Per- and polyfluoroalkyl substances (PFAS) exposure and thyroid cancer risk

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.

Per- and polyfluoroalkyl Substances (PFAS) and microRNA: an epigenome-wide association study in firefighters

The occupation of firefighting is classified as a Group 1 carcinogen. Increased cancer risk among firefighters may be partly attributable to increased occupational exposure to a range of chemicals, including per- and polyfluoroalkyl substances (PFAS). Some PFAS are known and suspect human carcinogens. Investigating epigenetic response to these PFAS exposures in firefighters may help to identify biological pathways of specific cancers, and previously unidentified health outcomes that are associated with PFAS. We therefore investigated the associations of serum PFAS concentrations with miRNA expression in firefighters. Serum samples collected from 303 firefighters from 6 sites across the USA were analyzed for 9 PFAS along with miRNA expression. Covariate-adjusted linear regression was used to estimate associations between log PFAS and miRNA expression, with false discovery rate (FDR) set to 0.05 for significance, and an exploratory cutoff of FDR q<0.20. Gene set enrichment analysis (GSEA) was performed using miRTarBase's miRWalk pathways. Age, race-ethnicity, BMI, fire department, and sex were controlled for in all models. At FDR<0.05, the linear isomer of perfluorooctane sulfonic acid (PFOS) was inversely associated with miR-128-1-5p expression (Beta = -0.146, 95% CI -0.216, -0.076). At a relaxed FDR of 0.20, we observed inverse associations for the sum of branched isomers of PFOS (Sm-PFOS) with 5 miRNAs (let-7d-5p, let-7a-5p, miR-423-5p, let-7b-5p, miR-629-5p). Several pathways were enriched for multiple PFAS, including those correlated with certain cancers, blood diseases, thyroid disorders, autoimmune disorders, and neurological outcomes. Some PFAS in firefighters were found to be associated with alteration of miRNA consistent with increased risk for a range of chronic diseases.

Comparing acute toxicity testing and extensive targeted chemical screening for risk assessment of urban stormwater pond sediments

32 urban stormwater pond sediment samples were analyzed for 259 organic substances, 13 trace elements, physico-chemical parameters and acute toxicity of eluates to the bioluminescent bacteria Aliivibrio fischeri according to the Microtox® method. Five of these samples showed some toxicity to Aliivibrio fischeri. Statistical analysis was conducted to identify substances with significantly different concentrations between toxic and non-toxic samples, as well as differences in contaminant patterns between these sets. Results showed no significant differences in trace element, organic contaminant concentrations or overall contaminant patterns between toxic and non-toxic samples. However, dissolved oxygen was significantly lower in toxic than in non-toxic samples, likely due to an influence on the lability of contaminants. This work highlights the difficulty of conducting a pertinent and robust environmental hazard assessment for complex matrices composed of a large number of substances present at low concentrations and discusses the advantages and limitations of both chemical and biological approaches to environmental hazard assessment for urban stormwater sediments. Because the evaluation of urban stormwater sediments is so complex, to comprehensively and accurately analyse its risks, it is very important to consider both biological and chemical factors. Considering both will provide an accurate identification of possible risks and enhanced control of environmental risks in urban areas.

Ten years of PFOS and PFOA human biomonitoring in Italy: Exposure levels and determinants of exposure

Per- and polyfluoroalkyl substances (PFAS) are industrial chemicals widely diffused in the environment and associated with toxic effects on humans. They became a global issue because of their environmental mobility and persistence. Control measures have been adopted to reduce their environmental presence and human exposure. Human biomonitoring studies have been conducted worldwide to estimate human exposure to these chemicals and to identify determinants of exposure, in order to provide indications to refine regulatory policy. In this paper, we studied concentrations of two legacy PFAS, Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS), in human serum. Serum samples were collected in Italy between 2007 and 2017 together with information on characteristics and lifestyle of the study participants. We applied univariate and multivariate statistical analyses to the resulting database to identify major determinants of PFAS exposure over time and in different exposure scenarios. PFOA concentrations ranged over four orders of magnitude, with a median value of 2.4 ng/mL and PFOS concentrations ranged over three orders of magnitude with a median value of 4.6 ng/mL. We identified exposure scenario and sex as the major factors in determining PFAS concentrations. In subjects at background PFAS exposure, we identified as other relevant determinants age, geographical area, degree of urbanization, level of education and skill level in occupation. A declining time-trend was observed for PFOA but not for PFOS. This study provided information about determinants of PFOA and PFOS human exposure in Italy. Results can support defining measures to limit future human exposure to these persistent contaminants.

Exposure to Per- and Polyfluoroalkyl Substances and the Risk of Prostate and Ovarian Cancer: An Epidemiologic Meta-Analysis

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) are persistent environmental contaminants. Previous research has linked PFAS exposure to prostate and ovarian cancer risk, however, the conclusions have been inconsistent. This research purpose was to determine the relationship between PFAS exposure and prostate and ovarian cancer at the population level.

METHODS

We systematically reviewed three databases-PubMed, Web of Science, and Embase-for research from when these databases were established to April 15, 2024. The quality of the retrieved research was evaluated using the Newcastle-Ottawa Scale (NOS) quality measurement tool. Meta-analysis of the extracted data was conducted using Stata 18. We also conducted sensitivity and subgroup analyses, as well as Begg's and Egger's tests.

RESULTS

Twelve publications were involved in the analysis for prostate cancer, and six were included for ovary cancer. The outcomes indicated that PFOS exposure was positively related to prostate cancer (OR: 1.13, 95% CI: 1.00-1.28), while mixed PFAS exposure was positively related to ovarian cancer (OR: 1.63, 95% CI: 1.49-1.78). The source of heterogeneity identified in the subgroup analysis was primarily attributable to variations in study design. No significant study bias was detected in the analysis.

CONCLUSION

The study demonstrated an association between PFAS exposure and both prostate and ovarian cancers. Further investigation is required to clarify the underlying mechanisms and potential associations.

Associations of Serum Per- and Polyfluoroalkyl Substances with Genotoxic Biomarkers: New Insights from Cross-Sectional and In Vivo Evidence

The effects of perfluoroalkyl and polyfluoroalkyl substances (PFAS) on genomic stability remain unclear. Here, a cross-sectional study was conducted to establish the associations of PFAS with genotoxic biomarkers. We recruited a cohort of 453 residents in 2021 in Zhejiang, China. Thirty PFAS in serum were quantified, alongside seven indicators of genomic stability [five rDNA copy numbers (rDNA-CN), mitochondrial DNA copy numbers (mtDNA-CN), and relative telomere length (RTL)] in whole blood. Results showed that PFUnDA, perfluorohexanesulfonic acid (PFHxS), perfluorooctanesulfonic acid (PFOS), 6:2 Cl-PFESA, and PFO5DoDA were positively correlated with rDNA-CN, while PFHpA, PFOA, and PFMOAA showed inverse associations. PFO4DA and PFO5DoDA were positively correlated with mtDNA-CN. PFOA, HFPO-TA, and PFMOAA were negatively associated with the RTL, while perfluorononanoic acid, PFHxS, PFOS, and 6:2 Cl-PFESA showed positive associations. Nonlinear exposure-response relationships were also observed between PFAS and genotoxic biomarkers using restricted cubic spline models. Furthermore, PFAS mixtures were positively associated with mtDNA-CN, with PFO5DoDA showing the highest contribution by the quantile-based g-computation model. In vivo studies further confirmed that PFO5DoDA increased mtDNA-CN in male mice in a dose-dependent manner. This study provides novel evidence that PFAS disrupt genomic stability, with effects varying by functional groups and fluoroalkyl(ether) chain lengths.

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.

Emerging Trends in Bioinspired Superhydrophobic and Superoleophobic Sustainable Surfaces

Inspired by nature's ability to master materials for performance and sustainability, biomimicry has enabled the creation of bioinspired materials for structural color, superadhesion, hydrophobicity and hydrophilicity, among many others. This review summarizes the emerging trends in novel sustainable fluorocarbon-free bioinspired designs for creating superhydrophobic and superoleophobic surfaces. It discusses methods, challenges, and future directions, alongside the impact of computational modeling and artificial intelligence in accelerating the experimental development of more sustainable surface materials. While significant progress is made in superhydrophobic materials, sustainable superoleophobic surfaces remain a challenge. However, bioinspiration and experimental techniques supported by computational platforms are paving the way to new renewable and biodegradable repellent surfaces that meet environmental standards without sacrificing performance. Nevertheless, despite environmental concerns, and policies, several bioinspired designs still continue to apply fluorination and other environmentally harmful techniques to achieve the required standard of repellency. As discussed in this critical review, a new paradigm that integrates advanced materials characterization, nanotechnology, additive manufacturing, computational modeling, and artificial intelligence is coming, to generate bioinspired materials with tailored superhydrophobicity and superoleophobicity while adhering to environmental standards.

Hepatotoxicity in Carp (Carassius auratus) Exposed to Perfluorooctane Sulfonate (PFOS): Integrative Histopathology and Transcriptomics Analysis

Perfluorooctane sulfonate (PFOS) contamination poses a significant environmental threat due to its widespread distribution and persistence. However, the hepatotoxic effects of PFOS on key aquatic species, such as crucian carp, remain understudied. This study systematically investigated the hepatotoxicity and underlying molecular mechanisms associated with PFOS exposure in crucian carp over a 21 day period. We determined a 96 h 50% lethal concentration (LC50) of 23.17 mg/L. Histopathological and transcriptomic analyses confirmed PFOS-induced liver damage in the carp, characterized by venous congestion, nucleolar dissolution and cellular vacuolation. Transcriptomic profiling further identified 1036 differentially expressed genes (DEGs), involving critical pathways related to lipid and energy metabolism, immunity, and endocrine regulation. These pathways are integral to the development of nonalcoholic fatty liver disease (NAFLD). Specifically, DEGs related to lipid metabolism showed significant changes, while those involved in energy metabolism indicated disrupted ATP production and mitochondrial function. Genes associated with immune response revealed an upregulation of pro-inflammatory markers, and hormone regulation genes highlighted alterations in endocrine signaling. Our findings emphasized that PFOS exhibits acute toxicity to crucian carp, potentially inducing hepatotoxicity by disrupting multiple physiological systems. This research provides a theoretical foundation for mitigating aquatic pollution and protecting eco-health, contributing to broader ecological and conservation biology discussions.

Per- and polyfluoroalkyl substances (PFAS) exposure is associated with radioiodine therapy resistance and dedifferentiation of differentiated thyroid cancer

Differentiated thyroid cancer (DTC) generally has a favorable prognosis, and radioactive iodine (RAI) therapy is typically used for metastatic DTC that continues to progress and poses life-threatening risks. However, resistance to RAI in metastatic DTC significantly impairs treatment effectiveness. This study aims to identify potential compounds that may influence RAI efficacy. We conducted untargeted metabolomics on pre-treatment serum samples from 42 RAI-refractory DTC (RAIR-DTC) patients and 52 RAI-sensitive patients. The results revealed significantly elevated levels of two per- and polyfluoroalkyl substances (PFAS), PFDA and PFNA, in RAI-resistant patients. This accumulation was significantly negatively correlated with the expression of the sodium-iodide symporter (NIS), which reflects the differentiation status and iodide uptake capability of thyroid cancer. Furthermore, high levels of PFDA and PFNA exposure were significantly associated with poor prognosis in patients undergoing RAI therapy. In vivo exposure simulations in a murine model showed that PFAS exposure significantly increased the malignant progression of thyroid cancer, reduced iodine uptake ability, and promoted dedifferentiation. Overall, these findings provide novel insights into the development of RAIR-DTC, highlighting the importance of continuous monitoring and control of PFAS exposure in cancer patients.

Global burden of thyroid cancer in adolescents and young adults (aged 15-39 years) from 1990 to 2021: A systematic analysis of the Global Burden of Disease Study 2021

BACKGROUND

Thyroid cancer (TC) is the most common malignancy of the endocrine system and head-and-neck region, yet data on its burden in adolescents and young adults (AYAs) is lacking. This study aimed to estimate the global burden of TC among AYAs from 1990 to 2021.

METHODS

Utilizing the Global Burden of Disease (GBD) 2021 data, we analyzed age-standardized rates of incidence, prevalence, and disability-adjusted life-years (DALYs) on global, regional, and national scales. Joinpoint regression was employed to determine average annual percentage change (AAPC), with frontier analysis revealing regions for improvement. Decomposition analysis assessed the impacts of population aging, growth, and epidemiological changes. Projections for disease burden extending to 2040 were generated using the Bayesian Age-Period-Cohort model.

RESULT

In 2021, there were 48.2 thousand incident cases, 436.1 thousand prevalent cases, and 183.5 thousand DALYs worldwide. Meantime, the age-standardized incidence rates (ASIR), age-standardized prevalence rates (ASPR), and age-standardized DALYs rates (ASDR) were 1.6, 14.3 and 6.1 per 100 000, respectively. From 1990 to 2021, the ASIR, ASPR and ASDR increased with AAPCs of 1.73, 1.77, and 0.38, respectively. Socio-demographic resources in Saudi Arabia, Taiwan (Province of China), Iceland, United Arab Emirates, and United States Virgin Islands have the potential to lower ASDR due to TC among AYAs. Furthermore, 13.3 thousand and 34.9 thousand new cases occurred in the males and females in 2021. Among 5 age groups, the highest numbers of incidence, prevalence, and DALYs, along with ASRs, were observed in the 35-39 age group. Global projections indicated a continuous rise in numbers of incidence, prevalence, and DALYs, with estimates of 60.2 thousand, 558.4 thousand, and 199.7 thousand by 2040, respectively.

CONCLUSION

The global burden of TC among AYAs was on the rise, with significant disparities by regions, genders, and age groups, highlighting the necessity for targeted and effective interventions.

Mass Spectrometry-Based Spatial Multiomics Revealed Bioaccumulation Preference and Region-Specific Responses of PFOS in Mice Cardiac Tissue

The distribution and bioaccumulation of environmental pollutants are essential to understanding their toxicological mechanism. However, achieving spatial resolution at the subtissue level is still challenging. Perfluorooctanesulfonate (PFOS) is a persistent environmental pollutant with widespread occurrence. The bioaccumulation behavior of PFOS is complicated by its dual affinity for phospholipids and protein albumin. It is intriguing to visualize the distribution preference of PFOS and investigate the differential microenvironment responses at a subtissue level. Herein, we developed a mass-spectrometry (MS)-based spatial multiomics workflow, integrating matrix-assisted laser desorption/ionization MS imaging, laser microdissection, and liquid chromatography MS analysis. This integrated workflow elucidates the spatial distribution of PFOS in mouse cardiac tissue, highlighting its preferential accumulation in the pericardium over the myocardium. This distribution pattern results in greater toxicity to the pericardium, significantly altering cardiolipin levels and disrupting energy metabolism and lipid transport pathways. Our integrated approach provides novel insights into the bioaccumulation behavior of PFOS and demonstrates significant potential for revealing complex molecular mechanisms underlying the health impacts of environmental pollutants.

Perfluorooctanoic acid induced lung toxicity via TGF-β1/Smad pathway, crosstalk between airway hyperresponsiveness and fibrosis: withdrawal impact

Perfluorooctanoic acid (PFOA) is an environmental persistent agent to which humans are exposed daily through food and water. This study investigated the lung toxic effects induced by ingested PFOA (30 mg/kg/day) for 8 weeks in adult male rats and the impact following 8 weeks of its withdrawal. PFOA increased MDA and reduced TAC inducing oxidative stress. It induced airway hyperresponsiveness (AHR) via increased bronchoalveolar lavage fluid (BALF) IL-4, IL-5, IL-13, IL-9, eosinophil count, TNF-α, and IL-1ß; reduced IL-12; increased serum IgE; and increased urocortin expression in lung tissues. Moreover, it induced pulmonary fibrosis via increased serum KL-6, and SFTP-D, altered pulmonary structure, and increased deposition of collagen fibers in lung tissues. Furthermore, it increased TGF-β1, Smad2, and Smad3 and reduced Smad7 gene expression in lung tissues. These gene alterations were positively correlated with AHR and fibrosis-related factors. The recovered lung upon PFOA withdrawal showed complete resolution of oxidative stress and slight amelioration of other studying parameters. Exposure to PFOA induced lung toxicity by disrupting the TGF-β1/Smad signaling pathway, which acts as a crosstalk between AHR and fibrosis. Additionally, PFOA altered pulmonary architecture, triggered inflammation, and caused oxidative stress. The lung exhibited partial alleviation upon recovery.

Exposure to per- and poly-fluoroalkyl substances and lung, head and neck, and thyroid cancer: A systematic review and meta-analysis

Recent evidence suggests that exposure to per- and polyfluoroalkyl substances (PFAS) may increase the risk of different cancer types, such as kidney and testicular cancers. Instead, evidence for lung, head and neck, and thyroid cancer is sparse. Hence, we aimed to summarize available literature on the topic. We searched Pubmed and Scopus in January 2024 to retrieve relevant studies and estimated pooled relative risks (RRs) and 95% confidence intervals (CIs) for lung, head and neck, and thyroid cancers according to PFAS exposure using restricted maximum likelihood method. Pooled RRs for occupational or environmental PFAS exposure were 1.20 (95% CI: 1.12-1.28; I2 = 0.0%, phet = 0.9; n. studies = 9), 1.15 (95% CI: 0.96-1.37; I2 = 0.0%, phet = 0.7; n. studies = 3), and 1.54 (95% CI: 0.86-2.78; I2 = 69.0%, phet = 0.02; n. studies = 4) for lung, head and neck, and thyroid cancer, respectively. We did not find compelling evidence of publication bias for lung cancer (p = 0.3). Studies on statistically modelled serum PFAS levels did not support associations with these cancers. We found no positive associations between measured serum levels of 6 different types of PFAS and thyroid cancer. However, the pooled RR of two case-control studies nested within cohorts on the association between natural log-unit increase of perfluorooctanesulfonic acid (PFOS) and thyroid cancer was 1.51 (95% CI: 1.11-2.05; I2 = 21.1%, phet = 0.3). PFAS exposure may be associated with lung and thyroid cancer. Due to the limited number of studies and their limitations, further prospective studies with appropriate account of co-exposure with other carcinogens and detailed exposure assessment are needed to establish causality of observed associations.

Serum metabolome associated with novel and legacy per- and polyfluoroalkyl substances exposure and thyroid cancer risk: A multi-module integrated analysis based on machine learning

BACKGROUND

Exposure to per- and polyfluoroalkyl substances (PFAS) may linked to thyroid cancer (TC) risk, but inconsistent findings and a lack of studies on mixed exposures exist, especially regarding novel PFAS compounds. Additionally, little is known about the potential mechanisms underlying the association.

OBJECTIVES

Explore the effects of PFAS exposure on the serum metabolome and its correlation with TC.

METHODS

A 1:1 age- and sex-matched case-control study was administered with 746 TC cases and healthy controls. Liquid chromatography-high resolution mass spectrometry determined serum 11 PFAS and untargeted metabolome profile. ENET and LightGBM models were used to explore the exposure patterns and perform variable selection. The mixed exposure effects were assessed using Weighted quantile sum regression and Bayesian kernel machine regression. Metabolome-wide association analyses were performed to assess metabolic dysregulation associated with PFAS, and a structural synthesis analysis was used to detect latent groups of individuals with TC based on PFAS levels and metabolite patterns.

RESULTS

Ten of the 11 PFAS were detected in > 80 % of the population. PFHxA and PFDoA exposure associated with increased TC risk, while PFHxS and PFOA associated with decreased TC risk in single compound models (all P < 0.05). Machine learning algorithms identified PFHxA, PFDoA, PFHxS, PFOA, and PFHpA as the key PFAS influencing the development of TC, and mixed exposures have an overall positive effect on TC risk, with PFHxA making the primary contribution. A novel integrative analysis identified a cluster of TC patients characterized by increased PFHxA, PFDoA, PFHpA and decreased PFOA, PFHxS levels, and altered metabolite patterns highlighted by the upregulation of free fatty acids.

CONCLUSIONS

PFAS exposure is linked to a higher risk of TC, possibly through changes in fatty acid metabolism. Larger, prospective studies are needed to confirm these findings, and the role of short-chain PFAS requires more attention.

Combined toxicity of perfluoroalkyl substances and microplastics on the sentinel species Daphnia magna: Implications for freshwater ecosystems

Persistent chemicals from industrial processes, particularly perfluoroalkyl substances (PFAS), have become pervasive in the environment due to their persistence, long half-lives, and bioaccumulative properties. Used globally for their thermal resistance and repellence to water and oil, PFAS have led to widespread environmental contamination. These compounds pose significant health risks with exposure through food, water, and dermal contact. Aquatic wildlife is particularly vulnerable as water bodies act as major transport and transformation mediums for PFAS. Their co-occurrence with microplastics may intensify the impact on aquatic species by influencing PFAS sorption and transport. Despite progress in understanding the occurrence and fate of PFAS and microplastics in aquatic ecosystems, the toxicity of PFAS mixtures and their co-occurrence with other high-concern compounds remains poorly understood, especially over organisms' life cycles. Our study investigates the chronic toxicity of PFAS and microplastics on the sentinel species Daphnia, a species central to aquatic foodwebs and an ecotoxicology model. We examined the effects of perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), and polyethylene terephthalate microplastics (PET) both individually and in mixtures on Daphnia ecological endpoints. Unlike conventional studies, we used two Daphnia genotypes with distinct histories of chemical exposure. This approach revealed that PFAS and microplastics cause developmental failures, delayed sexual maturity and reduced somatic growth, with historical exposure to environmental pollution reducing tolerance to these persistent chemicals due to cumulative fitness costs. We also observed that the combined effect of the persistent chemicals analysed was 59% additive and 41% synergistic, whereas no antagonistic interactions were observed. The genotype-specific responses observed highlight the complex interplay between genetic background and pollutant exposure, emphasizing the importance of incorporating multiple genotypes in environmental risk assessments to more accurately predict the ecological impact of chemical pollutants.

Adverse outcome pathway for the neurotoxicity of Per- and polyfluoroalkyl substances: A systematic review

Per- and polyfluoroalkyl substances (PFAS) are endocrine disruptors with unambiguous neurotoxic effects. However, due to variability in experimental models, population characteristics, and molecular endpoints, the elucidation of mechanisms underlying PFAS-induced neurotoxicity remains incomplete. In this review, we utilized the adverse outcome pathway (AOP) framework, a comprehensive tool for evaluating toxicity across multiple biological levels (molecular, cellular, tissue and organ, individual, and population), to elucidate the mechanisms of neurotoxicity induced by PFAS. Based on 271 studies, the reactive oxygen species (ROS) generation emerged as the molecular initiating event 1 (MIE1). Subsequent key events (KEs) at the cellular level include oxidative stress, neuroinflammation, apoptosis, altered Ca2+ signal transduction, glutamate and dopamine signaling dyshomeostasis, and reduction of cholinergic and serotonin. These KEs culminate in synaptic dysfunction at organ and tissue levels. Further insights were offered into MIE2 and upstream KEs associated with altered thyroid hormone levels, contributing to synaptic dysfunction and hypomyelination at the organ and tissue levels. The inhibition of Na+/I- symporter (NIS) was identified as the MIE2, initiating a cascade of KEs at the cellular level, including altered thyroid hormone synthesis, thyroid hormone transporters, thyroid hormone metabolism, and binding with thyroid hormone receptors. All KEs ultimately result in adverse outcomes (AOs), including cognition and memory impairment, autism spectrum disorders, attention deficit hyperactivity disorders, and neuromotor development impairment. To our knowledge, this review represents the first comprehensive and systematic AOP analysis delineating the intricate mechanisms responsible for PFAS-induced neurotoxic effects, providing valuable insights for risk assessments and mitigation strategies against PFAS-related health hazards.

Prenatal co-exposure to phthalate metabolites and bisphenols among non-syndromic cleft lip and/or palate in offspring

Phthalate metabolites and bisphenols can cause adverse pregnancy outcomes. However, there is no study to evaluate the associations of prenatal exposure to phthalate metabolites and bisphenols with non-syndromic cleft lip and/or palate (NSCL/P) risk in offspring. A population-based case-control study was conducted in a multicenter setting from 2005 to 2021, enrolling 448 pregnant women. Seven phthalate metabolites and six bisphenols were quantified in placenta using liquid chromatography-tandem mass spectrometry. In the logistic regression analysis, high levels of mono-ethyl phthalate, mono-cyclohexyl phthalate, mono-octyl phthalate, bisphenol A, bisphenol AF, bisphenol AP, and fluorene-9-bisphenol were associated with increased NSCL/P risk with odds ratios (95% confidence intervals) of 1.86(1.07,3.25), 6.56(3.47,12.39), 8.49(4.44,16.24), 8.34(4.32,16.08), 3.19(1.81,5.62), 2.78(1.59,4.86), and 5.16(2.82,9.44). The Bayesian kernel machine regression model revealed that co-exposure to phthalate metabolites and bisphenols was associated with increased NSCL/P risk. Similarly, quantile-based g-computation analysis indicated that each quantile increase in mixture concentration was positively related to higher risk for NSCL/P [odds ratio (95% confidence interval) = 2.98(1.97,4.51)]. This study provides novel evidence that prenatal single and co-exposure to phthalate metabolites and bisphenols were associated with increased NSCL/P risk, suggesting that exposure to phthalate metabolites and bisphenols during pregnancy should be minimized to reduce the incidence of NSCL/P in offspring.

Perfluoroalkyl and polyfluoroalkyl substances and Cancer risk: results from a dose-response Meta-analysis

Background

Perfluoroalkyl and polyfluoroalkyl substances (PFASs) are persistent organic pollutants in the environment. While some studies suggest that PFASs may contribute to cancer development, the link between PFAS exposure and cancer risk remains debated.

Methods

This dose-response meta-analysis explores the relationship between PFASs and cancer. It employs odds ratio (OR) and standardized mean difference (SMD), along with their 95% confidence interval (CI), to assess the effects of PFASs on cancer risk. Relevant studies were sourced from Web of Science, PubMed, Embase, Medline, and CNKI databases. The dose-response relationship was assessed by the fixed-effects model and least-squares regression.

Results

Forty studies, involving a total of 748,188 participants, were included in this meta-analysis. Out of these, 13 studies were specifically analyzed for the dose-response relationship. Findings revealed that exposure to PFASs, especially PFDA, significantly raises the risk of genitourinary cancers, and PFDA exposure shows a dose-dependent increase in overall and breast cancer risk. Additionally, PFOS exposure is associated with an increased cancer risk, and elevated PFOA levels were significantly observed in breast cancer patients.

Conclusions

The findings suggest that PFAS exposure is a potential cancer risk factor, with the carcinogenic potential of PFDA being dose-dependent.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40201-024-00899-w.

Poly- and per-fluoroalkyl substances (PFAS) in the African environments: progress, challenges, and future perspectives

Per- or poly-fluoroalkyl substances (PFAS) are a group of anthropogenic compounds that are used in a variety of industrial processes and consumer products with their ubiquitous presence in the environment recently gaining relevant attention. Progress and milestones on PFAS contamination within multiple environments from African continent are highlighted in this review. Identification and quantitation of PFAS within African environments is important to the public at large because of their toxicity and possible ecotoxicological risk. Two most studied classes of PFAS are perfluoro carboxylic acid (PFCA) (i.e., perfluorooctanoic acid (PFOA)) and perfluoro sulfonic acid (PFSA) (i.e., perfluoro sulfonic acid (PFOS)) with many more classes of PFAS been created by industry. Within the African continent, studies reported PFAS in water, sediments, soils, fish, dust, breastmilk, infant formulae, dust, atmosphere, marine species and wildlife. Southern Africa contributed more studies on the presence of PFAS in the environment with Central Africa contributing the least. Despite growing awareness of PFAS contamination in Africa, the number of studies, studied compounds, and concentration levels vary significantly across regions and matrices. While some countries in Southern and Western Africa have made progress in PFAS research, the overall disparity in research output highlights the urgency for increased attention, resources, and concerted efforts to comprehensively address PFAS contamination. This review also revealed PFAS contamination within freshwater environments, with non-existent data from marine water environments. Collaboration among scientists, policymakers, industry players as well as regional and international communities are essential to mitigate the impact of PFAS in the African environment.

Per- and polyfluoroalkyl substances (PFAS) and cancer: Detection methodologies, epidemiological insights, potential carcinogenic mechanisms, and future perspectives

Per- and polyfluoroalkyl substances (PFAS), known as "forever chemicals," are synthetic chemicals which have been used since the 1940s. Given their remarkable thermostability and chemical stability, PFAS have been widely utilized in commercial products, including textiles, surfactants, food packages, nonstick coatings, and fire-fighting foams. Thus, PFAS are widely distributed worldwide and have been detected in human urine, blood, breast milk, tissues and other substances. Growing concerns over the risks of PFAS, including their toxicity and carcinogenicity, have attracted people's attention. Recent reviews have predominantly emphasized advancements in the detection, adsorption, and degradation of PFAS through their chemical structures and toxic properties; however, further examination of the literature is needed to determine the link between PFAS exposure and cancer risk. Here, we introduced different PFAS detection methods based on sensors and liquid chromatography-mass spectrometry (LC-MS). Then, we discussed epidemiological investigations on PFAS levels and cancer risks in recent years, as well as the mechanisms underlying the carcinogenesis. Finally, we proposed the "4C principles" for ongoing exploration and refinement in this field. This review highlights PFAS-cancer associations to fill knowledge gaps and provide evidence-based strategies for future research.

Environmental factors related to the origin and evolution of differentiated thyroid cancer: a narrative review

INTRODUCTION

The global incidence of thyroid cancer (TC) has increased in the last decades. While improvements in diagnosis may contribute, overdiagnosis is also a possibility. This review focuses on the epidemiology, risk factors, and immune microenvironment associated with differentiated TC (DTC).

AREAS COVERED

A search was conducted in Scielo, Scopus, and EMBASE databases, involving 72 articles. TC is the most common endocrine neoplasm, with DTC form being predominant. Its incidence has globally risen, particularly among women aged over 45. Endogenous risk factors for DTC include genetic disorders, race, age, female gender, obesity, and type 2 diabetes mellitus. Environmental risks involve ionizing radiation, whether through therapeutic treatment or environmental contamination from nuclear accidents, iodine deficiency, endocrine disruptors, residence in volcanic areas, environmental pollution, and stress. The use of anti-obesity medications remains controversial. The tumor's immune microenvironment is the histological space where tumor cells interact with host cells, crucial for understanding aggressiveness. Immunotherapy emerges as a promising intervention.

EXPERT OPINION

Recent advances in DTC management offer transformative potential, requiring collaborative efforts for implementation. Emerging areas like precision medicine, molecular profiling, and immunotherapy present exciting prospects for future exploration, shaping the next era of diagnostic and therapeutic strategies in thyroid cancer research.

Low-salt diets and salt-free cooking help reduce exposure to Per- and polyfluoroalkyl substances (PFAS)

BACKGROUND

The ubiquity of Per- and polyfluoroalkyl substances (PFAS) in various consumer and industrial products poses a significant public health challenge, but effective strategies to reduce human exposure to PFAS are limited.

OBJECTIVES

This study aims to evaluate the association between dietary patterns, specifically low-salt diets and salt-free cooking, and serum PFAS levels in the general population.

METHODS

The study analyzed data from 11,137 participants from the National Health and Nutrition Examination Survey (NHANES) using weighted linear regression. We assessed associations between low-salt or low-sodium dietary patterns and the way salt was used during cooking or food preparation and serum levels of five highly detectable PFAS compounds: perfluorooctanoic acid (PFOA), perfluorooctanesulfonic acid (PFOS), perfluorohexanesulfonic acid (PFHxS), perfluorodecanoic acid (PFDA), and perfluorononanoic acid (PFNA). Since consuming fish and shellfish is a major source of PFAS exposure in humans, the intake status of these foods was adjusted for in the sensitivity analysis. Additionally, other sensitivity analyses, including propensity score matching, were conducted.

RESULTS

The analyses showed a significant negative association between low-salt or low-sodium diet and serum levels of the five PFAS compounds. In contrast, regular use of salt in cooking or food preparation was significantly and positively associated with higher serum levels of PFAS. These findings were consistent across all models. Also consistent were the results of sensitivity analyses based on participants' consumption of fish and shellfish and propensity score matching.

CONCLUSIONS

Low-salt or low-sodium dietary patterns, and salt-free cooking may be are associated with a reduced risk of PFAS exposure in the general population. While this study offers new insights into mitigating PFAS exposure, further validation in additional datasets is necessary, along with confirmation through intervention studies designed based on this hypothesis.

The role of Drp1 - Pink1 - Parkin - mediated mitophagy in perfluorobutane sulfonate- induced hepatocyte damage

Perfluorobutane sulfonate (PFBS) is recognized as a highly persistent environmental contaminant, notorious for its chemical stability and enduring presence in ecosystems. Its propensity for persistence and environmental mobility allows PFBS to infiltrate the human body, predominantly accumulating in the liver where it poses a potential risk for hepatic damage. This investigation aimed to explore the outcomes of PFBS on the physiological functionalities of hepatocytes in vitro. To this end, hepatocytes were exposed to 750 ug/ml PFBS, followed by an analysis of various cellular phenotypes and functionalities, including assessments of cell viability and mitochondrial integrity. The findings indicated that PFBS exposure led to a suppression of cell proliferation and an increase in apoptotic cell death. Moreover, PFBS exposure was found to augment the generation of reactive oxygen species (ROS) and induce significant mitochondrial dysfunction. Gene expression analysis identified significant changes in genes associated with numerous tumor signaling pathways and autophagy signaling pathways. Further examinations revealed an increase in cellular mitophagy following PFBS exposure, coupled with the activation of the mitophagy-associated Drp1/Pink1/Parkin pathway. Inhibition of mitophagy was observed to concurrently amplify cellular damage and inhibit the Drp1/Pink1/Parkin pathway. Together, these findings highlight PFBS's capacity to inflict hepatocyte injury through mitochondrial disruption, positioning Drp1/Pink1/Parkin-mediated mitophagy as a crucial cellular defense mechanism against PFBS-induced toxicity.

In vitro cytotoxicity of six per- and polyfluoroalkyl substances (PFAS) in human immune cell lines

Per- and Polyfluoroalkyl substances (PFAS) are a group of persistent long-lived chemicals with global environmental contamination. The published literature is rife with confusing and sometimes contradictory effects of PFAS on animal and cell models, as well as epidemiological studies. Cytotoxicity studies are often used as an early indicator to guide safety requirements, regulation, and further studies and thus can be useful to understand important toxicity differences by various PFAS. Recent studies have found that PFAS are not equivalently toxic on all cell types, and that not all cell types exhibit the same sensitivity to individual PFAS. However, immune cells have not been well studied. As immune cells are important for regulating responses to environmental toxins, infection, and cancer, we sought to discover the sensitivity of these cells to various PFAS, including legacy and replacement compounds. We assessed a range of concentrations and found that immune cells are generally more robust when exposed to PFAS, and that Jurkat T-cells were more sensitive than THP-1 monocytes. As monocytes are critical for coordinating inflammatory responses to external threats with cell death cascades, we further investigated these cells. We discovered that THP-1 cells do not undergo organized or programmed death, such as apoptosis or pyroptosis, and instead PFAS exposure results in a more necrotic/lytic and unorganized death, likely contributing to potential inflammatory effects downstream.

Advances in perfluoro-alkylated compounds (PFAS) detection in seafood and marine environments: A comprehensive review on analytical techniques and global regulations

Per- and poly-fluoroalkyl substances (PFAS) are persistent organic pollutants that severely threaten the environment and human health due to their distinct chemical composition, extensive production, widespread distribution, bioaccumulation in nature, and long-term persistence. This review focuses on the occurrence and sources of PFAS in seafood, with a particular emphasis on advanced detection methods viz. nanoparticle-based, biosensor-based, and metal-organic frameworks-based, and mass spectrometric techniques. The challenges associated with these advanced detection technologies are also discussed. Recent research and regulatory updates about PFAS, including hazardous and potential health effects, epidemiological studies, and various risk assessment models, have been reviewed. In addition, the need for global monitoring programs and regulations on PFAS are critically reviewed by underscoring their crucial role in protecting human health and the environment. Further, approaches for reducing PFAS in seafood are highlighted with future innovative remediation directions. Although advanced PFAS analytical methods are available, selectivity, sample preparation, and sensitivity are still significant challenges associated with detection of PFAS in seafood matrices.  Moreover, crucial research gaps and solutions to essential concerns are critically explored in this review.

Exploring the environmental contamination toxicity and potential carcinogenic pathways of perfluorinated and polyfluoroalkyl substances (PFAS): An integrated network toxicology and molecular docking strategy

The objective of this study was to investigate the potential carcinogenic toxicity and mechanisms of PFAS in thyroid, renal, and testicular cancers base on network toxicology and molecular docking techniques. Structural modeling was performed to predict relevant toxicity information, and compounds and cancer-related targets were screened in multiple databases. The interaction of PFAS with three cancers and their key protein targets were explored by combining protein network analysis, enrichment analysis and molecular docking techniques. PFOA, PFOS, and PFHXS exhibited significant carcinogenic and cytotoxic effects. These compounds may induce cancer by mediating active oxygen metabolism and the transduction of phosphatidylinositol 3-kinase/protein kinase B signaling pathway through genes such as ALB, mTOR, MDM2, and ERBB2. Furthermore, the underlying toxic mechanisms may be linked to the pathways in cancer, chemical carcinogenesis through reactive oxygen species/receptor activation, and the FoxO signaling pathway. The results contribute to a comprehensive understanding of the effects of these environmental pollutants on genes, proteins, and metabolic pathways in living organisms. It revealed their toxicity mechanisms in inducing thyroid, renal, and testicular cancers, and provided a solid theoretical foundation for designing new environmental control strategies and drug screening initiatives. Additionally, the integrated application of network toxicology and molecular docking technology can enhance our understanding of the toxicity and mechanisms of unknown environmental pollutants, which is beneficial for protecting the environment and human health.

Serum Erythritol and Risk of Overall and Cause-Specific Mortality in a Cohort of Men

Erythritol occurs naturally in some fruits and fermented foods, and has also been used as an artificial sweetener since the 1990s. Although there have been questions and some studies regarding its potential adverse health effects, the association between serum erythritol and long-term mortality has not been evaluated. To examine the association between serum erythritol's biochemical status and risk of overall and cause-specific mortality, a prospective cohort analysis was conducted using participants in the ATBC Study (1985-1993) previously selected for metabolomic sub-studies. The analysis included 4468 participants, among whom 3377 deaths occurred during an average of 19.1 years of follow-up. Serum erythritol was assayed using an untargeted, global, high-resolution, accurate-mass platform of ultra-high-performance liquid and gas chromatography. Cause-specific deaths were identified through Statistics Finland and defined by the International Classification of Diseases. After adjustment for potential confounders, serum erythritol was associated with increased risk of overall mortality (HR = 1.50 [95% CI = 1.17-1.92]). We found a positive association between serum erythritol and cardiovascular disease mortality risk (HR = 1.86 [95% CI = 1.18-2.94]), which was stronger for heart disease mortality than for stroke mortality risk (HR = 3.03 [95% CI = 1.00-9.17] and HR = 2.06 [95% CI = 0.72-5.90], respectively). Cancer mortality risk was also positively associated with erythritol (HR = 1.54 [95% CI = 1.09-2.19]). The serum erythritol-overall mortality risk association was stronger in men ≥ 55 years of age and those with diastolic blood pressure ≥ 88 mm Hg (p for interactions 0.045 and 0.01, respectively). Our study suggests that elevated serum erythritol is associated with increased risk of overall, cardiovascular disease, and cancer mortality. Additional studies clarifying the role of endogenous production and dietary/beverage intake of erythritol in human health and mortality are warranted.

Per- and polyfluoroalkyl substances in Chinese commercially available red swamp crayfish (Procambarus clarkii): Implications for human exposure and health risk assessment

The extensive utilization of per- and polyfluoroalkyl substances (PFASs) has led to their pervasive presence in the environment, resulting in contamination of aquatic products. Prolonged exposure to PFASs has been linked to direct hepatic and renal damage, along with the induction of oxidative stress, contributing to a spectrum of chronic ailments. Despite the recent surge in popularity of red swamp crayfish as a culinary delicacy in China, studies addressing PFASs' exposure and associated health risks from their consumption remain scarce. To address this gap, our study investigated the PFASs' content in 85 paired edible tissue samples sourced from the five primary red swamp crayfish breeding provinces in China. The health risks associated with dietary exposure were also assessed. Our findings revealed widespread detection of PFASs in crayfish samples, with short-chain perfluoroalkyl carboxylic acids (PFCAs) exhibiting the highest concentrations. Notably, the total PFAS concentration in the hepatopancreas (median: 160 ng/g) significantly exceeded that in muscle tissue (5.95 ng/g), as did the concentration of every single substance. The hazard quotient of perfluorohexanesulfonic acid (PFHxS) via consuming crayfish during peak season exceeded 1. In this case, a potential total non-cancer health risk of PFASs, which is mainly from the hepatopancreas and associated with PFHxS, is also observed (hazard index>1). Thus, it is recommended to avoid consuming the hepatopancreas of red swamp crayfish. Greater attention should be paid to governance technology innovation and regulatory measure strengthening for short-chain PFASs.

6:2 Cl-PFESA, a proposed safe alternative for PFOS, diminishes the gemcitabine effectiveness in the treatment of pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC)/pancreatic cancer, is a highly aggressive malignancy with poor prognosis. Gemcitabine-based chemotherapy remains the cornerstone of PDAC treatment. Nonetheless, the development of resistance to gemcitabine among patients is a major factor contributing to unfavorable prognostic outcomes. The resistance exhibited by tumors is modulated by a constellation of factors such as genetic mutations, tumor microenvironment transforms, environmental contaminants exposure. Currently, comprehension of the relationship between environmental pollutants and tumor drug resistance remains inadequate. Our study found that PFOS/6:2 Cl-PFESA exposure increases resistance to gemcitabine in PDAC. Subsequent in vivo trials confirmed that exposure to PFOS/6:2 Cl-PFESA reduces gemcitabine's efficacy in suppressing PDAC, with the inhibition rate decreasing from 79.5 % to 56.7 %/38.7 %, respectively. Integrative multi-omics sequencing and molecular biology analyses have identified the upregulation of ribonucleotide reductase catalytic subunit M1 (RRM1) as a critical factor in gemcitabine resistance. Subsequent research has demonstrated that exposure to PFOS and 6:2 Cl-PFESA results in the upregulation of the RRM1 pathway, consequently enhancing chemotherapy resistance. Remarkably, the influence exerted by 6:2 Cl-PFESA exceeds that of PFOS. Despite 6:2 Cl-PFESA being regarded as a safer substitute for PFOS, its pronounced effect on chemotherapeutic resistance in PDAC necessitates a thorough evaluation of its potential risks related to gastrointestinal toxicity.

Per- and polyfluoroalkyl substances (PFAS) exposure and thyroid cancer: Systematic review and meta-analysis

Per- and polyfluoroalkyl substances (PFAS) exposure is a potential risk factor for thyroid cancer and may be a contributor to the increasing thyroid cancer incidence rates. A systematic review and meta-analysis was performed to summarize all human studies to date investigating the association between PFAS exposure and thyroid cancer. A search of the National Library of Medicine and National Institutes of Health PubMed and Scopus databases was done to identify relevant articles published in English through January 2024. Studies reporting the association between PFAS exposure and thyroid cancer using odds ratios (OR) were included in the meta-analysis with summary estimate calculated using a random effects model (n=5). Perfluorooctanoic acid (PFOA) was the most investigated PFAS. Results of the included studies varied, ranging from significant positive to significant negative associations with thyroid cancer incidence for different PFAS. Meta-analyses of PFOA, Perfluorooctanesulfonic acid (PFOS), perfluorononanoic acid (PFNA), perfluorohexanesulfonic acid (PFHxS) were not significant. This comprehensive review of the current literature highlights the limited knowledge and inconsistent results of this association. Large longitudinal cohort studies with varying time between sample collection and thyroid cancer diagnosis are needed to better understand the role of PFAS exposure on thyroid carcinogenesis.

Changing the structure of PFOA and PFOS: a chemical industry strategy or a solution to avoid thyroid-disrupting effects?

BACKGROUND

The family of perfluoroalkyl and polyfluoroalkyl substances (PFAS) raised concern for their proven bioaccumulation and persistence in the environment and animals as well as for their hazardous health effects. As a result, new congeners of PFAS have rapidly replaced the so-called "old long-chain PFAS" (mainly PFOA and PFOS), currently out-of-law and banned by most countries. These compounds derive from the original structure of "old long-chain PFAS", by cutting or making little conformational changes to their structure, thus obtaining new molecules with similar industrial applications. The new congeners were designed to obtain "safer" compounds. Indeed, old-long-chain PFAS were reported to exert thyroid disruptive effects in vitro, and in vivo in animals and humans. However, shreds of evidence accumulated so far indicate that the "restyling" of the old PFAS leads to the production of compounds, not only functionally similar to the previous ones but also potentially not free of adverse health effects and bioaccumulation. Studies aimed at characterizing the effects of new-PFAS congeners on thyroid function indicate that some of these new-PFAS congeners showed similar effects.

PURPOSE

The present review is aimed at providing an overview of recent data regarding the effects of novel PFAS alternatives on thyroid function.

RESULTS AND CONCLUSIONS

An extensive review of current legislation and of the shreds of evidence obtained from in vitro and in vivo studies evaluating the effects of the exposure to novel PFOA and PFOS alternatives, as well as of PFAS mixture on thyroid function will be provided.

Large-Scale Screening of Per- and Polyfluoroalkyl Substance Binding Interactions and Their Mixtures with Nuclear Receptors

Despite their significant impact, comprehensive screenings and detailed analyses of per- and polyfluoroalkyl substance (PFAS) binding strengths at the orthosteric and allosteric sites of NRs are currently lacking. This study addresses this gap by focusing on the binding interaction analysis of both common and uncommon PFAS with the nuclear receptors (NRs) vitamin D receptor (VDR), peroxisome proliferator-activated receptor gamma (PPARγ), pregnane X receptor (PXR), and estrogen receptor alpha (ERα). Advanced docking simulations were used to screen 9507 PFAS chemicals at the orthosteric and allosteric sites of PPARγ, PXR, VDR, and ERα. All receptors exhibited strong binding interactions at the orthosteric and allosteric site with a significant number of PFAS. We verified the accuracy of the docking protocol through multiple docking controls and validations. A mixture modeling analysis indicates that PFAS can bind in various combinations with themselves and endogenous ligands simultaneously, to disrupt the endocrine system and cause carcinogenic responses. These findings reveal that PFAS can interfere with nuclear receptor activity by displacing endogenous or native ligands by binding to the orthosteric and allosteric sites. The purpose of this study is to explore the mechanisms through which PFAS exert their endocrine-disrupting effects, potentially leading to more targeted therapeutic strategies. Importantly, this study is the first to explore the binding of PFAS at allosteric sites and to model PFAS mixtures at nuclear receptors. Given the high concentration and persistence of PFAS in humans, this study further emphasizes the urgent need for further research into the carcinogenic mechanisms of PFAS and the development of therapeutic strategies that target nuclear receptors.

Per- and polyfluoroalkyl substances and human health outcomes: An umbrella review of systematic reviews with meta-analyses of observational studies

BACKGROUND

Although evidence on the association between per- and polyfluoroalkyl substances (PFASs) and human health outcomes has grown exponentially, specific health outcomes and their potential associations with PFASs have not been conclusively evaluated.

METHODS

We conducted a comprehensive search through the databases of PubMed, Embase, and Web of Science from inception to February 29, 2024, to identify systematic reviews with meta-analyses of observational studies examining the associations between the PFASs and multiple health outcomes. The quality of included studies was evaluated using the A Measurement Tool to Assess Systematic Reviews (AMSTAR) tool, and credibility of evidence was assessed using the Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) criteria. The protocol of this umbrella review (UR) had been registered in PROSPERO (CRD 42023480817).

RESULTS

The UR identified 157 meta-analyses from 29 articles. Using the AMSTAR measurement tool, all articles were categorized as of moderate-to-high quality. Based on the GRADE assessment, significant associations between specific types of PFASs and low birth weight, tetanus vaccine response, and triglyceride levels showed high certainty of evidence. Moreover, moderate certainty of evidence with statistical significance was observed between PFASs and health outcomes including lower BMI z-score in infancy, poor sperm progressive motility, and decreased risk of preterm birth as well as preeclampsia. Fifty-two (33%) associations (e.g., PFASs and gestational hypertension, cardiovascular disease, etc) presented low certainty evidence. Additionally, eighty-five (55%) associations (e.g., PFASs with infertility, lipid metabolism, etc) presented very low certainty evidence.

CONCLUSION

High certainty of evidence supported that certain PFASs were associated with the incidence of low birth weight, low efficiency of the tetanus vaccine, and low triglyceride levels.

Thyroid cancer and endocrine disruptive chemicals: a case-control study on per-fluoroalkyl substances and other persistent organic pollutants

Objective

The aim was to evaluate the possible association between some endocrine disruptive chemicals and thyroid cancer (TC) in an Italian case-control cohort.

Methods

We enrolled 112 TC patients and 112 sex- and age-matched controls without known thyroid diseases. Per- and poly-fluoroalkyl substances (PFAS), poly-chlorinated biphenyls (PCBs), and dichlorodiphenyltrichloroethane (4,4'-DDT and 4,4'-DDE) were measured in the serum by liquid or gas chromatography-mass spectrometry. Unconditional logistic regression, Bayesan kernel machine regression and weighted quantile sum models were used to estimate the association between TC and pollutants' levels, considered individually or as mixture. BRAFV600E mutation was assessed by standard methods.

Results

The detection of perfluorodecanoic acid (PFDA) was positively correlated to TC (OR = 2.03, 95% CI: 1.10-3.75, P = 0.02), while a negative association was found with perfluorohexanesulfonic acid (PFHxS) levels (OR = 0.63, 95% CI: 0.41-0.98, P = 0.04). Moreover, perfluorononanoic acid (PFNA) was positively associated with the presence of thyroiditis, while PFHxS and perfluorooctane sulfonic acid (PFOS) with higher levels of presurgical thyroid-stimulating hormone (TSH). PFHxS, PFOS, PFNA, and PFDA were correlated with less aggressive TC, while poly-chlorinated biphenyls (PCB-105 and PCB-118) with larger and more aggressive tumors. Statistical models showed a negative association between pollutants' mixture and TC. BRAF V600E mutations were associated with PCB-153, PCB-138, and PCB-180.

Conclusion

Our study suggests, for the first time in a case-control population, that exposure to some PFAS and PCBs associates with TC and some clinical and molecular features. On the contrary, an inverse correlation was found with both PFHxS and pollutants' mixture, likely due to a potential reverse causality.

Efficient removal of per/polyfluoroalkyl substances from water using recyclable chitosan-coated covalent organic frameworks: Experimental and theoretical methods

Covalent organic frameworks (COFs) demonstrate remarkable potential for adsorbing per/polyfluoroalkyl substances (PFAS). Nevertheless, the challenge of recycling powdered COFs hampers their practical application in water treatment. In this research, a quaternary amine COF with inherent positive surface charge was synthesised to adsorb perfluorooctanoic acid (PFOA) via electrostatic interactions. The COF was then combined with chitosan (CS) through a simple dissolution-evaporation process, resulting in a composite gel material termed COF@CS. The findings indicated that the adsorption capacity of COF@CS significantly surpassed that of the original COF and CS. According to the Langmuir model, COF@CS achieved a maximum PFOA capacity of 2.8 mmol g-1 at pH 5. Furthermore, the adsorption rate increased significantly to 6.2 mmol g-1 h-1, compared to 5.9 mmol g-1 h-1 for COF and 3.4 mmol g-1 h-1 for CS. Notably, COF@CS exhibited excellent removal efficacy for ten other types of PFAS. Moreover, COF@CS could be successfully regenerated using a mixture of 70% ethanol and 1 wt% NaCl, and it exhibited stable reusability for up to five cycles. X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) characterisation, and theoretical calculations revealed that the quaternary amine functional group in COF served as the primary adsorption site in the composite gel material, while the protonated amino group on CS enhanced PFOA adsorption through electrostatic interaction. This study highlights the significant practical potential of COF@CS in the removal of PFAS from aqueous solution and environmental remediation.

Do PFCAs drive the establishment of thyroid cancer microenvironment? Effects of C6O4, PFOA and PFHxA exposure in two models of human thyroid cells in primary culture

BACKGROUND

Exposure to environmental pollutants is suspected to be one of the potential causes accounting for the increase in thyroid cancer (TC) incidence worldwide. Among the ubiquitous pollutants, per-polyfluoroalkyl substances (PFASs), were demonstrated to exert thyroid disrupting effects. Perfluoroalkyl carboxylates (PFCAs) represent a subgroup of PFAS and include perfluoro carboxylic acids (PFOA and PFHxA) and perfluoropolyether carboxylic acid (C6O4). The potential relationship between exposure to PFCAs and TC was not yet fully elucidated. This in vitro study investigated whether certain PFCAs (C6O4, PFOA, and PFHxA) can influence the composition of TC microenvironment.

METHODS

Two models of normal thyroid cells in primary cultures: Adherent (A-NHT) and Spheroids (S-NHT) were employed. A-NHT and S-NHT were exposed to C6O4, PFOA or PFHxA (0; 0.01; 0.1, 1; 10; 100; 1000 ng/mL) to assess viability (WST-1 and AV/PI assay), evaluate spherification index (SI) and volume specifically in S-NHT. CXCL8 and CCL2 (mRNA and protein), and EMT-related genes were assessed in both models after exposure to PFCAs.

RESULTS

PFHxA reduced the viability of both A-NHT and S-NHT. None of the PFCAs interfered with the volume or spherification process in S-NHT. CXCL8 and CCL2 mRNA and protein levels were differently up-regulated by each PFCAs, being PFOA and PFHxA the stronger inducers. Moreover, among the tested PFCAs, PFHxA induced a more consistent increase in the mRNA levels of EMT-related genes.

CONCLUSIONS

This is the first evaluation of the effects of exposure to PFCAs on factors potentially involved in establishing the TC microenvironment. PFHxA modulated the TC microenvironment at three levels: cell viability, pro-tumorigenic chemokines, and EMT-genes. The results provide further evidence of the pro-tumorigenic effect of PFOA. On the other hand, a marginal effect was observed for C6O4 on pro-tumorigenic chemokines.