalkyl substance concentrations and longitudinal change in post-infection and post-vaccination SARS-CoV-2 antibodies

Per- and polyfluoroalkyl substances (PFAS) are ubiquitous throughout the United States. Previous studies have shown PFAS exposure to be associated with a reduced immune response. However, the relationship between serum PFAS and antibody levels following SARS-CoV-2 infection or COVID-19 vaccination has not been examined. We examined differences in peak immune response and the longitudinal decline of antibodies following SARS-CoV-2 infection and COVID-19 vaccination by serum PFAS levels in a cohort of essential workers in the United States. We measured serum antibodies using an in-house semi-quantitative enzyme-linked immunosorbent assay (ELISA). Two cohorts contributed blood samples following SARS-CoV-2 infection or COVID-19 vaccination. We used linear mixed regression models, adjusting for age, race/ethnicity, gender, presence of chronic conditions, location, and occupation, to estimate differences in immune response with respect to serum PFAS levels. Our study populations included 153 unvaccinated participants that contributed 316 blood draws over a 14-month period following infection, and 860 participants and 2451 blood draws over a 12-month period following vaccination. Higher perfluorooctane sulfonic acid (PFOS), perfluorohexane sulfonic acid (PFHxS), and perfluorononanoic acid (PFNA) concentrations were associated with a lower peak antibody response after infection (p = 0.009, 0.031, 0.015). Higher PFOS, perfluorooctanoic acid (PFOA), PFHxS, and PFNA concentrations were associated with slower declines in antibodies over time after infection (p = 0.003, 0.014, 0.026, 0.025). PFOA, PFOS, PFHxS, and PFNA serum concentrations prior to vaccination were not associated with differences in peak antibody response after vaccination or with differences in decline of antibodies over time after vaccination. These results suggest that elevated PFAS may impede potential immune response to SARS-CoV-2 infection by blunting peak antibody levels following infection; the same finding was not observed for immune response to vaccination.

Machine learning identifies phenotypic profile alterations of human dopaminergic neurons exposed to bisphenols and perfluoroalkyls

Parkinson's disease (PD) is the second most common neurodegenerative disease and is characterized by the loss of midbrain dopaminergic neurons. Endocrine disrupting chemicals (EDCs) are active substances that interfere with hormonal signaling. Among EDCs, bisphenols (BPs) and perfluoroalkyls (PFs) are chemicals leached from plastics and other household products, and humans are unavoidably exposed to these xenobiotics. Data from animal studies suggest that EDCs exposure may play a role in PD, but data about the effect of BPs and PFs on human models of the nervous system are lacking. Previous studies demonstrated that machine learning (ML) applied to microscopy data can classify different cell phenotypes based on image features. In this study, the effect of BPs and PFs at different concentrations within the real-life exposure range (0.01, 0.1, 1, and 2 µM) on the phenotypic profile of human stem cell-derived midbrain dopaminergic neurons (mDANs) was analyzed. Cells exposed for 72 h to the xenobiotics were stained with neuronal markers and evaluated using high content microscopy yielding 126 different phenotypic features. Three different ML models (LDA, XGBoost and LightGBM) were trained to classify EDC-treated versus control mDANs. EDC treated mDANs were identified with high accuracies (0.88-0.96). Assessment of the phenotypic feature contribution to the classification showed that EDCs induced a significant increase of alpha-synuclein (αSyn) and tyrosine hydroxylase (TH) staining intensity within the neurons. Moreover, microtubule-associated protein 2 (MAP2) neurite length and branching were significantly diminished in treated neurons. Our study shows that human mDANs are adversely impacted by exposure to EDCs, causing their phenotype to shift and exhibit more characteristics of PD. Importantly, ML-supported high-content imaging can identify concrete but subtle subcellular phenotypic changes that can be easily overlooked by visual inspection alone and that define EDCs effects in mDANs, thus enabling further pathological characterization in the future.

Effects of short-chain per- and polyfluoroalkyl substances (PFAS) on toxicologically relevant gene expression profiles in a liver-on-a-chip model

Short-chain per- and polyfluoroalkyl substances (PFAS) are highly stable and widely used environmental contaminants that pose potential health risks to humans. Aggregating reliable mechanistic information for safety assessments necessitates physiologically relevant high-throughput screening approaches. Here, we demonstrated the utility of a liver-on-a-chip model to investigate the effects of five short-chain PFAS at low (1 nM) and high (1 μM) concentrations on toxicologically-relevant gene expression profiles using the QuantiGene® Plex Assay. We found that the short-chain PFAS tested in this study modulated the expression of ABCG2, a gene encoding for the breast cancer resistance protein (BCRP), with marked and significant upregulation (up to 4-fold) observed for all but one of the short-chain PFAS tested. PFBS and HFPO-DA repressed SLCO1B3 expression, a gene that encodes for an essential liver-specific organic anion transporter. High concentrations of PFBS, PFHxA, and PFHxS upregulated the expression of genes encCYP1A1,CYP2B6 and CYP2C19 with the same treatments resulting in the repression of the expression of the gene encoding CYP1A2. This dysregulation could have consequences for the clearance of endogenous compounds and xenobiotics. However, we acknowledge that increased expression of genes encoding for transporters and biotransformation enzymes may or may not indicate changes to their protein expression or activity. Overall, our study provides important insights into the effects of short-chain PFAS on liver function and their potential implications for human health. The use of the liver-on-a-chip model in combination with the QuantiGene® Plex Assay may be a valuable tool for future high-throughput screening and gene expression profiling in toxicology studies.

Time trends in per- and polyfluoroalkyl substances (PFAS) concentrations in the Danish population: A review based on published and newly analyzed data

INTRODUCTION

Per- and polyfluoroalkyl substances (PFAS) are persistent chemicals used in many industries and everyday consumer products and exposure has been linked to several adverse health outcomes. Currently, no systematic monitoring of PFAS levels in the general Danish population has been conducted.

OBJECTIVE

To study temporal trends of PFAS concentrations in the Danish population.

MATERIALS AND METHODS

In August 2023, we performed a search for original peer-reviewed reports in PubMed using combinations of search terms for PFAS and Denmark. Reports were included if they comprised a Danish study population and direct measurements of PFAS in serum or plasma samples. Scatter plots of medians presented in the reports were used to visualize time-trends of PFAS concentrations among Danish individuals.

RESULTS

We included 29 reports based on a total of 18,231 individuals from 19 Danish study populations. A total of 24 PFAS measured in serum or plasma were presented in the reports, the most frequent being PFOS, PFOA, PFDA, PFNA, PFHpA, PFHpS, and PFHxS. Median concentrations of PFOS ranged from 4.0 ng/mL to 44.5 ng/mL, PFOA ranged from 0.8 ng/mL to 9.7 ng/mL, while lower concentrations were presented for the other PFAS. Median concentrations of PFOS and PFOA increased from 1988 until the late 1990s followed by a decrease until 2021. A less clear time-trend were observed for the other PFAS.

CONCLUSION

Blood concentrations of PFOS and PFOA in the Danish population have declined substantially from the late 1990s until 2021 reflecting a phase-out of the production and regulation of the use of these PFAS. Time-trends for PFDA, PFNA, PFHpA, PFHpS, and PFHxS were less evident, yet a tendency toward a decline was observed. As only some of the compounds are measured, it is not possible to determine if the decrease in some PFAS is outweighed by an increase in others.

Association between prenatal exposure to per- and polyfluoroalkyl substances and neurodevelopment in children: Evidence based on birth cohort

BACKGROUND

Although numerous studies have examined the effect of prenatal per- and polyfluoroalkyl substances (PFAS) exposure on neurodevelopment in children, findings have been inconsistent.

OBJECTIVE

To better understand the effects of PFAS exposure during pregnancy on offspring neurodevelopment, we conducted a systematic review of prenatal exposure to different types of PFAS and neurodevelopment in children.

METHODS

A comprehensive search was conducted in the PubMed, Web of Science, and EMBASE electronic databases up to March 2023. Only birth cohort studies that report a specific association between PFAS exposure during pregnancy and neurodevelopment were included in this review.

RESULTS

31 birth cohort studies that met the inclusion criteria were qualitatively integrated. Among these, 14 studies investigated the impact of PFAS exposure during pregnancy on cognition, 13 on neurobehavior, and 4 on both cognition and neurobehavior. Additionally, 4 studies explored the influence of PFAS on children's comprehensive development.

CONCLUSION

Prenatal PFAS exposure was associated with poor neurodevelopment in children, including psychomotor development, externalizing behavior, and comprehensive development. However, conclusive evidence regarding its effects on other neurological outcomes remains limited. In addition, sex-specific effects on social behavior and sleep problems were identified.

Cloth-Air Partitioning of Neutral Per- and Polyfluoroalkyl Substances (PFAS) in North Carolina Homes during the Indoor PFAS Assessment (IPA) Campaign

Partitioning of per- and polyfluoroalkyl substances (PFAS) to indoor materials, including clothing, may prolong the residence time of PFAS indoors and contribute to exposure. During the Indoor PFAS Assessment (IPA) Campaign, we measured concentrations of nine neutral PFAS in air and cotton cloth in 11 homes in North Carolina, for up to 9 months. Fluorotelomer alcohols (i.e., 6:2 FTOH, 8:2 FTOH, and 10:2 FTOH) are the dominant target species in indoor air, with concentrations ranging from 1.8 to 49 ng m-3, 1.2 to 53 ng m-3, and 0.21 to 5.7 ng m-3, respectively. In cloth, perfluorooctane sulfonamidoethanols (i.e., MeFOSE and EtFOSE) accumulated most significantly over time, reaching concentrations of up to 0.26 ng cm-2 and 0.24 ng cm-2, respectively. From paired measurements of neutral PFAS in air and suspended cloth, we derived cloth-air partition coefficients (Kca) for 6:2, 8:2, and 10:2 FTOH; ethylperfluorooctane sulfonamide (EtFOSA); MeFOSE; and EtFOSE. Mean log(Kca) values range from 4.7 to 6.6 and are positively correlated with the octanol-air partition coefficient. We investigated the effect of the cloth storage method on PFAS accumulation and the influence of home characteristics on air concentrations. Temperature had the overall greatest effect. This study provides valuable insights into PFAS distribution, fate, and exposure indoors.

Pets, Genuine Tools of Environmental Pollutant Detection

In a shared environment, our companion animals became unintended sentinels for pollutant exposure consequences, developing even earlier similar conditions to humans. This review focused on the human-pet cohabitation in an environment we all share. Alongside other species, canine and feline companions are veritable models in human medical research. The latency period for showing chronic exposure effects to pollutants is just a few years in them, compared to considerably more, decades in humans. Comparing the serum values of people and their companion animals can, for example, indicate the degree of poisonous lead load we are exposed to and of other substances as well. We can find 2.4 times higher perfluorochemicals from stain- and grease-proof coatings in canine companions, 23 times higher values of flame retardants in cats, and 5 times more mercury compared to the average levels tested in humans. All these represent early warning signals. Taking these into account, together with the animal welfare orientation of today's society, finding non-invasive methods to detect the degree of environmental pollution in our animals becomes paramount, alongside the need to raise awareness of the risks carried by certain chemicals we knowingly use.

Biomonitoring equivalents for perfluorooctanoic acid (PFOA) for the interpretation of biomonitoring data

BACKGROUND

Perfluorooctanoic acid (PFOA) is detected in the blood of virtually all biomonitoring study participants. Assessing health risks associated with blood PFOA levels is challenging because exposure guidance values (EGVs) are typically expressed in terms of external dose. Biomonitoring equivalents (BEs) consistent with EGVs could facilitate health-based interpretations.

OBJECTIVE

To i) derive BEs for serum/plasma PFOA corresponding to non-cancer EGVs of the U.S. Environmental Protection Agency (U.S. EPA), the Agency for Toxic Substances and Disease Registry (ATSDR) and Health Canada, and ii) compare with PFOA concentrations from national biomonitoring surveys.

METHODS

Starting from EGV points of departure, we employed pharmacokinetic data/models and uncertainty factors. Points of departure in pregnant rodents (U.S. EPA 2016, ATSDR) were converted into fetus and pup serum concentrations using an animal gestation/lactation pharmacokinetic model, and equivalent human fetus and child concentrations were converted into BEs in maternal serum using a human gestation/lactation model. The point of departure in adult rodents (Health Canada) was converted into a BE using experimental data. For epidemiology-based EGVs (U.S. EPA 2023, draft), BEs were directly based on epidemiological data or derived using a human gestation/lactation pharmacokinetic model. BEs were compared with Canadian/U.S. biomonitoring data.

RESULTS

Non-cancer BEs (ng/mL) were 684 (Health Canada, 2018) or ranged from 15 to 29 (U.S. EPA, 2016), 6-10 (ATSDR, 2021) and 0.2-0.8 (U.S. EPA, 2023, draft). Ninety-fifth percentiles of serum levels from the 2018-2019 Canadian Health Measures Survey (CHMS) and the 2017-2018 National Health and Nutrition Examination Survey (NHANES) were slightly below the BE for ATSDR, and geometric means were above the non-cancer BEs for the U.S. EPA (2023, draft).

CONCLUSION

Non-cancer BEs spanned three orders of magnitude. The lowest BEs were for EGVs based on developmental endpoints in epidemiological studies. Concentrations in Canadian/U.S. national surveys were higher than or close to BEs for the most recent non-cancer EGVs.

Per- and polyfluoroalkyl substances (PFAS) and thyroid hormone measurements in dried blood spots and neonatal characteristics: a pilot study

BACKGROUND

Pediatric thyroid diseases have been increasing in recent years. Environmental risk factors such as exposures to chemical contaminants may play a role but are largely unexplored. Archived neonatal dried blood spots (DBS) offer an innovative approach to investigate environmental exposures and effects.

OBJECTIVE

In this pilot study, we applied a new method for quantifying per- and polyfluoroalkyl substances (PFAS) to 18 archived DBS from babies born in California from 1985-2018 and acquired thyroid hormone measurements from newborn screening tests. Leveraging these novel data, we evaluated (1) changes in the concentrations of eight PFAS over time and (2) the relationship between PFAS concentrations, thyroid hormone concentrations, and neonatal characteristics to inform future research.

METHODS

PFAS concentrations in DBS were measured using ultra-high-performance liquid chromatography-mass spectrometry. Summary statistics and non-parametric Wilcoxon rank-sum and Kruskal-Wallis tests were used to evaluate temporal changes in PFAS concentrations and relationships between PFAS concentrations, thyroid hormone concentrations, and neonatal characteristics.

RESULTS

The concentration and detection frequencies of several PFAS (PFOA, PFOS, and PFOSA) declined over the assessment period. We observed that the timing of specimen collection in hours after birth was related to thyroid hormone but not PFAS concentrations, and that thyroid hormones were related to some PFAS concentrations (PFOA and PFOS).

IMPACT STATEMENT

This pilot study examines the relationship between concentrations of eight per- and polyfluoroalkyl substances (PFAS), thyroid hormone levels, and neonatal characteristics in newborn dried blood spots (DBS) collected over a period of 33 years. To our knowledge, 6 of the 22 PFAS we attempted to measure have not been quantified previously in neonatal DBS, and this is the first study to examine both PFAS and thyroid hormone concentrations using DBS. This research demonstrates the feasibility of using newborn DBS for quantifying PFAS exposures in population-based studies, highlights methodological considerations in the use of thyroid hormone data for future studies using newborn DBS, and indicates potential relationships between PFAS concentrations and thyroid hormones for follow-up in future research.

Effects of short-chain per- and polyfluoroalkyl substances (PFAS) on human cytochrome P450 (CYP450) enzymes and human hepatocytes: An in vitro study

Short-chain per- and polyfluoroalkyl substances (PFAS) have been developed as alternatives to legacy long-chain PFAS, but they may still pose risks due to their potential to interact with biomolecules. Cytochrome P450 (CYP450) enzymes are essential for xenobiotic metabolism, and disruptions of these enzymes by PFAS can have significant human health implications. The inhibitory potential of two legacy long-chain (PFOA and PFOS) and five short-chain alternative PFAS (PFBS, PFHxA, HFPO-DA, PFHxS, and 6:2 FTOH) were assessed in recombinant CYP1A2, - 2B6, -2C19, -2E1, and -3A4 enzymes. Most of the short-chain PFAS, except for PFHxS, tested did not result in significant inhibition up to 100 μM. PFOS inhibited recombinant CYP1A2, -2B6, -2C19, and -3A4 enzymes. However, concentrations where inhibition occurred, were all higher than the averages reported in population biomonitoring studies, with IC50 values higher than 10 µM. We also evaluated the activities of CYP1A2 and CYP3A4 in HepaRG monolayers following 48 h exposures of the short-chain PFAS at two concentrations (1 nM or 1 µM) and with or without an inducer (benzo[a]pyrene, BaP, for CYP1A2 and rifampicin for CYP3A4). Our findings suggest that both 1 nM and 1 µM exposures to short-chain PFAS can modulate the CYP1A2 activity induced by BaP. Except for PFHxS, the short-chain PFAS appear to have little effect on CYP3A4 activity. Understanding the effects of PFAS exposure on biotransformation can shed light on the mechanisms of PFAS toxicity and aid in developing effective strategies for managing chemical risks, enabling regulators to make more informed decisions.

Perfluorooctanoic acid (PFOA) affects steroidogenesis and antioxidant defence in granulosa cells from swine ovary

PFOA is mainly employed in products with water and oil repellent properties. Due to its persistence, bioaccumulation and critical effects on health, its use has been restricted in several countries. This research was intended to explore PFOA action on the main functions of swine ovarian granulosa cells, a valuable model for translational medicine. Moreover, since we previously demonstrated a disruptive effect on free radical generation we sought to explore PFOA effects on the main antioxidant enzymes. PFOA inhibited cell proliferation (p < 0.001), assessed by BrdU uptake. Steroidogenesis was disrupted: PFOA also stimulated 17β-estradiol production (p < 0.05), increased progesterone production (p < 0.05) at the lowest dose while it displayed an inhibitory effect at higher concentrations (p < 0.05). SOD (p < 0.001), catalase (p < 0.05) and peroxidase (p < 0.01) activities were stimulated. Therefore, our study supports a disruptive effect of PFOA in cultured swine granulosa cells.

An analysis of the use of the relative source contribution term in derivation of drinking water standards using perfluorooctanoic acid as an example

The relative source contribution (RSC) term has long been used by the US Environmental Protection Agency (USEPA) and state regulatory agencies in setting criteria in water. The RSC reflects the proportion of the total daily intake of a chemical that can be derived from water when all other sources of exposure (e.g., food, air) are considered. This term is applied by the USEPA and state regulatory agencies when deriving ambient water quality criteria, maximum contaminant level goals, and drinking water health advisories for noncarcinogenic and threshold carcinogenic compounds. The value assigned to the RSC term affects the calculated criteria directly, with the allowable concentration in water decreasing with a decreasing RSC. A default RSC value of 20%-applied by regulatory entities in the USA for more than 40 years-assumes that 80% of an individual's exposure to a chemical's reference dose is from nonwater sources. Although the RSC is a chemical-specific parameter, there are few instances where a value other than the default of 20% has been approved and used. In 2000, USEPA outlined the process for developing chemical-specific RSC values, yet primary use of the default RSC value has continued since then. This article reviews USEPA's methodology for deriving chemical-specific RSC values and provides a case example using perfluorooctanoic acid (PFOA) to explore how the USEPA and state regulatory agencies are applying USEPA's guidance. The case study highlights inconsistent derivation of the RSC term, rooted in limitations in the current methodology. We suggest additional clarification of and more thoughtful use of the available data that may not meet USEPA's current adequacy requirements. We also recommend that the USEPA discuss recommendations for using biomonitoring data to set RSCs. Integr Environ Assess Manag 2023;19:605-612. © 2022 SETAC.

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

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

Short-chain per- and polyfluoralkyl substances (PFAS) effects on oxidative stress biomarkers in human liver, kidney, muscle, and microglia cell lines

Long-chain per- and polyfluoralkyl substances (PFAS) are ubiquitous contaminants implicated in the induction of intracellular reactive oxygen species (ROS), compromising antioxidant defense mechanisms in vitro and in vivo. While a handful of studies have assessed oxidative stress effects by PFAS, few specifically address short-chain PFAS. We conducted an evaluation of oxidative stress biomarkers in vitro following exposures to low (1 nM) and high (1 μM) concentrations of five short-chain PFAS compounds: perfluorobutanesulfonic acid (PFBS), perfluorohexanoic acid (PFHxA), [undecafluoro-2-methyl-3-oxahexanoic acid (HFPO-DA)], 6:2 fluorotelomer alcohol (6:2 FTOH) and perfluorohexanesulfonic acid (PFHxS). We conducted experiments in human kidney (HEK293-hTLR2), liver (HepaRG), microglia (HMC-3), and muscle (RMS-13) cell lines. Fluorescence microscopy measurements in HepaRG cells indicated ROS generation in cells exposed to PFBS and PFHxA for 24 h. Antioxidant enzyme activities were determined following 24 h short-chain PFAS exposures in HepaRG, HEK293-hTLR2, HMC-3, and RMS-13. Notably, exposure to PFBS for 24 h increased the activity of GPX in all four cell types at 1 μM and 1 nM in HepaRG and RMS-13 cells. Every short-chain PFAS evaluated, except for PFHxS, increased the activity of at least one antioxidant enzyme. To our knowledge, this is the first study of its kind to explore antioxidant defense alterations to microglia and muscle cell lines by PFAS. The findings of this study hold great potential to contribute to the limited understanding of short-chain PFAS mechanisms of toxicity and provide data necessary to inform the human health risk assessment process.

Unveiling Distribution of Per- and Polyfluoroalkyl Substances in Matched Placenta-Serum Tetrads: Novel Implications for Birth Outcome Mediated by Placental Vascular Disruption

The placenta is pivotal for fetal development and maternal-fetal transfer of many substances, including per- and polyfluoroalkyl substances (PFASs). However, the intraplacental distribution of PFASs and their effects on placental vascular function remain unclear. In this study, 302 tetrads of matched subchorionic placenta (fetal-side), parabasal placenta (maternal-side), cord serum, and maternal serum samples were collected from Guangzhou, China. Eighteen emerging and legacy PFASs and five placental vascular biomarkers were measured. Results showed that higher levels of perfluorooctanoic (PFOA), perfluorooctane sulfonic acid (PFOS), and chlorinated polyfluorinated ether sulfonic acids (Cl-PFESAs) were detected in subchorionic placenta compared to parabasal placenta. There were significant associations of PFASs in the subchorionic placenta, but not in the serum, with placental vascular biomarkers (up to 32.5%) and lower birth size. Birth weight was negatively associated with PFOA (β: -103.8, 95% CI: -186.3 and -21.32) and 6:2 Cl-PFESA (β: -80.04, 95% CI: -139.5 and -20.61), primarily in subchorionic placenta. Mediation effects of altered placental angiopoietin-2 and vascular endothelial growth factor receptor-2 were evidenced on associations of adverse birth outcomes with intraplacental PFOS and 8:2 Cl-PFESA, explaining 9.5%-32.5% of the total effect. To the best of our knowledge, this study is the first to report on differential intraplacental distribution of PFASs and placental vascular effects mediating adverse birth outcomes and provides novel insights into the placental plate-specific measurement in PFAS-associated health risk assessment.

Bioaccessibility of per- and polyfluoroalkyl substances in food and dust: Implication for more accurate risk assessment

Humans are exposed to per- and polyfluoroalkyl substances (PFASs) mainly through oral exposure route, while little is known about their bioaccessibility (BC) in oral matrices. Here, the BC of 13 PFASs in simulated vegetable (VFs) and animal foods (AFs) as well as indoor dust was investigated using a physiology-based extraction test. The BC of PFASs in the AFs (78.5 ± 13.6 %) was distinctly higher than that in the VFs (60.6 ± 13.4 %), because high-saturated and long-chain fatty acids in the animal fat favored formation of more stable micelles. The BC of most long-chain PFASs was positively correlated with the protein content while negatively correlated with the carbohydrate content in the foods. The BC of polyfluoroalkyl phosphate diesters was negatively correlated with the lipid content. The BC of the very long-chain PFASs in the foods was 2.42-6.02 times higher than that in the dust, which might be attributed to their strong sequestration in dust. With the increase in bile salt concentration, the BC of PFASs in food increased and then remained constant, which was related to the changes in fatty acids and stability of the formed micelles. Comparing with the previous results obtained from animal study, the BC obtained in this study has the potential to predict PFAS bioavailability in food.

Systematic Evidence Mapping of Potential Exposure Pathways for Per- and Polyfluoroalkyl Substances Based on Measured Occurrence in Multiple Media

Given that human biomonitoring surveys show per- and polyfluoroalkyl substances (PFAS) to be ubiquitous, humans can be exposed to PFAS through various sources, including drinking water, food, and indoor environmental media. Data on the nature and level of PFAS in residential environments are required to identify important pathways for human exposure. This work investigated important pathways of exposure to PFAS by reviewing, curating, and mapping evidence for the measured occurrence of PFAS in exposure media. Real-world occurrence for 20 PFAS was targeted primarily in media commonly related to human exposure (outdoor and indoor air, indoor dust, drinking water, food, food packaging, articles, and products, and soil). A systematic-mapping process was implemented to conduct title-abstract and full-text screening and to extract PECO-relevant primary data into comprehensive evidence databases. Parameters of interest included the following: sampling dates and locations, numbers of collection sites and participants, detection frequencies, and occurrence statistics. Detailed data were extracted on PFAS occurrence in indoor and environmental media from 229 references and on PFAS occurrence in human matrices where available from those references. Studies of PFAS occurrence became numerous after 2005. Studies were most abundant for PFOA (80% of the references) and PFOS (77%). Many studies analyzed additional PFAS, particularly, PFNA and PFHxS (60% of references each). Food (38%) and drinking water (23%) were the commonly studied media. Most studies found detectable levels of PFAS, and detectable levels were reported in a majority of states in the United States. Half or more of the limited studies for indoor air and products detected PFAS in 50% or more of the collected samples. The resulting databases can inform problem formulation for systematic reviews to address specific PFAS exposure queries and questions, support prioritization of PFAS sampling, and inform PFAS exposure measurement studies. The search strategy should be extended and implemented to support living evidence review in this rapidly advancing area.

Determination of 21 per- and poly-fluoroalkyl substances in paper- and cardboard-based food contact materials by ultra-high-performance liquid chromatography coupled to high-resolution mass spectrometry

In this work, a new analytical method was developed and validated for the determination of the total content of 21 per- and poly-fluoroalkyl substances (PFASs) in paper- and cardboard-based food contact materials (FCMs). This method is based on green ultrasound-assisted lixiviation followed by ultra-high-performance liquid chromatography coupled to high-resolution mass spectrometry (UHPLC-Q-Orbitrap HRMS). The method was validated in various paper- and cardboard-based FCMs, showing good linearity (R² ≥ 0.99), limits of quantification (1.7-10 μg kg^-1), accuracy (74-115%), and precision (RSD < 20%). The eco-friendly characteristics of the proposed analytical method were assessed according to the analytical eco-scale, demonstrating that it can be considered an excellent green analytical method (EcoScale score > 75). Finally, 16 field samples of paper- and cardboard-based FCMs, including pizza boxes, popcorn boxes, paper bags and cardboard boxes for potato fries, ice cream tubs, pastry trays, and cardboard-based packaging for cooked Spanish omelets, fresh grapes, frozen fish, and salads were analyzed, showing that they comply with the current European regulations regarding the studied PFASs. The developed method is currently accredited according to UNE-EN ISO/IEC 17025 by the Spanish National Accreditation Body (ENAC) to be implemented for official control analysis of FCMs in the Public Health Laboratory of Valencia, Generalitat Valenciana (Valencia, Spain).

The Psychological Impact of Per- and Poly-Fluoroalkyl Substances (PFAS) Pollution in the Veneto Region, Italy: A Qualitative Study with Parents

Little is known about the psychosocial impact on people who live in polluted areas, and its consequences for the parental role have been neglected. This study addresses this gap, proposing qualitative research referring to the case of per- and poly-fluoroalkyl substances (PFAS) water pollution in the Veneto Region of Italy. The purpose of this study was to investigate the chronic exposure contamination (CEC) experience of parents. Semi-structured interviews were conducted with 32 parents living in the so-called 'Red Area' considered to have had maximum exposure. Grounded theory was used to analyse the data. The three themes to emerge were three phases of a dynamic process: shock around the discovery (phase 1), lifestyle change (phase 2), and living with PFAS (phase 3). The two transitions (loss of innocence and environmental adaptation) linked the phases. Our findings show that PFAS CEC experience is a process whereby parents need to move from the shock of discovery to adapting to the new situation in order to incorporate a change into their daily life, especially in regard to children. Two emerging aspects that characterised the process as a constant were uncertainty and health concerns, while role strains could be a stress source in the context of CEC. We suggest introducing the notion of chronic role strain (CRS).

Sources, occurrence, and treatment techniques of per- and polyfluoroalkyl substances in aqueous matrices: A comprehensive review

Per- and polyfluoroalkyl substances (PFAS), a class of synthetic organic pollutants, have prompted concerns about their global prevalence and possible health effects. This review consolidates the most recent data on different aspects of PFAS, such as their occurrence, and prominent sources. The current literature analysis of PFAS occurrence suggests significant variation in their concentration ranging from 0.025 to 1.2 × 10⁸ ng/L in wastewater, 0.01 to 8.9 × 10⁵ ng/L in surface water, and <0.01 to 1.3 × 10⁴ ng/L in groundwater globally. Since conventional treatment techniques are inadequate in remediating PFAS, innovative treatment approaches based on their removal or mineralization mechanism have been comprehensively reviewed. Advanced treatment technologies have shown degradation or removal of PFAS to be around 6 and > 99.9% in different aqueous matrices. However, due to significant drawbacks in their applicability in wastewater treatment plants (WWTPs), a novel treatment train approach has emerged as an effective alternative. This approach synergistically integrates multiple remediation techniques while addressing the impediments of individual treatments. Furthermore, nanofiltration (NF270) combined with electrochemical degradation has been demonstrated to be the most efficient (>98%) treatment train approach in PFAS remediation. If implemented in WWTPs, nanofiltration followed by adsorption using activated carbon is also a viable method for PFAS removal.

The Role of Ferroptosis in the Damage of Human Proximal Tubule Epithelial Cells Caused by Perfluorooctane Sulfonate

Perfluorooctane sulfonate (PFOS) is a typical persistent organic pollutant and environmental endocrine disruptor that has been shown to be associated with the development of many diseases; it poses a considerable threat to the ecological environment and to human health. PFOS is known to cause damage to renal cells; however, studies of PFOS-induced ferroptosis in cells have not been reported. We used the CCK-8 method to detect cell viability, flow cytometry and immunofluorescence methods to detect ROS levels and Western blot to detect ferroptosis, endoplasmic reticulum stress, antioxidant and apoptosis-related proteins. In our study, we found that PFOS could induce the onset of ferroptosis in HK-2 cells with decreased GPx4 expression and elevated ACSL4 and FTH1 expression, which are hallmarks for the development of ferroptosis. In addition, PFOS-induced ferroptosis in HK-2 cells could be reversed by Fer-1. We also found that endoplasmic reticulum stress and its mediated apoptotic mechanism and P53-mediated antioxidant mechanism are involved in the toxic damage of cells by PFOS. In this paper, we demonstrated for the first time that PFOS can induce ferroptosis in HK-2 cells. In addition, we preliminarily explored other mechanisms of cytotoxic damage by PFOS, which provides a new idea to study the toxicity of PFOS as well as the damage to the kidney and its mechanism.

Perfluorooctanoic Acid (PFOA) Induces Redox Status Disruption in Swine Granulosa Cells

Perfluorooctanoic acid (PFOA) is employed in the production and processing of several plastic materials, mainly during the production of waterproof fabrics or nonstick cookware. PFOA is identified as a substance of very high concern, as it is classified as a persistent, bioaccumulative, and toxic (PBT) substance because of its persistence in the environment and its potential accumulation in organisms. Thus, safe levels of exposure cannot be established, and PFOA emissions should be minimized. PFOA has recently been linked to several health concerns in humans. In particular, a disruptive effect on redox status homeostasis has been documented, with a potential impairment of normal reproductive function that requires adequate oxidative balance. Therefore, the aim of the present study was to evaluate the effects of PFOA (2, 20, and 200 ng/mL) on ovarian granulosa cells, a model of reproductive cells. The obtained results reveal that PFOA stimulated cell viability (p < 0.05). Regarding the effects on free radical production, O2−, NO, and H2O2 were significantly inhibited (p < 0.05), while the nonenzymatic antioxidant power was not significantly modified. Collectively, the present results deserve attention since free radical molecules play a crucial role in ovarian follicle development leading to a successful ovulation.