Adverse effects of gestational exposure to hexafluoropropylene oxide trimer acid (HFPO-TA) homologs on maternal, fetal, and placental health in mice

Homologues of PFOA substitutes in a semi-closed bay near source region: contamination status and risk assessments

Laizhou Bay (LZB) is heavily polluted by perfluoroalkyl substances (PFAS), especially perfluorooctanoic acid (PFOA), from the nearby industrial emission. PFOA has been subjected to strict control, leading to the increasing use of PFOA substitutes. However, the present pollution status of PFOA substitutes in the LZB area is unclear. In this study, 14 legacy and 18 emerging perfluoroalkyl substances (PFAS) in surface water and sediment samples from LZB area were investigated. Two homologues of hexafluoropropylene oxide trimer acid (HFPO-TrA (C7 and C8)) were first identified in LZB area. The results revealed that emerging PFAS have overtaken legacy PFAS as the major PFAS contaminants in seawater. Legacy PFAS constituted only ∼13-47 % of the total PFAS concentration (∑PFAS) in the seawater and ∼ 37-68 % of the ∑PFAS in the sediment. PFOA was found to be the major legacy PFAS in both seawater and sediment. Among the emerging PFAS, two series of perfluoropolyether carboxylic acid (PFECA) homologues accounted for 86-97 % of the total emerging PFAS in seawater and 57-96 % of the total emerging PFAS in sediment. The major source of PFAS was point source from the Xiaoqing River for the inner bay area, whereas the outer bay area may receive external input from the Bohai Sea. Although environmental risks were low for legacy PFAS, HFPO homologues as a whole may present high risks in a large area by an optimistic evaluation method. This highlights the urgent research needed for emerging PFAS - especially those PFOA substitutes - in the LZB area.

Maximum concentration level for groundwater (MCLgw) and soil control value to protect groundwater (CVSpgw) of hexafluoropropylene oxide trimer acid (HFPO-TA)

As a widely used alternative to the conventional per- and polyfluoroalkyl substances (PFAS) of perfluorooctanoic acid (PFOA), hexafluoropropylene oxide trimer acid (HFPO-TA) is of growing concern due to its toxicity and potential risks to human health. Water quality criteria of HFPO-TA for protecting human health were established, and 412 ng/L was set as the maximum concentration level for groundwater (MCLgw) to calculate the soil control value to protect groundwater (CVSpgw). Utilizing recommended default values for the properties of HFPO-TA and the soil, the generic CVSpgw value of 24.0 μg/kg was obtained. Subsequently, column experiments were conducted to investigate the transport of HFPO-TA in the site soil of a fluorochemical industrial park (FIP) in China. The resulted retardation factor (R) was applied to derive the site-specific CVSpgw, and a value of 2.48 μg/kg was obtained. Using the experimentally measured R instead of the default empirical values reduced the uncertainties in deriving the CVSpgw dramatically. The transport of 13 PFAS in the soil as a mixture was investigated and revealing a significant linear correlation between R and organic carbon-water partition coefficient (KOC) (r2 = 0.991, p < 0.01), which was utilized to predicted R values for PFAS compounds. Comparison to the site-specific CVSpgw, HFPO-TA in the soil near the FIP may pose a risk to the groundwater quality. HFPO-TA concentrations in the groundwater of certain areas around the FIP were higher than MCLgw and not recommended for directly consumption, while HFPO-TA in the tap water was at the safe level.

Impacts of hexafluoropropylene oxide tetrameric acid (HFPO-TeA) on neurodevelopment and GABAergic signaling in zebrafish larvae

Hexafluoropropylene oxide oligomer acids (HFPOs), an emerging environmental pollutant, are increasingly utilized in the manufacture of fluorinated synthetic materials as a substitute for traditional perfluorooctanoic acid (PFOA), resulting in a corresponding rise in detection rates in aquatic environments, which may present inherent safety hazards to ecosystems and public health. However, few data are available on the issue of their toxicity and mechanism. This study aimed to investigate the potential toxic effects of hexafluoroepoxypropane tetrameric acid (HFPO-TeA), a typical HFPO, on the early developmental stages of zebrafish larvae. It revealed that HFPO-TeA exposure resulted in significant detrimental effects, including adverse impacts on general morphological characteristics, such as eye area, heart rate, and swimming bladder, in zebrafish embryos and larvae. Targeted metabolomics and transcriptomics inquiries clarified that HFPO-TeA exposure reduced the levels of the neurotransmitter gamma-aminobutyric acid (GABA) and downregulated the expression of genes related to the GABA pathway. Simultaneously, transgenic zebrafish exhibited that exposure to HFPO-TeA impedes the growth of GABAergic neurons. Moreover, the molecular docking analysis indicated that GABAA receptors might be the potential targets of HFPO-TeA. Taken together, the current data highlights that the HFPO-TeA might not be safe alternatives to PFOA. This study presented a model for HFPO-TeA-induced neurotoxicity in developing zebrafish that can aid in ecological risk assessments.

Per- and polyfluoroalkyl substances (PFAS) and hypertensive disorders of Pregnancy- integration of epidemiological and mechanistic evidence

BACKGROUND

Hypertensive disorders of pregnancy (HDP) remain a significant global health burden despite medical advancements. HDP prevalence appears to be rising, leading to increased maternal and fetal complications, mortality, and substantial healthcare costs. The etiology of HDP are complex and multifaceted, influenced by factors like nutrition, obesity, stress, metabolic disorders, and genetics. Emerging evidence suggests environmental pollutants, particularly Per- and polyfluoroalkyl substances (PFAS), may contribute to HDP development.

OBJECTIVE

This review integrates epidemiological and mechanistic data to explore the intricate relationship between PFAS exposure and HDP.

EPIDEMIOLOGICAL EVIDENCE

Studies show varying degrees of association between PFAS exposure and HDP, with some demonstrating positive correlations, particularly with preeclampsia. Meta-analyses suggest potential fetal sex-specific differences in these associations.

MECHANISTIC INSIGHTS

Mechanistically, PFAS exposure appears to disrupt vascular hemodynamics, placental development, and critical processes like angiogenesis and sex steroid regulation. Experimental studies reveal alterations in the renin-angiotensin system, trophoblast invasion, oxidative stress, inflammation, and hormonal dysregulation - all of which contribute to HDP pathogenesis. Elucidating these mechanisms is crucial for developing preventive strategies.

THERAPEUTIC POTENTIAL

Targeted interventions such as AT2R agonists, caspase inhibitors, and modulation of specific microRNAs show promise in mitigating adverse outcomes associated with PFAS exposure during pregnancy.

KNOWLEDGE GAPS AND FUTURE DIRECTIONS

Further research is needed to comprehensively understand the full spectrum of PFAS-induced placental alterations and their long-term implications for maternal and fetal health. This knowledge will be instrumental in developing effective preventive and therapeutic strategies for HDP in a changing environmental landscape.

Unveiling Priority Emerging PFAS in Taihu Lake Using Integrated Nontarget Screening, Target Analysis, and Risk Characterization

Amidst tightening regulations, the proliferation of next-generation per- and polyfluoroalkyl substances (PFAS) necessitates a deeper understanding of their environmental fate and potential risks. Here, we conducted a comprehensive assessment of PFAS in the water and sediment of Taihu Lake, incorporating both nontarget and target screening, seasonal and geographical variation analysis, and risk prioritization. A total of 58 PFAS from 13 classes were identified, revealing complex PFAS contamination. In addition to short-chain perfluoroalkyl carboxylates (PFCAs) and sulfonates (PFSAs), bis(trifluoromethanesulfonyl)imide (Ntf2) and perfluoro-2,5-dimethyl-3,6-dioxo-heptanoic acid (C7 HFPO-TA) exhibited relatively high concentrations in water, with median values of 21.7 and 5.72 ng/L, respectively. Seasonal and geographical variation analysis revealed elevated levels of C7 HFPO-TA, Ntf2, and perfluorohexanoic acid (PFHxA) in the northeastern areas, suggesting transport via water diversion project. Multicriteria risk prioritization identified four high priority PFAS (Ntf2, C7 HFPO-TA, PFHxA, and perfluorooctanoic acid (PFOA)) in water and two high priority PFAS (hexafluoropropylene oxide dimer acid (HFPO-DA) and PFHxA) in sediment. Overall, this study revealed Ntf2 and C7 HFPO-TA as priority PFAS in Taihu Lake, underscoring the urgent necessity of evaluating risks associated with these emerging PFAS.

Differential impact of perfluorooctanoic acid and fluorotelomer ethoxylates on placental metabolism in mice

Poly- and perfluoroalkyl substances (PFAS) are a group of compounds with uses in industry and many consumer products. Concerns about the potential health effects of these compounds resulted in regulation by the Stockholm Convention on the use of three of the most common PFAS, including perfluorooctanoic acid (PFOA). Thousands of PFAS remain in production that are unregulated and for which their toxicity is unknown. Our group recently identified a new class of PFAS, fluorotelomer ethoxylates (FTEOs), in indoor dust and industrial wastewater. In this study, we investigated the effect of PFAS on placental metabolism by exposing healthy, pregnant CD-1 mice to PFOA or FTEOs at one of three concentrations (0 ng/L (controls), 5 ng/L, 100 ng/L) (n = 7-8/group). While PFOA is banned and PFOA concentrations in human blood are decreasing, we hypothesize that FTEOs will cause adverse pregnancy outcomes similar to PFOA, the compounds they were meant to replace. Placental tissue samples were collected at embryonic day 17.5 and 1H solid-state magic angle spinning nuclear magnetic resonance spectroscopy was used to determine the relative concentration of placental metabolites (n = 18-20/group). At the highest concentration, the relative concentrations of glucose and threonine were increased and the relative concentration of creatine was decreased in the PFOA-exposed placentas compared to controls (p < 0.05). In contrast, the relative concentrations of asparagine and lysine were decreased and the relative concentration of creatine was increased in the FTEOs-exposed placentas compared to controls (p < 0.05). Partial least squares - discriminant analysis showed the FTEOs-exposed and control groups were significantly separated (p < 0.005) and pathway analysis found four biochemical pathways were perturbed following PFOA exposure, while one pathway was altered following FTEOs exposure. Maternal exposure to PFOA and FTEOs had a significant impact on the placental metabolome, with the effect depending on the pollutant. This work motivates further studies to determine exposure levels and evaluate associations with adverse outcomes in human pregnancies.

Impact of Gestational Exposure to Individual and Combined Per- and Polyfluoroalkyl Substances on a Placental Structure and Efficiency: Findings from the Ma'anshan Birth Cohort

Prenatal exposure to perfluoroalkyl and polyfluoroalkyl substances (PFASs) is inevitable among pregnant women. Nevertheless, there is a scarcity of research investigating the connections between prenatal PFAS exposure and the placental structure and efficiency. Based on 712 maternal-fetal dyads in the Ma'anshan Birth Cohort, we analyzed associations between individual and mixed PFAS exposure and placental measures. We repeatedly measured 12 PFAS in the maternal serum during pregnancy. Placental weight, scaling exponent, chorionic disc area, and disc eccentricity were used as the outcome variables. Upon adjusting for confounders and implementing corrections for multiple comparisons, we identified positive associations between branched perfluorohexane sulfonate (br-PFHxS) and 6:2 chlorinated polyfluorinated ether sulfonate (6:2 Cl-PFESA) with placental weight. Additionally, a positive association was observed between br-PFHxS and the scaling exponent, where a higher scaling exponent signified reduced placental efficiency. Based on neonatal sex stratification, female infants were found to be more susceptible to the adverse effects of PFAS exposure. Mixed exposure modeling revealed that mixed PFAS exposure was positively associated with placental weight and scaling exponent, particularly during the second and third trimesters. Furthermore, br-PFHxS and 6:2 Cl-PFESA played major roles in the placental measures. This study provides the first epidemiological evidence of the relationship between prenatal PFAS exposure and placental measures.