An integrated assessment of ecological and human health risks of per- and polyfluoroalkyl substances through toxicity prediction approaches

Assessing microplastics, per- and polyfluoroalkyl substances (PFAS), and other contaminants of global concern in wadable agricultural streams in Iowa

Microplastics, per- and polyfluoroalkyl substances (PFAS), antibiotic resistance genes (ARGs), pharmaceuticals and personal care products (PPCPs), and pesticides may lead to unintended environmental contamination through many pathways in multiple matrices. This statewide, multi-matrix study of contaminants of global concern (CGCs) in agricultural streams across Iowa (United States) is the first to examine multiple CGCs in water, bed sediment, and fish to understand their occurrence in small streams located in regions of intense agriculture activity. Iowa plays a pivotal role in agriculture, with more than 85% of Iowa's landscape devoted to agriculture, making it an ideal location for determining the prevalence of CGCs to provide critical baseline exposure data. Fifteen sites were sampled across a range of predominant land uses (e.g., poultry, swine); all sites had detections of microplastics in all matrices. Concentrations of PFAS varied but were detected in water and sediment; all fish had detections of perfluorooctanesulfonate (PFOS), a type of PFAS. More than 50% of water and bed sediment samples had detections of ARGs. The most frequently detected PPCP was metformin. No sites had a cumulative exposure activity ratio greater than 1.0 for chemical exposures; 13 sites were above the 0.001 precautionary threshold. Toxicity quotients calculated using Aquatic Life Benchmarks were below the 0.1 moderate risk threshold for chemical exposures for all but one site. For fish, all sites exceeded the moderate and high-risk thresholds proposed for microplastic particles for food dilution (both chronic and acute exposures) and all sites exceeded the microplastic moderate threshold proposed for chronic tissue translocation, and two sites exceeded the threshold for acute tissue translocation.

Age-specific associations between per- and polyfluoroalkyl substances exposure and metabolic syndrome: a cross-sectional study

BACKGROUND

The widespread presence of per-and polyfluoroalkyl substances (PFAS) has raised global health concerns. This study aims to determine the age-specific relationships of PFAS compounds with metabolic syndrome (MetS) and its components.

METHODS

We used data from the National Health and Nutrition Examination Survey (NHANES) in 2003-2018. Modified Poisson regression was employed to estimate associations between individual PFAS compounds and prevalence of MetS, as well as its components. Multiple linear regression analyses were performed to examine the associations between PFAS congeners and metabolic markers, including lipid and glucose homeostasis traits. Additionally, weighted quantile sum (WQS) regression and Bayesian kernel machine regression (BKMR) models were conducted to investigate the joint effects of PFAS mixtures on the prevalence of MetS and its components across different age groups.

RESULTS

A total of 5850 participants were included for analysis. In the Modified Poisson regression model, ln-transformed perfluorononanoic acid (PFNA) level was positively correlated with MetS prevalence in adolescents (prevalence ratio [PR] = 1.42; 95% CI: 1.01-1.99). Conversely, ln-transformed perfluorohexanesulfonic acid (PFHxS) and ln-transformed 2-(N-Methylperfluorooctane sulfonamido) acetic acid (MeFOSAA) were negatively associated with the risks of MetS in young adults (PR = 0.86, 95% CI: 0.76-0.98) and middle-aged adults (PR = 0.88, 95% CI: 0.79-0.98), respectively. Notably, individual PFAS exposure was positively associated with levels of total cholesterol, low-density lipoprotein, non-high-density lipoprotein, and high-density lipoprotein in young and middle-aged adults. However, overall effect analyses using WQS and BKMR showed no significant associations of PFAS mixture with MetS in any age group. Nonetheless, in middle-aged adults, PFAS mixture was adversely correlated with hypertriglyceridemia and positively linked to a greater risk of hypertension and increased high-density lipoprotein cholesterol levels.

CONCLUSIONS

Our study highlighted the complex relationships between PFAS exposure and the risks of MetS and its components across different age groups. Co-exposure to PFAS was particularly linked to dyslipidemia in young and middle-aged adults. Prospective studies are needed for better comprehension of the causative impact of PFAS on the risks of MetS.

Per- and polyfluoroalkyl substances (PFAS) in drinking water systems in the lower Yangtze River: source, fate, and health risk assessment

The Yangtze River is significantly impacted by industrial activities related to per- and polyfluoroalkyl substances (PFAS) in China, posing potential threats to drinking water safety. So far, our knowledge of PFAS occurrence in the river and their fate in the whole drinking water supply systems remains limited. We conducted a comprehensive investigation of PFAS in Jiangsu's drinking water systems, using the target screening method. 12 perfluoroalkyl acids (PFAAs) and 7 emerging PFAS were detected and precisely quantified in the whole treatment process water flows, as well as source water and household tap water with concentrations of 61.34-90.40 ng/L. PFAAs [PFOA (30.26 ng/L), PFBS (23.25 ng/L), PFBA (18.82 ng/L) and PFHxA (16.89 ng/L)] and 8:8 PFPiA (13.63 ng/L) were the dominant pollutants in the low Yangtze River. PFBA (19.92 ng/L), PFBS (15.02 ng/L) and PFOA (11.94 ng/L) were major contaminants in tap water. The powder activated carbon pre-treatment in DWTP-B could remove 21.36-65.84% of long-chain PFAS, especially PFOA. Ozonation achieved slight emerging PFAS removal (3.22-11.06%), while PFAAs concentrations exhibited an increase. Granular active carbon filtration was effective in removing long-chain PFAS, with DWTP-B outperforming DWTP-A. PFSAs (3.12-22.09%) had a better removal than PFCAs (- 0.62 to 19.54%). Infants and children face a moderate health risk of PFAS intake through drinking water, peaking at the age group of 9 months to 1 year (HQ = 2.45). These findings underscore the necessity for improved PFAS removal technologies and stricter regulation of PFAS contamination in the Yangtze River to reduce exposure.

Perfluorinated compounds exposure and atherogenic risk characteristics in a high-fat diet condition: In vitro/in vivo models and population panel study

Perfluorinated compounds (PFCs) are a well-recognized environmental risk factor for atherosclerosis. However, corresponding atherogenic risk in susceptible populations consuming high-fat diets (HFDs) remains unclear. Here, we found that perfluorooctane sulfonic acid (PFOS), a canonical PFCs, elevated the atherogenic risk in mice fed with HFD, which was characterized by an increased number of pro-inflammatory phenotype macrophages. We also found that macrophages exhibited a metabolic reprogramming to glycolysis, which was attributed to increased intracellular Fe2+ level. Mechanistic investigation revealed that PFOS directly bound to the iron-storage site on the ferritin heavy chain, subsequently weakening the iron-storage function. Notably, PFCs with acidic substituents and short chains had a higher atherogenic risk, as evidenced in the crucial indicators and observed in a population with a high triglyceride level. These findings highlight the potential atherogenic risk posed by PFCs exposure in susceptible populations consuming HFD and provide a potential intervention target.

Investigating the molecular interactions of two long-chain PFASs with human serum albumin: Insights from multispectral analysis and computational methods

Long-chain perfluoroalkyl substances (FPAS) are commonly detected in environmental and biological contexts. This study investigated the interactions of perfluoroundecanoic acid (PFUnDA) and perfluorotridecanoic acid (PFTrDA) with human serum albumin (HSA). Fluorescence quenching experiments demonstrated static quenching of HSA's intrinsic fluorescence by both PFUnDA and PFTrDA, resulting in the formation of stable HSA-PFAS complexes. At 298 K, PFUnDA exhibited a higher binding constant (5.50 × 107 L/mol) than PFTrDA (1.01 × 105 L/mol), indicating stronger binding affinity. Thermodynamic analysis indicated that hydrogen bonds and van der Waals forces were the predominant interactions in the binding processes. Molecular docking confirmed that both PFASs bind to the IIA subdomain of HSA, with PFUnDA exhibiting lower binding energy (-8.690 kcal/mol) than PFTrDA. Molecular dynamics simulations further supported these findings, with PFUnDA showing stronger binding energy (-13.894 kcal/mol) driven primarily by van der Waals forces and electrostatic interactions. Quantum chemical analysis reveals that the carbonyl groups in PFUnDA and PFTrDA exhibit significant molecular reactivity, indicating a propensity for more vigorous chemical interactions. This study not only reveals the potential biological activity of PFUnDA and PFTrDA, but also provides scientific basis for evaluating their biosafety and risks.

Freshwater ecotoxicity characterization factors for PFASs

This research aims to address the data gaps in freshwater ecotoxicological characterization factors (CFs) for per- and polyfluoroalkyl substances (PFASs). These CFs are essential for incorporating the ecotoxicity impacts of PFAS emissions into life cycle assessments (LCAs). This study has three primary objectives: first, to calculate a comprehensive set of experimental aquatic ecotoxicity CFs for PFASs utilizing the USEtox model (version 2.13); second, to compare these newly derived CFs with those generated using the PFAS-adapted USEtox model; and finally, to test the hypothesis concerning a potential correlation between CFs and effect factors (EFs) with the number of perfluorinated carbons in PFASs. In this study, 367 PFASs were selected from the CompTox Chemicals Dashboard PFAS suspect lists and REACH (Registration, Evaluation, Authorisation and Restriction of Chemicals) registration dossiers. Experimental ecotoxicity data were extracted from CompTox Version 2.1.1 and REACH. Using both the USEtox model (version 2.13) and the PFAS-adapted USEtox model, CFs were calculated for 367 PFASs. Of these, 237 CFs were newly calculated using the HC20EC10eq-based methodology, enriching the representation of PFASs in LCA studies. The analysis revealed no correlation between the number of perfluorinated carbons and the calculated EFs and CFs using the USEtox models. This study covers only a small portion of the extensive list of millions of PFASs in PubChem, primarily due to data constraints and scarcity. Discrepancies between CFs generated by USEtox and PFAS-adapted USEtox are attributed to variations in foundational fate and exposure factor calculation methodologies, whereas ecotoxicity factors remained consistent. Consequently, it is suggested that CFs for PFASs are dependent on the modeling approach and require regular updates with the latest data to ensure accuracy and relevance.

Exposure to perfluorodecanoic acid impairs follicular development via inducing granulosa cell necroptosis

Per- and polyfluoroalkyl substances (PFAS) have attracted significant attention due to their environmental toxicity. However, the detrimental impact of PFAS on the development of the female reproductive system remains controversial. In this study, we investigated the effects of three specific PFAS compounds perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), and perfluorodecanoic acid (PFDA) on ovarian development. Among these compounds, PFDA demonstrated the most pronounced cytotoxic effect on ovarian granulosa cells. The results showed that a 200 μM concentration of PFDA induced cell apoptosis via the intrinsic pathway by elevating reactive oxygen species (ROS) levels and activating Caspase-9 and Caspase-3. Furthermore, 200 μM PFDA triggered necroptosis, a form of regulated cell death (RCD), through the receptor-interacting serine/threonine kinase 1 (RIPK1), receptor interacting protein kinase 3 (RIPK3), and mixed-lineage kinase domain-like protein (MLKL) axis, mediated by inhibition of the canonical apoptosis proteolytic enzyme Caspase-8. In vivo experiments confirmed that mice exposed to PFDA displayed a significantly reduced ovarian index compared to the control group, accompanied by evident follicular atresia. Ovarian tissues from the PFDA-exposed group showed upregulated necroptosis markers, which were effectively mitigated by inhibiting the phosphorylation of RIPK1 at Ser166. Importantly, this study provides the first evidence that PFDA disrupts ovarian development through a novel mechanism involving the RIPK1-mediated necroptosis pathway, alongside the detection of the intrinsic apoptosis pathway. This greatly expands our insight into the effects of PFDA on cell death. This finding highlights the potential public health hazards associated with PFDA exposure and emphasizes the need for further research to fully understand its broader implications.

Combined environmental relevant exposure to perfluorooctanoic acid and zinc sulfate enhances apoptosis through binding with endogenous antioxidants in Daphnia magna

Perfluorooctanoic acid (PFOA) is a long-chain legacy congener of the per- and polyfluoroalkyl substances (PFAS) family, notorious as a "forever chemical" owing to its environmental persistence and toxic nature. Essential elements such as zinc (Zn) can cause toxic effects when they change their metal speciation and become bioavailable, such as zinc sulfate (ZnSO4). Combined toxicity assessment is a realistic approach and a challenging task to evaluate chemical interactions and associated risks. Therefore, the present study aims to elucidate the acute mixture toxicity (12-48 h) of PFOA and ZnSO4 in Daphnia magna at environment-relevant concentrations (ERCs, low dose: PFOA 10 μg/L ZnSO4 20 μg/L; high dose: PFOA 20 μg/L ZnSO4 50 μg/L) in terms of developmental impact, apoptosis induction, and interaction with major endogenous antioxidants. Our results showed that deformity rates significantly increased (p < 0.05) with increasing exposure duration and exposure concentrations, compared to the control group. Further, lack of antenna, tale degeneration, and carapace alterations were the most commonly observed deformities following combined exposure to PFOA and ZnSO4, and these malformations were particularly pronounced after 48 h of exposure. Acridine orange (AO) staining was employed to examine apoptosis in D. magna, and apoptotic cells in terms of bright green fluorescence were detected in the abdominal claw carapace, heart, and post-abdominal area following exposure to a high dose of PFOA and ZnSO4. The molecular docking results revealed that both PFOA and ZnSO4 showed strong binding affinities with endogenous antioxidants CAT and GST, where PFOA was more strongly bound with CAT and GST with higher docking scores of -9.59 kcal/mol and -7.49 kcal/mol than those with ZnSO4 (-6.70 kcal/mol and -6.55 kcal/mol, respectively). In conclusion, the mixture exposure to PFOA and ZnSO4 at the environmental level induce developmental impacts and apoptosis through binding with major endogenous antioxidants in D. magna.

The phosphorylation of Smad3 by CaMKIIγ leads to the hepatocyte pyroptosis under perfluorooctane sulfonate exposure

Perfluorooctane sulfonate (PFOS) is a persistent organic pollutant and accumulated in the liver of mammals. PFOS exposure is closely associated with the development of pyroptosis. Nevertheless, the underlying mechanism is unclear. We found here that PFOS induced pyroptosis in the mice liver and L-02 cells as demonstrated by activation of the NOD-like receptor protein 3 inflammasome, gasdermin D cleavage and increased release of interleukin-1β and interleukin-18. The level of cytoplasmic calcium was accelerated in hepatocytes upon exposure to PFOS. The phosphorylated/activated form of calcium/calmodulin-dependent protein kinase II (CaMKII) was augmented by PFOS in vivo and in vitro. PFOS-induced pyroptosis was relieved by CaMKII inhibitor. Among various CaMKII subtypes, we identified that CaMKIIγ was activated specifically by PFOS. CaMKIIγ interacted with Smad family member 3 (Smad3) under PFOS exposure. PFOS increased the phosphorylation of Smad3, and CaMKII inhibitor or CaMKIIγ siRNA alleviated PFOS-caused phosphorylation of Smad3. Inhibiting Smad3 activity was found to alleviate PFOS-induced hepatocyte pyroptosis. This study puts forward that CaMKIIγ-Smad3 is the linkage between calcium homeostasis disturbance and pyroptosis, providing a mechanistic explanation for PFOS-induced pyroptosis.

Spatial distribution, trophic magnification, and risk assessment of per- and polyfluoroalkyl substances in Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis): Risks of emerging alternatives

The Yangtze finless porpoise (YFP, Neophocaena asiaeorientalis asiaeorientalis) is the only freshwater cetacean found in China. However, per- and polyfluoroalkyl substances (PFASs) risks in YFPs remain unclear. In this study, legacy PFASs, their precursors and alternatives, were determined in YFP muscles (n = 32), liver (n = 29), kidney (n = 24), skin (n = 5), and blubbers (n = 25) collected from Poyang Lake (PL) and Yangtze River (YR) between 2017 and 2023. Perfluorooctane sulfonic acid (PFOS) was the predominant PFAS in all YFP tissues, with a median hepatic concentration of 1700 ng/g wet weight, which is higher than that in other finless porpoises worldwide. PFOS, chlorinated polyfluorinated ether sulfonates (Cl-PFESAs), and perfluoroalkane sulfonamides concentrations in YFP livers from PL were significantly higher than those from YR (p < 0.05); however, the opposite was observed for hexafluoropropylene oxide acids. Biomagnification and trophic magnification factors (BMF and TMF, respectively) of most PFASs in the YFP food web were > 1. Perfluoroheptane sulfonic acid had the highest BMF value (99), followed by 6:2 Cl-PFESA (94) and PFOS (81). The TMFmuscle and TMFliver values of the total PFASs were 3.4 and 6.6, respectively, and were significantly positively correlated with the fluorinated carbon chain length (p < 0.01). In addition, up to 62 % of the hazard quotients for 6:2 Cl-PFESA were > 1, which was higher than that of PFOS (48 %), suggesting a high hepatotoxicity of 6:2 Cl-PFESA to YFPs. Bioaccumulation and biotoxicity of legacy and emerging alternatives in aquatic organisms continue to be a concern, especially for underscoring the vulnerability of the long-lived and endangered species.

Structural investigation of the complexation between vitamin B12 and per- and polyfluoroalkyl substances: Insights into degradation using density functional theory

Environmental remediation of per- and polyfluoroalkyl substances (PFAS) has become a significant research topic in recent years due to the fact that these materials are omnipresent, resistant to degradation and thus environmentally persistent. Unfortunately, they have also been shown to cause health concerns. PFAS are widely used in industrial applications and consumer products. Vitamin B12 (B12) has been identified as being catalytically active towards a variety of halogenated compounds such as PFAS. It has also been shown to be effective when using sulfide as a reducing agent for B12. This is promising as sulfide is readily available in the environment. However, there are many unknowns with respect to PFAS interactions with B12. These include the reaction mechanism and B12's specificity for PFAS with certain functionalization(s). In order to understand the specificity of B12 towards branched PFAS, we examined the atomistic interactions between B12 and eight different PFAS molecules using Density Functional Theory (B3LYP/cc-pVDZ). The PFAS test set included linear PFAS and their branched analogs, carboxylic acid and sulfonic acid headgroups, and aromatic and non-aromatic cyclic structures. Conformational analyses were carried out to determine the lowest energy configurations. This analysis showed that small chain PFAS such as perfluorobutanoic acid interact with the cobalt center of B12. Bulkier PFAS prefer to interact with the amine and carbonyl groups on the sidechains of the B12 ring system. Furthermore, computed complexation energies determined that, in general, branched PFAS (e.g. perfluoro-5-methylheptane sulfonic acid) interact more strongly than linear molecules (e.g. perfluorooctanesulfonic acid). Our results indicate that it may be possible to alter the interactions between B12 and PFAS by synthetically modifying the sidechains of the ring structure.

Mechanisms of colon toxicity induced by long-term perfluorooctanoic acid exposure in mice

Perfluorooctanoic acid (PFOA), a persistent organic pollutant known for its chemical stability, is widely dispersed in the environment, posing significant health risks to mammals through various exposure routes such as ingestion, inhalation, and dermal contact. In this study, mice were exposed to PFOA (0, 0.2, 2 mg/L) through drinking water for 180 days to investigate its toxic effects on the colon. We identified differentially expressed genes through RNA sequencing and validated the impact of PFOA on the expression of these genes in colon tissue. Our findings revealed that long-term exposure to PFOA caused inflammatory bowel disease (IBD)-like damage to the mouse colon. We found PFOA could induce damage to the intestinal barrier. Inhibition of the Wnt signaling pathway following PFOA exposure results in impaired stem cell function in the colon of mice. Furthermore, PFOA activated the PPAR signaling pathway, disrupting cellular lipid metabolism in colon tissues. Additionally, PFOA induced inflammatory responses in colon tissue, facilitating NLR family, pyrin domain containing 3 (NLRP3) inflammasome activation and cell apoptosis. This study offers a thorough understanding of the mechanisms responsible for the damage to mouse colon tissue resulting from long-term exposure to PFOA.

PFAS and their association with the increased risk of cardiovascular disease in postmenopausal women

Cardiovascular diseases (CVDs) are one of the major causes of death globally. In addition to traditional risk factors such as unhealthy lifestyles (smoking, obesity, sedentary) and genetics, common environmental exposures, including persistent environmental contaminants, may also influence CVD risk. Per- and polyfluoroalkyl substances (PFASs) are a class of highly fluorinated chemicals used in household consumer and industrial products known to persist in our environment for years, causing health concerns that are now linked to endocrine disruptions and related outcomes in women, including interference of the cardiovascular and reproductive systems. In postmenopausal women, higher levels of PFAS are observed than in premenopausal women due to the cessation of menstruation, which is crucial for PFAS excretion. Because of these findings, we explored the association between perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS), and perfluorobutanesulfonic acid in postmenopausal women from our previously established CVD study. We used liquid chromatography with tandem mass spectrometry, supported by machine learning approaches, and the detection and quantification of serum metabolites and proteins. Here, we show that PFOS can be a good predictor of coronary artery disease, whereas PFOA can be an intermediate predictor of coronary microvascular disease. We also found that the PFAS levels in our study are significantly associated with inflammation-related proteins. Our findings may provide new insight into the potential mechanisms underlying the PFAS-induced risk of CVDs in this population. This study shows that exposure to PFOA and PFOS is associated with an increased risk of cardiovascular disease in postmenopausal women. PFOS and PFOA levels correlate with amino acids and proteins related to inflammation. These circulating biomarkers contribute to the etiology of CVD and potentially implicate a mechanistic relationship between PFAS exposure and increased risk of cardiovascular events in this population.

Exploring pollutant joint effects in disease through interpretable machine learning

Identifying the impact of pollutants on diseases is crucial. However, assessing the health risks posed by the interplay of multiple pollutants is challenging. This study introduces the concept of Pollutants Outcome Disease, integrating multidisciplinary knowledge and employing explainable artificial intelligence (AI) to explore the joint effects of industrial pollutants on diseases. Using lung cancer as a representative case study, an extreme gradient boosting predictive model that integrates meteorological, socio-economic, pollutants, and lung cancer statistical data is developed. The joint effects of industrial pollutants on lung cancer are identified and analyzed by employing the SHAP (Shapley Additive exPlanations) interpretable machine learning technique. Results reveal substantial spatial heterogeneity in emissions from CPG and ILC, highlighting pronounced nonlinear relationships among variables. The model yielded strong predictions (an R of 0.954, an RMSE of 4283, and an R2 of 0.911) and emphasized the impact of pollutant emission amounts on lung cancer responses. Diverse joint effects patterns were observed, varying in terms of patterns, regions (frequency), and the extent of antagonistic and synergistic effects among pollutants. The study provides a new perspective for exploring the joint effects of pollutants on diseases and demonstrates the potential of AI technology to assist scientific discovery.

Toxicity of Metal Oxides, Dyes, and Dissolved Organic Matter in Water: Implications for the Environment and Human Health

This study delves into the critical issue of water pollution caused by the presence of metal oxides, synthetic dyes, and dissolved organic matter, shedding light on their potential ramifications for both the environment and human health. Metal oxides, ubiquitous in industrial processes and consumer products, are known to leach into water bodies, posing a significant threat to aquatic ecosystems. Additionally, synthetic dyes, extensively used in various industries, can persist in water systems and exhibit complex chemical behavior. This review provides a comprehensive examination of the toxicity associated with metal oxides, synthetic dyes, and dissolved organic matter in water systems. We delve into the sources and environmental fate of these contaminants, highlighting their prevalence in natural water bodies and wastewater effluents. The study highlights the multifaceted impacts of them on human health and aquatic ecosystems, encompassing effects on microbial communities, aquatic flora and fauna, and the overall ecological balance. The novelty of this review lies in its unique presentation, focusing on the toxicity of metal oxides, dyes, and dissolved organic matter. This approach aims to facilitate the accessibility of results for readers, providing a streamlined and clear understanding of the reported findings.