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

A review of the occurrence and distribution of Per- and polyfluoroalkyl substances (PFAS) in human organs and fetal tissues

This review synthesizes current evidence on PFAS concentrations across human organs and tissues, excluding blood matrices. Literature search was conducted using PubMed, Web of Science, and Scopus. The earliest reported study on the topic measured PFOS, PFOSA, PFOA, and PFHxS levels in human liver and serum, showing mean liver concentrations of 18.8 ng/g and a liver-to-serum ratio of 1.3:1 for PFOS. Subsequent research extended these findings to other organs, with measurements in pooled samples indicating organ-specific accumulation patterns. PFOS was predominant in liver, kidney, and lung, while PFOA was more prominent in bone. Pathological conditions, such as liver disease, have shown to influence PFAS distribution, with diseased tissues exhibiting altered accumulation patterns. On the other hand, the occurrence of PFAS in fetal and placental tissues demonstrated that these compounds cross the placenta, although fetal exposure levels were significantly lower than maternal levels. Tissue-specific accumulation has been reported, with liver and lung showing higher concentrations compared to other fetal tissues. Associations between PFAS levels in the placenta and birth outcomes indicated potential sex-specific effects, including reduced birth weight in male infants exposed to higher PFOS levels. This review highlights important differences in the detection frequencies and concentrations of PFAS across organs and the specific studies. These variations are attributed to differences in analytical methods, sample characteristics, and exposure sources. The findings underscore the need for standardized methodologies and further research to better understand PFAS distribution in human tissues and their potential health impacts, particularly during critical developmental stages.

Perfluoroalkyl acids interact with major human blood protein fibrinogen: Experimental and computation study

PFAS (per- and polyfluorinated alkyl substances) are synthetic compounds prized for their stability across various industries, but they pose an increasing threat to the environment and human health. Following the regulation of long-chain PFAS, short-chain and ultra-short-chain molecules have been introduced as substitutes, yet their bioaccumulation potential remains poorly understood. In this study, we combined experimental (intrinsic fluorescence, microscale thermophoresis, clotting assays) and computational approaches to investigate how trifluoroacetic acid, perfluorobutanoic acid, and perfluorooctanoic acid bind to fibrinogen, a key human blood protein. All tested perfluoroalkyl acids (PFAAs) exhibited moderate binding affinity (Kd in the 10-4-10-5 M range), yet circular dichroism and fibrin clot formation assays revealed no functional impairment of fibrinogen. Molecular docking indicated distinct, chain-length-specific binding sites, suggesting multiple routes for PFAAs to interact with fibrinogen without disrupting its primary biological role. These findings challenge the assumption that short-chain PFAS are less bioaccumulative and underscore the need for further research into their long-term health impacts, particularly given their widespread presence in the environment and potential accumulation in human blood.

Perfluorooctane Sulfonate (PFOS) and Related Compounds Induce Nuclear Receptor 4A1 (NR4A1)-Dependent Carcinogenesis

Polyfluoroalkyl substances (PFAS) are widely used industrial compounds that have been identified as contaminants in almost every component of the global ecosystem, and in human studies, higher levels of PFAS have been correlated with increased incidence of multiple diseases. Based on the results of human and laboratory animal studies, we hypothesize that the orphan nuclear receptor 4A1 (NR4A1) may be a critical target for some PFAS such as the legacy linear polyfluorooctanesulfonate (PFOS) and other sulfonates. We show that PFOS and related compounds bound the ligand binding domain (LBD) of NR4A1 and induced the growth of several cancer cell lines and enhanced tumor growth in an athymic nude mouse model. Using NR4A1-responsive rhabdomyosarcoma Rh30 cells as a model, PFOS induced NR4A1-dependent cell proliferation and Rh30 cell migration and invasion. Moreover, in Rh30 cells, PFOS also induces several NR4A1-regulated genes including the PAX3-FOXO1 oncogene and downstream gene products, and in a chromatin immunoprecipitation assay, PFOS does not decrease NR4A1 binding to the promoter. These results demonstrate that PFOS is an NR4A1 ligand and enhances tumorigenesis through the activation of this receptor.

Towards a Better Understanding of the Human Health Risk of Per- and Polyfluoroalkyl Substances Using Organoid Models

The ubiquitous presence of per- and polyfluoroalkyl substances (PFAS) in the environment has garnered global public concern. Epidemiological studies have proved that exposure to PFAS is associated with human health risks. Although evidence demonstrated the toxic mechanisms of PFAS based on animal models and traditional cell cultures, their limitations in inter-species differences and lack of human-relevant microenvironments hinder the understanding of health risks from PFAS exposure. There is an increasing necessity to explore alternative methodologies that can effectively evaluate human health risks. Human organoids derived from stem cells accurately mimic the sophisticated and multicellular structures of native human organs, providing promising models for toxicology research. Advanced organoids combined with innovative technologies are expected to improve understanding of the breadth and depth of PFAS toxicity.

Association between exposure to per- and polyfluoroalkyl substances and kidney function: a population study

Background

The relationship between per- and polyfluoroalkyl substances (PFAS) and kidney function markers remains uncertain.

Methods

We used PFAS detection data from 5,947 adults in NHANES 2005-2012. We employed multivariable linear regression models to examine associations between PFAS and estimated glomerular filtration rate (eGFR), urine creatinine (UCR), urine albumin (UAL), and urine albumin/creatinine ratio (UACR). To capture non-linear trends, restricted cubic splines were applied. The WQS (weighted quantile sum) and Q-gcomp (quantile g computation) models were used for the mixture analysis. Subgroup analyses were conducted to explore potential interactions.

Results

Perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS), perfluorohexane sulfonic acid (PFHxS), 2-(N-methyl-perfluorooctane sulfonamido) acetic acid (N-MEFOSAA), and perfluorononanoic acid (PFNA) were negatively related to eGFR (β = -2.04, 95% CI = -2.85, -1.23; β = -0.97, 95% CI = -1.78, -0.16; β = -1.50, 95% CI = -2.24, -0.76; β = -0.49, 95% CI = -1.25, 0.27; β = -0.68, 95% CI = -1.46, 0.10). PFOA and PFOS were positive associated with UCR (β = 10.61, 95% CI = -1.89, 23.11; β = 12.98, 95% CI = 0.56, 25.41). PFOA, PFOS, PFHxS, PFNA, and PFUA were negatively related to UAL (β = -0.53, 95% CI = -0.73, -0.32; β = -0.39, 95% CI = -0.59, -0.18; β = -0.59, 95% CI = -0.78, -0.40; β = -0.42, 95% CI = -0.65, -0.19; β = -0.04, 95% CI = -0.22, 0.14). PFDA, PFOA, PFOS, PFHxS, and PFNA are significantly inversely associated with UACR (β = -0.01, 95% CI = -0.16, 0.14; β = -0.52, 95% CI = -0.69, -0.35; β = -0.50, 95% CI = -0.67, -0.33; β = -0.49, 95% CI = -0.64, -0.33; β = -0.27, 95% CI = -0.44, -0.10). Nonlinear relationships were found between PFAS and all kidney function indicators. Mixed PFAS exposure showed a negative association with eGFR, UAL and UACR, while showed a positive relationship with UCR. Interactions between PFASs and most subgroups were observed.

Conclusion

Our study revealed significant associations between PFAS exposure and various kidney function indicators. These findings provide an epidemiological perspective on how PFAS may lead to kidney dysfunction.

Per- and polyfluoroalkyl substances in environment and potential health impacts: Sources, remediation treatment and management, policy guidelines, destructive technologies, and techno-economic analysis

Per- and polyfluoroalkyl Substances (PFAS), also known as forever chemicals and ubiquitous persistence, pose significant public health challenges due to their potential toxicity, particularly in drinking water and soil contamination. However, PFAS occurrence and their concentrations in different environmental matrices vary globally, but factors influencing trends, transport, fate, toxicity, and interactions with co-contaminants remain largely unexplored. Therefore, this review critically examines the state-of-the-art worldwide PFAS sources, distribution, and pathways, and evaluates how PFASs are processed in wastewater treatment, generally, which causes severe problems with the quality and safety of drinking water. Importantly, the review also underscores health issues due to PFAS consumption and recent research trends on developing effective treatment strategies to manage PFAS contamination. Potential effects of PFAS were linked to urban land use and the proportion of wastewater effluent in streamflow. Besides, major emphasis was provided on challenges for conventional treatment, destructive technologies, environmental accumulation, precursor transformation, and cost-investment related to PFAS removal technologies. To combat PFAS contamination, this review proposes a framework that promotes the comprehensive identification of prevalent compounds, with a focus on their eradication through knowledge-based and targeted analysis. Additionally, it explores the ongoing debate surrounding PFAS laws and legal frameworks, offering ideas for enhancing contamination management. Lastly, this review provides a strategic plan for improving response and preparedness, serving as a foundation for addressing future environmental challenges and informing health risk assessments.

Prenatal exposure to per- and polyfluoroalkyl substances (PFAS) from contaminated water and risk of childhood cancer in California, 2000-2015

Background

Few studies have investigated associations between per- and polyfluoroalkyl substances (PFAS) and childhood cancers. Detectable levels of PFAS in California water districts were reported in the Third Unregulated Contaminant Monitoring Rule for 2013-2015.

Methods

Geocoded residences at birth were linked to corresponding water district boundaries for 10,220 California-born children (aged 0-15 years) diagnosed with cancers (2000-2015) and 29,974 healthy controls. A pharmacokinetic model was used to predict average steady-state maternal serum concentrations of perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) from contaminated drinking water. Adjusted odds ratios (AORs) and 95% confidence intervals (CIs) per doubling of background exposure were calculated for cancers with at least 90 cases.

Results

Predicted PFOS and PFOA maternal serum concentrations ranged from background (5 ng/ml PFOS and 2 ng/ml PFOA) to 22.89 ng/ml and 6.66 ng/ml, respectively. There were suggestive associations between PFOS and nonastrocytoma gliomas (n = 268; AOR = 1.26; 95% CI: 0.99, 1.60), acute myeloid leukemia (n = 500; AOR = 1.14; 95% CI: 0.94, 1.39), Wilms tumors (n = 556, AOR = 1.15; 95% CI: 0.96, 1.38), and noncentral system embryonal tumors (n = 2,880; AOR = 1.07; 95% CI: 0.98, 1.17), and between PFOA and non-Hodgkin lymphoma (n = 384; AOR = 1.19; 95% CI: 0.95, 1.49). Among children of Mexico-born mothers, there was increased risk of Wilms tumor (n = 101; AORPFOS = 1.52; 95% CI: 1.06, 2.18; AORPFOA = 1.59, 95% CI: 1.12, 2.24) and noncentral system embryonal tumors (n = 557; AORPFOS = 1.24, 95% CI: 1.03, 1.50; AORPFOA = 1.19, 95% CI: 0.98, 1.45).

Conclusion

Results suggest associations between predicted prenatal maternal PFAS serum concentrations and some childhood cancers. Future analyses are warranted.

Individual and joint associations of exposure to per- and polyfluoroalkyl substances with children's mitochondrial DNA copy number, and modified by estimated glomerular filtration rate

BACKGROUND

The association between per- and polyfluoroalkyl substances (PFAS) and mitochondrial DNA copy number (mtDNAcn) in children, and the potential impact of estimated glomerular filtration rate (eGFR) on this association, remains unclear.

METHODS

We conducted a panel study with up to 3 surveys over 3 seasons in Weinan and Guangzhou, China. A total of 284 children aged 4-12 years were available, with 742 measurements of 11 PFAS and mtDNAcn. Linear mixed-effect (LME), quantile g-computation (qgcomp), weighted quantile sum (WQS) regression, and Bayesian kernel machine regression (BKMR) models were used to investigate the associations of individuals and a mixture of PFAS with mtDNAcn, and the modifying effect of eGFR on these associations.

RESULTS

Legacy PFAS, including perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), perfluoroundecanoic acid (PFUnDA), perfluorooctane sulfonate (PFOS) and emerging PFAS, 6:2 chlorinated polyfluorinated ether sulfonate (6:2 Cl-PFESA), were significantly associated with decreased mtDNAcn in a linear dose-response manner (FDR <0.05). The multiple PFAS model showed each doubling increase in PFOA related to a 6.36% (95%CI: -10.22%, -2.34%) decrement in mtDNAcn. Meanwhile, the PFAS mixture was dose-responsive related to decreased mtDNAcn, with PFOA being the largest contributor, followed by PFUnDA and PFNA. Notably, eGFR modified the inverse association between PFOA and mtDNAcn (P-int = 0.039), with a more pronounced decrement in children with an eGFR below the 20th value (101.71 mL/min/1.73m2). In addition, age significantly modified the relationship between PFOA and decreased mtDNAcn (P-int = 0.028), with a stronger association in those aged 7 years or older.

CONCLUSION

Both individual and the mixture of legacy and emerging PFAS exposure were associated with decreased mtDNAcn in children, with PFOA as the main contributor and modification of eGFR.

Perfluorooctane sulfonate causes HK-2 cell injury through ferroptosis and endoplasmic reticulum stress pathways

Perfluorooctane sulfonate (PFOS) is a synthetic persistent organic compound that is widely used in industrial products. Studies have shown that PFOS can accumulate in environment and pose a threat to human health. As the kidney is the main excretory organ for PFOS, it is important to study PFOS damage to the kidney to investigate its toxicity. Human proximal tubular epithelial cells (HK-2) were treated with 200 μM PFOS or 1 μM Fer-1. Cell viability, the levels of MDA, GSH, intracellular iron ion, and GPX-4 were determined. The expression of KIM-1 and endoplasmic reticulum stress (ERS) related proteins were determined. The expression levels of KIM-1, a marker of renal tubular injury, and ERS-related proteins, GRP78, ATF6, IRE1, and PERK, were significantly increased in HK-2 cells exposed to PFOS. The levels of MDA and intracellular total iron ion also were significantly increased in HK-2 cells exposed to PFOS and the levels of GSH and GPX-4 were significantly decreased. PFOS can damage HK-2 cells through ferroptosis and endoplasmic reticulum stress, which provides a theoretical foundation for exploring the toxicity of PFOS to the kidney.

Per- and Polyfluoroalkyl Substances and Female Health Concern: Gender-based Accumulation Differences, Adverse Outcomes, and Mechanisms

The deleterious health implications of perfluoroalkyl and polyfluoroalkyl substances (PFAS) are widely recognized. Females, in contrast to males, exhibit unique pathways for PFAS exposure and excretion, leading to complex health outcomes. The health status of females is largely influenced by hormone-related processes. PFAS have been reported to be associated with various aspects of female health, including reproductive system disorders and pregnancy-related diseases. In this article, we provide insights into the correlations between PFAS and female-prevalent diseases. Current epidemiological and toxicological evidence has demonstrated that the adverse effects of PFAS on the health of the female reproductive system are primarily attributed to the disruption of the hypothalamic-pituitary-gonadal (HPG) axis and hormonal homeostasis. However, these findings do not sufficiently elucidate the intricate associations between PFAS and specific diseases. Furthermore, autoimmune disorders, another category that is more prevalent in women compared to men, require additional investigation. Immune biomarkers pertinent to autoimmune disorders have been observed to be influenced by PFAS exposure, although epidemiological evidence is insufficient to substantiate these relations. Further thorough exploration encompassing epidemiological and toxicological studies is essential to elucidating the inherent influence of PFAS on human pathologies. Additionally, comprehensive investigations into female health issues beyond their reproductive functions is essential.

Association Between Serum Levels of Perfluoroalkyl and Polyfluoroalkyl Substances and Dental Floss Use: The Double-Edged Sword of Dental Floss Use-A Cross-Sectional Study

BACKGROUND

Although evidence suggests that dental floss contains perfluoroalkyl and polyfluoroalkyl substances (PFASs), it is still uncertain whether the use of dental floss contributes to an increased risk of PFAS exposure.

METHODS

We analysed data on serum PFAS concentrations and dental floss usage in a cohort of 6750 adults who participated in the National Health and Nutrition Examination Survey (NHANES) from 2009 to 2020. In our study, we used logistic regression, a survey-weighted linear model, item response theory (IRT) scores, inverse probability weights (IPWs) and sensitivity analysis to assess the potential impact of dental floss usage on human serum PFAS levels.

RESULTS

The analysis of six PFASs revealed that dental floss users had higher serum concentrations of perfluorooctanoic acid (PFOA) compared with non-users, while serum concentrations of other PFASs were lower. Dental floss users recorded a lower level of overall PFAS burden score compared with non-users. Sensitivity analysis showed a statistically significant increase in serum PFOA concentration among dental floss users.

CONCLUSION

Our findings suggest that the use of dental floss may be associated differently with serum concentrations of specific PFASs. Among a large representative sample of U.S. adults, individuals reporting the use of dental floss had lower levels of serum PFASs overall, with the exception of PFOA, which was slightly elevated. Dental floss is an important oral hygiene tool, and further research is needed to clarify its role in PFAS exposure.

Associations between per-and polyfluoroalkyl substances (PFAS) and county-level cancer incidence between 2016 and 2021 and incident cancer burden attributable to PFAS in drinking water in the United States

BACKGROUND

Exposure to per- and polyfluoroalkyl substances (PFAS) has been linked with various cancers. Assessment of PFAS in drinking water and cancers can help inform biomonitoring and prevention efforts.

OBJECTIVE

To screen for incident cancer (2016-2021) and assess associations with PFAS contamination in drinking water in the US.

METHODS

We obtained county-level age-adjusted cancer incidence (2016-2021) from the Surveillance, Epidemiology, and End Results (SEER) Program. Data on PFAS levels in public drinking water systems were obtained from the Third (UCMR3; 2013-2015) and Fifth (UCMR5; 2023-2024) Unregulated Contaminant Monitoring Rule. UCMR3 measured PFOS, PFOA, PFNA, PFHxS, PFHpA, and PFBS. UCMR5 expanded measurements to include PFBA, PFHxA, PFPeA, and PFPeS. We created indicators of PFAS detection and, for UCMR5, concentrations above Maximum Contaminant Levels (MCLs). MCLs for PFOA and PFOS are 4 ng/L, and for PFNA and PFHxS are 10 ng/L. We used Poisson regression models to assess associations between PFAS detection or MCL violation and cancer incidence, adjusting for potential confounders. We estimated the number of attributable cancer cases.

RESULTS

PFAS in drinking water was associated with increased cancer incidence in the digestive, endocrine, oral cavity/pharynx, and respiratory systems. Incidence rate ratios (IRRs) ranged from 1.02 to 1.33. The strongest association was observed between PFBS and oral cavity/pharynx cancers (IRR: 1.33 [1.04, 1.71]). Among males, PFAS was associated with cancers in the urinary, brain, leukemia, and soft tissues. Among females, PFAS was associated with cancers in the thyroid, oral cavity/pharynx, and soft tissue. PFAS in drinking water is estimated to contribute to 4626 [95% CI: 1,377, 8046] incident cancer cases per year based on UCMR3 data and 6864 [95% CI: 991, 12,804] based on UCMR5.

IMPACT STATEMENT

The ecological study examined the associations between PFAS in drinking water measured in two waves (2013-2015 and 2023-2024) and cancer incidence between 2016 and 2021. We found that PFAS in drinking water was associated with cancers in the organ system including the oral cavity/pharynx, lung, digestive system, brain, urinary system, soft tissue, and thyroid. Some cancers have not been widely studied for their associations with PFAS. We also observed sex differences in the associations between PFAS and cancer risks. This is the first ecological study that examined PFAS exposure in drinking water and various cancer risks.

6:2 chlorinated polyfluoroalkyl ether sulfonate (F-53B) induced nephrotoxicity associated with oxidative stress, inflammation and fibrosis in mice

6:2 Chlorinated polyfluoroalkyl ether sulfonate (trade name F-53B) is a substitute for perfluorooctane sulfonate (PFOS) used in the plating industry, and has been found in a range of environmental matrices and livings. There are numerous ways by which it is biotoxic to mammals. The kidneys are critical for maintaining homeostasis. However, little research has been conducted on how F-53B affects the kidneys. In this work, we investigated the renal toxicity of long-term oral F-53B treatment in C57BL/6J mice. Mice were allowed to drink F-53B freely at concentrations of 0, 0.057, 0.57, and 5.7 mg/L for 8 weeks. Renal oxidative stress, inflammation, and fibrosis were detected in mice exposed to F-53B, and the expression of related biochemical markers was significantly altered. Further investigations revealed that the TGF-β1/Smad3 and NF-κB signaling pathways may be associated with F-53B-induced renal fibrotic damage and inflammation. Overall, this study suggested that F-53B causes renal injury possibly via oxidative stress, activating the TGF-β1/Smad3 and NF-κB signaling pathways. This provides a foundation for further research into the harmful mechanism of F-53B in mammals.

Current trends and patterns of PFAS in agroecosystems and environment: A review

Per- and polyfluoroalkyl substances (PFASs) are one of the more well-known highly persistent organic pollutants with potential risks to agroecological systems. These compounds are of global concern due to their persistence and mobility, and they often lead to serious impacts on environmental, agricultural, and human health. In the past 20 years, the number of science publications on PFAS has risen; despite this, certain fundamental questions about PFAS occurrence, sources, mechanism of transport, and impacts on agroecosystems and the societies dependent on them are still open and evolving. There is a lack of systematic and comprehensive analysis of these concerns in agroecosystems. Therefore, we reviewed the current literature on PFAS with a focus on agroecosystems; our review suggests that PFASs are nearly ubiquitous in agricultural systems. We found the current research has limitations in analyzing PFAS in complex matrices because of their small size, distribution, and persistence within various environmental systems. There is consistency in the properties and composition of PFAS in and around agroecosystems, suggesting evidence of shared sources and similar components within different tropic levels. The introduction of new and varied sources of PFAS appear to be growing, adding to their residual accumulation in environmental matrices and leading to possible new types of chemical compounds that are difficult to assess accurately. This review determines existing research trends, understands mechanisms and incidence of PFAS within agroecosystems and their impact on human health, and thereby recommends further studies to remedy research gaps.

Per- And Poly-Fluoroalkyl Substances (PFAS) Exposure and Risk of Breast, and Female Genital Cancers: A Systematic Review and Meta-Analysis

BACKGROUND

PFASs, synthetic chemicals, can be encountered by humans through occupational or environmental exposure, and some reports suggest that they can disrupt endocrine and hormonal activities. In this comprehensive review and meta-analysis, we explored the connection between exposure to PFASs and the risks of breast and female genital cancers.

METHODS

We systematically reviewed the literature from IARC Monographs, ATSDR documents, and PubMed (as of January 2024) for cohort, case-control, and ecological studies on PFAS exposure and breast or female genital cancers. Four reviewers independently screened studies, and data extraction included study design, patient characteristics, and effect size measures. The quality of studies was assessed using the modified version of the Newcastle-Ottawa Scale (NOS). Forest plots of relative risks (RR) were constructed for breast and female genital cancer. Meta-analyses were conducted using random-effects models, stratified analyses, dose-response assessments, and publication bias evaluation.

RESULTS

The meta-analysis included 24 studies, comprising 10 cohort, 13 case-control, and one ecological study. The summary relative risk (RR) of breast cancer for PFOA exposure was 1.08 (95% CI = 0.97-1.20; n=21), and for PFOS was 1.00 (95% CI = 0.85-1.18; n=12). The RR for ovarian cancer and PFAS was 1.07 (95% CI = 1.04-1.09; n=12). The stratification by quality score, year of publication, and exposure source did not reveal any differences. However, analysis by geographical region (p=0.01) and study design (p=0.03) did show differences, particularly in terms of incidence. Stratified analyses of the dose-response relationship did not reveal a trend in the risk of breast cancer or female genital cancers, and no publication bias was found for either cancer type. No results were available for cervical and endometrial cancers.

CONCLUSION

In summary, we have found an association between PFAS exposure and ovarian cancer and a possible effect on breast cancer incidence in some specific groups. Although potential bias and confounding prevent conclusions regarding causality, these findings may hold significance for females who encounter such pollutants in their occupational or daily environments.

Kidney toxicology of a novel compound Lithium Bis(trifluoromethanesulfonyl)imide (LiTFSI, ie. HQ-115) used in energy applications: An epigenetic perspective

Exposure to emerging energy-based environmental contaminants such as lithium bis(trifluoromethanesulfonyl)imide (LiTFSI, trade name HQ-115), poses a significant threat to human health, yet its impact on kidney function and epigenetic regulation remains poorly understood. Here, we investigated the effects of LiTFSI exposure on kidney-related biochemical indicators, renal injuries, and epigenetic alterations in male CD-1 mice under both 14-day and 30-day exposure durations. Our study revealed that LiTFSI exposure led to changes in kidney-related markers, notably affecting serum bicarbonate levels, while relative kidney weight remained unaffected. Histological analysis revealed tubule dilation, inflammation, and loss of kidney structure in LiTFSI-exposed mice, alongside dysregulated expression of genes associated with inflammation, renal function, and uric acid metabolism. Epigenetic analysis further identified widespread DNA methylation changes in the two exposure regimes. Functional analysis revealed that differentially methylated regions are implicated in cell apoptosis and cancer-related pathways and are enriched with development-related transcription factor binding motifs, suggesting a potential mechanism of action underlying exposure induced kidney damage. These findings underscore the intricate interplay between environmental exposures, epigenetic modulation, and kidney health, emphasizing the need for additional research to unravel precise mechanisms and develop targeted interventions to mitigate the adverse effects of LiTFSI and exposure of similar clean energy compounds on human health.

Kidney function mediates the effects of four per-and polyfluoroalkyl substances (PFAS) on atherosclerotic cardiovascular disease

BACKGROUND

PFAS pose a significant threat to cardiovascular health and increase the risk of atherosclerotic cardiovascular disease (ASCVD). However, there is limited research evidence regarding the mechanisms by which PFAS affect the risk of ASCVD and the exposure-risk (E-R) relationship. The effect of kidney function in the relationship between PFAS and ASCVD risk has not been adequately validated.

OBJECTIVE

This study aims to explore the mechanisms by which four PFAS (Perfluorooctanoic acid (PFOA), Perfluorooctanesulfonic acid (PFOS), Perfluorohexanesulfonic acid (PFHS), and Perfluorononanoic acid (PFNA)) affect the risk of ASCVD and to verify and discuss the mediating effect of kidney function in this impact.

METHODS

This study utilizes data from 14,607 participants in the NHANES 2005-2018 to conduct a cross-sectional study. Initially, Generalized Linear Model (GLM) and Restricted Cubic Splines models are used to assess the impact of four PFAS on ASCVD risk and the E-R relationship. Subsequently, the Weighted Quantile Sum regression (WQS) model is used to evaluate the relationship between mixed four PFAS exposure and ASCVD risk. Finally, Directed Acyclic Graphs (DAG) and causal mediation models are used to confirm and analyze whether the decline in kidney function mediates the impact of four PFAS on ASCVD risk.

RESULTS

The results from GLM and WQS models indicate that both singular and mixed four PFAS exposures are associated with an increased risk of ASCVD. The E-R curves between four PFAS singular and mixed exposures and ASCVD risk are all characterized by nonlinearity. The results from DAG and causal mediation models clearly indicate that the decline in kidney function plays a significant mediating role in the relationship between four PFAS and ASCVD risk.

CONCLUSION

Exposure levels of four PFAS do not significantly increase the risk of ASCVD unless they reach a certain threshold, and the decline in kidney function exerts a significant mediating effect in the relationship between four PFAS exposure and ASCVD risk.

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.

Exploring the sources, occurrence, transformation, toxicity, monitoring, and remediation strategies of per- and polyfluoroalkyl substances: a review

Per- and polyfluoroalkyl substances (PFAS), a class of man-made chemicals, possess unique properties that have rendered them indispensable in various industries and consumer goods. However, their extensive use and persistence in the environment have raised concerns about their potential repercussions on human health and the ecosystem. This review provides insights into the sources, occurrence, transformation, impacts, fate, monitoring, and remediation strategies for PFAS. Once released into the environment, these chemicals undergo intricate transformation processes, such as degradation, bioaccumulation, and biomagnification, which result in their far-reaching distribution and persistence. Their chemical stability results in persistent pollution, with far-reaching ecological and human health implications. Remediation strategies for PFAS are still in their infancy, and researchers are exploring innovative and sustainable methods for treating contaminated environments. Promising technologies such as adsorption, biodegradation, and electrochemical oxidation have shown the potential to remove PFAS from contaminated sites, yet the search for more efficient and sustainable solutions continues. In conclusion, this review emphasizes the urgent need for continued research and innovation to address the global environmental challenge posed by PFAS. As we move forward, it is imperative to prioritize sustainable solutions that minimize the detrimental consequences of these substances on human health and the environment.

Superhydrophobic surfaces for the sustainable maintenance of building materials and stone-built heritage: The challenges, opportunities and perspectives

Bio-inspired superhydrophobic surfaces have demonstrated great potential for functional applications across a wide range of fields, including the surface maintenance of building materials. In the outdoor environment, the degradation of building materials, such as concretes, stones, bricks, tiles and mortars, poses severe structural, functional and aesthetic risks to the entire construction, raising growing concerns worldwide. Superhydrophobic surfaces are ideal multifunctional protective coatings, owing to the inhibition of liquid adhesion/penetration, spontaneous surface self-cleaning and hindering the adhesion of bacterial cells to surfaces. Yet, despite the appealing multi-functionalities and the large number of materials reported in recent years, several drawbacks that hamper wide production and application remain unresolved, e.g., poor chemical/mechanical/weathering durability, low transparency, insufficient antimicrobial effect in humid environments, toxic and environmentally unfriendly raw materials upon fabrication. In this review, the key bottlenecks identified after tentative applications are summarized underlying the underpinning mechanisms in depth. The newly proposed emerging strategies for addressing the specific limitations are then categorized and discussed in detail. Additionally, taking into account the physicochemical properties of building materials, the particular requirements concerning stone-built heritage conservation and the outdoor environment, the feasibility and the pros and cons of novel strategies are critically reviewed, outlining the future prospects of the field.

Clinical, histological, molecular, and toxicokinetic renal outcomes of per-/polyfluoroalkyl substances (PFAS) exposure: Systematic review and meta-analysis

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) are synthetic chemicals present in the environment that can negatively affect health. Kidney is the major target organ of PFAS exposure, yet the renal impact of PFAS is not completely understood. Here we review the effects of PFAS exposure on kidney health to identify gaps in our understanding and mark potential avenues for future research.

METHODS

PubMed and SCOPUS databases were searched for studies that examined the association between PFAS exposure and kidney-related outcomes. We included all epidemiological, animal, and cell studies and categorized outcomes into four categories: clinical, histological, molecular and toxicokinetic.

RESULTS

We identified 169 studies, including 51 on clinical outcomes, 28 on histological changes, 42 on molecular mechanisms, and 68 on toxicokinetics. Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) exposure were associated with kidney dysfunction, chronic kidney diseases, and increased risk of kidney cancer. Various histological changes were reported, especially in tubular epithelial cells, and the etiology of PFAS-induced kidney injury included various molecular mechanisms. Although PFOA and PFOS are not considered genotoxic, they exhibit several characteristics of carcinogens. Toxicokinetics of PFOA and PFOS differed significantly between species, with renal elimination influenced by various factors such as sex, age, and structure of the compound.

CONCLUSION

Evidence suggests that PFAS, especially PFOA and PFOS, negatively affects kidney health, though gaps in our understanding of such effects call for further research.

Carry-over rate of per- and polyfluoroalkyl substances to raw milk and human exposure risks in different regions of China

The widespread presence of per- and polyfluoroalkyl substances (PFAS) in various environmental matrices and their adverse health effects have gained worldwide attention. Therefore, numerous studies have focused on human exposure to PFAS through different pathways, such as fish and drinking water, and little attention has been paid to milk consumption. This study aimed to explore the transfer of PFAS by investigating the occurrence of PFAS in cow feed, drinking water, and raw milk from 20 regions of China and to assess the risk of human exposure to PFAS from raw milk. In total, 13, 15, and 7 PFAS were detected in cow feed, drinking water, and raw milk with total concentrations (∑PFAS) of 5.59 ± 2.91 ng/g (mean ± standard deviation), 11.91 ± 23.12 ng/L, and 0.15 ± 0.13 ng/mL, respectively. Perfluoropentanoic acid (PFPeA) was dominant with a concentration of 2.28 ± 1.75 ng/g, approximately 40.7 % of ∑PFAS in feed. Perfluorooctanoic acid (PFOA) and perfluorobutanoic acid (PFBA) were the dominant compounds found in drinking water at 4.80 ± 14.37 and 3.01 ± 6.06 ng/L, respectively. Additionally, PFOA (0.08 ± 0.09 ng/mL) was the most significant compound in raw milk, contributing 51.5 % of ∑PFAS. Moreover, the results of the carry-over rate (COR) were as follows: perfluorooctanesulfonic acid (PFOS, 29.58 %) > PFOA (15.78 %) > perfluorobutanesulfonic acid (PFBS, 9.45 %). According to the reference dose (RfD) established by the European Food Safety Authority (EFSA) in 2018, there is a potential toxicological hazard of PFOA exposure for preschool children through milk consumption. Notably, the health risk from PFOS for 1-year-old children in Central China exceeded that observed for humans in other regions and age groups. Our results showed that PFOS and PFOA were more likely to accumulate in cows and to be constantly transferred to milk, thus increasing the human health risk, especially in children.

An automated and high-throughput data processing workflow for PFAS identification in biota by direct infusion ultra-high resolution mass spectrometry

The increasing recognition of the health impacts from human exposure to per- and polyfluorinated alkyl substances (PFAS) has surged the need for sophisticated analytical techniques and advanced data analyses, especially for assessing exposure by food of animal origin. Despite the existence of nearly 15,000 PFAS listed in the CompTox chemicals dashboard by the US Environmental Protection Agency, conventional monitoring and suspect screening methods often fall short, covering only a fraction of these substances. This study introduces an innovative automated data processing workflow, named PFlow, for identifying PFAS in environmental samples using direct infusion Fourier transform ion cyclotron resonance mass spectrometry (DI-FT-ICR MS). PFlow's validation on a bream liver sample, representative of low-concentration biota, involves data pre-processing, annotation of PFAS based on their precursor masses, and verification through isotopologues. Notably, PFlow annotated 17 PFAS absent in the comprehensive targeted approach and tentatively identified an additional 53 compounds, thereby demonstrating its efficiency in enhancing PFAS detection coverage. From an initial dataset of 30,332 distinct m/z values, PFlow thoroughly narrowed down the candidates to 84 potential PFAS compounds, utilizing precise mass measurements and chemical logic criteria, underscoring its potential in advancing our understanding of PFAS prevalence and of human exposure.

Multicomponent and Surface Charge Effects on PFOS Sorption and Transport in Goethite-Coated Porous Media under Variable Hydrochemical Conditions

Perfluorooctanesulfonate (PFOS), a toxic anionic perfluorinated surfactant, exhibits variable electrostatic adsorption mechanisms on charge-regulated minerals depending on solution hydrochemistry. This work explores the interplay of multicomponent interactions and surface charge effects on PFOS adsorption to goethite surfaces under flow-through conditions. We conducted a series of column experiments in saturated goethite-coated porous media subjected to dynamic hydrochemical conditions triggered by step changes in the electrolyte concentration of the injected solutions. Measurements of pH and PFOS breakthrough curves at the outlet allowed tracking the propagation of multicomponent reactive fronts. We performed process-based reactive transport simulations incorporating a mechanistic network of surface complexation reactions to quantitatively interpret the geochemical processes. The experimental and modeling outcomes reveal that the coupled spatio-temporal evolution of pH and electrolyte fronts, driven by the electrostatic properties of the mineral, exerts a key control on PFOS mobility by determining its adsorption and speciation reactions on goethite surfaces. These results illuminate the important influence of multicomponent transport processes and surface charge effects on PFOS mobility, emphasizing the need for mechanistic adsorption models in reactive transport simulations of ionizable PFAS compounds to determine their environmental fate and to perform accurate risk assessment.

Associations of Serum Per- and Polyfluoroalkyl Substances with Hyperuricemia in Adults: A Nationwide Cross-Sectional Study

There has been widespread concern about the health hazards of per- and polyfluoroalkyl substances (PFAS), which may be the risk factor for hyperuricemia with evidence still insufficient in the general population in China. Here, we conducted a nationwide study involving 9,580 adults aged 18 years or older from 2017 to 2018, measured serum concentrations of uric acid and PFAS (PFOA, PFOS, 6:2 Cl-PFESA, PFNA, PFHxS) in participants, to assess the associations of individual PFAS with hyperuricemia, and estimated a joint effect of PFAS mixtures. We found positive associations of higher serum PFAS with elevated odds of hyperuricemia in Chinese adults, with the greatest contribution from PFOA (69.37%). The nonmonotonic dose-response (NMDR) relationships were observed for 6:2 Cl-PFESA and PFHxS with hyperuricemia. Participants with less marine fish consumption, overweight, and obesity may be the sensitive groups to the effects of PFAS on hyperuricemia. We highlight the potential health hazards of legacy long-chain PFAS (PFOA) once again because of the higher weights of joint effects. This study also provides more evidence about the NMDR relationships in PFAS with hyperuricemia and emphasizes a theoretical basis for public health planning to reduce the health hazards of PFAS in sensitive groups.

Hunting Metabolic Biomarkers for Exposure to Per- and Polyfluoroalkyl Substances: A Review

Per- and polyfluoroalkyl substances (PFAS) represent a class of persistent synthetic chemicals extensively utilized across industrial and consumer sectors, raising substantial environmental and human health concerns. Epidemiological investigations have robustly linked PFAS exposure to a spectrum of adverse health outcomes. Altered metabolites stand as promising biomarkers, offering insights into the identification of specific environmental pollutants and their deleterious impacts on human health. However, elucidating metabolic alterations attributable to PFAS exposure and their ensuing health effects has remained challenging. In light of this, this review aims to elucidate potential biomarkers of PFAS exposure by presenting a comprehensive overview of recent metabolomics-based studies exploring PFAS toxicity. Details of PFAS types, sources, and human exposure patterns are provided. Furthermore, insights into PFAS-induced liver toxicity, reproductive and developmental toxicity, cardiovascular toxicity, glucose homeostasis disruption, kidney toxicity, and carcinogenesis are synthesized. Additionally, a thorough examination of studies utilizing metabolomics to delineate PFAS exposure and toxicity biomarkers across blood, liver, and urine specimens is presented. This review endeavors to advance our understanding of PFAS biomarkers regarding exposure and associated toxicological effects.

An environmentally relevant mixture of per- and polyfluoroalkyl substances (PFAS) impacts proliferation, steroid hormone synthesis, and gene transcription in primary human granulosa cells

Per- and polyfluoroalkyl substances (PFAS) are a group of synthetic chemicals that are resistant to biodegradation and are environmentally persistent. PFAS are found in many consumer products and are a major source of water and soil contamination. This study investigated the effects of an environmentally relevant PFAS mixture (perfluorooctanoic acid [PFOA], perfluorooctanesulfonic acid [PFOS], perfluorohexanesulfonic acid [PFHxS]) on the transcriptome and function of human granulosa cells (hGCs). Primary hGCs were harvested from follicular aspirates of healthy, reproductive-age women who were undergoing oocyte retrieval for in vitro fertilization. Liquid Chromatography with tandem mass spectrometry (LC/MS-MS) was performed to identify PFAS compounds in pure follicular fluid. Cells were cultured with vehicle control or a PFAS mixture (2 nM PFHxS, 7 nM PFOA, 10 nM PFOS) for 96 h. Analyses of cell proliferation/apoptosis, steroidogenesis, and gene expression were measured via 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays/immunofluorescence, ELISA/western blotting, and RNA sequencing/bioinformatics, respectively. PFOA, PFOS, and PFHxS were detected in 100% of follicle fluid samples. Increased cell proliferation was observed in hGCs treated with the PFAS mixture with no impacts on cellular apoptosis. The PFAS mixture also altered steroid hormone synthesis, increasing both follicle-stimulating hormone-stimulated and basal progesterone secretion and concomitant upregulation of STAR protein. RNA sequencing revealed inherent differences in transcriptomic profiles in hGCs after PFAS exposure. This study demonstrates functional and transcriptomic changes in hGCs after exposure to a PFAS mixture, improving our knowledge about the impacts of PFAS exposures and female reproductive health. These findings suggest that PFAS compounds can disrupt normal granulosa cell function with possible long-term consequences on overall reproductive health.

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.

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.

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.

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.

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.

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.