Perfluoroalkyl Substances Research Articles

Structure, orientation, and dynamics of per- and polyfluoroalkyl substance (PFAS) surfactants at the air-water interface: Molecular-level insights

HypothesisUnderstanding the intricate molecular-level details of toxic per- and polyfluoroalkyl substances (PFAS) partitioning to the air–water interface holds paramount importance in evaluating their fate and transport, as well as for finding safer alternatives for various applications, including aqueous film forming foams. The behavior of these substances at interfaces strongly depends on molecular architecture, chemistry, and concentration, which define molecular packing, self-assembly, interfacial diffusion, and the surface tension. SimulationsModeling of three PFAS surfactants, namely, longer-tail (perfluorooctanoate (PFOA)) and shorter-tail (perfluorobutanoate (PFBA) and 2,3,3,3-tetrafluoro-2-(heptafluoropropoxy) propanoate (GenX)) has been conducted using atomistic molecular dynamics simulations. A systematic comparison between these representative PFAS of different sizes and structure reveals factors influencing their association behavior, mechanism of surface tension reduction, and interfacial mobility as a function of surface coverage. FindingsShorter-chain PFAS surfactants (GenX or PFBA) require lower surface coverage compared to longer chain (PFOA) PFAS to achieve the same decrease in surface tension. However, a higher concentration of GenX and PFBA is necessary in the bulk aqueous solution to achieve the same surface coverage as PFOA, due to their higher solubility in water. The PFAS molecular orientation and mobility at the interface are found to be vastly influenced by the length and architecture of the hydrophobic fluorocarbon tail. A significant ordering of the water dipole moment near the anionic headgroup is apparent at high surface concentration. A direct correlation is established between the PFAS interfacial properties and PFAS-PFAS, PFAS-counterion, and PFAS-water interactions.

Association of coexposure to perfluoroalkyl and polyfluoroalkyl compounds and heavy metals with pregnancy loss and reproductive lifespan: The mediating role of cholesterol

Previous studies have demonstrated the toxic effects of per- and polyfluoroalkyl substances (PFASs) and heavy metals on the reproductive system. However, the interactions and combined effects of these substances remain unexplored. This study utilizes data from the National Health and Nutrition Examination Survey to investigate the associations between coexposure to four types of PFASs, lead (Pb), mercury (Hg) and self-reported pregnancy loss and reproductive lifespan in females. Genes associated with these substances and abortion were identified via the Comparative Toxicogenomics Database. The results revealed that Ln-PFOA (IRR=1.88, 95 % CI=1.42–2.50, Ln--: log transformed), Ln-PFOS (IRR=1.58, 95 % CI=1.12–2.22), Ln-PFHxS (IRR=1.99, 95 % CI=1.57–2.52), and Ln-Hg (IRR=1.92, 95 % CI=1.41–2.43) were positively associated with the risk of pregnancy loss. Ln-PFOA (β=1.27, 95 % CI=0.28–2.27), Ln-PFOS (β=1.01, 95 % CI=0.39–1.63), Ln-PFHxS (β=0.71, 95 % CI=0.12–1.63), Ln-PFNA (β=1.15, 95 % CI=0.23–2.08), Ln-Pb (β=3.87, 95 % CI=2.58–5.15), and Ln-Hg (β=1.01, 95 % CI=0.39–1.64) exposures were positively associated with reproductive lifespan. The mixed and overall effects of coexposure to PFASs and heavy metals were positively correlated with the risk of pregnancy loss and reproductive lifespan. Cholesterol partially mediated the association with the risk of pregnancy loss, whereas delay in menopause fully mediated the association with reproductive lifespan. Significant additive interactions were observed between PFOA and Pb and between PFOS, PFHxS, PFNA and Hg at high levels of coexposure. Thirty-nine overlapping genes associated with abortion were identified for these substances, and further analyses revealed that these genes significantly interact and may contribute to abortion through oxidative stress.

Associations of PFASs and Pesticides with Lung Function Changes from Adolescence to Young Adulthood in the ESPINA study.

Per- and polyfluoroalkyl substances (PFASs) and pesticides are ubiquitous environmental exposures with increasingly recognized adverse health outcomes; however, their impact on lung function, particularly in combination, remains poorly understood. We included 381 adolescent participants from a prospective cohort study in Ecuador who underwent measurements of serum PFAS (perfluorooctanoic acid [PFOA], perfluorooctanesulfonic acid [PFOS] and perfluorononanoic acid [PFNA]) and urinary herbicides (glyphosate, 2,4D) and fungicides (ethylene thiourea) and had spirometric measurements in either 2016 or 2022. We characterized the association between each PFAS or pesticide and each lung function measure in log-log models estimated via ordinary least squares regression. We used quantile g-computation to assess the association of the mixture of PFAS and pesticides with lung function outcomes. After accounting for multiple hypothesis testing, and in models adjusting for household income, parental education, and exposure to tobacco, we found that, individually, PFOA, glyphosate, and ETU were associated with slight increases in FEV 1 /FVC between 2016 and 2022. No other individual associations were significant. In mixtures analyses, a one quartile increase in all PFASs and pesticides simultaneously was also not associated with statistically significant changes in lung function outcomes after accounting for multiple hypothesis testing. In large part, we do not provide evidence for associations of PFAS and herbicide and fungicide pesticides with lung function among adolescents in moderate-to-high-altitude agricultural communities in Ecuador.

Effects of Perfluorinated Alkyl Substances (PFAS) on Amphibian Body and Liver Conditions: Is Lipid Metabolism Being Perturbed throughout Metamorphosis?

Per- and polyfluoroalkyl substances (PFAS) may interact with peroxisome proliferator activated receptors (PPARs) and alter lipid homeostasis. Using Xenopus laevis, we investigated the effect of PFAS on (a) lipid homeostasis and whether this correlated to changes in body and hepatic condition; (b) the expression of hepatic genes regulated by PPAR; and (c) the hepatic lipidome. We chronically exposed tadpoles to 0.5 µg/L of either PFOS, PFHxS, PFOA, PFHxA, a binary mixture of PFOS and PFHxS (0.5 µg/L of each), or a control, from NF stage 52 through metamorphic climax. Growth, development, and survival were not affected, but we detected a sex-specific decrease in body condition at NF 66 (6.8%) and in hepatic condition (16.6%) across metamorphic climax for male tadpoles exposed to PFOS. We observed weak evidence for the transient downregulation of apolipoprotein-V (apoa5) at NF 62 in tadpoles exposed to PFHxA. Acyl-CoA oxidase 1 (acox1) was downregulated only in males exposed to PFHxS (Ln(Fold Change) = -0.54). We detected PFAS-specific downregulation of structural glycerophospholipids, while semi-quantitative profiling detected the upregulation in numerous glycerophospholipids, sphingomyelins, and diglycerides. Overall, our findings indicate that PFAS can induce sex-specific effects that change across larval development and metamorphosis. We demonstrate that PFAS alter lipid metabolism at environmentally relevant concentrations through divergent mechanisms that may not be related to PPARs, with an absence of effects on body condition, demonstrating the need for more molecular studies to elucidate mechanisms of PFAS-induced lipid dysregulation in amphibians and in other taxa.

Cellulose Nanocrystal-in-Solvent Processing for Efficient One-Pot Upcycling of Commercial Polymeric PFAS.

Upcoming regulations aim to ban per- and polyfluoroalkyl substances (PFAS), including commercial polymeric PFAS, or fluoropolymers, such as poly(tetrafluoroethylene) (PTFE) and poly(vinylidene fluoride) (PVDF), due to their environmental and toxicological impacts. However, fluoropolymers also provide crucial properties for clean energy transitions, and their regulation may hinder further technological advancements. Therefore, a facile one-pot recycling-upcycling strategy for fluoropolymers using inexpensive biomass, such as cellulose nanocrystals (CNCs), as absorbents and cocomponents for fluoro-functionalized composites could align with global sustainability goals and technological demands. Herein, we present a closed-loop CNC-in-solvent (CiS) processing system, which involves stirring fluoropolymers and CNCs in only low-polarity solvents like toluene (CiS-T). Our study reveals that CiS-T is a two-step process where the CNC-solvent interaction exposes CNCs' reducing end aldehyde protons due to solvent polarity and promotes H-F bond formation. The solvent used was recollected and reused. Additionally, we demonstrate the practical application of PTFE- and PVDF-CNC hybrids, byproducts of the CiS-T process, as performance-enhancing agents in green-energy-harvesting devices such as triboelectric nanogenerators. Our findings not only offer a sustainable method to overcome challenges from regulations against commercial fluoropolymers but also offer insights into developing an efficient, solvent-mediated CNC functionalization process that addresses forthcoming challenges in key industries.

Serum per- and polyfluoroalkyl substance (PFAS) levels and health-related biomarkers in a pilot study of skiers in New England

BackgroundPer- and polyfluoroalkyl substances (PFAS), synthetic chemicals with adverse health effects, are used extensively in consumer products. Ski waxes, applied to the base of skis, contain up to 100% PFAS by mass, but exposure and health effects are poorly characterized. ObjectivesOur objectives were to quantify serum PFAS concentrations among skiers and explore associations with reported ski wax use and biomarkers of cardiometabolic, thyroid, and immune health. MethodsWe recruited 30 active adult skiers to provide non-fasting blood samples and complete questionnaires. We quantified 18 PFAS using mass spectrometry, and measured serum lipids, thyroid hormones, and immunoglobulins. We explored associations of individual and aggregate measures of serum PFAS with wax use indicators and health biomarkers using multivariable regression models, adjusted for age and gender identity. ResultsNine PFAS (PFBS, PFHpS, PFHxS, Sm-PFOS, n-PFOS, PFDA, PFNA, PFUnDA, n-PFOA) were detected in 100% of participants, and MeFOSAA in 93%. Compared to NHANES, median serum concentrations (ng/ml) were similar, but higher in coaches (e.g., PFOAall: 1.1, PFOAcoaches: 2.7, PFOANHANES: 1.2; PFNAall: 0.5, PFNAcoaches: 1.7, PFNANHANES: 0.4). Factors reflecting wax exposure were positively associated with PFAS: e.g., >10 years as a snow sport athlete, compared to ≤10 years, was associated with 3.2 (95% CI: 0.7, 5.6) ng/ml higher aggregate PFAS, as defined by National Academies of Science, Engineering, and Medicine (NASEM). An IQR (6.3 ng/ml) increase in NASEM PFAS was associated with 32.1 (95% CI: 7.0, 57.2), 35.5 (13.5, 57.5), and 12.8 (0.6, 25.1) mg/dl higher total cholesterol, LDL-C, and sdLDL-C, respectively. DiscussionOur study provides early evidence that recreational skiers, particularly coaches, are exposed to PFAS through ski wax. Several PFAS were associated with higher serum lipids among these physically active adults. Interventions to remove PFAS from fluorinated wax could decrease direct exposure to skiers and reduce PFAS release into the environment.

Bioaccumulation potentials of per-and polyfluoroalkyl substances (PFAS) in recreational fisheries: Occurrence, health risk assessment and oxidative stress biomarkers in coastal Biscayne Bay

Per-and polyfluoroalkyl substances (PFAS) are a group of synthetic, highly fluorinated, and emerging chemicals that are reported to be used for both industrial and domestic applications. Several PFAS have demonstrated persistent, bioaccumulative and toxic tendencies in marine organisms. Therefore, this research aims to characterize and quantify these compounds in both recreational fisheries and surface water samples, including estimating their bioaccumulation potentials. In addition, we assessed the potential contribution of biomonitoring tools such as oxidative stressors and morphological index on fish and ecological health. Finally, human health risk assessment was performed based on available toxicological data on limited PFAS. All PFAS were detected in at least one sample except for N-EtFOSAA in lobster which was below the method detection limit. ƩPFAS body burden ranged from 0.15 to 3.40 ng/g wet weight (ww) in blackfin tuna samples and 0.37–5.15 ng/g ww in lobster samples, respectively. Wilcoxon rank paired test (α = 0.05) shows that there is statistical significance (ρ < 0.05) of ƩPFAS between species. Bioaccumulation factors (BAF) suggest an increasing trend in PFAS classes (PFCAs < PFSAs < FTSs), with higher BAFs observed in tuna compared to lobster. Long-chain PFESAs and FASAA were reported at higher concentrations in lobster compared to Blackfin tuna due to their bioavailability through sediment-sorption interactions. Although Fulton’s condition factor (FCF) indicates healthy fish conditions, oxidative stress biomarkers suggest that tuna and lobster might be under stress, which can weaken their immune system against exposure to emerging contaminants such as PFAS. Hazard risk (HR) suggests a low risk to human health based on the consumption of the studied species; however, the risk of contaminant exposure may be higher than estimated. This study is aimed at improving food safety by providing better understanding of how PFAS infiltrate into human diet and incorporating data on influence of contaminant exposure and environmental stressors on marine health.

Gestational diabetes mellitus in relation to serum per- and polyfluoroalkyl substances: A scoping review to evaluate the need for a new systematic review.

Per- and polyfluoroalkyl substances (PFAS) were used or are being used in the manufacturing of products, including consumer-use products. The resulting environmental contamination has led to widespread human exposure. This review aimed to scope the characteristics of evidence covered and applied methodology of evidence to understand -- regardless of any results on the association of gestational diabetes mellitus (GDM) and PFAS -- if a new systematic review would be justified. We systematically identified reports investigating associations of PFAS with GDM following a pre-specified and pre-registered PECO framework and protocol. The previous systematic reviews included 8-11 reports and either conducted meta-analyses stratified by comparator, analyzed results based on only high and low exposure categories, or pooled results across comparators. Included 20 reports presented data on 24 PFAS with PFOA, PFOS, PFHxS, PFNA, and PFDA being examined in almost all. The comparators employed were heterogeneous across the reports. Because data from at least one new report on GDM is available since the previous systematic reviews and heterogeneous comparators, an updated systematic review using SWiM could add value to the literature.

Per- and poly-fluoroalkyl substances (PFAS) accelerate biological aging mediated by increased C-reactive protein

Unhealthy biological aging is related to higher incidence of varied age-related diseases, even higher all-cause mortality. Previous small sample size study suggested that Per- and poly-fluoroalkyl substances (PFAS) was associated with biological aging, but the evidence of exposure-response relationships, potential effect modifiers, and potential mediators were not investigated. Therefore, we conducted a cross-sectional analysis of national study including 14, 865 adults in the US from 8 survey cycles of NHANES from 2003 to 2018, to investigate the associations of PFAS compounds in body serum, including perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS), perfluorononanoic acid (PFNA), and perfluorohexane sulfonic acid (PFHxS), with biological aging. Generalized linear models showed that higher human exposure to PFAS was associated with accelerated biological aging. Importantly, human exposure to PFOA, PFOS, PFNA, and PFHxS with detected level (above 0.10 ng/mL) was associated with an average of 3.3 year (95 %CI: 2.7, 3.9, P < 0.001), 14.9 year (95 %CI: 7.2, 22.7, P < 0.001), 10.9 years (95 %CI: 3.9, 17.7, P < 0.001), and 8.8 years (95 %CI: 4.8, 12.9, P < 0.001) of biological aging acceleration. Cubic spline models indicated exposure-response relationships where there was no safe threshold of PFAS level regarding harms to human healthy aging. The weighted sum regression model found the significant associations of PFAS compound mixture with biological aging acceleration, and PFOA was the dominant contributor among 4 PFAS compounds. Mediation analysis suggested that C-reactive protein, one of the inflammation biomarkers, might play as mediator in PFAS-induced accelerated biological aging, but not Triglyceride-glucose index. In summary, our study suggests that the effects of PFAS on biological aging acceleration should be of concern and more action plans to address their negative impact on human health should be launched.

Persistent organic pollutants in the Antarctic marine environment: The influence impacts of human activity, regulations, and climate change

This study investigates the presence, distribution, and potential impacts of perfluoroalkyl substances (PFASs) and hexabromocyclododecanes (HBCDs) on the Antarctic marine environment. The analysis results from the King Sejong Station, the Jang Bogo Station, and Cape Evans revealed the highest concentrations of both PFASs and HBCDs at King Sejong Station, indicating the significant influence of human activity. Short-chain perfluorocarboxylic acids (PFCAs) dominated the seawater samples, with PFPeA at the highest concentration (0.076 ng/L) at King Sejong Station, whereas perfluorosulfonic acids (PFSAs) were prevalent in the sediments, with PFHxS reaching 0.985 ng/g. Total PFASs in benthos ranged from N.D. to 2.40 ng/g ww across all stations. This indicated the effects of long-range transport and glacial meltwater. α-HBCD was the most common diastereomer in benthos samples, detected in 58.3% of samples, suggesting its selective persistency. Although risk quotient analysis revealed low immediate risks to lower-trophic organisms, potential risks remain owing to their persistence and bioaccumulation potential. Contaminant patterns changed after regulations: perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) levels decreased, unregulated PFASs increased, HBCD stereoisomer ratios shifted towards α-HBCD dominance, and overall HBCD concentrations declined. Widespread persistence of regulated substances was observed in Antarctic environments, highlighting the need for comprehensive and long-term monitoring strategies. This study provides essential baseline data on contaminant distributions across the Southern Ocean, contributing to our understanding of emerging pollutants in Antarctic regions and informing future environmental protection efforts.

Are Hazard Assessment Methods in the Assessment of Chemical Alternatives Suitable for REACH?

The assessment of chemical alternatives for hazardous substances is an important prerequisite for avoiding regrettable substitution, and several methods have been developed in the past to perform such a hazard assessment for chemical alternatives. We investigate here whether GreenScreen, Cradle to Cradle, multiple-criteria decision analysis (MCDA), the Pollution Prevention Options Analysis System, the U.S. EPA Safer Choice Standard and Criteria, and the GHS column model 2020 from IFA use similar criteria for the evaluation of substances as Article 57 of the European chemicals regulation, REACH, and how suitable these methods are for assessing per- and polyfluoroalkyl substances. MCDA and GreenScreen were analyzed in detail using two different data sets. The results of the assessments show that none of the investigated hazard assessment methods use the same criteria as described in Article 57 of REACH. It was also not possible to parametrize multi-attribute value theory (MAVT), a commonly used MCDA method, to align with Article 57 of REACH by using the relatively simple objective hierarchy that has been proposed in previous publications. There is therefore an urgent need for a modified/new method that can be used in the future to assess organic substances that are used within the European Economic Area.

Stimulating Acidimicrobium sp. Strain A6 in iron-rich, acidic sediments from AFFF-impacted sites for PFAS defluorination

Per- and polyfluoroalkyl substances (PFAS) are persistent and bioaccumulative contaminants that are widely used in industrial applications and consumer products and pose significant risks to ecosystems and human health. Acidimicrobium sp. Strain A6 (A6), which is common in acidic, and iron rich soils and sediments is capable of both anaerobic ammonium (NH4+) oxidation under iron reduction (Feammox) and defluorination of perfluorinated alkyl substances, such as perfluoroalkyl acids (PFAAs). This study investigates the potential for biostimulating A6 via the supply of NH4+ and ferric iron (Fe(III)) with the goal of defluorinating PFAAs. Sediment samples from acidic, iron-rich, AFFF (aqueous film forming foam) impacted sites were collected and incubated with added Fe(III) and NH4+. Quantitative PCR was used to track A6 numbers as well as dehalogenase and F− ion transporter genes during these incubations; changes in the microbial community structure were tracked through 16S rRNA gene sequencing. The findings reveal that the addition of Fe(III) and NH4+ stimulated the Feammox reaction and A6 growth and enhanced the degradation of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS). Results also show a significant presence and activity of the above-mentioned genes in these incubations. The insights gained from this study could inform bioremediation strategies for PFAS-contaminated environments, especially in geochemical settings that favor the presence of A6.

Exposure to PFOA, PFOS, and PFHxS induces Alzheimer's disease-like neuropathology in cerebral organoids

Per- and polyfluoroalkyl substances (PFASs), a class of ubiquitous synthetic organic chemicals, are widely utilized across various industrial applications. However, the long-term neurological health effects of PFAS mixture exposure in humans remain poorly understood. To address this gap, we have designed a comprehensive study to predict and validate cell-type-specific neurotoxicity of PFASs using single-cell RNA sequencing (scRNA-seq) and cerebral organoids. Cerebral organoids were exposed to a PFAS mixture at concentrations of 1 × (10 ng/ml PFOS and PFOA, and 1 ng/ml PFHxS), 30 × , and 900 × over 35 days, with a follow-up analysis at day 70. Pathological alterations and lipidomic profiles were analyzed to identify disrupted molecular pathways and mechanisms. The scRNA-seq data revealed a significant impact of PFASs on neurons, suggesting a potential role in Alzheimer's Disease (AD) pathology, as well as intellectual and cognitive impairments. PFAS-treated cerebral organoids exhibited Aβ accumulation and tau phosphorylation. Lipidomic analyses further revealed lipid disturbances in response to PFAS mixture exposure, linking PFAS-induced AD-like neuropathology to sphingolipid metabolism disruption. Collectively, our findings provide novel insights into the PFAS-induced neurotoxicity, highlighting the significance of sphingolipid metabolism in the development of AD-like neuropathology. The use of cerebral organoids and scRNA-seq offers a powerful methodology for evaluating the health risks associated with environmental contaminants, particularly those with neurotoxic potential.

The Interplay of Persistent Organic Pollutants and Mediterranean Diet in Association With the Risk of Gestational Diabetes Mellitus.

Certain foods characterizing the alternate Mediterranean diet (aMED) are high in persistent organic pollutants (POPs), which are related to greater gestational diabetes mellitus (GDM) risk. We examined the associations of combined aMED and POP exposure with GDM. aMED score of 1,572 pregnant women was derived from food frequency questionnaires at early pregnancy within the U.S. Fetal Growth Study and plasma concentrations of 76 POPs, including organochlorine pesticides, polybrominated diphenyl ethers, polychlorinated biphenyls (PCBs), and per- and polyfluoroalkyl substances, were measured. Associations of combined aMED score and exposure to POPs with GDM risk were examined by multivariable logistic regression models. In 61 of 1,572 (3.88%) women with GDM, 25 of 53 included POPs had a detection rate >50%. Higher POP levels appeared to diminish potential beneficial associations of aMED score with GDM risk, with the lowest GDM risk observed among women with both high aMED score and low POP concentrations. Specifically, adjusted log-odds ratios of GDM risk comparing women with low PCB and high aMED score with those with low aMED score and high PCB concentrations was -0.74 (95% CI -1.41, -0.07). Inverse associations were also observed among women with low aMED score and high TransNo_chlor, PCB182_187, PCB196_203, PCB199, and PCB206. These associations were more pronounced among women with overweight or obesity. Pregnant women who consumed a healthy Mediterranean diet but had a low exposure to POP concentrations had the lowest GDM risk. Future endeavors to promote a healthy diet to prevent GDM may consider concurrent POP exposure.

Environmentally relevant level of PFDA exacerbates intestinal inflammation by activating the cGAS/STING/NF-κB signaling pathway

As a constituent of the Per- and Polyfluoroalkyl Substances (PFAS) family, perfluorodecanoic acid (PFDA) is ubiquitous in the environment and enters the human body through environmental exposure, the food chain, and other pathways, resulting in various toxic effects. Previous population-based studies have suggested a correlation between PFDA exposure and inflammation. However, the evidence is still limited, and the potential mechanisms underlying this correlation remain to be further elucidated. In our study, we observed that exposure to internal doses of PFDA significantly promoted macrophage inflammation through in vitro assays. Utilizing RNA-seq screening and molecular experiments, we identified that environmentally relevant concentration of PFDA promote inflammation mainly by activating non-canonical cGAS/STING/NF-κB pathways in vitro. Finally, we confirmed in the typical mouse inflammatory bowel disease (IBD) model that PFDA could exacerbate intestinal inflammation in a cGAS dependent manner. In conclusion, our research firstly demonstrated that even at environmentally relevant concentrations, PFDA could promote the progression of intestinal inflammation primarily through the cGAS/STING/NF-κB pathway, revealing the potential risk associated with PFDA exposure and providing theoretical evidence for its management.

Uptake of Per- and Polyfluoroalkyl Substances in Mixed Forages on Biosolid-Amended Farm Fields.

Models to predict perfluorooctanesulfonic acid (PFOS) concentrations in livestock based on soil concentrations are essential to guide decisions surrounding food testing and farm management. A key parameter in modeling soil-to-livestock exposure pathways is the plant transfer factor (TF) from soil into forages. Uptake of PFOS and other individual per- and polyfluoroalkyl substances (PFASs) were examined in perennial mixed grasses and legumes on PFAS-contaminated farm fields. In a field plot study, PFOS TFs were similar within each plot over three consecutive years but varied 10-fold among the four plots with mean TFs ranging from 0.026 to 0.27. In a multifarm field survey study, mean PFOS TFs ranged from 0.039 to 0.37. Increasing concentrations of two PFOS precursors in soil were significantly associated with increasing PFOS TFs. These data represent a substantial increase in empirical observations of PFAS TFs for grass-based forages for use in modeling soil-to-livestock exposure scenarios.

County-level associations between drinking water PFAS contamination and COVID-19 mortality in the United States.

Epidemiologic and animal studies both support relationships between exposures to per- and polyfluoroalkyl substances (PFAS) and harmful effects on the immune system. Accordingly, PFAS have been identified as potential environmental risk factors for adverse COVID-19 outcomes. Here, we examine associations between PFAS contamination of U.S. community water systems (CWS) and county-level COVID-19 mortality records. Our analyses leverage two datasets: one at the subnational scale (5371 CWS serving 621 counties) and one at the national scale (4798 CWS serving 1677 counties). The subnational monitoring dataset was obtained from statewide drinking monitoring of PFAS (2016-2020) and the national monitoring dataset was obtained from a survey of unregulated contaminants (2013-2015). We conducted parallel analyses using multilevel quasi-Poisson regressions to estimate cumulative incidence ratios for the association between county-level measures of PFAS drinking water contamination and COVID-19 mortality prior to vaccination onset (Jan-Dec 2020). In the primary analyses, these regressions were adjusted for several county-level sociodemographic factors, days after the first reported case in the county, and total hospital beds. In the subnational analysis, detection of at least one PFAS over 5 ng/L was associated with 12% higher [95% CI: 4%, 19%] COVID-19 mortality. In the national analysis, detection of at least one PFAS above the reporting limits (20-90 ng/L) was associated with 13% higher [95% CI: 8%, 19%] COVID-19 mortality. Our findings provide evidence for an association between area-level drinking water PFAS contamination and higher COVID-19 mortality in the United States. These findings reinforce the importance of ongoing state and federal monitoring efforts supporting the U.S. Environmental Protection Agency's 2024 drinking water regulations for PFAS. More broadly, this example suggests that drinking water quality could play a role in infectious disease severity. Future research would benefit from study designs that combine area-level exposure measures with individual-level outcome data.

Microplastics and per- and polyfluoroalkyl substances (PFAS) in landfill-wastewater treatment systems: A field study

Landfills and wastewater treatment plants (WWTP) are point sources for many emerging contaminants, including microplastics and per- and polyfluoroalkyl substances (PFAS). Previous studies have estimated the abundance and transport of microplastics and PFAS separately in landfills and WWTPs. In addition, previous studies typically report concentrations of microplastics as particle count/L or count/g sediment, which do not provide the information needed to calculate mass balances. We measured microplastics and PFAS in four landfill-WWTP systems in Illinois, USA, and quantified mass of both contaminants in landfill leachate, WWTP influent, effluent, and biosolids. Microplastic concentrations in WWTP influent were similar in magnitude to landfill leachates, in the order of 102 μg plastic/L (parts-per-billion). In contrast, PFAS concentrations were higher in leachates (parts-per-billion range) than WWTP influent (parts-per-trillion range). After treatment, both contaminants had lower concentrations in WWTP effluent, although were abundant in biosolids. We concluded that WWTPs reduce PFAS and microplastics, lowering concentrations in the effluent that is discharged to nearby surface waters. However, partitioning of both contaminants to biosolids may reintroduce them as pollutants when biosolids are landfilled or used as fertilizer.

6669 Association Between Serum Levels of Thyroid Function and Per- and Polyfluoroalkyl Compounds Concentrations in Central Precocious Puberty in Girls

Abstract Disclosure: Y. Li: None. Y. Xing: None. X. Yin: None. J. Yang: None. S. Zang: None. T. Dong: None. Y. Pan: None. J. Dai: None. P. Li: None. Background: Exposure to per- and polyfluoroalkyl substances (PFASs) may interfere with thyroid function in the general population and disturb the timing of puberty onset. Objectives: We investigated the possible relationship between PFASs and thyroid hormone (THs) exposure in girls with central precocious puberty (CPP). Methods: In a prospective study initially established for assessing CPP, 627 serum samples were collected with (n = 226) and without (n = 401) CPP. The concentrations of 25 PFASs, thyroxin (T4), 3,5,3’-triiodothyronine (T3), and 3,3’,5’-triiodothyronine (rT3) were measured. We used logistic regression to examine the association of THs with the odds of having CPP and multiple linear regression to analyze the associations between THs and various PFASs in the CPP and control groups. Results: The levels of T4 in the CPP group were significantly lower than those in the control group, and the levels of T3 and rT3 were significantly higher than those in the control group. After adjusting for confounders, T3 concentrations were associated with 1.526-fold increased odds of having CPP [odds ratio (OR) = 1.526, 95% confidence interval (CI):1.216-1.914]. In the CPP cohort, perfluoroheptanoic acid (PFHpA), perfluoro (2-ethoxyethane) sulphonic acid (PFEESA), and fluorotelomer phosphate diester (6:2/8:2 diPAP) were inversely associated with T3; perfluorobutanoic acid (PFBA) was inversely associated with T4, and PFEESA and 6:2/8:2 diPAP positively associated with T4; PFBA was positively associated with rT3, and perfluorooctane sulfonic acid (PFOS) was inversely associated with rT. In the control cohort, perfluorobutanesulfonic acid (PFBS) was positively associated with T3, and PFEESA and 6:2/8:2 diPAP were inversely associated with T3, and these PFASs had an adverse association with T4. Perfluorohexanoic acid (PFHxA) was positively associated with rT3, and 6:2/8:2 diPAP was negatively associated with rT3. Conclusion: In this study, different measurements of PFASs and THs were observed in the CPP and control groups. Discrepancies in exposure to PFASs were associated with THs in the CPP cohort and healthy girls. Further research is necessary to investigate the mechanism by which PFASs affect the timing of puberty onset and thyroid function. Presentation: 6/1/2024

8054 Temporal Trends In Thyroidal Endocrine Disruptor Exposure Among United States Reproductive-Age And Pregnant Women Over 20 Years And Differences By Socioeconomic Status

Abstract Disclosure: C. Han: None. S. Lee: None. E.N. Pearce: None. Background: Widespread exposure to endocrine disrupting chemicals (EDCs) poses a risk to public health and environmental safety. Women of reproductive age and pregnant women may be uniquely vulnerable to adverse thyroidal effects of EDCs. A better understanding of thyroidal EDCs exposure is needed to inform public health strategies. Objective: To examine temporal trends in EDC exposure and their effects on thyroid function among reproductive-age and pregnant women in the U.S. over the last two decades, with a focus on the impact of socioeconomic status. Methods: We analyzed data from the National Health and Nutrition Examination Survey (NHANES) from 1999 to 2020 in 25,320 reproductive-age women and 2,525 pregnant women to assess the levels of exposure to thyroid-disrupting chemicals, including dioxins, organochlorides, polyfluoroalkyl substances (PFAS) from serum samples, and polyaromatic hydrocarbons, perchlorates, and metabolites from personal care products, phthalates, and plasticizers from urine samples. We used Kruskal-Wallis tests to analyze changes in EDC exposures over the past 20 years and multivariate linear regression models to identify factors influencing these levels. Results: We found a significant decline in exposures to 20 types of dioxins, 7 organochlorides, 6 PFAS, 5 personal care product chemicals, 6 phthalate metabolites, perchlorate, and thiocyanate, but substantial increases in exposure to 2 polyaromatic hydrocarbons among reproductive-age women. Among pregnant women, trends were similar, with declines in exposures to dioxins, organochlorides, PFAS, and phthalate metabolites; whereas exposure to 3 Polyaromatic hydrocarbons, 1 personal care product chemical, nitrates, and thiocyanates increased. Linear regression indicated a significant positive association between socioeconomic status and the levels of dioxin and PFAS in both reproductive-age and pregnant women, and a negative association between socioeconomic status and perchlorate and polyaromatic hydrocarbons in the participants. Conclusion: The past two decades have witnessed a general decline in the levels of most thyroidal EDCs in U.S. reproductive-age and pregnant women; however, some, particularly polyaromatic hydrocarbons, exposures have increased, especially among women with lower socioeconomic status. This has the potential to worsen disparities in health outcomes. These findings highlight the necessity for targeted public health interventions to reduce the impact of EDCs on thyroid health and address socioeconomic health disparities. Presentation: 6/3/2024