Perfluorinated Chemicals as Emerging Environmental Threats to Kidney Health: A Scoping Review

Changes in plasma concentrations of per- and Polyfluoroalkyl substances after bariatric surgery in adolescents from the Teen-Longitudinal Assessment of Bariatric Surgery (Teen-LABS) study

Exposure to per- and poly-fluoroalkyl substances (PFAS) is ubiquitous due to their persistence in the environment and in humans. Extreme weight loss has been shown to influence concentrations of circulating persistent organic pollutants (POPs). Using data from the multi-center perspective Teen-Longitudinal Assessment of Bariatric Surgery (Teen-LABS) cohort, we investigated changes in plasma-PFAS in adolescents after bariatric surgery. Adolescents (Mean age = 17.1 years, SD = 1.5 years) undergoing bariatric surgery were enrolled in the Teen-LABS study. Plasma-PFAS were measured at the time of surgery and then 6-, 12-, and 36 months post-surgery. Linear mixed effect models were used to evaluate longitudinal changes in plasma-PFAS after the time of bariatric surgery. This study included 214 adolescents with severe obesity who had available longitudinal measures of plasma-PFAS and underwent bariatric surgery between 2007 and 2012. Underlying effects related to undergoing bariatric surgery were found to be associated with an initial increase or plateau in concentrations of circulating PFAS up to 6 months after surgery followed by a persistent decline in concentrations of 36 months (p < 0.001 for all plasma-PFAS). Bariatric surgery in adolescents was associated with a decline in circulating PFAS concentrations. Initially following bariatric surgery (0-6 months) concentrations were static followed by decline from 6 to 36 months following surgery. This may have large public health implications as PFAS are known to be associated with numerous metabolic related diseases and the significant reduction in circulating PFAS in individuals who have undergone bariatric surgery may be related to the improvement of such metabolic related diseases following bariatric surgery.

Kidney function decline mediates the adverse effects of per- and poly-fluoroalkyl substances (PFAS) on uric acid levels and hyperuricemia risk

Previous studies indicated per- and poly-fluoroalkyl substances (PFAS) were related to uric acid and hyperuricemia risk, but evidence for the exposure-response (E-R) curves and combined effect of PFAS mixture is limited. Moreover, the potential mediation effect of kidney function was not assessed. Hence, we conducted a national cross-sectional study involving 13,979 US adults in NHANES 2003-2018 to examine the associations of serum PFAS with uric acid and hyperuricemia risk, and the mediation effects of kidney function. Generalized linear models and E-R curves showed positive associations of individual PFAS with uric acid and hyperuricemia risk, and nearly linear E-R curves indicated no safe threshold for PFAS. Weighted quantile sum regression found positive associations of PFAS mixture with uric acid and hyperuricemia risk, and PFOA was the dominant contributor to the adverse effect of PFAS on uric acid and hyperuricemia risk. Causal mediation analysis indicated significant mediation effects of kidney function decline in the associations of PFAS with uric acid and hyperuricemia risk, with the mediated proportion ranging from 19 % to 57 %. Our findings suggested that PFAS, especially PFOA, may cause increased uric acid and hyperuricemia risk increase even at low levels, and kidney function decline plays a crucial mediation effect.

Involvement of per- and polyfluoroalkyl compounds in tumor development

Per- and polyfluoroalkyl substances (PFAS) are a large group of synthetic persistent chemicals, which are used in many industrial and commercial applications. Hundreds of different PFAS have been identified in the environment and they are commonly found also in human blood. Due to the chemical stability and extensive use, PFAS pose a risk for human health and wildlife. Mounting evidence indicates that PFAS-exposure adversely affects many organs including liver, kidney, and reproductive tissues and induces tumors in laboratory rodents. Epidemiological studies show association between PFAS-exposure and some tumors also in humans. Effects of PFAS-exposure are complex and obviously do not depend only on the concentration and the structure of PFAS, but also on age and sex of the exposed individuals. It has been difficult to show a causal link between PFAS-exposure and tumors. Moreover, molecular mechanisms of the PFAS effects in different tissues are poorly understood. PFAS are not directly mutagenic and they do not induce formation of DNA binding metabolites, and thus are assumed to act more through non-genotoxic mechanisms. In this review, we discuss the involvement of PFAS-compounds in tumor development in tissues where PFAS exposure has been associated with cancer in epidemiological and animal studies (liver, kidney, testicle and breast). We will focus on molecular pathways and mechanisms related to tumor formation following PFAS-exposure.

Temporal Trend of Serum Perfluorooctanoic Acid and Perfluorooctane Sulfonic Acid among U.S. Adults with or without Comorbidities in NHANES 1999-2018

Perfluoroalkyl and polyfluoroalkyl substances (PFAS) are associated with adverse health effects. This study examined the trend of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) levels in individuals with and without pre-existing comorbidities. We analyzed the characteristics of 13,887 participants across nine U.S. NHANES cycles (1999-2000 to 2017-2018) and calculated the geometric mean (GM) of PFOA and PFOS levels, standardized by sex and age. A joinpoint regression model was used to analyze the temporal trends of serum PFOA and PFOS levels. We observed declining PFOA and PFOS serum levels among adults in NHANES from 1999-2000 to 2017-2018. Serum PFOA and PFOS concentrations were higher in men, smokers, and individuals with pre-existing CKD, hyperlipidemia, CVD, and cancer. We observed faster decline rates in PFOA levels among individuals with diabetes and CKD and faster decline rates in PFOS levels among individuals with diabetes and those without CKD. This study provided evidence of varying levels and changing trends of PFOA and PFOS between groups with and without established chronic disease, highlighting the role of environmental chemicals in the onset and development of chronic diseases.

Lipid responses to perfluorooctane sulfonate exposure for multiple rat organs

Perfluorooctane sulfonate (PFOS) is a persistent chemical that has long been a threat to human health. However, the molecular effects of PFOS on various organs are not well studied. In this study, male Sprague-Dawley rats were treated with various doses of PFOS through gavage for 21 days. Subsequently, the liver, lung, heart, kidney, pancreas, testis, and serum of the rats were harvested for lipid analysis. We applied a focusing lipidomic analytical strategy to identify key lipid responses of phosphorylcholine-containing lipids, including phosphatidylcholines and sphingomyelins. Partial least squares discriminant analysis revealed that the organs most influenced by PFOS exposure were the liver, kidney, and testis. Changes in the lipid profiles of the rats indicated that after exposure, levels of diacyl-phosphatidylcholines and 22:6-containing phosphatidylcholines in the liver, kidney, and testis of the rats decreased, whereas the level of 20:3-containing phosphatidylcholines increased. Furthermore, levels of polyunsaturated fatty acids-containing plasmenylcholines decreased. Changes in sphingomyelin levels indicated organ-dependent responses. Decreased levels of sphingomyelins in the liver, nonmonotonic dose responses in the kidney, and irregular responses in the testis after PFOS exposure are observed. These lipid responses may be associated with alterations pertaining to phosphatidylcholine synthesis, fatty acid metabolism, membrane properties, and oxidative stress in the liver, kidney, and testis. Lipid responses in the liver could have contributed to the observed increase in liver to body weight ratios. The findings suggest potential toxicity and possible mechanisms associated with PFOS in multiple organs.

Exposure to per- and polyfluoroalkyl substances and bone health: a systematic review and meta-analysis

Perfluoroalkyl substances (PFAS) as a large group of synthetic compounds widely contaminated the environment and lead to health problems. However, the correlation between PFAS exposure, bone health parameters and osteoporosis remains controversial. Therefore, we conducted a systematic review and meta-analysis of published literature to evaluate the effects of PFAS on human bone health. All observational studies were collected up to 2 December 2023. A total of 2096 articles were retrieved. Of these, 21 articles investigated the association between PFAS exposure and human bone health. However, only 10 studies were included in the final meta-analysis. Doubling of serum perfluorooctanoic acid (PFOA) (β = -0.11, 95% confidence interval (CI): -0.18, -0.05) and perfluorooctane sulfonic acid (PFOS) (β = -0.06, 95% CI: -0.11, -0.01) levels showed significant negative correlations with total body less head bone mineral density (TBLH-BMD). Subgrouping showed that only perfluorohexane sulfonate (PFHxS) (odds ratio [OR] = 1.37, 95% CI: 1.12, 1.68) was correlated with osteoporosis.

Relationship of single and co-exposure of per-and polyfluoroalkyl substances and their alternatives with uric acid: A community-based study in China

Numerous studies have suggested per-and polyfluoroalkyl substances (PFASs) are related to uric acid levels, but evidence related to PFAS alternatives is limited. Moreover, the effect of the combined exposure to PFASs and their alternatives on uric acid has not been reported. Hence, we conducted a cross-sectional study involving 1312 adults in Guangzhou, China. Generalized linear regression model was adopted to explore the effect of single PFAS exposure on serum uric acid levels. Further, multi-pollutant models such as Bayesian kernel machine regression, weighted quantile sum, and quantile G-computation were employed to investigate the combined association of PFASs and alternatives with serum uric acid levels. We performed molecular docking to understand the potential interaction of PFAS with Organic Anion Transporters (OATs), involved in the secretion of uric acid. Per log serum 6:2 Cl-PFESA and PFOA increases were accompanied with an increase of serum uric acid with statistical significance (for 6:2 Cl-PFESA: beta: 0.19 ng/mL, 95% CI 0.11-0.26 and for PFOA: beta: 0.43 ng/mL, 95% CI 0.34-0.52). The associations were strongest among overweight and elderly. Multi-pollutant models also revealed a positive association. These positive associations may be PFASs can competitively combine with OAT1 and OAT3, leading to the increase of serum uric acid.

Comparative hepatotoxicity of novel lithium bis(trifluoromethanesulfonyl)imide (LiTFSI, ie. HQ-115) and legacy Perfluorooctanoic acid (PFOA) in male mice: Insights into epigenetic mechanisms and pathway-specific responses

Lithium Bis(trifluoromethanesulfonyl)imide (LiTFSI ie. HQ-115), a polymer electrolyte used in energy applications, has been detected in the environment, yet its health risks and environmental epigenetic effects remain unknown. This study aims to unravel the potential health risks associated with LiTFSI, investigate the role of DNA methylation-induced toxic mechanisms in its effects, and compare its hepatotoxic impact with the well-studied Perfluorooctanoic Acid (PFOA). Using a murine model, six-week-old male CD1 mice were exposed to 10 and 20 mg/kg/day of each chemical for 14 days as 14-day exposure and 1 and 5 mg/kg/day for 30 days as 30-day exposure. Results indicate that PFOA exposure induced significant hepatotoxicity, characterized by liver enlargement, and elevated serum biomarkers. In contrast, LiTFSI exposure showed lower hepatotoxicity, accompanied by mild liver injuries. Despite higher bioaccumulation of PFOA in serum, LiTFSI exhibited a similar range of liver concentrations compared to PFOA. Reduced Representative Bisulfite Sequencing (RRBS) analysis revealed distinct DNA methylation patterns between 14-day and 30-day exposure for the two compounds. Both LiTFSI and PFOA implicated liver inflammatory pathways and lipid metabolism. Transcriptional results showed that differentially methylated regions in both exposures are enriched with cancer/disease-related motifs. Furthermore, Peroxisome proliferator-activated receptor alpha (PPARα), a regulator of lipid metabolism, was upregulated in both exposures, with downstream genes indicating potential oxidative damages. Overall, LiTFSI exhibits distinct hepatotoxicity profiles, emphasizing the need for comprehensive assessment of emerging PFAS compounds.

Interspecies comparison of metabolism of two novel prototype PFAS

As a result of proposed global restrictions and regulations on current-use per-and polyfluoroalkyl substances (PFAS), research on possible alternatives is highly required. In this study, phase I in vitro metabolism of two novel prototype PFAS in human and rat was investigated. These prototype chemicals are intended to be safer-by-design and expected to mineralize completely, and thus be less persistent in the environment compared to the PFAS available on the market. Following incubation with rat liver S9 (RL-S9) fractions, two main metabolites per initial substance were produced, namely an alcohol and a short-chain carboxylic acid. While with human liver S9 (HL-S9) fractions, only the short-chain carboxylic acid was detected. Beyond these major metabolites, two and five additional metabolites were identified at very low levels by non-targeted screening for the ether- and thioether-linked prototype chemicals, respectively. Overall, complete mineralization during the in vitro hepatic metabolism of these novel PFAS by HL-S9 and RL-S9 fractions was not observed. The reaction kinetics of the surfactants was determined by using the metabolite formation, rather than the substrate depletion approach. With rat liver enzymes, the formation rates of primary metabolite alcohols were at least two orders of magnitude higher than those of secondary metabolite carboxylic acids. When incubating with human liver enzymes, the formation rates of single metabolite carboxylic acids, were similar or smaller than those experienced in rat. It also indicates that the overall metabolic rate and clearance of surfactants are significantly higher in rat liver than in human liver. The maximum formation rate of the thioether congener exceeded 10-fold that of the ether in humans but were similar in rats. Overall, the results suggest that metabolism of the prototype chemicals followed a similar trend to those reported in studies of fluorotelomer alcohols.

Studying mixture effects on uptake and tissue distribution of PFAS in zebrafish (Danio rerio) using physiologically based kinetic (PBK) modelling

Per- and polyfluoroalkyl substances (PFAS) are ubiquitously distributed in the aquatic environment. They include persistent, mobile, bioaccumulative, and toxic chemicals and it is therefore critical to increase our understanding on their adsorption, distribution, metabolism, excretion (ADME). The current study focused on uptake of seven emerging PFAS in zebrafish (Danio rerio) and their potential maternal transfer. In addition, we aimed at increasing our understanding on mixture effects on ADME by developing a physiologically based kinetic (PBK) model capable of handling co-exposure scenarios of any number of chemicals. All studied chemicals were taken up in the fish to varying degrees, whereas only perfluorononanoate (PFNA) and perfluorooctanoate (PFOA) were quantified in all analysed tissues. Perfluorooctane sulfonamide (FOSA) was measured at concerningly high concentrations in the brain (Cmax over 15 μg/g) but also in the liver and ovaries. All studied PFAS were maternally transferred to the eggs, with FOSA and 6:2 perfluorooctane sulfonate (6,2 FTSA) showing significant (p < 0.02) signs of elimination from the embryos during the first 6 days of development, while perfluorobutane sulfonate (PFBS), PFNA, and perfluorohexane sulfonate (PFHxS) were not eliminated in embryos during this time-frame. The mixture PBK model resulted in >85 % of predictions within a 10-fold error and 60 % of predictions within a 3-fold error. At studied levels of PFAS exposure, competitive binding was not a critical factor for PFAS kinetics. Gill surface pH influenced uptake for some carboxylates but not the sulfonates. The developed PBK model provides an important tool in understanding kinetics under complex mixture scenarios and this use of New Approach Methodologies (NAMs) is critical in future risk assessment of chemicals and early warning systems.

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

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

Efficient and fast remediation of soil contaminated by per- and polyfluoroalkyl substances (PFAS) by high-frequency heating

This study presents a novel thermal technology (high-frequency heating, HFH) for the decontamination of soil containing per- and polyfluoroalkyl substances (PFAS) and aqueous film-forming foams (AFFFs). Ultra-fast degradation of short-chain PFAS, long-chain homologs, precursors, legacy PFAS, emerging PFAS was achieved in a matter of minutes. The concentrations of PFAS and the soil type had a negligible impact on degradation efficiency, possibly due to the ultra-fast degradation rate overwhelming potential differences. Under the current HFH experiment setup, we achieved near-complete degradation (e.g., >99.9%) after 1 min for perfluoroalkyl carboxylic acids and perfluoroalkyl ether carboxylic acids and 2 min for perfluoroalkanesulfonic acids. Polyfluoroalkyl precursors in AFFFs were found to degrade completely within 1 min of HFH; no residual cationic, zwitterionic, anionic, or non-ionic intermediate products were detected following the treatment. The gaseous byproducts were considered. Most of gaseous organofluorine products of PFAS at low-and-moderate temperatures disappeared when temperatures reached 890 °C, which is in the temperature zone of HFH. For the first time, we demonstrated minimal loss of PFAS in water during the boiling process, indicating a low risk of PFAS entering the atmosphere with the water vapor. The findings highlight HFH its potential as a promising remediation tool for PFAS-contaminated soils.

Impact of Variable Water Chemistry on PFOS-Goethite Interactions: Experimental Evidence and Surface Complexation Modeling

Perfluorooctanesulfonate (PFOS) has become a major concern due to its widespread occurrence in the environment and severe toxic effects. In this study, we investigate PFOS sorption on goethite surfaces under different water chemistry conditions to understand the impact of variable groundwater chemistry. Our investigation is based on multiple lines of evidence, including (i) a series of sorption experiments with varying pH, ionic strength, and PFOS initial concentration, (ii) IR spectroscopy analysis, and (iii) surface complexation modeling. PFOS was found to bind to goethite through a strong hydrogen-bonded (HB) complex and a weaker outer-sphere complex involving Na+ coadsorption (OS-Na+). The pH and ionic strength of the solution had a nontrivial impact on the speciation and coexistence of these surface complexes. Acidic conditions and low ionic strength promoted hydrogen bonding between the sulfonate headgroup and protonated hydroxo surface sites. Higher electrolyte concentrations and pH values hindered the formation of strong hydrogen bonds upon the formation of a ternary PFOS-Na+-goethite outer-sphere complex. The findings of this study illuminate the key control of variable solution chemistry on PFOS adsorption to mineral surfaces and the importance to develop surface complexation models integrating mechanistic insights for the accurate prediction of PFOS mobility and environmental fate.

Validating blood microsampling for per- and polyfluoroalkyl substances quantification in whole blood

Microsampling allows the collection of blood samples using a method which is inexpensive, simple and minimally-invasive, without the need for specially-trained medical staff. Analysis of whole blood provides a more holistic understanding of per- and polyfluoroalkyl substances (PFAS) body burden. Capillary action microsamplers (Trajan hemaPEN®) allow the controlled collection of whole blood as dried blood spots (DBS) (four 2.74 µL ± 5 %). The quantification of 75 PFAS from DBS was evaluated by comparing five common extraction techniques. Spiked blood (5 ng/mL PFAS) was extracted by protein precipitation (centrifuged; filtered), acid-base liquid-liquid extraction, trypsin protease digestion, and weak anion exchange (WAX) solid-phase extraction with analysis by high-performance liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). Filtered protein precipitation was the most effective extraction method, recovering 72 of the 75 PFAS within 70 to 130 % with method reporting limit (MRL) for PFOS of 0.17 ng/L and ranging between 0.05 ng/mL and 0.34 ng/mL for all other PFAS. The optimised method was applied to human blood samples to examine Inter- (n = 7) and intra-day (n = 5) PFAS blood levels in one individual. Sixteen PFAS were detected with an overall Σ16PFAS mean = 6.3 (range = 5.7-7.0) ng/mL and perfluorooctane sulfonate (branched and linear isomers, ΣPFOS) = 3.3 (2.8-3.7) ng/mL being the dominant PFAS present. To the authors knowledge, this minimally invasive self-sampling protocol is the most extensive method for PFAS in blood reported and could be a useful tool for large scale human biomonitoring studies.

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

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

Association of per- and polyfluoroalkyl substance exposure with metabolic syndrome and its components in adults and adolescents

Per- and polyfluoroalkyl substances (PFAS) are widespread contaminants, but few studies have explored the relationship between PFAS and levels of metabolic syndrome (MetS) in the population. The available evidence of an association is also conflicting. We selected adults and adolescents with complete PFAS data from the National Health and Nutrition Examination Survey conducted between 2003 and 2018. We analyzed the association between PFAS and MetS using multivariate logistic regression models and evaluated potential nonlinear relationships with restricted cubic spline models. Additionally, we employed weighted quantile sum (WQS) regressions to uncover the multiple exposure effects and relative weights of each PFAS. Finally, we conducted a series of sensitivity analyses to test the robustness of our findings. In this population-based study, we analyzed data from a total of 4,973 adults, aged 20-85 years, and 1,381 adolescents, aged 12-19 years. Using fully adjusted multivariate logistic regression models, we found that serum levels of perfluorodecanoate (PFDA) [0.65 (0.50, 0.85)] and total PFAS [0.92 (0.85, 0.99)] were negatively associated with the prevalence of MetS in adults. Similarly, in adolescents, we observed negative correlations between the prevalence of MetS and levels of PFDA [0.55 (0.38, 0.80)], perfluorooctanoic acid (PFOA) [0.62 (0.39, 1.00)], perfluorooctane sulfonic acid (PFOS) [0.59 (0.36, 0.96)], and total PFAS [0.61 (0.37, 0.99)]. Additionally, our study identified statistically significant negative associations between serum levels of PFAS and certain components of MetS, primarily elevated fasting glucose and lower high-density lipoprotein cholesterol. Our study found that PFAS was associated with a lower prevalence of MetS in both adults and adolescents, offering new insights into the relationship between PFAS and metabolic health. Interestingly, however, we observed conflicting findings across the components of MetS. Specifically, we observed that PFAS had a negative correlation with some metrics and a positive correlation with others. These conflicting results point to a complex interplay between PFAS and various metrics of metabolic health.

Novel Insights into the Adverse Health Effects of per- and Polyfluoroalkyl Substances on the Kidney via Human Urine Metabolomics

Per- and polyfluoroalkyl substances (PFAS) receive significant research attention due to their potential adverse effects on human health. Evidence shows that the kidney is one of the target organs of PFAS. In occupational exposure scenarios, high PFAS concentrations may adversely affect kidney metabolism, but whether this effect is reflected in the small metabolic molecules contained in urine remains unknown. In this study, 72 matched serum and urine samples from occupational workers of a fluorochemical manufactory as well as 153 urine samples from local residents were collected, and 23 PFAS levels were quantified. The concentrations of Σ23PFAS in the serum and urine samples of workers were 5.43 ± 1.02 μg/mL and 201 ± 46.9 ng/mL, respectively, while the Σ23PFAS concentration in the urine of the residents was 6.18 ± 0.76 ng/mL. For workers, high levels of urinary PFAS were strongly correlated with levels in serum (r = 0.57-0.93), indicating that urinary PFAS can be a good indicator for serum PFAS levels. Further, a urine nontargeted metabolomics study was conducted. The results of association models, including Bayesian kernel machine regression, demonstrated positive correlations between urinary PFAS levels and key small kidney molecules. A total of eight potential biomarkers associated with PFAS exposure were identified, and all of them showed significant positive correlations with markers of kidney function. These findings provide the first evidence that urine can serve as a matrix to indicate the adverse health effects of high levels of exposure to PFAS on the kidneys.

Per- and Poly-fluoroalkyl Substances (PFAS) Exposure and Risk of Kidney, Liver, and Testicular Cancers: A Systematic Review and Meta-Analysis

INTRODUCTION

Per- and poly-fluoroalkyl substances (PFASs) are a large, complex group of synthetic chemicals humans can be exposed to from occupational or environmental sources. In this systematic review and meta-analysis, we examined the association between PFAS exposure, particularly Perfluorooctanoic Acid (PFOA), and Perfluorooctane Sulfonic Acid (PFOS), and risk of kidney, liver, and testicular cancer.

METHODS

We systematically searched PubMed to identify cohort and case-control studies reported after the Monograph of the International Agency for Research on Cancer and the Toxicological Profile of the Agency for Toxic Substances and Disease Registry. We assessed the quality of the studies by using a modified version of the Newcastle-Ottawa Scale (NOS). Forest relative risk (RR) plots were constructed for liver, kidney, and testicular cancer. We conducted stratified analyses by geographic region, study design, quality score, outcome, years of publication, exposure source, and PFAS type. A random-effects model was used to address heterogeneity between studies.

RESULTS

Fifteen studies, including ten cohort studies, three case-control studies nested in a cohort, and two case-control studies were included after removing duplicate and irrelevant reports. We found an association between overall PFAS exposure and the risk of kidney cancers (RR=1.18, 95% CI =1.05-1.32; I =52.8%, 11 studies). Also, we showed an association between high-level exposure to PFAS and kidney cancer (RR=1.74, 95% CI =1.23-2.47; p=0.005) and testicular cancer (RR=2.22, 95% CI =1.12-4.39; p=0.057). There was no association with liver cancer. We found no heterogeneity by geographical region, PFAS type, study design, outcome, quality score, year of publication, or exposure source. Only two studies reported results among women.

CONCLUSIONS

We detected an association between overall PFAS exposure and kidney cancer and high doses of PFAS with testicular cancer. However, bias and confounding cannot be excluded, precluding a conclusion in terms of causality.

Decreased levels of perfluoroalkyl substances in patients receiving hemodialysis treatment

Perfluoroalkyl substances (PFAS) have been reported to be harmful to multiple organs in the human body. Based on a previous study suggesting that hemodialysis (HD) may be a means of eliminating PFAS from the human body, we aimed to compare the serum PFAS concentrations of patients undergoing regular HD, patients with chronic kidney disease (CKD) and controls. Additionally, we also investigated the correlation between PFAS and biochemical data, as well as concurrent comorbidities. We recruited 301 participants who had been on maintenance dialysis for >90 days, 20 participants with stage 5 non-dialysis CKD, and 55 control participants who did not have a diagnosis of kidney disease, with a mean creatinine level of 0.77 mg/dl. Eight different PFAS, namely perfluorooctanoic acid (PFOA), total and linear perfluorooctanesulfonic acid (PFOS), perfluoroheptanoic acid (PFHpA), perfluorohexanesulfonic acid (PFHxS), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), and perfluoroundecanoic acid (PFUnDA), were measured using ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Spearman correlation and multivariable linear regression with 5 % false discovery rate were used to evaluate the relationships between PFAS and clinical parameters in HD patients and controls. Circulating concentrations of seven PFAS, including total and linear PFOS (T-PFOS and L-PFOS) PFDA, PFNA, PFHxS, PFOA, and PFUnDA, were significantly lower in the HD group compared to the CKD and control group. For the interplay between biochemical data and PFAS, all of the studied PFAS were positively correlated with aspartate aminotransferase, alanine aminotransferase, glucose, blood urea nitrogen, ferritin, and vitamin D in the controls, while in HD patients, the PFAS were all positively correlated with albumin, uric acid, iron, and vitamin D. These findings may offer valuable insights for future studies seeking to eliminate PFAS.

Paired Liver:Plasma PFAS Concentration Ratios from Adolescents in the Teen-LABS Study and Derivation of Empirical and Mass Balance Models to Predict and Explain Liver PFAS Accumulation

Animal studies have pointed at the liver as a hotspot for per- and polyfluoroalkyl substances (PFAS) accumulation and toxicity; however, these findings have not been replicated in human populations. We measured concentrations of seven PFAS in matched liver and plasma samples collected at the time of bariatric surgery from 64 adolescents in the Teen-Longitudinal Assessment of Bariatric Surgery (Teen-LABS) study. Liver:plasma concentration ratios were perfectly explained (r2 > 0.99) in a multilinear regression (MLR) model based on toxicokinetic (TK) descriptors consisting of binding to tissue constituents and membrane permeabilities. Of the seven matched plasma and liver PFAS concentrations compared in this study, the liver:plasma concentration ratio of perfluoroheptanoic acid (PFHpA) was considerably higher than the liver:plasma concentration ratio of other PFAS congeners. Comparing the MLR model with an equilibrium mass balance model (MBM) suggested that complex kinetic transport processes are driving the unexpectedly high liver:plasma concentration ratio of PFHpA. Intratissue MBM modeling pointed to membrane lipids as the tissue constituents that drive the liver accumulation of long-chain, hydrophobic PFAS, whereas albumin binding of hydrophobic PFAS dominated PFAS distribution in plasma. The liver:plasma concentration data set, empirical MLR model, and mechanistic MBM modeling allow the prediction of liver from plasma concentrations measured in human cohort studies. Our study demonstrates that combining biomonitoring data with mechanistic modeling can identify underlying mechanisms of internal distribution and specific target organ toxicity of PFAS in humans.

Per- and polyfluoroalkyl substances and the associated thyroid cancer risk: A case-control study in China

The role of perfluoroalkyl and polyfluoroalkyl substances (PFAS) as thyroid carcinogens is unclear. Therefore, we intended to identify associations between each PFAS congener and their mixture with thyroid cancer risk. This case-control study of thyroid cancer was conducted in Shijiazhuang, Hebei Province, China. Three hundred participants were recruited from January to May 2022 and were matched according to sex and age. Twelve PFAS were assessed using ultra-high-performance liquid chromatography-tandem mass spectrometry. Associations between PFAS congeners and thyroid cancer risk were considered under conditional logistic regression analysis and a restricted cubic spline model. Mixture effects were also assessed with quantile g-computation and a Bayesian kernel machine regression model. Compared to the first tertile, third tertile PFOA, PFNA, PFHxS, PFDA, and PFUnDA concentrations were associated with lower thyroid cancer risk (ORPFOA: 0.32, 95% confidence interval (CI): 0.15-0.69; ORPFNA: 0.18, 95% CI: 0.07-0.46; ORPFHxS: 0.37, 95% CI: 0.15-0.92; ORPFDA: 0.07, 95% CI: 0.02-0.23; ORPFUnDA: 0.12, 95% CI: 0.05-0.30) after adjusting for confounding factors. PFNA, PFDA, and PFUnDA had a negative dose-response relationship with thyroid cancer risk. Mixture analysis also showed that thyroid cancer risk is negatively associated with the overall mixture and carboxylates. In the overall mixture, PFOS and PFDA contributed most to positive and negative changes in thyroid cancer risk, respectively. However, PFOS, PFNA, PFDA, and PFUnDA were of equally high importance. This study is the first to confirm the effects of the PFAS mixture on thyroid cancer, and further large-scale prospective studies are still warranted to test these inverse associations.

Serum concentrations of per- and polyfluoroalkyl substances and risk of renal cell carcinoma in the Multiethnic Cohort Study

Per- and polyfluoroalkyl substances (PFAS) are environmentally persistent organic pollutants detectable in the serum of most U.S. adults. We previously reported a positive association between serum perfluorooctanoate (PFOA) concentrations and risk of renal cell carcinoma (RCC) within the Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial, comprising predominantly White individuals enrolled in 1993-2001. To extend our investigations to a larger and more racially and ethnically diverse population, we conducted a nested case-control study of serum PFAS concentrations and RCC within the Multiethnic Cohort Study. We measured pre-diagnostic serum concentrations of nine PFAS among 428 RCC cases and 428 individually matched controls. We estimated odds ratios (ORs) and 95 % confidence intervals (CIs) for risk of RCC in relation to each PFAS using conditional logistic regression, adjusting for RCC risk factors and other PFAS. PFOA was not associated with RCC risk overall [doubling in serum concentration, ORcontinuous = 0.89 (95 %CI = 0.67, 1.18)]. However, we observed suggestive positive associations among White participants [2.12 (0.87, 5.18)] and among participants who had blood drawn before 2002 [1.49 (0.77, 2.87)]. Furthermore, higher perfluorononanoate (PFNA) concentration was associated with increased risk of RCC overall [fourth vs. first quartile, OR = 1.84 (0.97, 3.50), Ptrend = 0.04; ORcontinuous = 1.29 (0.97, 1.71)], with the strongest association observed among African American participants [ORcontinuous = 3.69 (1.33, 10.25)], followed by Native Hawaiian [2.24 (0.70, 7.19)] and White [1.98 (0.92, 4.25)] participants. Most other PFAS were not associated with RCC. While PFOA was not associated with RCC risk overall in this racially and ethnically diverse population, the positive associations observed among White participants and those with sera collected before 2002 are consistent with previous PLCO findings. Our study also provided new evidence of a positive association between PFNA and RCC risk that was strongest in African American participants. These findings highlight the need for additional epidemiologic research investigating PFAS exposures and RCC in large racially and ethnically diverse populations.

Finding a way out? Comprehensive biotransformation study of novel fluorinated surfactants

In this study the environmental fate of two novel trifluoromethoxy-substituted surfactants with respectively an ether or thioether linkage were investigated, of which the design aimed for less persistency and complete mineralization. Long-term microbial transformation studies under aerobic conditions in activated sludge-wastewater medium were performed for 126 days. A semi-closed experimental system with a trapping sorbent was selected to avoid losses of possible volatile transformation products (TPs). The changes in the concentration of the surfactants and their expected TPs were monitored by target analysis using liquid chromatography-tandem mass spectrometry. Significant decrease in the concentration of the surfactants was observed over the incubation period. The main detected TPs were short-chained carboxylic acids (CAs), including a CA with two fluorinated carbon atoms representing the last product prior to mineralization. High stability of these CAs and lack in the formation of inorganic fluoride over the incubation time was however observed. Consequently, unequivocal final mineralization of the investigated surfactants could not be confirmed. Regarding the mass balance, the total amount of detected substances achieved only 30-37% of the expected concentration at the end of the incubation time. The reason of the incomplete mass balance should be further investigated.

A genetically-encoded biosensor for direct detection of perfluorooctanoic acid

Determination of per- and polyfluoroalkyl substances (PFAS) in drinking water at the low levels set by regulatory officials has been a major focus for sensor developing researchers. However, it is becoming more apparent that detection of these contaminants in soils, foods and consumer products is relevant and necessary at part per billion and even part per million levels. Here, a fluorescent biosensor for the rapid detection of PFOA was engineered based on human liver fatty acid binding protein (hLFABP). By conjugating circularly permuted green fluorescent protein (cp.GFP) to a split hLFABP construct, the biosensor was able to detect perfluorooctanoic acid PFOA in PBS as well as environmental water samples with LODs of 236 and 330 ppb respectively. Furthermore, E. coli cells cytosolically expressing the protein-based sensor were demonstrated to quickly detect PFOA, demonstrating feasibility of whole-cell sensing. Overall, this work demonstrates a platform technology utilizing a circularly permuted GFP and split hLFABP conjugate as a label-free optical biosensor for PFOA.

Immune response to COVID-19 vaccination in a population with a history of elevated exposure to per- and polyfluoroalkyl substances (PFAS) through drinking water

BACKGROUND

Exposure to per- and polyfluoroalkyl substances (PFAS) has been linked to lower vaccine-induced antibody concentrations in children, while data from adults remains limited and equivocal. Characteristics of PFAS exposure and age at vaccination may modify such effects.

OBJECTIVE

We used the mass administration of novel COVID-19 vaccines to test the hypothesis that prior exposure to environmentally-relevant concentrations of PFAS affect antibody response to vaccines in adolescents and adults.

METHODS

Between April and June 2021, 226 participants aged 12-90 years with a history of exposure to PFAS in drinking water and who received an mRNA COVID-19 vaccine participated in our prospective cohort study. SARS-CoV-2 anti-spike and anti-nucleocapsid antibodies (IgG) were quantified before the first and second vaccine doses and again at two follow-ups in the following months (up to 103 days post dose 1). Serum PFAS concentrations (n = 39 individual PFAS) were measured once for each participant during baseline, before their first vaccination. The association between PFAS exposure and immune response to vaccination was investigated using linear regression and generalized estimating equation (GEE) models with adjustment for covariates that affect antibody response. PFAS mixture effects were assessed using weighted quantile sum and Bayesian kernel machine regression methods.

RESULTS

The geometric mean (standard deviation) of perfluorooctane sulfonate and perfluorooctanoic acid serum concentrations in this population was 10.49 (3.22) and 3.90 (4.90) µg/L, respectively. PFAS concentrations were not associated with peak anti-spike antibody response, the initial increase in anti-spike antibody response following vaccination, or the waning over time of the anti-spike antibody response. Neither individual PFAS concentrations nor their evaluation as a mixture was associated with antibody response to mRNA vaccination against COVID-19.

IMPACT STATEMENT

Given the importance of understanding vaccine response among populations exposed to environmental contaminants and the current gaps in understanding this relationship outside of early life/childhood vaccinations, our manuscript contributes meaningful data from an adolescent and adult population receiving a novel vaccination.

Long-chain perfluoroalkyl carboxylates induce cytoskeletal abnormalities and activate epithelial-mesenchymal transition in both renal cell carcinoma 3D cultures and Caki-1 xenografted mouse model

Exposure to perfluorooctanoate (PFOA; a type of perfluoroalkyl carboxylates [PFACs]) may be correlated with the incidence of kidney cancer in individuals exposed to high levels of PFOA. However, mechanistic studies on the influence of PFACs on renal cell carcinoma (RCC) development are lacking. We explored the effects of five types of PFACs on RCC using in vitro and in vivo models to fill this knowledge gap and provide information for environmental/usage regulations. Using 2D/3D cultures of Caki-1 cells, a human clear cell RCC line, we examined the effects of short-chain (SC) PFACs and long-chain (LC) PFACs on RCC physio/pathological markers, including the cytoskeleton, epithelial-mesenchymal transition (EMT)-related proteins, and Na+/K+-ATPase. We also administered three different PFACs orally to mice harboring Caki-1 xenografts to assess the impact of these compounds on engrafted RCC in vivo. Compared with the effects of SCPFACs, mice with Caki-1 xenografts treated with LCPFACs showed increased EMT-related protein expression and exhibited liver toxicity. Therefore, LCPFACs induced EMT, influencing cancer metastasis activity, and displayed higher toxicity in vivo compared with SCPFACs. These findings improve our understanding of the effects of PFACs on RCC development and their corresponding in vivo toxicity, which is crucial for regulating these substances to protect public health.

Firefighters and the liver: Exposure to PFAS and PAHs in relation to liver function and serum lipids (CELSPAC-FIREexpo study)

INTRODUCTION

Firefighting is one of the most hazardous occupations due to exposure to per- and polyfluoroalkyl substances (PFAS) and polycyclic aromatic hydrocarbons (PAHs). Such exposure is suspected to affect the cardiometabolic profile, e.g., liver function and serum lipids. However, only a few studies have investigated the impact of this specific exposure among firefighters.

METHODS

Men included in the CELSPAC-FIREexpo study were professional firefighters (n = 52), newly recruited firefighters in training (n = 58), and controls (n = 54). They completed exposure questionnaires and provided 1-3 samples of urine and blood during the 11-week study period to allow assessment of their exposure to PFAS (6 compounds) and PAHs (6 compounds), and to determine biomarkers of liver function (alanine aminotransferase (ALT), gamma-glutamyl transferase (GGT), aspartate aminotransferase (AST), alkaline phosphatase (ALP) and total bilirubin (BIL)) and levels of serum lipids (total cholesterol (CHOL), low-density lipoprotein cholesterol (LDL) and triglycerides (TG)). The associations between biomarkers were investigated both cross-sectionally using multiple linear regression (MLR) and Bayesian weighted quantile sum (BWQS) regression and prospectively using MLR. The models were adjusted for potential confounders and false discovery rate correction was applied to account for multiplicity.

RESULTS

A positive association between exposure to PFAS and PAH mixture and BIL (β = 28.6%, 95% CrI = 14.6-45.7%) was observed by the BWQS model. When the study population was stratified, in professional firefighters and controls the mixture showed a positive association with CHOL (β = 29.5%, CrI = 10.3-53.6%) and LDL (β = 26.7%, CrI = 8.3-48.5%). No statistically significant associations with individual compounds were detected using MLR.

CONCLUSIONS

This study investigated the associations between exposure to PFAS and PAHs and biomarkers of cardiometabolic health in the Czech men, including firefighters. The results suggest that higher exposure to a mixture of these compounds is associated with an increase in BIL and the alteration of serum lipids, which can result in an unfavourable cardiometabolic profile.

Deciphering the Mechanistic Basis for Perfluoroalkyl-Protein Interactions

Although rarely used in nature, fluorine has emerged as an important elemental ingredient in the design of proteins with altered folding, stability, oligomerization propensities, and bioactivity. Adding to the molecular modification toolbox, here we report the ability of privileged perfluorinated amphiphiles to noncovalently decorate proteins to alter their conformational plasticity and potentiate their dispersion into fluorous phases. Employing a complementary suite of biophysical, in-silico and in-vitro approaches, we establish structure-activity relationships defining these phenomena and investigate their impact on protein structural dynamics and intracellular trafficking. Notably, we show that the lead compound, perfluorononanoic acid, is 106 times more potent in inducing non-native protein secondary structure in select proteins than is the well-known helix inducer trifluoroethanol, and also significantly enhances the cellular uptake of complexed proteins. These findings could advance the rational design of fluorinated proteins, inform on potential modes of toxicity for perfluoroalkyl substances, and guide the development of fluorine-modified biologics with desirable functional properties for drug discovery and delivery applications.

Factors affecting serum PFAS concentrations among US females with surgically and naturally induced menopause: data from NHANES 2003-2018

Sex hormones influence excretion of the biopersistent per-and polyfluoroalkyl substances (PFAS) in rodents, but such influences in human studies are less clear. Data from National Health and Nutrition Examination Survey (NHANES) for 2003-2018 for US females aged ≥ 20 years who reported having hysterectomy (HYST, N=1064) and who reported being in natural menopause (MENOP, N=1505) were analyzed for associations of ever use of birth control pills, past pregnancies, live births, and other factors with serum concentrations of six per- and polyfluoroalkyl substances (PFAS). For both HYST and MENOP, PFAS concentrations computed as adjusted geometric means (AGM) were higher among those who took female replacement hormone therapy (HRT) compared to nonusers in multivariable adjusted models, for example PFOS in HRT takers (10.70 ng/mL; 95% C.I. 9.46-12.11) vs. 8.70 ng/mL (95% C.I. 8.07-9.37) in nonusers (p<0.01), and PFOA in HRT users was 2.85 ng/mL (95% C.I. 2.53-3.21) vs. 2.44 ng/mL (95% C.I. 2.32-2.36) in nonusers (p=0.01), with similar findings across race/ethnicity stratifications. HYST participants with retained ovaries sometimes had higher serum PFAS than those without ovaries in post-HYST participants not taking HRT, but results had overlapping confidence intervals in all cases and were inconsistent. PFASs were inversely associated with obesity and directly associated with higher SES as reflected in poverty income ratio (PIR) in most cases, yet HRT results for the entire population are robust to adjustments for obesity and PIR. The results suggest the hypothesis that exogenous hormone use, and specifically estrogen hormones, are associated with higher serum PFAS in postmenopausal women. We discuss potential explanations for the findings, including data from other populations that estrogens may delay the onset of kidney disease, a finding which might paradoxically increase serum PFAS among the HRT population to explain some or all of our findings in a menopausal population.

Transport behavior difference and transport model of long- and short-chain per- and polyfluoroalkyl substances in underground environmental media: A review

Perfluoroalkyl carboxylic acids (PFCAs) and perfluoroalkyl sulfonates (PFSAs), which are the most commonly regulated and most widely concerned per- and polyfluoroalkyl substances (PFAS) have received increasing attention on a global scale due to their amphiphilicity, stability, and long-range transport. Thus, understanding the typical PFAS transport behavior and using models to predict the evolution of PFAS contamination plumes is important for evaluating the potential risks. In this study, the effects of organic matter (OM), minerals, water saturation, and solution chemistry on the transport and retention of PFAS were investigated, and the interaction mechanism between long-chain/short-chain PFAS and the surrounding environment was analyzed. The results revealed that high content of OM/minerals, low saturation, low pH, and divalent cation had a great retardation effect on long-chain PFAS transport. The retention caused by hydrophobic interaction was the prominent mechanism for long-chain PFAS, whereas, the retention caused by electrostatic interaction was more relevant for short-chain PFAS. Additional adsorption at the air-water and nonaqueous-phase liquids (NAPL)-water interface was another potential interaction for retarding PFAS transport in the unsaturated media, which preferred to retard long-chain PFAS. Furthermore, the developing models for describing PFAS transport were investigated and summarized in detail, including the convection-dispersion equation, two-site model (TSM), continuous-distribution multi-rate model, modified-TSM, multi-process mass-transfer (MPMT) model, MPMT-1D model, MPMT-3D model, tempered one-sided stable density transport model, and a comprehensive compartment model. The research revealed PFAS transport mechanisms and provided the model tools, which supported the theoretical basis for the practical prediction of the evolution of PFAS contamination plumes.

Association between perfluoroalkyl and polyfluoroalkyl internal exposure and serum α-Klotho levels in middle-old aged participants

Purpose

Exposure to perfluoroalkyl and polyfluoroalkyl substances causes oxidative stress, which is strongly associated with adverse health effects. Klotho protein plays an anti-aging role via antioxidation activity.

Methods

We investigated the levels of serum α-Klotho and PFAS exposure in adults who participated in the National Health and Nutrition Examination Survey from 2013 to 2016. A nationally representative subsample of 1,499 adults aged 40-79 years was analyzed for the associations of serum α-Klotho levels with serum PFAS exposures by correlation analysis and multiple general linear models. Of note, the potential confounding factors including age and gender were adjusted. Quantile-based g-computation models were used to assess the effects of mixed PFAS exposure on serum α-Klotho levels.

Results

The weighted geometric mean of serum α-Klotho was 791.38 pg/mL for the subjects during 2013-2016. After adjusting for potential confounders, serum Klotho levels showed a statistically significant downward trend with increasing quartiles of PFOA and PFNA. Multivariate adjusted general linear regression analysis showed that increased exposure to PFNA was substantially associated with lower serum levels of α-Klotho, and each 1-unit increase in PFNA concentration was accompanied by a 20.23 pg/mL decrease in α-Klotho level; while no significant association was observed between other PFAS exposures and serum α-Klotho levels. It was negatively correlated between α-Klotho and Q4 for PFNA relative to the lowest quartile (Q1) of exposure (P = 0.025). It was found that the strongest negative correlation between PFNA exposure and serum α-Klotho levels was in the middle-aged (40-59 years) female participants. Furthermore, the mixture of the four PFAS substances showed an overall inverse association with serum α-Klotho concentrations, with PFNA being the major contributor.

Conclusions

Taken together, in a representative sample of the U.S. middle-aged and elderly populations, serum concentrations of PFAS, especially PFNA, have been negatively associated with serum levels of α-Klotho, which is strongly associated with cognition and aging. It was important to note that the majority of associations were limited to middle-aged women. It will be meaningful to clarify the causal relationship and the pathogenic mechanisms of PFAS exposure and α-Klotho levels, which is helpful to aging and aging-related diseases.

Exposure to perfluoroalkyl and polyfluoroalkyl substances and estimated glomerular filtration rate in adults: a cross-sectional study based on NHANES (2017-2018)

Perfluoroalkyl and polyfluoroalkyl substances (PFASs) may be important environmental risk factors affecting renal function. This study aimed to investigate the relationships between PFASs and estimated glomerular filtration rate (eGFR) in univariate exposure and multivariate co-exposure models of PFASs. A total of 1700 people over 18 years from National Health and Nutrition Examination Survey (NHANES) in 2017-2018 were selected as subjects to explore the relationships between eGFR and six PFASs (perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFUA), perfluorodecanoic acid (PFDeA), and perfluorohexane sulfonate (PFHxS)). First, multiple linear regression was used to estimate the association of each PFAS with eGFR, and the joint effect of PFAS mixtures was evaluated by Bayesian kernel machine regression (BKMR). Multiple linear regression analysis showed PFOS (β =  - 0.246, p = 0.026) and PFHxS (β = 0.538, p = 0.049) were significantly associated with eGFR in total population. In BKMR analysis, there was joint effect between PFOS and PFHxS for eGFR. And there were the joint effects of multiple PFAS on eGFR, especially the significant joint effect between PFHxS and PFDeA/PFNA/PFUA. Future cohort studies need to explore the association of multiple PFASs and health.

Suitability of remediated heat-treated soil in concrete applications

Significant quantities of soil are adversely impacted by organic contaminants, including per- and poly-fluoroalkyl substances (PFAS). One proven technology for remediating PFAS affected soils is excavation and heat-treatment which destroys the PFAS, but renders the soil as an industrial waste that is normally diverted to landfill. This study investigated alternative uses for heat-treated industrial waste (HIW) soils as components in concrete, as aggregate replacement and as partial substitution of cement binder. At a replacement rate of 100% fine aggregate and ≈15% coarse aggregate, concretes made with HIW soil exhibited a strength of 47.2-48.3 MPa after 28 days' curing, compared with a reference concrete of 49.7-53.1 MPa, making the HIW ideal for aggregate replacement. Overall, the study demonstrated a novel, holistic approach to (1) remediating PFAS-affected soils, (2) diverting contaminated soil away from landfill, (3) reducing the use of high quality quarried concrete aggregates and (4) producing normal-strength concretes with a lower embodied carbon footprint than existing approaches. This study reveals that in Australia, up to 93% of all contaminated soil currently sent to landfill annually could instead be used a resource for mid-strength concretes, suitable for many applications.

Joint effects of per- and polyfluoroalkyl substance alternatives and heavy metals on renal health: A community-based population study in China

BACKGROUND

Previous studies have indicated that chlorinated polyfluorinated ether sulfonic acids (Cl-PFESAs), when used as an alternative to per- and polyfluoroalkyl substances (PFASs), result in kidney toxicity. However, their co-exposure with heavy metals, has not yet been described.

OBJECTIVES

To explore the joint effects of Cl-PFESAs and heavy metal exposure on renal health in Chinese adults, and identify specific pollutants driving the associations.

METHODS

Our sample consists of 1312 adults from a cross-sectional survey of general communities in Guangzhou, China. We measured Cl-PFESAs, legacy PFASs (perfluorooctanoic acid [PFOA] and perfluorooctane sulfonated [PFOS]), and heavy metals (arsenic, cadmium, and lead). The relationship between single pollutant and glomerular filtration rate (eGFR) and the odds ratio (OR) of chronic kidney disease (CKD) was studied using Generalized additive models (GAMs). Bayesian Kernel Machine Regression (BKMR) models were applied to assess joint effects of Cl-PFESAs and heavy metals. Additionally, we conducted a sex-specific analysis to determine the modification effect of this variable.

RESULTS

In single pollutant models, CI-PFESAs, PFOA, PFOS and arsenic were negatively associated with eGFR. Additionally, PFOA and heavy metals were positively correlated with the OR of CKD. For example, the estimated change with 95% confidence intervals (CI) of eGFR at from the highest quantile of 6:2 Cl-PFESA versus the lowest quantile was -5.65 ng/mL (95% CI: -8.21, -3.10). Sex played a role in modifying the association between 8:2 Cl-PFESA, PFOS and eGFR. In BKMR models, pollutant mixtures had a negative joint association with eGFR and a positive joint effect on CKD, especially in women. Arsenic appeared to be the primary contributing pollutant.

CONCLUSION

We provide epidemiological evidence that Cl-PFESAs independently and jointly with heavy metals impaired kidney health. More population-based human and animal studies are needed to confirm our results.

Serum concentrations of perfluoro-1-heptane sulfonate (PFHpS) among US adults: variabilities across different stages of kidney function

For the first time, data (N = 1311) from US National Health and Nutrition Examination Survey for 2017-2018 were analyzed for gender and racial/ethnic differences for perfluoro-1-heptane sulfonate (PFHpS) for US adults aged ≥ 20 years. In addition, variability in adjusted concentrations across various stages of glomerular filtration (GF) was also studied. While no racial/ethnic differences were observed, males had statistically significantly higher concentrations of PFHpS than females (0.30 vs. 0.19 ng/mL, p < 0.01). Concentrations of PFHpS across various stages of kidney function were located on inverted U-shaped curves with point of inflection located at GF-3A (45 ≤ eGFR < 60 mL/min/1.73 m²) for all participants, males, as well as females. After moderate increase from GF-1 (eGFR ≥ 60 mL/min/1.73 m²) to GF-2 (60 ≤ eGFR < 90 mL/min/1.73 m²), the increase in PFHpS concentration from GF-2 to GF-3A was quite steep. For example, for females, concentration from GF-1 to GF-2 increased from 0.17 ng/mL to 0.23 ng/mL for an increase of 35% but from GF-2 to GF-3A, concentrations of PFHpS increased from 0.23 ng/mL to 0.43 ng/mL for an increase of about 87%. Following this, at GF-3B/4 (15 ≤ eGFR < 45 mL/min/1.73 m²), concentrations decreased sharply to the almost the same levels as for GF-1. For example, for males, the decrease from GF-3A (0.67 ng/mL) to GF-3B/4 (0.21 ng/mL) was about 69%. Concentration curves for each race/ethnicity were also located on inverted U-shaped curves but relatively very small sample sizes for Hispanics and non-Hispanic Asians, and others at GF-3A and GF-3B/4 lead to substantial variability. The balance between reabsorption-excretion in favor of reabsorption at GF-1 and GF-2 switched to in favor of excretion starting at the end of GF-3A.

Association between per- and polyfluoroalkyl substances and semen quality

Some studies have suggested that perfluoroalkyl and polyfluoroalkyl substance (PFAS) exposure may be associated with semen quality in the general population, but with inconsistent results. To identify a more precise relationship between them, a meta-analysis was performed. We searched Embase, the PubMed, The Cochrane Library, Ovid databases, and Web of Science databases (before March 2022) for appropriate studies on the correlations of PFAS exposure with semen parameters. We extracted β value and 95% confidence intervals (CIs) to conduct meta-analysis. Subgroup analyses was performed by sample size, geographic location, and sample type. A total of seven articles involving 2190 participants were included in this study. The concentrations of perfluorooctanoic acid (PFOA) (β value =  - 1.38; 95% CI: - 2.44, - 0.32) and perfluorononanoic acid (PFNA) (β value =  - 1.31, 95% CI: - 2.35, - 0.26) were negatively associated with sperm progressive motility. Subgroup analysis revealed that PFNA exposure was related to sperm morphology in studies with the sample size exceeding 200 people (β value =  - 0.14; 95% CI: - 0.26, - 0.01). Our study supports that exposure to some PFASs (e.g., PFNA, PFOA) may be associated with semen quality, such as lower sperm progressive motility. Therefore, it is of great significance for the prevention of male infertility by control the use of PFASs.

Perfluorooctanoic acid (PFOA) exposure in relation to the kidneys: A review of current available literature

Perfluorooctanoic acid is an artificial and non-degradable chemical. It is widely used due to its stable nature. It can enter the human body through food, drinking water, inhalation of household dust and contact with products containing perfluorooctanoic acid. It accumulates in the human body, causing potential harmful effects on human health. Based on the biodegradability and bioaccumulation of perfluorooctanoic acid in the human body, there are increasing concerns about the adverse effects of perfluorooctanoic acid exposure on kidneys. Research shows that kidney is the main accumulation organ of Perfluorooctanoic acid, and Perfluorooctanoic acid can cause nephrotoxicity and produce adverse effects on kidney function, but the exact mechanism is still unknown. In this review, we summarize the relationship between Perfluorooctanoic acid exposure and kidney health, evaluate risks more clearly, and provide a theoretical basis for subsequent research.

Isomer-Specific Serum Concentrations of Perfluorooctane Sulfonic Acid among U.S. Adults: Results from the National Health and Nutrition Examination Survey (NHANES) and the Study of Women's Health Across the Nation Multi-Pollutant Study (SWAN-MPS)

Electrochemical fluorination manufacture of perfluorooctane sulfonic acid (PFOS), one of the most studied per- and polyfluoroalkyl substances, produces mixtures of linear and branched isomers, but little is known about human exposure to linear or branched PFOS isomers. We examined determinants affecting isomer-specific patterns of PFOS in serum in two adult populations in the United States, the National Health and Nutrition Examination Survey (NHANES) and the Study of Women's Health Across the Nation Multi-Pollutant Study (SWAN-MPS). After adjusting for demographic variables, fish consumption (in both populations), a glomerular filtration rate above 90 mL/min/1.73 m2 (observed in NHANES; not tested in SWAN-MPS), premenopausal status (only observed in SWAN-MPS), and less consumption of processed food (observed in SWAN-MPS; not tested in NHANES) were associated with a higher proportion of linear PFOS. Non-Hispanic Black and Asian participants were likely to have a higher proportion of linear PFOS than non-Hispanic White participants in both populations. Our findings suggest that isomer-specific patterns of PFOS serum concentrations in humans vary depending on population characteristics that affect PFOS exposure and excretion. Consideration of specific PFOS isomers in future human biomonitoring and epidemiologic studies can provide useful insight to better understand PFOS exposure.

The association of perfluoroalkyl substances (PFAS) exposure and kidney function in Korean adolescents using data from Korean National Environmental Health Survey (KoNEHS) cycle 4 (2018–2020): a cross-sectional study

Background

Perfluoroalkyl substances (PFAS) are chemicals widely used in various products in everyday life. Due to its unique strong binding force, the half-life of PFAS is very long, so bioaccumulation and toxicity to the human body are long-standing concerns. In particular, effects on kidney function have recently emerged and there are no studies on the effect of PFAS on kidney function through epidemiological investigations in Korea. From 2018 to 2020, the Korean National Environmental Health Survey (KoNEHS) cycle 4, conducted an epidemiological investigation on the blood concentration of PFAS for the first time in Korea. Based on this data, the relationship between PFAS blood concentration and kidney function was analyzed for adolescents.

Methods

We investigated 5 types of PFAS and their total blood concentration in 811 middle and high school students, living in Korea and included in KoNEHS cycle 4, and tried to find changes in kidney function in relation to PFAS concentration. After dividing the concentration of each of the 5 PFAS and the total concentration into quartiles, multivariable linear regression was performed to assess the correlation with kidney function. The bedside Schwartz equation was used as an indicator of kidney function.

Results

As a result of multivariable linear regression, when observing a change in kidney function according to the increase in the concentration of each of the 5 PFAS and their total, a significant decrease in kidney function was confirmed in some or all quartiles.

Conclusions

In this cross-sectional study of Korean adolescents based on KoNEHS data, a negative correlation between serum PFAS concentration and kidney function was found. A well-designed longitudinal study and continuous follow-up are necessary.

The Relationship between Typical Environmental Endocrine Disruptors and Kidney Disease

Endocrine disrupting chemicals (EDCs) are exogenous substances that alter the endocrine function of an organism, to result in adverse effects on growth and development, metabolism, and reproductive function. The kidney is one of the most important organs in the urinary system and an accumulation point. Studies have shown that EDCs can cause proteinuria, affect glomeruli and renal tubules, and even lead to diabetes and renal fibrosis in animal and human studies. In this review, we discuss renal accumulation of select EDCs such as dioxins, per- and polyfluoroalkyl substances (PFAS), bisphenol A (BPA), and phthalates, and delineate how exposures to such EDCs cause renal lesions and diseases, including cancer. The regulation of typical EDCs with specific target genes and the activation of related pathways are summarized.

Environmental Exposures and Kidney Disease

Accumulating evidence underscores the large role played by the environment in the health of communities and individuals. We review the currently known contribution of environmental exposures and pollutants on kidney disease and its associated morbidity. We review air pollutants, such as particulate matter; water pollutants, such as trace elements, per- and polyfluoroalkyl substances, and pesticides; and extreme weather events and natural disasters. We also discuss gaps in the evidence that presently relies heavily on observational studies and animal models, and propose using recently developed analytic methods to help bridge the gaps. With the expected increase in the intensity and frequency of many environmental exposures in the decades to come, an improved understanding of their potential effect on kidney disease is crucial to mitigate potential morbidity and mortality.

Thermal decomposition mechanism and kinetics of perfluorooctanoic acid (PFOA) and other perfluorinated carboxylic acids: a theoretical study

Perfluorinated carboxylic acids (PFCAs), particularly perfluorooctanoic acid (PFOA), are broadly used for chemical synthesis and as surfactants, but they pose a serious threat to humans and wildlife because of toxicity concerns, environmental stability, and tendency to bioaccumulate. PFCA waste is commercially treated in incinerators, however, their exact degradation mechanisms are still unknown. In the present work, we report the decomposition mechanism and kinetics of straight-chain PFCAs using quantum chemistry and reaction rate theory calculations. Degradation mechanisms and associated kinetic parameters are determined for the complete series of straight-chain PFCAs from perfluorononanoic acid (C₈F₁₇COOH, C9) to fluoroformic acid (FCOOH, C1). Our results show that PFCA decomposition follows an analogous mechanism to perfluorinated sulfonic acids, where HF elimination from the acid head group produces a three membered ring intermediate, in this case a perfluorinated α-lactone. These perfluorinated α-lactones are short-lived intermediates that readily degrade into perfluorinated acyl fluorides and CO, thus shortening the perfluorinated chain by one C atom. Because perfluorinated acyl fluorides are known to hydrolyse to PFCAs, repeated cycles of carboxylic acid decomposition followed by acyl fluoride hydrolysis provides a mechanism for the complete mineralization of PFCAs to HF, CO, CO₂, COF₂, and CF₂ during thermal decomposition in the presence of water vapor. These results provide a theoretical basis for future detailed chemical kinetic studies of incineration reactors and will assist in their design and optimisation so as to more efficiently decompose PFCAs and related waste.

Organic Fluorine as an Indicator of Per- and Polyfluoroalkyl Substances in Dust from Buildings with Healthier versus Conventional Materials

Per- and polyfluoroalkyl substances (PFAS) are a class of thousands of persistent, organic fluorinated chemicals added to materials and products mainly to repel stains and water. PFAS have been associated with many adverse human health effects. We aimed to determine whether buildings with "healthier" materials─defined here as reportedly free of all PFAS─exhibit lower PFAS in dust. In addition to analyzing targeted PFAS with available commercial standards, we measured extractable organic fluorine (EOF) as a novel proxy that includes both known and unknown types of PFAS. We measured at least 15 targeted PFAS (n = 24), EOF (n = 24), and total fluorine (TF; n = 14) in dust collected from university common spaces and classrooms, half of which had "healthier" furniture and carpet. We observed lower PFAS contamination in buildings with "healthier" materials: "healthier" rooms had a 66% lower median summed PFAS and a 49% lower Kaplan-Meier estimated mean EOF level in dust in comparison to conventional rooms. The summed targeted PFAS were significantly correlated with EOF but accounted for up to only 9% of EOF, indicating the likely presence of unidentified PFAS. EOF levels explained less than 1% of TF in dust. We emphasize the need to use chemical class-based methods (e.g., EOF) for evaluating class-based solutions and to expand non-PFAS solutions for other building materials.

Associations of exposure to perfluoroalkyl substances with serum uric acid change and hyperuricemia among Chinese women: Results from a longitudinal study

BACKGROUND

Cross-sectional studies have reported associations of perfluorooctanoic acid (PFOA) with concurrent serum uric acid (UA) levels. However, the prospective associations of other commonly detected perfluoroalkyl substances (PFASs) with serum UA and hyperuricemia remain unclear.

METHODS

A total of 654 females from the Dongfeng-Tongji cohort, who were followed up from 2008 to 2018, were included in this study. We measured their baseline plasma concentrations of six PFASs [including perfluorooctane sulfonic acid (PFOS), PFOA, perfluorononanoic acid (PFNA), perfluorohexane sulfonic acid (PFHxS), perfluorodecanoic acid (PFDA), and perfluoroheptanoic acid (PFHpA)], as well as their serum UA levels at both baseline and follow-up visits. General linear and logistic regression models were constructed to explore the associations of each PFAS with annual change of serum UA and incident hyperuricemia. Mixture effects of PFASs were further assessed by using the quantile g-computation approach.

RESULTS

Compared to participants with low PFNA exposure (≤50^th), those with high PFNA exposure (>75^th) had significantly increased annual increment of serum UA [β(95%CI) = 2.58 (0.60, 4.55)]. No significant associations of PFOS, PFOA, PFDA, PFHxS, or PFHpA with serum UA change were observed. Besides, females with high PFOA or PFHpA (>75^th) exposure had higher incident risk of hyperuricemia than those with low exposure (<50^th) [OR (95%CI) = 1.94 (1.00, 3.76) and 1.86 (1.03, 3.36), respectively]. No significant associations of PFOS, PFNA, PFDA, and PFHxS with hyperuricemia risk were observed. Quantile g-computation approach didn't find significant effects of PFAS co-exposure on serum UA change or hyperuricemia incidence.

CONCLUSIONS

Our findings suggested exposure to PFASs as a risk factor for hyperuricemia and shed light on hyperuricemia prevention for elderly females.

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).

Epidemiology of Renal Cell Carcinoma: 2022 Update

CONTEXT

International variations in the rates of kidney cancer (KC) are considerable. An understanding of the risk factors for KC development is necessary to generate opportunities to reduce its incidence through prevention and surveillance.

OBJECTIVE

To retrieve and summarize global incidence and mortality rates of KC and risk factors associated with its development, and to describe known familial syndromes and genetic alterations that represent biologic risk factors.

EVIDENCE ACQUISITION

A systematic review was conducted via Medline (PubMed) and Scopus to include meta-analyses, reviews, and original studies regarding renal cell carcinoma, epidemiology, and risk factors.

EVIDENCE SYNTHESIS

Our narrative review provides a detailed analysis of KC incidence and mortality, with significant variations across time, geography, and sex. In particular, while KC incidence has continued to increase, mortality models have leveled off. Among the many risk factors, hypertension, obesity, and smoking are the most well established. The emergence of new genetic data coupled with observational data allows for integrated management and surveillance strategies for KC care.

CONCLUSIONS

KC incidence and mortality rates vary significantly by geography, sex, and age. Associations of the development of KC with modifiable and fixed risk factors such as obesity, hypertension, smoking, and chronic kidney disease (CKD)/end-stage kidney disease (ESKD) are well described. Recent advances in the genetic characterization of these cancers have led to a better understanding of the germline and somatic mutations that predispose patients to KC development, with potential for identification of therapeutic targets that may improve outcomes for these at-risk patients.

PATIENT SUMMARY

We reviewed evidence on the occurrence of kidney cancer (KC) around the world. Currently, the main avoidable causes are smoking, obesity, and high blood pressure. Although other risk factors also contribute, prevention and treatment of these three factors provide the best opportunities to reduce the risk of developing KC at present.

Co-exposure to perfluoroalkyl acids and heavy metals mixtures associated with impaired kidney function in adults: A community-based population study in China

BACKGROUND

Previous studies have separately linked either perfluoroalkyl acid (PFAA) or heavy metal exposure with kidney dysfunction. However, the relationships of co-exposure to PFAAs and heavy metals with kidney function are still unclear.

OBJECTIVES

To explore the associations between exposure to PFAAs and heavy metals mixtures and kidney function in adults.

METHODS

We conducted a cross-sectional community-based population study in Guangzhou, China, enrolling 1312 adults from November 2018 to August 2019. We quantified 13 PFAAs in serum and 14 heavy metals in plasma. We chose estimated glomerular filtration rate (eGFR) and chronic kidney disease (CKD) as outcomes of interest. Distributed lag non-linear models (DLNMs) were used to check nonlinearity of individual pollutant with kidney function. Joint associations of pollutant mixtures on kidney function were assessed by Bayesian Kernel Machine Regression (BKMR) models. We further explored modification effects of gender.

RESULTS

Most individual PFAA and heavy metal were associated with declined kidney function in single-pollutant models. We also observed significant dose-response relationships of pollutant mixtures with reduced eGFR levels and increased odds of CKD in BKMR models. Perfluoroheptanesulfonic acid (PFHpS), arsenic (As) and strontium (Sr) were the predominant contributors among pollutant mixtures. A change in log PFHpS, As and Sr concentrations from the 25th to the 75th percentile were associated with a decrease in eGFR of -5.42 (95% confidence interval (CI): -6.86, -3.98), -2.14 (95% CI: -3.70, -0.58) and -1.87 (95% CI: -3.03, -0.72) mL/min/1.73 m², respectively, when other pollutants were at their median values. In addition, the observed associations were more obvious in females.

CONCLUSIONS

We provided new evidence that co-exposure to PFAAs and heavy metals mixtures was associated with reduced kidney function in adults and PFHpS, As and Sr appeared to be the major contributors. Further studies are warranted to confirm our findings and elucidate the underlying mechanisms.

Evaluating maternal exposure to an environmental per and polyfluoroalkyl substances (PFAS) mixture during pregnancy: Adverse maternal and fetoplacental effects in a New Zealand White (NZW) rabbit model

Mixtures of per- and polyfluoroalkyl substances (PFAS) are often found in drinking water, and serum PFAS are detected in up to 99% of the population. However, very little is known about how exposure to mixtures of PFAS affects maternal and fetal health. The aim of this study was to investigate maternal, fetal, and placental outcomes after preconceptional and gestational exposure to an environmentally relevant PFAS mixture in a New Zealand White (NZW) rabbit model. Dams were exposed via drinking water to control (no detectable PFAS) or a PFAS mixture for 32 days. This mixture was formulated with PFAS to resemble levels measured in tap water from Pittsboro, NC (10 PFAS compounds; total PFAS load = 758.6 ng/L). Maternal, fetal, and placental outcomes were evaluated at necropsy. Thyroid hormones were measured in maternal serum and kit blood. Placental gene expression was evaluated by RNAseq and qPCR. PFAS exposure resulted in higher body weight (p = 0.01), liver (p = 0.01) and kidney (p = 0.01) weights, blood pressure (p = 0.05), and BUN:CRE ratio (p = 0.04) in dams, along with microscopic changes in renal cortices. Fetal weight, measures, and histopathology were unchanged, but a significant interaction between dose and sex was detected in the fetal: placental weight ratio (p = 0.036). Placental macroscopic changes were present in PFAS-exposed dams. Dam serum showed lower T4 and a higher T3:T4 ratio, although not statistically significant. RNAseq revealed that 11 of the 14 differentially expressed genes (adj. p < 0.1) are involved in placentation or pregnancy complications. In summary, exposure elicited maternal weight gain and signs of hypertension, renal injury, sex-specific changes in placental response, and differential expression of genes involved in placentation and preeclampsia. Importantly, these are the first results to show adverse maternal and placental effects of an environmentally-relevant PFAS mixture in vivo.

Associations between the concentrations of α-klotho and selected perfluoroalkyl substances in the presence of eGFR based kidney function and albuminuria: Data for US adults aged 40-79 years

Exposures to per- and polyfluoroalkyl substances (PFAS) cause oxidative stress, a risk factor for tissue damage leading to kidney and cardiovascular diseases. The antiaging protein klotho is known to act as an anti-oxidative agent, and how klotho homeostasis interacts with PFAS has not been reported. This study among 3981 US adults aged 40-79 years old evaluated relationships of internal PFAS contamination to α-klotho across stages of estimated glomerular filtration rate or eGFR-based kidney function and albuminuria defined as urinary albumin creatinine ratio of >30 mg/g creatinine. In the absence of albuminuria and when eGFR based kidney function was in stage GF-1 (eGFR ≥ 90 mL/min/1.73 m²), statistically significant inverse associations between α-klotho and PFNA (β = -0.04930, p < 0.01), PFDA (β = -0.03307, p = 0.02), and PFUnDA (β = -0.03451, p = 0.01), PFHxS (β = -0.03011, p = 0.04) and PFOS (β = -0.03126, p = 0.03) were noted. No associations between α-klotho and PFAS were observed when kidney function was in stages GF-2 (60 ≤ eGFR < 90 mL/min/1.73 m²) or GF-3A (45 ≤ eGFR < 60 mL/min/1.73 m²) in the presence or absence of albuminuria. Unexpectedly, however, in the absence of albuminuria, with kidney function in stage GF-3B/4 (15 ≤ eGFR < 45 mL/min/1.73 m²), associations were positive between α-klotho and PFOA (β = 0.20989, p < 0.01), PFNA (β = 0.18373, p < 0.1), PFDA (β = 0.20413, p < 0.01), PFUnDA (β = 0.17660, p < 0.01), and PFOS (β = 0.14267, p < 0.01). The inverse relationship of PFAS to the antioxidant protein α-klotho in those with healthy kidney function has not been previously reported and should be evaluated in other populations.

Health-related toxicity of emerging per- and polyfluoroalkyl substances: Comparison to legacy PFOS and PFOA

Per- and polyfluoroalkyl substances (PFAS) are highly persistent, manufactured chemicals used in various manufacturing processes and found in numerous commercial products. With over 9000 compounds belonging to this chemical class, there is increasing concern regarding human exposure to these compounds due to their persistent, bioaccumulative, and toxic nature. Human exposure to PFAS may occur from a variety of exposure sources, including, air, food, indoor dust, soil, water, from the transfer of PFAS from non-stick wrappers to food, use of cosmetics, and other personal care products. This critical review presents recent research on the health-related impacts of PFAS exposure, highlighting compounds other than Perfluorooctanoic acid (PFOA) and Perfluoroctane sulfonate (PFOS) that cause adverse health effects, updates the current state of knowledge on PFAS toxicity, and, where possible, elucidates cause-and-effect relationships. Recent reviews identified that exposure to PFAS was associated with adverse health impacts on female and male fertility, metabolism in pregnancy, endocrine function including pancreatic dysfunction and risk of developing Type 2 diabetes, lipid metabolism and risk of childhood adiposity, hepatic and renal function, immune function, cardiovascular health (atherosclerosis), bone health including risk for dental cavities, osteoporosis, and vitamin D deficiency, neurological function, and risk of developing breast cancer. However, while cause-and-effect relationships for many of these outcomes were not able to be clearly elucidated, it was identified that 1) the evidence derived from both animal models and humans suggested that PFAS may exert harmful impacts on both animals and humans, however extrapolating data from animal to human studies was complicated due to differences in exposure/elimination kinetics, 2) PFAS precursor kinetics and toxicity mechanism data are still limited despite ongoing exposures, and 3) studies in humans, which provide contrasting results require further investigation of the long-term-exposed population to better evaluate the biological toxicity of chronic exposure to PFAS.