Maternal per- and poly-fluoroalkyl substances exposure and child adiposity measures: A birth cohort study

Maternal exposure to per- and polyfluoroalkyl substances (PFAS) during pregnancy may have a programming effect on the physical development of the offspring. However, the findings of the association between PFAS and the physical development of offspring were inconsistent, and the overall effects of the PFAS mixture were unclear. In this study, we examined the associations between maternal PFAS exposure and offspring adiposity during the first two years of life. A total of 937 mother-child pairs from the Jiashan Birth Cohort Study were investigated. Thirteen PFASs were analyzed in maternal blood samples. Child weight and length were measured at birth, 1, 3, 6, 8, 12, and 24 months, and the ponderal index (PI) and weight-for-age z-scores (WAZ) were calculated. Longitudinal associations of PFAS concentrations (by quartile) with repeated data of PI and WAZ were examined using linear mixed model, and the overall effect of the PFAS mixture on adiposity measures was evaluated using quantile g-computation (QGC). Maternal PFAS exposure was associated with increased PI in both the linear mixed model and the QGC model. Among the PFAS examined, the associations between maternal PFTrDA exposure and PI were the strongest. Maternal PFAS and WAZ showed similar patterns of association. In the longitudinal cohort study, we found that adiposity in young children is increased by maternal PFAS exposure. The associations between maternal PFASs concentrations and child adiposity may be chemical-specific.

What Happens In Utero Does Not Stay In Utero: a Review of Evidence for Prenatal Epigenetic Programming by Per- and Polyfluoroalkyl Substances (PFAS) in Infants, Children, and Adolescents

PURPOSE OF REVIEW

Review human literature on the relationship between prenatal exposure to per- and polyfluoroalkyl substances (PFAS) and epigenetic modifications in infants, children, and adolescents < 18 years of age.

RECENT FINDINGS

Eleven studies were identified, with study populations located in the U.S., Taiwan, Japan, and the Kingdom of Denmark. Many studies (n = 5) were cross-sectional, with PFAS exposure and epigenetic outcomes measured in the same tissue collected at delivery via cord blood or dried newborn blood spots. The other six studies were prospective, with prenatal PFAS measured on maternal blood during pregnancy and DNA methylation (DNAm) assessed in cord blood and childhood peripheral leukocytes (n = 1 study). Epigenetic marks of interest included global DNAm measures (LINE-1, Alu, and an ELISA-based method), candidate genes (IFG2, H19, and MEST), and epigenome-wide DNA methylation via array-based methods (Infinium 450 K and EPIC). Two studies using array-based methods employed discovery and validation paradigms, in which a small subset of loci (n = 6 and n = 4) were replicated in the discovery population. One site (TNXB) was a hit in two independent studies. Collectively, loci associated with PFAS were in regions involved in growth and development, lipid metabolism, and nutrient metabolism. There is moderate human evidence supporting associations of prenatal PFAS exposure on DNAm at birth, with one study suggesting sustained effects into childhood. Future studies are warranted to link PFAS-associated DNAm to health outcomes, as well as to investigate the role of other epigenetic marks such as hydroxymethylation, miRNA expression, and histone modifications.

Metabolome-wide association study of four groups of persistent organic pollutants and abnormal blood lipids

Environmental exposure increases the risk of dyslipidemia, which affects human health. Research has shown that persistent organic pollutants (POPs), including per- and polyfluoroalkyl substances (PFASs), polychlorinated biphenyls, polybrominated diphenyl ethers, and phthalate metabolites, are associated with a higher risk of abnormal blood lipid levels in humans. However, the key molecules involved in dyslipidemia and the mechanisms are not fully understood. This study aims to investigate the biomarkers that mediate the relationships between blood lipids and four groups of POPs and revealed their potential mechanisms. Specifically, in 278 male blood samples, blood lipid and POPs levels were measured and metabolites were detected using untargeted metabolomics. Spearman's correlation analysis and binary logistic regression were employed to assess the relationship between POPs and lipid indexes. We observed that PFASs were associated with a higher risk of abnormal total cholesterol (TC) and low-density lipoprotein (LDL), while other POPs displayed little association with abnormal lipid indexes. Among all the PFASs, 6:2Cl-PFESA was associated with the fewest metabolites. A metabolome-wide association study combined with a meet-in-the-middle approach was used to identify potential biomarkers that mediate the association between POPs and abnormal blood lipids. The mediation analysis pointed to 105 significant mediators as potential biomarkers mediating the association between PFASs and TC, and 82 significant mediators were potential biomarkers that mediated the association between PFASs and LDL. 24-Hydroxycholesterol, 3alpha,7alpha-dihydroxy-5beta-cholestan-26-al, PC(18:0/0:0), PC(22:5/0:0), GPCho(18:1/18:1), LysoPC(22:2(13Z,16Z)), LysoPC(16:0), 9(S)-HODE, 9,10-DHOME, l-glutamate, 4-hydroxybutyric acid, cytosine, PC(14:1(9Z)/18:0), sphinganine, and (S)-beta-aminoisobutyrate were identified as important biomarkers. The mechanism may mainly involves glycerophospholipid metabolism, primary bile acid biosynthesis, and linoleic acid metabolism. PPARγ likely plays a role in the associations between PFASs and abnormal cholesterol metabolism. Overall, our study provides clues for the early detection of PFAS-induced dyslipidemia and brings forth a theoretical framework for further research into this mechanism.

PFAS-induced lipidomic dysregulations and their associations with developmental toxicity in zebrafish embryos

Per- and polyfluoroalkyl substances (PFASs) are persistent environmental contaminants, posing developmental toxicity to fish and human. PFAS-induced lipid metabolism disorders were demonstrated using the zebrafish (Danio rerio) embryo model, but the detailed changes of lipid compositions and the influence of these changes on the biological development are still unclear. Herein, lipidomics analysis was performed to reveal the dysregulations of lipid metabolism in zebrafish embryos exposed to perfluorooctanoic acid (PFOA) or perfluorooctane sulfonate (PFOS) through microinjection. Various abnormal phenotypes were observed, including heart bleeding, pericardium edema, spinal curvature and increased heart rate at 72 h after fertilization, especially in the PFOS exposure groups. Lipidomic profiling found downregulated phosphatidylethanolamines in the PFAS-exposed embryos, especially those containing a docosahexaenoyl (DHA) chain, indicating an excessive oxidative damage to the embryos. Glycerolipids were mainly upregulated in the PFOA groups but downregulated in the PFOS groups. These aberrations may reflect oxidative stress, energy metabolism malfunction and proinflammatory signals induced by PFASs. However, supplement of DHA may not be effective in recovering the lipidomic dysregulations and protecting from the developmental toxicity induced by PFASs, showing the complexity of the toxicological mechanisms. This work has revealed the associations between the abnormal phenotypes and dysregulations of lipid metabolism in zebrafish embryos induced by PFASs from the aspect of lipidomics, and discovered the underlying molecular mechanisms of the developmental toxicity of PFASs.

Contaminants in fish from U.S. rivers: Probability-based national assessments

Most fish consumption advisories in the United States (U.S.) are issued for mercury and polychlorinated biphenyls (PCBs), and recently per- and polyfluoroalkyl substances (PFAS) have become a contaminant group that warrants fish consumption advice. An unequal probability survey design was developed to allow a comprehensive characterization of mercury, PCB, and PFAS contamination in fish from U.S. rivers on a national scale. During 2013-14 and 2018-19, fish fillet samples were collected from 353 and 290 river sites, respectively, selected randomly from the target population of rivers (≥5th order in size) in the conterminous U.S. These comprised nationally representative samples, with results extrapolated to chemical-specific sampled populations of 48,826-79,448 river kilometers (km) in 2013-14 and 66,142 river km in 2018-19. National distribution estimates were developed for total mercury, all 209 PCB congeners, and up to 33 PFAS (including perfluorooctane sulfonate or PFOS) in river fish. All fillet tissue samples contained detectable levels of mercury and PCBs. One or more PFAS were detected in 99.7 % and 95.2 % of the fillet samples from fish collected in 2013-14 and 2018-19, respectively. Fish tissue screening levels applied to national contaminant probability distributions allowed an estimation of the percentage of the sampled population of river lengths that contained fish with fillet concentrations above a level protective of human health. Fish tissue screening level exceedances for an average level of fish consumption ranged from 23.5 % to 26.0 % for mercury, 17.3 % to 51.6 % for PCBs, and 0.7 % to 9.1 % for PFOS.

Consideration of pathways for immunotoxicity of per- and polyfluoroalkyl substances (PFAS)

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) are of public health concern, because of their ubiquitous and extremely persistent occurrence, and depending on their structure, their bio-accumulative, mobile and toxic properties. Human health effects associated with exposure to PFAS include adverse effects on the immune system. In 2020, EFSA (the European Food Safety Authority) defined adverse effects on the immune system as the most critical effect for human health risk assessment, based on reduced antibody responses to childhood vaccines and similar effects observed in experimental animal studies. Likewise, the U.S. EPA (Environmental Protection Agency) considers PFAS-induced immunotoxicity, especially in children, as the critical effect for risk assessment. However, the mechanisms by which antibody concentrations are impacted are not completely understood. Furthermore, other targets of the immune system functions have been reported in the literature.

OBJECTIVE

The aim of this review is to explore PFAS-associated immune-related effects. This includes, relevant mechanisms that may underlie the observed effects on the immune system, immunosuppression as well as immunoenhancement, such as i) modulation of cell signalling and nuclear receptors, such as NF-κB and PPARs; ii) alteration of calcium signalling and homoeostasis in immune cells; iii) modulation of immune cell populations; iv) oxidative stress and v) impact on fatty acid metabolism & secondary effects on the immune system.

METHODS

A literature research was conducted using three databases (Web of Science, PubMed, and Scopus), which were searched in July 2021 for relevant studies published in the time frame from 2018 to 2021. In total, 487 publications were identified as potentially eligible and following expert-based judgement, articles relevant for mechanisms of PFAS induced immunotoxicity are discussed.

CONCLUSIONS

Taken together, we show that there is substantial evidence from both in vitro and in vivo experimental as well as epidemiological studies, supporting that various PFAS, not only PFOA and PFOS, affect multiple aspects of the immune system. Timing of exposure is critical, because the developing immune system is especially vulnerable to toxic insults, resulting in a higher risk of particularly adverse immune effects but also other organs later in life.

Curbing per- and polyfluoroalkyl substances (PFASs): First investigation in a constructed wetland-microbial fuel cell system

The presence of per- and polyfluoroalkyl substances (PFASs) in water environments has been linked to a slew of negative health effects in both animals and humans, but the green and eco-sustainable removal technologies remain largely unknown. Constructed wetland coupled microbial fuel cell (CW-MFC) is termed a "green process" to control pollutants and recover energy. However, so far, no study has investigated the removal of PFASs and their effects on the performance of the CW-MFC systems. Here, we investigated the removal performance of PFOA and PFOS in the CW-MFC systems both in the absence and presence of electricity circuit, and explored the distribution and fate of PFASs and their interactions with other elements in the systems. Our findings demonstrated excellent removal efficiency of >96% PFOA and PFOS in CW-MFC systems. PFOA and PFOS were distributed throughout the system via wastewater flow, while electrode material and plants are the main enrichment sites in which MFC enhanced up to 10% PFASs removal. However, a loss of 7.2-13.5% of nitrogen removal and a decrease of 7.3% in bioelectricity output were observed when PFASs were introduced in the system. The driven force led to the loss of nitrogen removal and bioelectricity generation lies in the accumulation of PFASs in system composition, which affected microbial activity and community composition, damaging the health of the plant, and in turn reducing CW-MFC's functioning. No doubt, CW-MFC systems provide an alternative technique for PFASs removal, alleviating some limitations to the physical and chemical techniques, but further investigation is highly needed.

Identification and characterization of diverse isomers of per- and polyfluoroalkyl substances in Chinese municipal wastewater

Linear and branched isomers of per- and polyfluoroalkyl substances (PFASs) are simultaneously present in the environment. However, isomer profiles of PFASs in municipal wastewater treatment plants (WWTPs) are still unknown because of the limitations of standards. Here, influent and effluent samples from 148 municipal WWTPs in China were collected. Ion mobility spectrometry was introduced into high-resolution mass spectrometry-based suspect screening methods to identify the target and suspect PFAS isomers. A total of 38 branched isomers of 14 typical PFASs were identified in wastewater samples. Linear PFASs had higher detection rates (22.3%-100%) than branched isomers (2.0%-98%). Compared to the influents, proportions of branched isomers of most PFASs (except for perfluoropentanoic acid and perfluorohexanoic acid) increased in the effluents. The conventional biological treatment processes (such as anaerobic-anoxic-aerobic and oxidation ditch treatments) had poor removal efficiency for linear PFASs (<21.4%) and branched isomers (<13.4%). No difference on removal efficiency among treatment processes was found. Furthermore, isomer composition in the WWTPs showed obvious differences between East China region and other regions, and the usage of short-chain PFASs (perfluorobutanesulfonic acid and perfluorohexanesulfonic acid) may be a key factor for driving this difference. This study sheds lights on the identification and characterization of PFAS isomers in WWTPs, which would be useful for development of monitoring and control strategies of PFASs.

Occurrences of legacy and emerging per- and polyfluoroalkyl substances in human milk in China: Results of the third National Human Milk Survey (2017-2020)

Per- and polyfluoroalkyl substances (PFAS) are persistent organic pollutants widely contaminated and exposed in humans. China is a major manufacturer and consumer of these chemicals. To characterize the occurrences, geographical variations, temporal trends, and exposure risks of legacy and emerging PFAS in perinatal women and their children in China, 30 PFAS were measured in 100 pooled human milk samples consisting of 3531 individual samples collected from 100 sites in 24 provinces during the 2017-2020 National Human Milk Survey. Linear-perfluorooctanoic acid (L-PFOA, 151 pg/mL) and linear-perfluorooctane sulfonate (L-PFOS, 57.0 pg/mL) were the predominant PFAS in human milk, followed by 6:2 chlorinated polyfluorinated ether sulfonate (6:2 Cl-PFESA, 25.9 pg/mL). The geographic variation trend of PFOA was different from PFOS and Cl-PFESA, and a special geographic trend of perfluoropentanesulfonate (PFPeS) was observed. Comparison of National Human Milk surveys from different periods showed a sharp decrease of PFAS exposure in old industrial areas including Shanghai and Liaoning, but higher PFAS exposure observed in Shandong and Hubei indicated a possible domestic shift of PFAS manufacture to these areas. Worldwide comparison of PFAS in human milk indicated high PFOA exposure in China. Risk assessments for mothers and breastfeeding infants showed that PFAS exposure is of concern in China.

Early-life exposure to per- and polyfluoroalkyl substances and infant gut microbial composition

Human milk is rich in essential nutrients and immune-activating compounds but is also a source of toxicants including per- and polyfluoroalkyl substances (PFAS). Evidence suggests that immune-related effects of PFAS may, in part, be due to alterations of the microbiome. We aimed to identify the association between milk PFAS exposure and the infant gut microbiome.

Methods

PFAS [perfluorooctane sulfonic acid (PFOS) and perfluorooctanoate (PFOA)] were quantified in milk from ~6 weeks postpartum using high-performance liquid chromatography with tandem mass spectrometry. A molar sum (ΣPFAS) was calculated. Caregivers collected infant stool samples at 6 weeks (n = 116) and/or 1 year postpartum (n = 119). Stool DNA underwent metagenomic sequencing. We estimated the association of PFAS with diversity and relative abundances of species with linear regression. Single- and multi-PFAS models adjusted for potential confounders in complete case analyses and with imputed missing covariate data for 6-week and 1-year microbiomes separately. We assessed sensitive populations with stratification.

Results

PFOS and PFOA were detected in 94% and 83% of milk samples, respectively. PFOS was associated with increased diversity at 6 weeks among infants fed exclusively human milk [β = 0.24 per PFOS doubling, (95% CI = 0.03, 0.45), P = 0.03] and born to primiparous mothers [β = 0.37 (0.06, 0.67), P = 0.02]. Estimates were strongest in multi-PFAS models and among complete cases. ΣPFAS was associated with Bacteroides vulgatus relative abundance at 1 year [(β = -2.34% per doubling (-3.63, -1.05), FDR q = 0.099].

Conclusions

PFAS may increase infant gut microbiome diversity and alter the relative abundance of biologically relevant bacteria. Additional analyses may identify related health outcomes.

High maternal glucose exacerbates the association between prenatal per- and polyfluoroalkyl substance exposure and reduced birth weight

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) exposure has been associated with reduced birth weight. However, the association may be complicated by glucose status due to PFAS impact on fetal growth and placental transport.

OBJECTIVES

To examine whether maternal glucose status modifies the association between prenatal PFAS exposure and birth weight z-score.

METHODS

We analyzed data of 1405 mother-child pairs from the prospective Shanghai Birth Cohort. Plasma concentrations of six PFAS were quantified in the first trimester. Fasting plasma glucose (FPG) was collected at 24-28 gestation weeks. A range of FPG cutoffs (4.9-5.4 mmol/L) covering current recommendations for gestational diabetes mellitus were used to define high and low FPG groups. Association between PFAS concentration and birth weight z-score was evaluated using multivariate linear regression in two FPG groups respectively, and the dose-response relationship was estimated with cutoffs ranging from low to high. We then used propensity score to counterbalance the effects of different PFAS concentrations between the high and low FPG groups, and run the regression again.

RESULTS

A doubling increase in concentrations of several PFAS was inversely associated with birth weight z-score. The association was more evident in high FPG groups and the magnitudes intensified when FPG cutoff increased. The strongest association was observed for PFOA, with the magnitude increased from -0.34 (95 % CI: -0.66, -0.03) for 5.0 mmol/L cutoff, to -0.41 (95 % CI: -0.77, -0.05) for 5.1 mmol/L cutoff, and further to -0.51 (95 % CI: -0.98, -0.03) for 5.3 mmol/L. Propensity score matching yielded similar results.

CONCLUSIONS

High maternal glucose level may increase the risk of reduced birth weight z-score related to prenatal PFAS exposure. Moreover, exploring the effects with different FPG cutoffs may contribute to providing intervention strategies for pregnant women with high PFAS exposure.

Sex-specific associations between legacy and novel per- and polyfluoroalkyl substances and telomere length in newborns in Wuhan, China: Mixture and single pollutant associations

Telomere length (TL) at birth predicts later life TL and is related to health. Prenatal exposure to environmental pollutants might affect TL, but the associations between intrauterine per- and polyfluoroalkyl substances (PFASs) exposure and neonatal TL remained inconclusive. This study aimed to explore the single pollutant and mixture associations between legacy and novel PFASs and TL in newborns. In 908 mother-newborn pairs from Wuhan, China, thirteen PFASs were measured in cord serum, and TL was determined in cord leukocytes. Weighted quantile sum (WQS) regression and generalized linear model (GLM) were utilized to analyze the associations between PFASs mixture and single PFASs and TL in newborns. Furthermore, stratified and interaction analyses were performed to evaluate if there were sex-specific associations. The concentrations of perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), and 6:2 chlorinated polyfluorinated ether sulfonate (6:2 Cl-PFESA) ranked the highest (geometric mean, 4.12, 1.61, and 0.77 ng/mL, respectively) among the 13 measured PFASs. Each unit increase in WQS index of PFASs mixture was associated with -5.19 % change (95% CI, -9.44, -0.73) of neonatal TL, and 8:2 Cl-PFESA contributed most (32.59 %) to the mixture association. In stratified analyses by neonatal sex, PFOS (-4.73 % change, 95% CI, -8.40, -0.93 for per doubling concentration) and 8:2 Cl-PFESA (-4.52 % change, 95% CI, -8.20, -0.70) were negatively associated with neonatal TL in male newborns, but no significant association appeared in females. In summary, intrauterine exposure to PFASs in mixture was associated with shorter neonatal TL, and the negative associations of 8:2 Cl-PFESA and PFOS with neonatal TL were observed only in boys. Future risk assessments are needed to pay more attention to the health effects of novel PFASs.

Spatial distribution, compositional profile, sources, ecological and human health risks of legacy and emerging per- and polyfluoroalkyl substances (PFASs) in freshwater reservoirs of Punjab, Pakistan

Per- and polyfluoroalkyl substances (PFASs) are a large group of chemicals reported in global environment and are responsible for various adverse impacts on humans and environment. We report a comprehensive study on occurrence of PFASs, including legacy, substitute and emerging ones, from Pakistan. Surface water samples were collected from five ecologically important freshwater reservoirs in Pakistan, namely, Head Panjnad (HP), Head Trimmu (HT), Chashma Barrage (CB), Head Blloki (HB), and Head Qadirabad (HQ). The detection frequencies of PFASs ranged between 37 %-100 %. The highest concentration of ∑₁₅PFASs was detected at HP (114.1 ng L^-1), whereas the lowest at HQ (19.9 ng L^-1). Among the analyzed PFASs, 6:2 fluorotelomer sulfonic acid (6:2 FTS) and perfluorooctanoic acid (PFOA) showed maximum mean concentrations of 9.1 ng L^-1 and 7 ng L^-1 at HP, followed by Perfluorooctane sulfonic acid (PFOS) with level of 0.99 ng L^-1 at HT. The ecological risk assessment for selected species i.e., daphnid, mysid, fish and green algae showed that PFOS, perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA) exhibited moderate risk i.e., Hazard Quotients (HQs) < 1 to the modeled organisms, whereas perfluorobutane sulfonic acid (PFBS) showed the high risk to green algae (HQs = 8.6) and PFOA presented a high risk to all the organisms (HQs ranged between 1.04 and 7.38). The level of ∑PFASs at HP (114.1 ng L^-1) exceed the EU guideline value of ∑PFASs in water (100 ng L^-1), however the risk quotient (RQ_mix) values of all age groups were < 1 implying that the detected PFASs in water do not pose risk to human health. Source apportionment through Positive Matrix Factorization (PMF) showed that industrial effluent is the main source of PFASs in freshwater reservoirs. Comparable concentrations of legacy and substitute PFASs in this study indicate that legacy PFASs are still in use adjacent to ecologically important water reservoirs.

Exposure and Health Risk Assessment of Per- and Polyfluoroalkyl Substances in Crayfish from the Middle and Lower Reaches of the Yangtze River

Per- and polyfluoroalkyl substances (PFASs) are a novel class of emerging persistent organic pollutants (POPs) owing to their environmental persistence and bioaccumulation. Red swamp crayfish is a major source of exposure to PFASs, while the dietary intake of PFASs from crayfish is still unclear. We investigated the concentrations of PFASs in 130 batches of crayfish and 100 environmental samples from Middle and Lower Reaches of the Yangtze River Delta. Seven Perfluoroalkyl carboxylic acids (PFCAs), 3 Perfluoroalkyl sulfonates (PFSAs), and 6:2 Cl-PFESA were analyzed by ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Meanwhile, PFASs exposure levels were examined concretely in four tissues of crayfish and different circulation links. The average daily intake (ADI) risk model was used to evaluate the human health risk of consuming crayfish and suggested that the risk of PFASs exposure is at a low level.

Solvent-Free, Ambient Temperature and Pressure Destruction of Perfluorosulfonic Acids under Mechanochemical Conditions: Degradation Intermediates and Fluorine Fate

Perfluorosulfonic acids (PFSAs) are a recalcitrant subclass of per- and polyfluoroalkyl substances (PFASs) linked to numerous negative health effects in humans. Scalable technologies that effectively destroy PFSAs will greatly reduce the future health and ecological impact of these "forever chemicals". Herein, we show that several PFSAs undergo facile mechanochemical destruction (MCD) in the presence of quartz sand (SiO₂). This process operates in the absence of solvent, at ambient temperature and pressure, generating a benign solid byproduct. Quantitative analysis of milled samples revealed high destruction efficiencies of 99.95% to 100% for five different PFSAs subjected to MCD conditions in the presence of SiO₂ only. Extensive nontargeted analysis showed that, during degradation, other PFASs form and are ultimately destroyed upon extended mechanochemical treatment. Direct polarization (DP) and cross-polarization (CP) solid-state nuclear magnetic resonance (SSNMR) spectroscopy showed abundant silicon-fluorine (Si-F) bond formation post-MCD, indicating that fluorine was secured in a stable reservoir. Collectively, these results identified the degradation profile for an environmentally sound and effective PFSA degradation process that is amenable to scale-up.

Temporal trends in PFAS concentrations in livers of a terrestrial raptor (common buzzard; Buteo buteo) collected in Belgium during the period 2000-2005 and in 2021

Per- and polyfluoroalkyl substances (PFAS) are anthropogenic chemicals that have been globally distributed. Biological time series data suggest variation in temporal PFAS concentrations due to regulations and the phase-out of multiple PFAS analytes. Nonetheless, biomonitoring temporal trends of PFAS concentrations in raptors has only been done sporadically in Europe at a national scale. In the present study, we examined the concentrations of 28 PFAS in livers of common buzzard (Buteo buteo) collected in Belgium in the period 2000-2005 and in 2021. Despite the regulations and phase-out, the ΣPFAS concentrations remained similar in the livers over the past 20 years. However, over time the abundance of perfluorooctane sulfonate (PFOS), dominant in livers collected in 2000-2005, to the ΣPFAS concentration decreased from 46% to 27%, whereas the abundance of perfluorotetradecanoic acid (PFTeDA), dominant in 2021, increased from 19% to 43%. The PFOS concentrations in the present study did not exceed the Toxicity Reference Values (TRVs), which were determined in liver on the characteristics of an avian top predator. The absence of temporal changes in PFAS concentrations is hypothesized to be due to a lagged response in environmental concentrations compared to atmospheric concentrations.

Removing per- and polyfluoroalkyl substances (PFAS) in water by foam fractionation

Treatment of large volumes of waters contaminated by per- and polyfluoroalkyl substances (PFAS) remains a challenge. This work presented a systematic study on PFAS removal by foam fractionation (FF). Experiments were conducted on both laboratory-spiked and environmental water samples containing PFASs. It is found that higher air flow, greater ionic strength, and addition of thickener boosted PFAS removal in the defoamed bottom solutions and intensified enrichment in the collected foam. FF treatments of a landfill leachate, a groundwater contaminated by aqueous film-forming foams, and a wastewater treatment plant effluent sample were evaluated. The removal reached above 70% for most monitored PFASs, except the ones of short alkyl chains. PFAS concentrations in the final collected foams were up to over 30 × than that in the original samples. Analysis using high-resolution mass spectrometry revealed enrichment of non-target PFASs by FF. The results of this study demonstrate great effectiveness of FF in removing most PFASs from waters, producing low-volume, highly concentrated solutions of PFASs in all tested environmental samples.

Associations of PFAS-related plasma metabolites with cholesterol and triglyceride concentrations

The wide-spread environmental pollutants per- and polyfluoroalkyl substances (PFAS) have repeatedly been associated with elevated serum cholesterol in humans. However, underlying mechanisms are still unclear. Furthermore, we have previously observed inverse associations with plasma triglycerides. To better understand PFAS-induced effects on lipid pathways we investigated associations of PFAS-related metabolite features with plasma cholesterol and triglyceride concentrations. We used 290 PFAS-related metabolite features that we previously discovered from untargeted liquid chromatography-mass spectometry metabolomics in a case-control study within the Swedish Västerbotten Intervention Programme cohort. Herein, we studied associations of these PFAS-related metabolite features with plasma cholesterol and triglyceride concentrations in plasma samples from 187 healthy control subjects collected on two occasions between 1991 and 2013. The PFAS-related features did not associate with cholesterol, but 50 features were associated with triglycerides. Principal component analysis on these features indicated that one metabolite pattern, dominated by glycerophospholipids, correlated with longer chain PFAS and associated inversely with triglycerides (both cross-sectionally and prospectively), after adjustment for confounders. The observed time-trend of the metabolite pattern resembled that of the longer chain PFAS, with higher levels during the years 2004-2010. Mechanisms linking PFAS exposures to triglycerides may thus occur via longer chain PFAS affecting glycerophospholipid metabolism. If the results reflect a cause-effect association, as implied by the time-trend and prospective analyses, this may affect the general adult population.

Occurrence and behavior of per- and polyfluoroalkyl substances and conversion of oxidizable precursors in the waters of coastal tourist resorts in China

Per- and polyfluorolkyl substances (PFAS) were measured in the water and fish from 20 coastal tourist resorts in China, to investigate their sources, seasonal differences, and bioconcentration. An oxidative method with hydroxyl radicals was used to extract potential perfluoroalkyl acid (PFAA) precursors in the water of resorts. The results indicated that the total concentrations of target chemicals (i.e., ΣPFAS) in the original water were 59.4-138, 32.7-77.2, and 14.6-29.9 ng L^-1 in December, April, and August, respectively. C₄-C₁₀ perfluorocarboxlate (PFCA) and perfluorooctane sulfonate (PFOS) accounted for 67%-92% of the ΣPFAS contents in all water samples. The PFAS concentrations in the muscles and liver of fish were 16.0-162 ng g^-1 ww and 186-1240 ng g^-1 ww, respectively. The dominant compounds were perfluorobutanoate acid (PFBA) and PFOS in the water, and perfluorooctanoic acid (PFOA) and PFOS in fish tissues. High bioconcentration were observed for PFCA (C ≥ 8) and perfluorosulfonate (PFSA, C ≥ 6). After oxidative conversion, the water exhibited a noticeable increase in the ΣPFAS value. Precursors that generated C₄-C₉ PFCA were more prevalent than precursors that generated other PFCA upon oxidation. The concentration of C₈-based precursor was higher than that of C₆-based precursor in wet and dry seasons. This study is the first to apply an oxidative method to investigate PFAS pollution in the water of coastal tourist resorts. The results verified that PFAA precursors exist in the water of coastal tourist resorts, and more attention should be given to the existence of PFAA precursors and the safety of water in coastal tourist resorts.

Association between per- and polyfluoroalkyl substances exposure and risk of diabetes: a systematic review and meta-analysis

BACKGROUND

Emerging evidence suggests that per- and polyfluoroalkyl substances (PFAS) are endocrine disruptors and may contribute to the etiology of diabetes.

OBJECTIVES

This study aimed to systematically review the epidemiological evidence on the associations of PFAS with mortality and morbidity of diabetes and to quantitatively evaluate the summary effect estimates of the existing literature.

METHODS

We searched three electronic databases for epidemiological studies concerning PFAS and diabetes published before April 1, 2022. Summary odds ratio (OR), hazard ratio (HR), or β and their 95% confidence intervals (CIs) were respectively calculated to evaluate the association between PFAS and diabetes using random-effects model by the exposure type, and dose-response meta-analyses were also performed when possible. We also assessed the risk of bias of the studies included and the confidence in the body of evidence.

RESULTS

An initial literature search identified 1969 studies, of which 22 studies were eventually included. The meta-analyses indicated that the observed statistically significant PFAS-T2DM associations were consistent in cohort studies, while the associations were almost non-significant in case-control and cross-sectional studies. Dose-response meta-analysis showed a "parabolic-shaped" association between perfluorooctanoate acid (PFOA) exposure and T2DM risk. Available evidence was rated with "low" risk of bias, and the level of evidence for PFAS and incident T2DM was considered "moderate".

CONCLUSIONS

Our findings suggest that PFAS exposure may increase the risk of incident T2DM, and that PFOA may exert non-monotonic dose-response effect on T2DM risk. Considering the widespread exposure, persistence, and potential for adverse health effects of PFAS, further cohort studies with improvements in expanding the sample size, adjusting the covariates, and considering different types of PFAS exposure at various doses, are needed to elucidate the putative causal associations and potential mode of action of different PFAS on diabetes.

IMPACT STATEMENT

A growing body of evidence suggests that per- and polyfluoroalkyl substances (PFAS) are endocrine disruptors and may contribute to the development of diabetes. However, epidemiological evidence on the associations of PFAS and diabetes is inconsistent. We performed this comprehensive systematic review and meta-analysis to quantitatively synthesize the evidence. The findings of this study suggest that exposure to PFAS may increase diabetes risk among the general population. Reduced exposure to these "forever and everywhere chemicals" may be an important preventative approach to reducing the risk of diabetes across the population.

Per- and polyfluoroalkyl substances exposure and bone mineral density in the U.S. population from NHANES 2005-2014

BACKGROUND

Environmental exposures such as perfluoroalkyl substances (PFASs) were considered potential risks for bone mineral density (BMD).

OBJECTIVE

To examine the associations between PFASs and BMD among the U.S. population.

METHODS

This study included a total of 6416 participants from the National Health and Nutrition Examination Survey (NHANES 2005-2014). Multiple linear regression models were used to analyze the associations between serum PFASs and BMD and the coefficient β with 95% confidence intervals (95% CI) was calculated as the effect estimate. Covariates such as age, race, BMI, smoking, alcohol intake, milk intake, and physical activity were adjusted in these models. Additionally, gender and menopausal period were considered in further subgroup analyses.

RESULTS

Based on the combined data of NHANES 2005-2014, the effects from exposure to PFASs on BMD were found with gender and menopausal status differences. Positive associations were found in PFOA (β = 0.010; 95% CI: 0.003, 0.016), PFHxS (β = 0.007; 95% CI: 0.003, 0.012), and PFNA (β = 0.001; 95% CI: 0.001, 0.017) in total population. Negative associations for PFOA (β = -0.020; 95% CI: -0.029, -0.012), PFOS (β = -0.011; 95% CI: -0.028, -0.011), PFHxS (β = -0.019; 95% CI: -0.025, -0.013), PFDE (β = -0.010; 95% CI: -0.016, -0.005), and PFNA (β = -0.011; 95% CI: -0.021, -0.002) were found in women, while no significant association was found in men. In further subgroup analyses, women in pre-menopause status showed consistent negative associations.

SIGNIFICANCE

PFASs exposure may be associated with BMD and gender and menopausal status confound the associations.

A sensitive and robust method for the simultaneous determination of thirty-three legacy and emerging per- and polyfluoroalkyl substances in human plasma and serum

Legacy and emerging per- and polyfluoroalkyl substances (PFAS) have attracted growing attention due to their potential adverse effects on humans. We developed a method to simultaneously determine thirty-three PFAS (legacy PFAS, precursors, and alternatives) in human plasma and serum using solid phase extraction coupled to ultra-performance liquid chromatography-tandem mass spectrometry (SPE-UPLC-MS/MS). The method yielded good linearity (>0.995) and excellent limits of detection (LODs) (0.0005~0.012 ng mL^-1 in plasma and 0.002~0.016 ng mL^-1 in serum). The relative recoveries ranged from 80.1 to 116%, with intra- and inter-day precision less than 14.3%. The robustness of this method has been tested continuously for 10 months (coefficients of variation <14.9%). Our method was successfully applied to the PFAS analysis of 42 real human plasma and serum samples collected from women. The proposed method is attractive for the biomonitoring of multi-class PFAS in human health risk assessment and epidemiological studies.

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

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

Overview of African water resources contamination by contaminants of emerging concern

This review look at several classes of contaminants of emerging concern (CECs) in conventional and non-conventional water resources across the African continent's five regions. According to the review, pharmaceuticals, endocrine-disrupting chemicals, personal care products, pesticides, per- and polyfluoroalkyl compounds, and microplastics were found in conventional and non-conventional water resources. Most conventional water resources, such as rivers, streams, lakes, wells, and boreholes, are used as drinking water sources. Non-conventional water sources, such as treated wastewater (effluents), are used for domestic and agricultural purposes. However, CECs remain part of the treated wastewater, which is being discharged to surface water or used for agriculture. Thus, wastewater (effluent) is the main contributor to the pollution of other water resources. For African countries, the prevalence of rising emerging pollutants in water poses a severe environmental threat. There are different adverse effects of CECs, including the development of antibiotic-resistant bacteria, ecotoxicological effects, and several endocrine disorders. Therefore, this needs the urgent attention of the African Union, policymakers, Non-Governmental Organizations, and researchers to come together and tackle the problem.

Persistent Organic Pollutant Exposure and Thyroid Function among 12-Year-Old Children

INTRODUCTION

Polychlorobiphenyls (PCBs), organochlorine pesticides (OCPs), and per- and polyfluoroalkyl substances (PFASs) are persistent organic pollutants (POPs) having numerous toxicological properties, including thyroid endocrine disruption. Our aim was to assess the impact of POPs on thyroid hormones among 12-year-old children, while taking puberty into consideration.

METHODS

Exposure to 7 PCBs, 4 OCPs, and 6 PFASs (in µg/L), and free tri-iodothyronine (fT3, pg/mL), free thyroxine (fT4, ng/dL), and thyroid-stimulating hormones (TSH, mIU/L) were assessed through blood-serum measurements at age 12 years in 249 boys and 227 girls of the PELAGIE mother-child cohort (France). Pubertal status was clinically rated using the Tanner stages. For each POP, associations were estimated using linear regression, adjusted for potential confounders.

RESULTS

Among boys, hexachlorobenzene and perfluorodecanoic acid were associated with decreased fT3 (log-scale; β [95% confidence interval] = -0.07 [-0.12,-0.02] and β = -0.03 [-0.06,-0.00], respectively). Intermediate levels of perfluorohexanesulfonic acid (PFHxS) and PCB180 were associated, respectively, with increased and decreased fT4. After stratification on pubertal status, PCBs and OCPs were associated with decreased TSH only in the more advanced Tanner stages (3-5) and with decreased fT3 among early Tanner stages (1-2). Among girls, PFHxS was associated with decreased TSH (log-scale; β = -0.15 [-0.29,-0.00]), and perfluorooctanoic acid was associated with decreased fT3 (β2nd_tercile = -0.06 [-0.10,-0.03] and β3rd_tercile = -0.04 [-0.08,-0.00], versus. 1st tercile).

DISCUSSION

This cross-sectional study highlights associations between some POPs and thyroid function disruption, which appears consistent with the literature. Considering that the associations were sex-specific and moderated by pubertal status in boys, complex endocrine interactions are likely involved.