Exploring maternal and developmental toxicity of perfluoroalkyl ether acids PFO4DA and PFO5DoA using hepatic transcriptomics and serum metabolomics

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.

Polystyrene nanoplastics amplify the toxic effects of PFOA on the Chinese mitten crab (Eriocheir sinensis)

Nanoplastics (NPs), the final form of degraded microplastics in the environment, can adsorb PFOA (an emerging organic pollutant in recent years) in several ways. Current research on these has focused on bony fishes and mollusks, however, the combined toxicity of PFOA and NPs remains unknown in Eriocheir sinensis. Therefore, the effects of single or combined exposure to PFOA and NPs were investigated. The results showed that NPs aggravated PFOA exposure-induced oxidative stress, serum lipid disorders, immune responses, and morphological damage. DEGs altered by NPs-PFOA exposure were predominantly enriched in GO terms for cell lumen, and organelle structure, and KEGG terms for spliceosome and endocrine disorders-related diseases. Notably, the apoptotic pathway plays a central role enriched under different exposure modes. PFOA or NPs-PFOA exposure disrupted the levels of lipids molecules-related metabolites by mediating the glycerophospholipid pathway, and the NPs mediated the ferroptosis pathway to exacerbate PFOA-induced metabolic toxicity. In addition, NPs exacerbated the inflammatory response and metabolic imbalance by mediating Fusobacterium ulcerans in the intestinal. In conclusion, this study provides a valuable reference for the characterization of NPs-PFOA combined pollution and a scientific basis for the development of environmental protection policies and pollution management strategies.

Per- and Polyfluoroalkyl Ether Acid (PFEA) Concentrations in Indoor Dust are Higher in Homes Closer to a Fluorochemical Manufacturing Facility

Concentrations of 48 per- and polyfluoroalkyl substances (PFAS) were measured in settled dust samples from 65 homes of GenX Exposure Study participants residing near a fluorochemical manufacturing facility in North Carolina. Eight PFAS [perfluoro(3,5-dioxahexanoic) acid (aka PFO2HxA), perfluoro-2-(perfluoromethoxy)propanoic acid (PMPA), perfluoro-2-ethoxypropanoic acid (PEPA), 6:2 fluorotelomer phosphate diester (6:2 diPAP), 6:2/8:2 fluorotelomer phosphate diester (6:2/8:2 diPAP), perfluoropropanoic acid (PFPrA), perfluorodecanesulfonic acid (PFDS), and 2-(N-ethyl-perfluorooctanesulfonamido)acetic acid (N-EtFOSAA)] were detected in >90% of the dust samples. Dust concentrations of six per- and polyfluoroalkyl ether acids (PFEAs) produced at the facility (PEPA, PMPA, perfluoro-2-methoxyacetic acid (PFMOAA), PFO2HxA, hexafluoropropylene oxide dimer acid (HFPO-DA aka GenX), and ethanesulfonic acid, 2-[1-[difluoro(1,2,2,2-tetrafluoroethoxy)methyl]-1,2,2,2- tetrafluoroethoxy]-1,1,2,2-tetrafluoro- (Nafion byproduct 2) were significantly negatively associated with home distance from the facility. Homes closer to the facility had higher summed mass concentrations of 12 targeted PFEAs (∑ 12 PFEAs ) but not higher ∑ 48 PFAS . Trifluoroacetic acid (TFA), an ultrashort chain PFAS, and three diPAPs (8:2/6:2 diPAP, 6:2 diPAP, and 8:2 diPAP) were the major contributors to ∑ 48 PFAS , and these compounds did not show relationships with distance. Based on our previous findings associating PFEAs in well water and human serum, our current findings indicate dust could be an important PFAS exposure source.

Synthesis and Characterization of a Series of Biofriendly Fluoroether Betaines

Fluoroether approach has been extensively employed as an alternative to conventional fluorinated surfactants; however, it faces challenges such as inadequate performance of short fluoroether chains and environmental contamination from long fluoroether chains. This study aims to address the conflict between environmental compatibility and the performance of fluoroether surfactants. The design of the surfactants is centered around the OC chain (CF3(OCF2)n-), utilizing reduced fluorine content to achieve superior surface activity. A series of surfactant molecules featuring elongated hydrophobic chains and dual-chain structures have been synthesized and characterized. All of the molecules have good surface activity at low concentrations. Among them, CF3(OCF2)4CH2O(CH2)3SO2NH(CH2)3N+(CH3)2CH2COO- (OC4F-B), which employs a strategy of extending the hydrophobic chain by insertion of -CH2O(CH2)3-, shows the best performance. This surfactant can achieve a surface tension of 20 mN/m at a concentration of 0.005 wt %, which is 20 times lower than that required for CF3(OCF2)4CONH(CH2)3N+(CH3)2CH2COO- (OC4-betaine) to attain the same surface tension. In contrast, (CF3(OCF2)3CH2O(CH2)3SO2NHCH2CH2)2N+(CH3)CH2COO- (DOC3F-B), utilizing both dual-chain and extended carbon chain strategies, exhibits a critical micelle concentration that is diminished by 2 orders of magnitude relative to OC3-betaine, reaching to 0.047 g/L. Merely adjusting the length of the fluorocarbon chain is insufficient to reconcile the conflict between the performance and environmental impact of fluorinated surfactants. This study introduces an innovative approach by incorporating hydrocarbon hydrophobic chains and adopting a dual-chain design, thereby addressing this challenge effectively.

Emerging per- and polyfluoroalkyl substance perfluoro-(3,5,7,9-tetraoxadecanoic) acid (PFO4DA) impairs steroidogenesis and spermatogenesis by suppressing StAR and CYP11A1 expression in mice

Perfluoroalkyl ether carboxylic acids (PFECA) represent an important group of emerging per- and polyfluoroalkyl substances (PFAS). PFECA have been found in a variety of environmental matrices. While legacy PFAS have been extensively documented for their reproductive toxicity, the health implications of emerging alternatives like PFECA remains unclear. The present study is aimed at investigating the potential reproductive toxicity of perfluoro-(3,5,7,9-tetraoxadecanoic) acid (PFO4DA), a type of PFECA, through combining in vivo and in vitro assays. Adult male BALB/c mice were exposed to 2 and 10 mg/kg body-weight/day of PFO4DA via oral gavage for four consecutive weeks. While no overt structural or morphological changes were observed in the testes following PFO4DA exposure, significant reductions in both sperm quantity and quality were evident, correlating with increased PFO4DA dosage. PFO4DA exposure compromised the integrity of the blood-testis barrier (BTB) and led to a moderate decrease in BTB-associated junction proteins, including Connexin-43 and Claudin-11. Notably, PFO4DA disrupted androgen production, resulting in a significant reduction in testosterone (T) levels (> 60 %) in both serum and testicular tissue. Mechanistic analysis revealed that PFO4DA significantly repressed the expression levels of steroidogenic genes StAR and CYP11A1 both in testes and in cultured Leydig cells (TM3). These findings suggest that PFO4DA primarily targets the steroidogenic pathway in Leydig cells by suppressing StAR and CYP11A1, thereby inhibiting T synthesis. The subsequent T deficiency impairs Sertoli cell function and BTB integrity, ultimately disrupting spermatogenesis and impacting male reproductive health.

Long-chain perfluoroalkylether carboxylic acids PFO5DoA and PFO4DA alter glucose, bile acid, and thyroid hormone homeostasis in fetal rats from 5-day maternal oral exposure

Chemical monitoring studies in North Carolina, USA and Shandong, China have reported detections of perfluoroalkylether carboxylic acids of increasing chain length with ether bonds between each fluorinated carbon. Despite detection there is limited hazard data available to inform risk assessment. Here, we exposed pregnant Sprague-Dawley rats to two of these compounds, perfluoro-3,5,7,9-butaoxadecanoic acid (PFO4DA) and perfluoro-3,5,7,9,11-pentaoxadodecanoic acid (PFO5DoA), from gestation days 18-22 across a series of doses (0.3-62.5 mg/kg/d) via oral gavage. PFO5DoA was acutely toxic to rat dams and fetuses at the top two doses (30 and 62.5 mg/kg), while PFO4DA did not cause acute toxicity at any doses tested. PFO5DoA significantly increased maternal liver weight (≥3 mg/kg; 28% increase at 10 mg/kg) while PFO4DA did not affect maternal liver weight up to 62.5 mg/kg. PFO4DA and PFO5DoA both significantly reduced serum total thyroxine in maternal (≥10 mg/kg for both) and fetal (≥1 mg/kg) rats. Both compounds significantly reduced fetal liver glycogen concentrations, increased fetal serum total bile acids, and altered expression levels of multiple genes associated with glucose metabolism in the fetal liver. Serum concentrations of PFO5DoA were higher than PFO4DA in both rat dams and fetuses at equivalent maternal oral doses indicating greater accumulation. Dose response modelling of several fetal endpoints as a function of serum molar concentration indicates PFO5DoA was ∼3-4-fold more potent than PFO4DA. PFO5DoA and PFO4DA produced maternal and fetal toxicity from short-term oral maternal exposure indicating need for additional toxicity data to evaluate potential human health risks.