6:2 Chlorinated polyfluorinated ether sulfonate, a PFOS alternative, induces embryotoxicity and disrupts cardiac development in zebrafish embryos

Rethinking alternatives to fluorinated pops in aqueous environment and corresponding destructive treatment strategies

Alternatives are being developed to replace fluorinated persistent organic pollutants (POPs) listed in the Stockholm Convention, bypass environmental regulations, and overcome environmental risks. However, the extensive usage of fluorinated POPs alternatives has revealed potential risks such as high exposure levels, long-range transport properties, and physiological toxicity. Therefore, it is imperative to rethink the alternatives and their treatment technologies. This review aims to consider the existing destructive technologies for completely eliminating fluorinated POPs alternatives from the earth based on the updated classification and risks overview. Herein, the types of common alternatives were renewed and categorized, and their risks to the environment and organisms were concluded. The efficiency, effectiveness, energy utilization, sustainability, and cost of various degradation technologies in the treatment of fluorinated POPs alternatives were reviewed and evaluated. Meanwhile, the reaction mechanisms of different fluorinated POPs alternatives are systematically generalized, and the correlation between the structure of alternatives and the degradation characteristics was discussed, providing mechanistic insights for their removal from the environment. Overall, the review supplies a theoretical foundation and reference for the control and treatment of fluorinated POPs alternatives pollution.

Impact of the novel chlorinated polyfluorinated ether sulfonate, F-53B, on gill structure and reproductive toxicity in zebrafish

6:2 Chlorinated polyfluorinated ether sulfonate, commonly known as F-53B, is widely used as a mist suppressant in various industries and is frequently detected in the environment. Despite its prevalent presence, the adverse effects of F-53B are not well understood and require future investigation. This study utilized zebrafish embryos and adults to examine the toxic effects of F-53B. Our findings revealed that F-53B impaired gill structure and increased erythrocyte numbers in adult zebrafish. Notably, F-53B demonstrated a higher sensitivity for inducing mortality (LC50 at 96 h) in adult zebrafish compared to embryos. Additionally, F-53B disrupted the expression of critical steroidogenic genes and hindered sex hormone production, which negatively affecting egg production. In conclusion, this study underscores the detrimental impact of F-53B on gill structure and reproductive toxicity in zebrafish, providing valuable insights into its overall toxicity.

Distribution and ecological risk assessment of perfluoroalkyl carboxylic acids (PFCAs) in the coastal river, China

Perfluoroalkyl carboxylic acids (PFCAs) enter surface waters through wastewater discharge and atmospheric deposition, accumulating within aquatic ecosystems and organisms, causing dysfunction or mortality. This study investigates the migration, sources and ecological risks of six PFCAs in the coastal Wulong River basin and the estuary along the eastern coast of China. The six PFCAs detected in the Wulong River included, at concentrations ranging from 17.36 to 57.92 ng/L. The distribution of PFCAs concentrations throughout the estuary were as follows: Northeast China (414.07 ng/L) > North China (325.97 ng/L) > East China (249.53 ng/L) > South China (63.61 ng/L), with perfluorooctanoic acid (PFOA) being the dominant PFCA. Toxicity data was collected for all detected PFCAs and the species sensitivity distribution (SSD) method was used to derive the predicted no effect concentrations (PNECs) for all six PFCAs. The risk quotient (RQ) method showed that the risk posed to aquatic organisms in the river basin from all six PFCAs was relatively low (RQ < 1). However, joint probability curve (JPC) analysis revealed that the probability of perfluoropentanoic acid (PFPeA) causing harm to 5% of aquatic species reached 41.13%. Considering the frequency of occurrence and persistence of PFCAs in aquatic environments, these findings indicate they have the potential to induce serious toxic effects on aquatic organisms.

Legacy and alternative per- and polyfluoroalkyl substances spatiotemporal distribution in China: Human exposure, environmental media, and risk assessment

In recent decades, China's rapid development has led to significant environmental pollution from the widespread use of chemical products. Per- and polyfluoroalkyl substances (PFAS) are among the most concerning pollutants due to their persistence and bioaccumulation. This article assesses PFAS exposure levels, distribution, and health risks in Chinese blood, environment, and food. Out of 4037 papers retrieved from November 2022 to December 31, 2023, 351 articles met the criteria. Findings show perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) as the main PFAS in both Chinese populations and the environment. The highest PFOA levels in Chinese populations were in Shandong (53.868 ng/mL), while Hubei had the highest PFOS levels (43.874 ng/mL). Similarly, water samples from Sichuan (2115.204 ng/L) and Jiangsu (368.134 ng/L) had the highest PFOA and PFOS levels, respectively. Although localized areas showed high PFAS concentrations. Additionally, developed areas had higher PFAS contamination. The researches conducted in areas such as Qinghai and Hainan remain limited, underscoring the imperative for further investigation. Temporal analysis indicates declining levels of some PFAS, but emerging alternatives require more research. Limited studies on PFAS concentrations in soil, atmosphere, and food emphasize the need for comprehensive research to mitigate human exposure.

Emergency of per- and polyfluoroalkyl substances in drinking water: Status, regulation, and mitigation strategies in developing countries

The detection of per- and polyfluoroalkyl substances (PFAS) in water presents a significant challenge for developing countries, requiring urgent attention. This review focuses on understanding the emergence of PFAS in drinking water, health concerns, and removal strategies for PFAS in water systems in developing countries. This review indicates the need for more studies to be conducted in many developing nations due to limited information on the environmental status and fate of PFAS. The health consequences of PFAS in water are enormous and cannot be overemphasized. Efforts are ongoing to legislate a national standard for PFAS in drinking water. Currently, there are few known mitigation efforts from African countries, in contrast to several developing nations in Asia. Therefore, there is an urgent need to develop economically viable techniques that could be integrated into large-scale operations to remove PFAS from water systems in the region. However, despite the success achieved with removing long-chain PFAS from water, more studies are required on strategies for eliminating short-chain moieties in water.

Tissue distribution of emerging per- and polyfluoroalkyl substances in wild fish species from Qiantang river, east China: Comparison of 6:2 Cl-PFESA with PFOS

This study argued for the first time that 6:2 chlorinated polyfluorinated ether sulfonate (6:2 Cl-PFESA) and perfluorooctanesulfonic acid (PFOS) might have different tissue distribution mechanisms in wild fish species. Nine emerging and legacy per- and polyfluoroalkyl substances (PFASs) were detected in the water and wild fish tissues samples collected from the Qiantang River. Perfluorooctanoic acid (213 ng/L) was the predominant PFAS contaminant, and the other contaminants included perfluorohexanoate (19 ng/L), perfluorobutanoate (199 ng/L) and hexafuoropropylene oxide dimer acid (55 ng/L), which are the main fluorinated alternatives used in various industries located along the Qiantang River. Furthermore, PFOS (742 ng/g) and 6:2 Cl-PFESA (9.0 ng/g) were the predominant PFAS contaminants detected in the fish tissue samples. The differences in the potential molecular mechanism of the tissue distribution of PFOS and 6:2 Cl-PFESA in wild fish species are discussed. Additionally, we hypothesize that phospholipid partitioning is the primary mechanism underlying the tissue distribution of PFOS, and that a specific protein-binding mechanism is involved in the tissue distribution of 6:2 Cl-PFESA.

Maternal F-53B exposure during pregnancy and lactation affects bone growth and development in male offspring

6:2 Chlorinated polyfluoroalkyl ether sulfonate (F-53B) is a new type of perfluorinated and polyfluoroalkyl substance (PFAS) that is used extensively in industry and manufacturing. F-53B causes damage to multiple mammalian organs. However, the impacts of F-53B on bone are unknown. Maternal exposure to F-53B is of particular concern because of the vulnerability of the developing fetus and newborn to contaminants from the mother. The goal of this study was to examine the impacts of maternal F-53B exposure on bone growth and development in offspring and to explore its underlying mechanisms. Herein, C57BL/6 J mice were given free access to deionized water containing 0, 0.57, or 5.7 mg/L F-53B during pregnancy and lactation. F-53B exposure resulted in impaired liver function, decreased IGF-1 secretion, dysregulation of bone metabolism and disruption of the dynamic balance between osteoblasts and osteoclasts in male offspring. F-53B inhibits longitudinal bone growth and development and causes osteoporosis in male offspring. F-53B may affect the growth and development of offspring bone via the IGF-1/OPG/RANKL/CTSK signaling pathway. This study provides new insights for the study of short stature and bone injury caused by F-53B.

Prenatal exposure to poly/perfluoroalkyl substances and risk for congenital heart disease in offspring

Congenital heart disease (CHD) is the most prevalent congenital malformation worldwide, and the association between per- and polyfluoroalkyl substances (PFASs) exposure and CHD in population has only received limited study. Therefore, we conducted a multicenter case-control study to explore the associations between prenatal exposure to individual PFASs, and also a PFAS mixture, and CHD risk, including 185 CHDs and 247 controls in China from 2016 to 2021. Thirteen PFASs in maternal plasma were quantified using liquid chromatography-tandem mass spectrometry. Logistic regression and two multipollutant models (Bayesian kernel machine regression [BKMR] and quantile g-computation [qgcomp]) were used to assess the potential associations between any individual PFAS, and also a PFAS mixture, and CHD risk. After adjusting for potential confounders, logistic regression indicated significant associations between elevated levels of perfluorononanoic acid (odds ratio [OR]= 1.30, 95% confidence intervals [CI]: 1.07-1.58), perfluorodecanoic acid (OR=2.07, 95%CI: 1.32-3.26), and perfluoroundecanoic acid (OR=2.86, 95%CI:1.45-5.65) and CHD risk. The BKMR model and qgcomp approach identified that a significant positive association between the PFAS mixture and risk for CHD. These findings provide essential evidence that there is indeed a health crisis associated with PFASs and that it is linked to CHD.

Angiotoxic effects of chlorinated polyfluorinated ether sulfonate, a novel perfluorooctane sulfonate substitute, in vivo and in vitro

Chlorinated polyfluorinated ether sulfonate (Cl-PFESA), a substitute for perfluorooctane sulfonate (PFOS), has been widely used in the Chinese electroplating industry under the trade name F-53B. The production and use of F-53B is keep increasing in recent years, consequently causing more emissions into the environment. Thus, there is a growing concern about the adverse effects of F-53B on human health. However, related research is very limited, particularly in terms of its toxicity to the vascular system. In this study, C57BL/6 J mice were exposed to 0.04, 0.2, and 1 mg/kg F-53B for 12 weeks to assess its impact on the vascular system. We found that F-53B exposure caused aortic wall thickening, collagen deposition, and reduced elasticity in mice. In addition, F-53B exposure led to a loss of vascular endothelial integrity and a vascular inflammatory response. Intercellular cell adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) were found to be indispensable for this process. Furthermore, RNA sequencing analysis revealed that F-53B can decrease the repair capacity of endothelial cells by inhibiting their proliferation and migration. Collectively, our findings demonstrate that F-53B exposure induces vascular inflammation and loss of endothelial integrity as well as suppresses the repair capacity of endothelial cells, which ultimately results in vascular injury, highlighting the need for a more thorough risk assessment of F-53B to human health.

Hepatotoxicity induced in rats by chronic exposure to F-53B, an emerging replacement of perfluorooctane sulfonate (PFOS)

A plethora of studies have shown the prominent hepatotoxicity caused by perfluorooctane sulfonate (PFOS), yet the research on the causality of F-53 B (an alternative for PFOS) exposure and liver toxicity, especially in mammals, is largely limited. To investigate the effects that chronic exposure to F-53 B exert on livers, in the present study, male SD rats were administrated with F-53 B in a certain dose range (0, 1, 10, 100, 1000 μg/L, eight rats per group) for 6 months via drinking water and the hepatotoxicity resulted in was explored. We reported that chronic exposure to 100 and 1000 μg/L F-53 B induced remarkable histopathological changes in liver tissues such as distinct swollen cells and portal vein congestion. In addition, the increase of cytokines IL-6, IL-2, and IL-8 upon long-term administration of F-53 B demonstrated the high level of inflammation. Moreover, F-53 B exposure was revealed to disrupt the lipid metabolism in the rat livers, mainly manifesting as the upregulation of some proteins involved in lipid synthesis and degradation, including ACC, FASN, SREBP-1c as well as ACOX1. These findings provided new evidence for the adverse effects caused by chronic exposure to F-53 B in rodents. It is crucial for industries, regulatory agencies as well as the public to remain vigilant about the adverse health effects associated with the emerging PFOS substitutes such as F-53 B. Implementation of regular monitoring and risk assessments is of great importance to alleviate environmental concerns towards PFOS alternatives exposure, and furthermore, to minimize the latent health risks to the public health.

Environmental pollutant sodium omadine: toxic effects in zebra fish (Danio rerio)

In recent years one of the most striking results of over-population and consumption activities in the world is the rapid increase in environmental pollutants. Environmental pollutants, one of the harmful consequences of technological and modern life, threaten the health of people and other living organisms. In this study, we aimed to determine the effects of sodium omadine (NaOM) on superoxide dismutase enzyme (SOD) activity as an antioxidant and on 8-OHdG levels as oxidative DNA damage in zebrafish. Zebrafish, obtained from the aquarium fish producer, were stocked in experimental aquariums to ensure their adaptation period to the experimental conditions 15 days before the experiment. The fish were exposed to 1 ug/L and 5 ug/L concentrations of NaOM for 24, 72, and 96 h. SOD enzyme activity (U/100 mg tissue) and 8-OHdG (pg/100 mg tissue) were measured using commercial kits. The statistically significant differences in tissue SOD levels and data for DNA damage between the groups were determined as time and dose-dependent (p < 0.05). Biocidal products are environmental pollutants that cause changes in antioxidant enzyme activities, especially in non-target organisms. Marine pollution and the degradation of ecosystems directly affect people, and the results of the study offer awareness of health problems, environmental pollution, and marine pollution.

Legacy and alternative per-and polyfluoroalkyl substances (PFASs) in the Bohai Bay Rim: Occurrence, partitioning behavior, risk assessment, and emission scenario analysis

The use of alternative per- and polyfluoroalkyl substances (PFASs) has been practiced because of the restrictions on legacy PFASs. However, knowledge gaps exist on the ecological risks of alternatives and relationships between restrictions and emissions. This study systematically analyzed the occurrence characteristics, water-sediment partitioning behaviors, ecological risks, and emissions of legacy and alternative PFASs in the Bohai Bay Rim (BBR). The mean concentration of total PFASs was 46.105 ng/L in surface water and 6.125 ng/g dry weight (dw) in sediments. As an alternative for perfluorooctanoic acid (PFOA), hexafluoropropylene oxide dimer acid (GenX) had a concentration second only to PFOA in surface water. In sediments, perfluorobutyric acid (PFBA) and GenX were the two predominant contaminants. In the water-sediment partitioning system, GenX, 9-chlorohexadecafluoro-3-oxanone-1-sulfonic acid (F-53B), and 11-chloroeicosafluoro-3-oxaundecane-1-sulfonic acid (8:2 Cl-PFESA) tended to be enriched towards sediments. The species sensitivity distribution (SSD) models revealed the low ecological risks of PFASs and their alternatives in the BBR. Moreover, predicted no-effected concentrations (PNECs) indicated that short-chain alternatives like PFBA and perfluorobutane sulfonate (PFBS) were safer for aquatic ecosystems, while caution should be exercised when using GenX and F-53B. Due to the incremental replacement of PFOA by GenX, cumulative emissions of 1317.96 kg PFOA and 667.22 kg GenX were estimated during 2004-2022, in which PFOA emissions were reduced by 59.2 % due to restrictions implemented since 2016. If more stringent restrictions are implemented from 2023 to 2030, PFOA emissions will further decrease by 85.0 %, but GenX emissions will increase by an additional 21.3 %. Simultaneously, GenX concentrations in surface water are forecasted to surge by 2.02 to 2.45 times in 2023. This study deepens the understanding of PFAS alternatives and assists authorities in developing policies to administer PFAS alternatives.

PFOS and F-53B disrupted inner cell mass development in mouse preimplantation embryo

Perfluorooctane sulfonic acid (PFOS) is a perfluoroalkyl and polyfluoroalkyl substance (PFAS) widely used in daily life. As its toxicity was confirmed, it has been gradually substituted by F-53B (chlorinated polyfluoroalkyl sulfonates, Cl-PFESAs) in China. PFOS exposure during prenatal development may hinder the development of preimplantation embryos, as indicated by recent epidemiological research and in vivo assays. However, the embryotoxicity data for F-53B are scarce. Furthermore, knowledge about the toxicity of F-53B and PFOS exposure to internal follicular fluid concentrations on early preimplantation embryo development remains limited. In this study, internal exposure concentrations of PFOS (10 nM) and F-53B (2 nM) in human follicular fluid were chosen to study the effects of PFAS on early mouse preimplantation embryo development. We found that both PFOS and F-53B treated zygotes exhibited higher ROS activity in 8-cell embryos but not in 2-cell stage embryos. PFOS and F-53B significantly affected the proportion and aggregation of the inner cell mass (ICM) in the blastocyst, but not the total cell number. Mouse embryonic stem cells (mESCs, isolated from the ICM) and embryoid body (EB) assays were employed to assess the toxicity of PFOS and F-53B on the development and differentiation of embryonic pluripotent cells. These results suggested that mESCs exhibited more DNA damage and abnormal germ layer differentiation after brief exposure to PFOS or F-53B. Finally, RNA-sequencing revealed that PFOS and F-53B exposure affected mESCs biosynthetic processes and chromatin-nucleosome assembly. Our results indicate that F-53B has potential risks as an alternative to PFOS, which disrupts ICM development and differentiation.

Single-cell RNA sequencing reveals the role of mitochondrial dysfunction in the cardiogenic toxicity of perfluorooctane sulfonate in human embryonic stem cells

Perfluorooctane sulfonate (PFOS), an endocrine-disrupting chemical pollutant, affects embryonic heart development; however, the mechanisms underlying its toxicity have not been fully elucidated. Here, Single-cell RNA sequencing (scRNA-seq) was used to investigate the overall effects of PFOS on myocardial differentiation from human embryonic stem cells (hESCs). Additionally, apoptosis, mitochondrial membrane potential, and ATP assays were performed. Downregulated cardiogenesis-related genes and inhibited cardiac differentiation were observed after PFOS exposure in vitro. The percentages of cardiomyocyte and cardiac progenitor cell clusters decreased significantly following exposure to PFOS, while the proportion of primitive endoderm cell was increased in PFOS group. Moreover, PFOS inhibited myocardial differentiation and blocked cellular development at the early- and middle-stage. A Gene Ontology analysis and pseudo-time trajectory illustrated that PFOS disturbed multiple processes related to cardiogenesis and oxidative phosphorylation in the mitochondria. Furthermore, PFOS decreased mitochondrial membrane potential and induced apoptosis. These results offer meaningful insights into the cardiogenic toxicity of PFOS exposure during heart formation as well as the adverse effects of PFOS on mitochondria.

Structure-Related Thyroid Disrupting Effect of Perfluorooctanesulfonate-like Substances in Zebrafish Larvae

Chlorinated polyfluorooctane ether sulfonate (6:2 Cl-PFESA), hydrogenated polyfluorooctane ether sulfonate (6:2 H-PFESA), and chlorinated polyfluorooctanesulfonate (Cl-PFOS) share structural similarities with the regulated perfluorooctanesulfonate (PFOS), but their toxic potential is rarely known. Here, the thyroid disrupting potential of these four compounds in zebrafish larvae has been comparably investigated. PFOS, Cl-PFOS, and 6:2 Cl-PFESA were accumulated in the larvae at similar levels, approximately 1.3-1.6 times higher than 6:2 H-PFESA. Additionally, PFOS, Cl-PFOS, and 6:2 Cl-PFESA exhibited stronger disruption than 6:2 H-PFESA on genetic regulation, particularly concerning thyroid hormone (TH) activation and action and on TH homeostasis in both free and total forms of thyroxine (T4) and 3,5,3'-triiodothyronine (T3). These results indicate that chlorination or oxygen insertion does not substantially alter the thyrotoxicity of PFOS, but hydrogenation mitigates it. Molecular docking analysis and the luciferase reporter gene assay provided mechanistic perspectives that the PFOS-like substances could competitively replace THs to bind with TH plasma and membrane transporters, thereby disrupting TH transport and action, respectively. Moreover, they are also potent to disrupt TH synthesis and activation through Na+/K+-dependent transport of I- or competitive binding to the sites of deiodinases.

Maternal transfer of F-53B inhibited neurobehavior in zebrafish offspring larvae and potential mechanisms: Dopaminergic dysfunction, eye development defects and disrupted calcium homeostasis

Maternal exposure to environment toxicants is an important risk factor for neurobehavioral health in their offspring. In our study, we investigated the impact of maternal exposure to chlorinated polyfluoroalkyl ether sulfonic acids (Cl-PFESAs, commercial name: F-53B) on behavioral changes and the potential mechanism in the offspring larvae of zebrafish. Adult zebrafish exposed to Cl-PFESAs (0, 0.2, 2, 20 and 200 μg/L) for 21 days were subsequently mated their embryos were cultured for 5 days. Higher concentrations of Cl-PFESAs in zebrafish embryos were observed, along with, reduced swimming speed and distance travelled in the offspring larvae. Molecular docking analysis revealed that Cl-PFESAs can form hydrogen bonds with brain-derived neurotropic factor (BDNF), protein kinase C, alpha, (PKCα), Ca2+-ATPase and Na, K - ATPase. Molecular and biochemical studies evidenced Cl-PFESAs induce dopaminergic dysfunction, eye developmental defects and disrupted Ca2+ homeostasis. Together, our results showed that maternal exposure to Cl-PFESAs lead to behavioral alteration in offspring mediated by disruption in Ca2+ homeostasis, dopaminergic dysfunction and eye developmental defects.

Environmental pollutant pre- and polyfluoroalkyl substances are associated with electrocardiogram parameters disorder in adults

Environmental pollutants exposure might disrupt cardiac function, but evidence about the associations of per- and polyfluoroalkyl substances (PFASs) exposure and cardiac conduction system remains sparse. To explore the associations between serum PFASs exposure and electrocardiogram (ECG) parameters changes in adults, we recruited 1229 participants (mean age: 55.1 years) from communities of Guangzhou, China. 13 serum PFASs with detection rate > 85% were analyzed finally. We selected 6 ECG parameters [heart rate (HR), PR interval, QRS duration, Bazett heart rate-corrected QT interval (QTc), QRS electric axis and RV5 + SV1 voltage] as outcomes. Generalized linear models (GLMs) and Bayesian kernel machine regression (BKMR) model were conducted to explore the associations of individual and joint PFASs exposure and ECG parameters changes, respectively. We detected significant associations of PFASs exposure with decreased HR, QRS duration, but with increased PR interval. For example, at the 95th percentile of 6:2 Cl-PFESA, HR and QRS duration were - 6.98 [95% confidence interval (CI): - 9.07, - 4.90] and - 6.54(95% CI: -9.05, -4.03) lower, but PR interval was 7.35 (95% CI: 3.52, 11.17) longer than those at the 25th percentile. Similarly, significant joint associations were observed in HR, PR interval and QRS duration when analyzed by BKMR model.

Per- and polyfluoroalkyl substances in marine organisms along the coast of China

Per- and polyfluoroalkyl substances (PFASs) are a large and complex class of synthetic chemicals widely used in industrial and domestic products. This study compiled and analyzed the distribution and composition of PFASs in marine organisms sampled along the coast of China from 2002 to 2020. Perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) were dominant in bivalves, cephalopods, crustaceans, bony fish and mammals. PFOA in bivalves, crustaceans, bony fish and mammals gradually decreased from north to south along the coast of China, and the PFOA contents of bivalves and gastropods in the Bohai Sea (BS) and the Yellow Sea (YS) were higher than those of PFOS. The increased production and use of PFOA have been detected by biomonitoring temporal treads in mammals. For the organisms in the East China Sea (ECS) and the South China Sea (SCS), which were less polluted by PFOA compared to BS and YS, PFOS was universally higher than PFOA. The PFOS of mammals with high trophic levels was significantly higher than that of other taxa. This study is conducive to better understanding the monitoring information of PFASs of marine organisms in China and is of great significance for PFAS pollution control and management.

Evaluation of the research trends on perfluorinated compounds using bibliometric analysis: knowledge gap and future perspectives

Detection of perfluorinated compounds (PFCs) in the environment has been a global concern because of the risk they pose due to their endocrine-disruptive properties. This study analyzed the global trends and research productivity of PFCs from 1990 to 2021. A total number of 3256 articles on PFCs were retrieved from the Web of Science focusing on different environmental and biological matrices. An increase in the productivity of research on PFCs was observed during the survey period which indicates that more research and publications on this class of contaminants are expected in the future. Evaluating the most productive countries and the number of citations per country on PFCs research shows that China and the United States of America were ranked in first and second places. It was also observed that research on PFCs received the most attention from scientists in developed countries, with little research emerging from Africa. Hence, research on PFCs in developing countries, especially low-income countries should be promoted. Consequently, more research programs should be implemented to investigate PFCs in countries and regions where research on these contaminants is low. The study will help researchers, government agencies and policymakers to tailor future research, allocation of funds to PFCs research and countries' collaboration.

Development of a Completely New PFOS Alternative with Lower Surface Tension for Minimizing the Environmental Burden

Improving the technical performance of related industrial products is an efficient strategy to reducing the application quantities and environmental burden for toxic chemicals. A novel polyfluoroalkyl surfactant potassium 1,1,2,2,3,3,4,4-octafluoro-4-(perfluorobutoxy)butane-1-sulfonate(F404) was synthesized by a commercializable route. It had a surface tension(γ) of 18.2 mN/m at the critical micelle concentration(CMC, 1.04 g/L), significantly lower than that of perfluorooctane sulfonate(PFOS, ca. 33.0 mN/m, 0.72 g/L), and exhibited remarkable suppression of chromium-fog at a dose half that of PFOS. The half maximal inhibitory concentration(IC50) values in HepG2 cells and the lethal concentration of 50%(LC50) in zebrafish embryos after 72 hpf indicated a lower toxicity for F404 in comparison to PFOS. In a UV/sulphite system, 89.3% of F404 were decomposed after 3 h, representing a defluorination efficiency of 43%. The cleavage of the ether C-O bond during the decomposition would be expected to form a short chain·C4F9 as the position of the ether C-O in the F404 fluorocarbon chains is C4-O5. The ether unit is introduced in the perfluoroalkyl chain to improve water solubility, biocompatibility and degradation, thereby minimizing the environmental burden.

Electronic Supplementary Material

Supplementary material is available in the online version of this article at 10.1007/s40242-023-3030-4.

A review of cardiovascular effects and underlying mechanisms of legacy and emerging per- and polyfluoroalkyl substances (PFAS)

Cardiovascular disease (CVD) poses the leading threats to human health and life, and their occurrence and severity are associated with exposure to environmental pollutants. Per- and polyfluoroalkyl substances (PFAS), a group of widely used industrial chemicals, are characterized by persistence, long-distance migration, bioaccumulation, and toxicity. Some PFAS, particularly perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA) and perfluorohexanesulfonic acid (PFHxS), have been banned, leaving only legacy exposure to the environment and human body, while a number of novel PFAS alternatives have emerged and raised concerns, such as polyfluoroalkyl ether sulfonic and carboxylic acid (PFESA and PFECA) and sodium p-perfluorous nonenoxybenzene sulfonate (OBS). Overall, this review systematically elucidated the adverse cardiovascular (CV) effects of legacy and emerging PFAS, emphasized the dose/concentration-dependent, time-dependent, carbon chain length-dependent, sex-specific, and coexposure effects, and discussed the underlying mechanisms and possible prevention and treatment. Extensive epidemiological and laboratory evidence suggests that accumulated serum levels of legacy PFAS possibly contribute to an increased risk of CVD and its subclinical course, such as cardiac toxicity, vascular disorder, hypertension, and dyslipidemia. The underlying biological mechanisms may include oxidative stress, signaling pathway disturbance, lipid metabolism disturbance, and so on. Various emerging alternatives to PFAS also play increasingly prominent toxic roles in CV outcomes that are milder, similar to, or more severe than legacy PFAS. Future research is recommended to conduct more in-depth CV toxicity assessments of legacy and emerging PFAS and explore more effective surveillance, prevention, and treatment strategies, accordingly.

Sources, occurrence and toxic effects of emerging per- and polyfluoroalkyl substances (PFAS)

Per- and polyfluoroalkyl substances (PFAS) cause potential threats to biota and are persistent and never-ending substances in the environment. Regulations and ban on legacy PFAS by various global organizations and national level regulatory agencies had shifted the fluorochemical production to emerging PFAS and fluorinated alternatives. Emerging PFAS are mobile and more persistent in aquatic systems, posing potential greater threats to human and environmental health. Emerging PFAS have been found in aquatic animals, rivers, food products, aqueous film-forming foams, sediments, and a variety of other ecological media. This review summarizes the physicochemical properties, sources, occurrence in biota and the environment, and toxicity of the emerging PFAS. Fluorinated and non-fluorinated alternatives for several industrial applications and consumer goods as the replacement of historical PFAS are also discussed in the review. Fluorochemical production plants and wastewater treatment plants are the main sources of emerging PFAS to various environmental matrices. Information and research are scarcely available on the sources, existence, transport, fate, and toxic effects of emerging PFAS to date.

Emerging and Legacy Perfluoroalkyl Substances in Breastfed Chinese Infants: Renal Clearance, Body Burden, and Implications

BACKGROUND

Human breast milk is a primary route of exposure to perfluoroalkyl substances (PFAS) in infants. To understand the associated risks, the occurrence of PFAS in human milk and the toxicokinetics of PFAS in infants need to be addressed.

OBJECTIVES

We determined levels of emerging and legacy PFAS in human milk and urine samples from Chinese breastfed infants, estimated renal clearance, and predicted infant serum PFAS levels.

METHODS

In total, human milk samples were collected from 1,151 lactating mothers in 21 cities in China. In addition, 80 paired infant cord blood and urine samples were obtained from two cities. Nine emerging PFAS and 13 legacy PFAS were analyzed in the samples using ultra high-performance liquid chromatography tandem mass spectrometry. Renal clearance rates (CLrenals) of PFAS were estimated in the paired samples. PFAS serum concentrations in infants (<1 year of age) were predicted using a first-order pharmacokinetic model.

RESULTS

All nine emerging PFAS were detected in human milk, with the detection rates of 6:2 Cl-PFESA, PFMOAA, and PFO5DoDA all exceeding 70%. The level of 6:2 Cl-PFESA in human milk (median concentration=13.6 ng/L) ranked third after PFOA (336 ng/L) and PFOS (49.7 ng/L). The estimated daily intake (EDI) values of PFOA and PFOS exceeded the reference dose (RfD) of 20 ng/kg BW per day recommended by the U.S. Environmental Protection Agency in 78% and 17% of breastfed infant samples, respectively. 6:2 Cl-PFESA had the lowest infant CLrenal (0.009mL/kg BW per day), corresponding to the longest estimated half-life of 49 y. The average half-lives of PFMOAA, PFO2HxA, and PFO3OA were 0.221, 0.075, and 0.304 y, respectively. The CLrenals of PFOA, PFNA, and PFDA were slower in infants than in adults.

CONCLUSIONS

Our results demonstrate the widespread occurrence of emerging PFAS in human milk in China. The relatively high EDIs and half-lives of emerging PFAS suggest potential health risks of postnatal exposure in newborns. https://doi.org/10.1289/EHP11403.

Maternal plasma perfluoroalkyl substances concentrations in early pregnancy and cardiovascular development in offspring: A prospective cohort study

BACKGROUND

High maternal plasma perfluoroalkyl substances (PFAS) concentrations has been associated with adverse birth outcomes, but data on early childhood cardiovascular health is limited. This study aimed to assess the potential association between maternal plasma PFAS concentrations during early pregnancy and cardiovascular development in offspring.

MATERIAL AND METHODS

Cardiovascular development was assessed through blood pressure measurement, echocardiography and carotid ultrasound examinations among 957 children from the Shanghai Birth Cohort aged at 4 years old. Maternal plasma concentrations of PFAS were measured at mean gestational age of 14.4 (SD:1.8) weeks. The joint associations between PFAS mixture concentrations and cardiovascular parameters were analyzed using a Bayesian kernel machine regression (BKMR). The potential association of individual PFAS chemicals concentrations was explored using multiple linear regression.

RESULTS

In BKMR analyses, carotid intima media thickness (cIMT), interventricular septum thickness in diastole and systole, posterior wall thicknesses in diastole and systole, and relative wall thickness were significantly lower when all log10-transformed PFAS were fixed at 75th percentile in comparison to at their 50th percentile[Estimated overall Risk:-0.31 (95%CI: -0.42, -0.20), -0.09 (95%CI: -0.11, -0.07), -0.21 (95%CI: -0.26, -0.16), -0.09 (95%CI: -0.11, -0.07), -0.07 (95%CI: -0.10, -0.04) and -0.005 (95%CI: -0.006, -0.004)].Furthermore, maternal plasma concentrations of individual short-chain PFAS was associated with a decrease in left ventricular wall thickness, intraventricular septum thickness and enlarged chamber volume, and long-chain with a decrease in cIMT.

CONCLUSIONS

Our findings suggest that maternal plasma PFAS concentrations during early pregnancy was adversely associated with cardiovascular development in offspring, including thinner cardiac wall thickness and cIMT.

PFAS-induced lipidomic dysregulations and their associations with developmental toxicity in zebrafish embryos

Per- and polyfluoroalkyl substances (PFASs) are persistent environmental contaminants, posing developmental toxicity to fish and human. PFAS-induced lipid metabolism disorders were demonstrated using the zebrafish (Danio rerio) embryo model, but the detailed changes of lipid compositions and the influence of these changes on the biological development are still unclear. Herein, lipidomics analysis was performed to reveal the dysregulations of lipid metabolism in zebrafish embryos exposed to perfluorooctanoic acid (PFOA) or perfluorooctane sulfonate (PFOS) through microinjection. Various abnormal phenotypes were observed, including heart bleeding, pericardium edema, spinal curvature and increased heart rate at 72 h after fertilization, especially in the PFOS exposure groups. Lipidomic profiling found downregulated phosphatidylethanolamines in the PFAS-exposed embryos, especially those containing a docosahexaenoyl (DHA) chain, indicating an excessive oxidative damage to the embryos. Glycerolipids were mainly upregulated in the PFOA groups but downregulated in the PFOS groups. These aberrations may reflect oxidative stress, energy metabolism malfunction and proinflammatory signals induced by PFASs. However, supplement of DHA may not be effective in recovering the lipidomic dysregulations and protecting from the developmental toxicity induced by PFASs, showing the complexity of the toxicological mechanisms. This work has revealed the associations between the abnormal phenotypes and dysregulations of lipid metabolism in zebrafish embryos induced by PFASs from the aspect of lipidomics, and discovered the underlying molecular mechanisms of the developmental toxicity of PFASs.

Impacts of PFOAC8, GenXC6, and their mixtures on zebrafish developmental toxicity and gene expression provide insight about tumor-related disease

Concerns about per- and polyfluoroalkyl substances (PFASs) have grown in importance in the fields of ecotoxicology and public health. This study aims to compare the potential effects of long-chain (carbon atoms ≥ 7) and short-chain derivatives and their mixtures' exposure according to PFASs-exposed (1, 2, 5, 10, and 20 mg/L) zebrafish's (Danio rerio) toxic effects and their differential gene expression. Here, PFOA_C8, GenX_C6, and their mixtures (v/v, 1:1) could reduce embryo hatchability and increase teratogenicity and mortality. The toxicity of PFOA_C8 was higher than that of GenX_C6, and the toxicity of their mixtures was irregular. Their exposure (2 mg/L) caused zebrafish ventricular edema, malformation of the spine, blood accumulation, or developmental delay. In addition, all of them had significant differences in gene expression. PFOA_C8 exposure causes overall genetic changes, and the pathways of this transformation were autophagy and apoptosis. More importantly, in order to protect cells from PFOA_C8, GenX_C6, and their mixtures' influences, zebrafish inhibited the expression of ATPase and Ca²⁺ transport gene (atp1b2b), mitochondrial function-related regulatory genes (mt-co2, mt-co3, and mt-cyb), and tumor or carcinogenic cell proliferation genes (laptm4b and ctsbb). Overall, PFOA_C8, GenX_C6, and their mixtures' exposures will affect the gene expression effects of zebrafish embryos, indicating that PFASs may pose a potential threat to aquatic biological safety. These results showed that the relevant genes in zebrafish that were inhibited by PFASs exposure were related to tumorigenesis. Therefore, the effect of PFASs on zebrafish can be further used to study the pathogenesis of tumors.

F-53B induces hepatotoxic effects and slows self-healing in ulcerative colitis in mice

Chlorinated polyfluorinated ether sulfonate (F-53 B) is a distinct substitute for perfluorooctane sulphonate. It has been reported to be biologically toxic to mammals, causing enteric toxicity, liver toxicity and neurotoxicity. However, studies about the effects of F-53 B on patients with gastrointestinal diseases such as inflammatory bowel disease are very limited. In this study, whether the toxic impacts of F-53 B on the gut and liver can be exacerbated in mice with colitis was explored. The sensitivity of mice with acute colitis caused by dextran sulfate sodium salt (DSS) to F-53 B was compared with that of healthy mice. The mice were administered water containing F-53 B at doses of 10 and 100 μg/L sequentially for two weeks, respectively. F-53 B exposure exacerbated DSS-induced colonic inflammation, including inducing shortening of colon length, inflammatory cell infiltration and more severe histopathological symptoms. In addition, F-53 B administration significantly increased the levels of inflammatory cytokines, including interleukin (IL)-1, IL-6 and tumour necrosis factor-α, in the plasma of mice with enteritis compared with control group. F-53 B impaired intestinal integrity of mice with colitis by downregulating Claudin-1 and antimicrobial peptide-related genes while elevating serum lipopolysaccharide levels. In addition, in mice with colitis, F-53 B increased the levels of serum total cholesterol, triglyceride, low-density lipoprotein cholesterol, aspartate aminotransferase, and alanine aminotransferase, resulted in more severe liver inflammation and increased the level of genes related to the Gasdermin D-mediated pyrolysis. Conclusively, our results indicated that F-53 B delayed the self-healing of ulcerative colitis (UC) and caused liver inflammation in mice. This study provided some new insights into the health risks of F-53 B and raises concerns about the health of individuals with UC.

The acute toxicity, mechanism, bioconcentration and elimination of fluxametamide on zebrafish (Danio rerio)

Fluxametamide is a completely novel and the first isoxazoline insecticide used to control agricultural pests and has high insecticidal properties. To expand its usage in the paddy field, its potential toxicological effects on fish are necessary to make clear. In this study, the acute toxicity, bioconcentration and elimination of fluxametamide to zebrafish Danio rerio, and the action mode of it on the heteromeric Drα1β2Sγ2 and Drα1β2S GABA receptor was respectively determined by HPLC and two-electrode voltage clamp technique. Fluxametamide exhibited high toxicity to D. rerio, whereas slightly inhibited the GABA-stimulated current of Drα1β2Sγ2 or Drα1β2S. It showed high bioconcentration level in D. rerio at 0.0314 mg L^-1 and 0.157 mg L^-1, with bioconcentration factors at steady state of 1491.55 and 2875.28, respectively. The concentration of fluxametamide in D. rerio rapidly decreased from 47.84 ± 0.12 to 9.77 ± 1.13 mg kg^-1 in 0.0314 mg L^-1 or from 393.19 ± 0.46 to 46.93 ± 2.88 mg kg^-1 in 0.157 mg L^-1 within 10 days, and steadily kept at a low level after 18 days. In conclusion, fluxametamide has highly acute toxicity to D. rerio, and might induce high bioconcentration in a short time. As we know, this is the first report to provide a theoretical basis for evaluating the potential risk of fluxametamide on fish, and guidance for the application of fluxametamide.

Prenatal exposure to perfluorooctane sulfonate alternatives and associations with neonatal thyroid stimulating hormone concentration: A birth cohort study

BACKGROUND

Chlorinated polyfluorinated ether sulfonic acids (Cl-PFESA) and perfluorobutane sulfonate (PFBS), used as perfluorooctanesulfonate (PFOS) alternatives, were indicated as thyroid hormone disruptive toxicants in experimental studies. However, it is unclear whether prenatal exposure to Cl-PFESA and PFBS affects neonatal thyroid stimulating hormone (TSH) in human.

OBJECTIVE

To disclose the relationships between prenatal Cl-PFESAs and PFBS exposure and neonatal thyroid-stimulating hormone (TSH) levels based on a perspective cohort study.

METHODS

A total of 1015 pairs of mother and newborn were included from an ongoing birth cohort study in Wuhan, China, between 2013 and 2014. Six PFASs in cord blood sera and TSH concentration in neonatal postpartum heel sticks blood were quantified. Mixed linear and weighted quantile sum (WQS) regression models were applied to assess the individual and combination effects of PFASs exposure on neonatal TSH levels with multiple covariates adjustments.

RESULTS

After adjusting for potential confounders and other five PFASs, for each 1-ng/mL increase of PFBS or 8:2 Cl-PFESA, was negatively associated with 25.90% (95%CI: 37.37%, -12.32%; P < 0.001) and 27.19% (95%CI: 46.15%, -1.55%; P = 0.033) change in TSH in male but not female infants, respectively. No significant association was found between other PFASs exposure and neonatal TSH. Higher PFAS mixture in cord blood was significantly associated with decrease TSH concentration in all newborns (β = -0.36; 95%CI: 0.58, -0.13; P = 0.001) identified by WQS regression model. PFBS, PFOS and 6:2 Cl-PFESA were the major contributors to the neonatal TSH decrement with the weights of 56.50%, 18.71%, 12.81% among PFAS mixture, respectively.

CONCLUSIONS

our prospective cohort study suggested a negative association of cord serum PFBS and 8:2 CI-PFESA with TSH concentration in newborns, especially for boys. Additional studies are required to elaborate on the underlying biological mechanisms, especially for PFBS.

Comparison of developmental toxicity induced by PFOA, HFPO-DA, and HFPO-TA in zebrafish embryos

Hexafluoropropylene oxide dimer acids (HFPO-DA) and hexafluoropropylene oxide trimer acids (HFPO-TA) are alternatives to perfluorooctanoic acid (PFOA). However, little information on the comparison of their toxicities is available. Here, zebrafish embryos were exposed to PFOA, HFPO-DA, and HFPO-TA with exposure concentrations of 5 and 500 μg/L. Behavioral abnormal, enzyme activities and gene expression profiles in zebrafish embryos were determined. Results showed that exposure to PFOA and its alternatives increased heart rates and inhibited locomotor activity of zebrafish embryos. Further, their exposures changed the enzyme activities (acetylcholinesterase and oxidative stress-related enzymes), ATP content, and expressions of genes related to hypothalamic-pituitary-thyroid (HPT) axis, apoptosis, and lipid metabolism. Comparison analyses found that PFOA, HFPO-TA, and HFPO-DA exposures induced different effects on the embryonic development of zebrafish, which indicates the different modes of action. The HFPO-DA exposure induced specific effects on the disorder of lipid metabolism, HPT axis, and neurodevelopment. The HFPO-TA exposure also induced different effects from the PFOA exposure, which focused on lipid metabolism. The current data shows that the HFPO-DA and HFPO-TA might not be safe alternatives to PFOA. This study provides a new understanding of the biological hazards of PFOA alternatives in aquatic organisms, which can guide their usage.

Integration of metabolomics and proteomics reveals the underlying hepatotoxic mechanism of perfluorooctane sulfonate (PFOS) and 6:2 chlorinated polyfluoroalkyl ether sulfonic acid (6:2 Cl-PFESA) in primary human hepatocytes

Perfluorooctane sulfonate (PFOS) and its alternative 6:2 chlorinated polyfluorinated ether sulfonate (6:2 Cl-PFESA) are ubiquitous in various environmental and human samples. They have been reported to have hepatotoxicity effects, but the potential mechanisms remain unclear. Herein, we integrated metabolomics and proteomics analysis to investigate the altered profiles in metabolite and protein levels in primary human hepatocytes (PHH) exposed to 6:2 Cl-PFESA and PFOS at human exposure relevant concentrations. Our results showed that 6:2 Cl-PFESA exhibited higher perturbation effects on cell viability, metabolome and proteome than PFOS. Integration of metabolomics and proteomics revealed that the alteration of glycerophospholipid metabolism was the critical pathway of 6:2 Cl-PFESA and PFOS-induced lipid metabolism disorder in primary human hepatocytes. Interestingly, 6:2 Cl-PFESA-induced cellular metabolic process disorder was associated with the cellular membrane-bounded signaling pathway, while PFOS was associated with the intracellular transport process. Moreover, the disruption effects of 6:2 Cl-PFESA were also involved in inositol phosphate metabolism and phosphatidylinositol signaling system. Overall, this study provided comprehensive insights into the hepatic lipid toxicity mechanisms of 6:2 Cl-PFESA and PFOS in human primary hepatocytes.

Nontarget Identification of Novel Per- and Polyfluoroalkyl Substances in Cord Blood Samples

Per- and polyfluoroalkyl substances (PFASs) can penetrate the placental barrier and reach embryos through cord blood, probably causing adverse birth outcomes. Therefore, novel PFASs identification in cord blood and their relationships with birth outcomes are essential to evaluate prenatal exposure risk of PFASs. Herein, 16 legacy and 12 novel PFASs were identified in 326 cord blood samples collected from pregnant women in Jinan, Shandong, China. The presence of perfluoropolyether carboxylic acids, hydrogen-substituted polyfluoroetherpropane sulfate, and 3:3 chlorinated polyfluoroalkyl ether alcohol in cord blood was reported for the first time. Two extensive OECD (Organization for Economic Co-operation and Development)-defined PFASs named fipronil sulfone and 2-chloro-6-(trifluoromethyl)pyridine-3-ol were also identified. Quantification results showed that the emerging and OECD-defined PFASs separately accounted for 9.4 and 9.7% of the total quantified PFASs, while the legacy PFOA, PFOS, and PFHxS were still the most abundant PFASs with median concentrations of 2.12, 0.58, and 0.37 ng/mL, respectively. Several PFASs (C₉-C₁₂ PFCAs, C₆-C₈ PFSAs, and 6:2 Cl-PFESA) showed significantly higher levels for older maternities than younger ones. PFHxS levels were positively associated with birth weight and ponderal index (p < 0.05). The results provide comprehensive information on the presence and exposure risks of several novel PFASs during the early life stage.

Environmentally relevant concentrations of F-53B induce eye development disorders-mediated locomotor behavior in zebrafish larvae

The perfluorooctane sulfonate alternative, F-53B, induces multiple physiological defects but whether it can disrupt eye development is unknown. We exposed zebrafish to F-53B at four different concentrations (0, 0.15, 1.5, and 15 μg/L) for 120 h post-fertilization (hpf). Locomotor behavior, neurotransmitters content, histopathological alterations, morphological changes, cell apoptosis, and retinoic acid signaling were studied. Histology and morphological analyses showed that F-53B induced pathological changes in lens and retina of larvae and eye size were significantly reduced as compared to control. Acridine orange (AO) staining revealed a dose-dependent increase in early apoptosis, accompanied by upregulation of p53, casp-9 and casp-3 genes. Genes related to retinoic acid signaling (aldh1a2), lens developmental (cryaa, crybb, crygn, and mipa) and retinal development (pax6, rx1, gant1, rho, opn1sw and opn1lw) were significantly downregulated. In addition, behavioral responses (swimming speed) were significantly increased, while no significant changes in the neurotransmitters (dopamine and acetylcholine) level were observed. Therefore, in this study we observed that exposure to F-53B inflicted histological and morphological changes in zebrafish larvae eye, induced visual motor dysfunctions, perturbed retinoid signaling and retinal development and ultimately triggering apoptosis.

Perfluorooctane sulfonic acid (PFOS) exposures interfere with behaviors and transcription of genes on nervous and muscle system in zebrafish embryos

Perfluorooctane sulfonic acid (PFOS) has been widely detected in environment and organisms. PFOS has been identified as the driving agent for the behavioral changes of zebrafish larvae, while the underlying molecular mechanism remains unclear. In this study, zebrafish embryos/larvae were exposed to 0, 0.04, 0.1, 0.4 and 1 μM PFOS for 166 h. The locomotor behaviors and the mRNA transcription of genes in neuromuscular system were detected. Exposure to PFOS did not affect the hatching/death rates and body length, but increased the heart beat rates and frequency of spontaneous tail coiling. Locomotor behavior in zebrafish larvae of 0.4 and 1 μM PFOS groups were increased in the light condition. Additionally, the levels of acetylcholine (Ach) in 0.4 μM PFOS group and dopamine (DA) in 0.1, 0.4 and 1 μM PFOS groups were found to be significantly increased. The expression of genes related to the synthesis and decomposition of ACh，the synthesis and receptor of DA, and fosab was increased in the different PFOS treatment groups, while the expression of all the other genes of the neuromuscular system were significantly reduced. The findings of this investigation demonstrated that PFOS exposure may alter the locomotor behavior of zebrafish through disrupting the expressions of genes in neuromuscular system. The disturbed process of neurotransmitter transmission and muscle contraction caused by PFOS may be the dominant mechanism of hyperactivity in zebrafish.

Monitoring and ecological risk assessment of contaminants in freshwater bodies by bioindicators in China: a proposed framework

Bioindicators can provide pollution information with longer temporal duration and larger spatial scale. It is an ideal strategy for long-term monitoring of bioaccumulative contaminants. Bioindicator monitoring has been widely used; however, there were seldom detailed studies about bioindicator methodology in literature. The present study proposed a bioindicator framework suitable for the local conditions of China, including selection of bioindicator species, evaluation of impact factors, and derivation of threshold values using per- and polyfluoroalkyl substances (PFASs) as an example. The criteria that proper bioindicator species should meet and the procedure how the bioindicator species is selected were proposed, under which crucian carp (Carassius auratus) was selected as the local bioindicator for studied PFASs. Several factors which may affect accumulation of contaminants in bioindicators were suggested to produce reliable and comparable results. Derivation method of bioindicator thresholds for ecological risk assessment of aquatic ecosystems was firstly developed. The long-term and short-term ecological thresholds of perfluorooctanesulfonate using crucian carp as bioindicator are 3.329 and 1.402 μg/g wet weight respectively. Using the long-term thresholds derived from chronic toxicity data and the accumulative concentrations of contaminants obtained by bioindicator results, the bioindicator monitoring can be used for long-term ecological risk surveillance. The threshold derivation method can extend the application of bioindicator monitoring from the occurrence study to ecological risk surveillance, which is especially important for China who has made progresses on regular contaminant control and starts to be concerned about the ecological risks of the emerging contaminants. The framework can be used to create national and regional long-term freshwater bioindicator monitoring programs, with the purposes of ecological risk assessment, occurrence and temporal trend study, pollution source identification, international convention fulfillment, retrospective study, etc. The bioindicator framework will benefit the aquatic environmental safety and the hazardous chemical management in China.

A review of omics-based PFAS exposure studies reveals common biochemical response pathways

Per and Polyfluoroalkyl Substances (PFAS) are a diverse group of man-made chemicals with a range of industrial applications and which are widespread in the environment. They are structurally diverse but comprise a common chemical feature of at least one (though usually more) perfluorocarbon moiety (-C_nF_2n-) attached to a functional group such as a carboxylic or sulphonic acid. The strength of the Carbon-Fluorine bond means the compounds do not break down easily and can thus bioaccumulate. PFAS are of high concern to regulators and the public due to their potential toxicity and high persistence. At high exposure levels, PFAS have been implicated in a range of harmful effects on human and environmental health, particularly problems in/with development, cholesterol and endocrine disruption, immune system function, and oncogenesis. However, most environmental toxicology studies use far higher levels of PFAS than are generally found in the environment. Additionally, since the type of exposure, the PFAS used, and the organisms tested all vary between studies, so do the results. Traditional ecotoxicology studies may thus not identify PFAS effects at environmentally relevant exposures. Here we conduct a review of omics-based PFAS exposure studies using laboratory ecotoxicological methodologies and environmentally relevant exposure levels and show that common biochemical response pathways are identified in multiple studies. A major pathway identified was the pentose phosphate shunt pathway. Such molecular markers of sublethal PFAS exposure will greatly benefit accurate and effective risk assessments to ensure that new PFAS regulations can consider the full effects of PFAS exposure on environmental and human health receptors.

Per- and polyfluoroalkyl substances (PFAS) exposure in women seeking in vitro fertilization-embryo transfer treatment (IVF-ET) in China: Blood-follicular transfer and associations with IVF-ET outcomes

As follicular fluid constitutes a critical microenvironment for the development of oocytes, investigation of environmental contaminants in follicular fluid may facilitate a better understanding of the influence of environmental exposure on reproductive health. In the present study, we aimed to investigate per- and polyfluoroalkyl substances (PFAS) exposure in women receiving in vitro fertilization-embryo transfer (IVF-ET) treatment, determine the blood-follicle transfer efficiencies (BFTE) of PFAS, and explore potential associations between PFAS exposure and selected IVF-ET outcomes. Our results revealed that n-PFOA was the most abundant PFAS in both serum and follicular fluid (FF) (median = 5.85 and 5.56 ng/mL, respectively), followed by n-PFOS (4.95 and 4.28 ng/mL), 6:2 Cl-PFESA (2.18 and 2.10 ng/mL), PFNA (1.37 and 1.37 ng/mL), PFUdA (0.33 and 0.97 ng/mL), PFDA (0.37 and 0.66 ng/mL), PFHxS (0.42 and 0.39 ng/mL), and PFHpS (0.11 and 0.10 ng/mL). The median BFTE ranged from 0.65 to 0.92 for individual PFAS, indicating a relatively high tendency of PFAS to cross the blood-follicle barrier (BFB). An inverted V-shaped trend was observed between the median BFTE and the number of fluorinated carbon atoms or the log K_ow (octanol-water partition coefficient) for individual PFAS, suggesting the influence by physicochemical properties and molecular structures. Although our data did not find any clear pattern in the link between blood or follicular fluid concentrations of PFAS and selected IVF-ET outcomes, our study raises the need for better characterization of exposure to environmental chemicals in follicular fluid together with its potential influence on reproductive health.

Persistent impairment of gonadal development in rare minnow (Gobiocypris rarus) after chronic exposure to chlorinated polyfluorinated ether sulfonate

The delayed and persistent adverse effects caused by developmental exposure to per- and poly-fluorinated substances are of significant concern. Juvenile rare minnows (Gobiocypris rarus), were exposed to chlorinated polyfluoroalkyl ether sulfonate (Cl-PFESA) at measured medium concentrations of 86.5 μg/L, 162 μg/L and 329 μg/L, for 4 weeks followed by 12 weeks of depuration. After 4 weeks of exposure, the body weight and length of the juvenile fish were increased compared to controls. Gene expression of gnrh3, lhβ, and cyp19a was decreased, and ar and erα were upregulated. Transcriptomic analysis revealed enrichment of multiple pathways related to gonadal development. After 12 weeks of depuration, the gonadosomatic indices were decreased in female fish in a concentration-dependent manner, with a significant decrease to 59% of control in 329 μg/L group. Histological analysis found increasing numbers of degenerating oocytes and perinucleolar oocytes, and decreasing numbers of mature vitellogenic oocytes in female fish treated by Cl-PFESA. Enlarged interstitial space of the testis was observed in the exposed male fish. Gene expression levels of gnrh3, lhβ, ar, erα, and vtg were upregulated in the adult fish. Chronic developmental exposure to Cl-PFESA caused persistent effects on gonadal development of fish, highlighting the necessity of a comprehensive ecological risk assessment.

A pilot study on extractable organofluorine and per- and polyfluoroalkyl substances (PFAS) in water from drinking water treatment plants around Taihu Lake, China: what is missed by target PFAS analysis?

Per- and polyfluoroalkyl substances (PFAS) have raised concerns due to their worldwide occurrence and adverse effects on both the environment and humans as well as posing challenges for monitoring. Further collection of information is required for a better understanding of their occurrence and the unknown fractions of the extractable organofluorine (EOF) not explained by commonly monitored target PFAS. In this study, eight pairs of raw and treated water were collected from drinking water treatment plants (DWTPs) around Taihu Lake in China and analyzed for EOF and 34 target PFAS. Mass balance analysis of organofluorine revealed that at least 68% of EOF could not be explained by target PFAS. Relatively higher total target concentrations were observed in 4 DWTPs (D1 to D4) when compared to other samples with the highest sum concentration up to 189 ng L^-1. PFOA, PFOS and PFHxS were the abundant compounds. Suspect screening analysis identified 10 emerging PFAS (e.g., H-PFAAs, H-PFESAs and OBS) in addition to target PFAS in raw or treated water. The ratios PFBA/PFOA and PFBS/PFOS between previous and current studies showed significant replacements of short-chain to long-chain PFAS. The ratios of the measured PFAS concentrations to the guideline values showed that some of the treated drinking water exceeds guideline values, appealing for efforts on drinking water safety guarantee.

Perfluorooctane Sulfonamide (PFOSA) Induces Cardiotoxicity via Aryl Hydrocarbon Receptor Activation in Zebrafish

Perfluorooctane sulfonamide (PFOSA), a precursor of perfluorooctanesulfonate (PFOS), is widely used during industrial processes, though little is known about its toxicity, particularly to early life stage organisms that are generally sensitive to xenobiotic exposure. Here, following exposure to concentrations of 0.01, 0.1, 1, 10, and 100 μg/L PFOSA, transcriptional, morphological, physiological, and biochemical assays were used to evaluate the potential effects on aquatic organisms. The top Tox functions in exposed zebrafish were related to cardiac diseases predicted by Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway, and Ingenuity Pathway Analysis (IPA) analysis. Consistent with impacts predicted by transcriptional changes, abnormal cardiac morphology, disordered heartbeat signals, as well as reduced heart rate and cardiac output were observed following the exposure of 0.1, 1, 10, or 100 μg/L PFOSA. Furthermore, these PFOSA-induced cardiac effects were either prevented or alleviated by supplementation with an aryl hydrocarbon receptor (AHR) antagonist or ahr2-morpholino knock-down, uncovering a seminal role of AHR in PFOSA-induced cardiotoxicity. Our results provide the first evidence in fish that PFOSA can impair proper heart development and function and raises concern for PFOSA analogues in the natural environment.

Tissue-Specific Uptake, Depuration Kinetics, and Suspected Metabolites of Three Emerging Per- and Polyfluoroalkyl Substances (PFASs) in Marine Medaka

Restrictions on legacy per- and polyfluoroalkyl substances (PFASs) have led to the widespread use of emerging PFASs. However, their toxicokinetics have rarely been reported. Here, tissue-specific uptake and depuration kinetics of perfluoroethylcyclohexanesulfonate (PFECHS) and 6:2 and 8:2 chlorinated polyfluoroalkyl ether sulfonates (Cl-PFESAs) were studied in marine medaka (Oryzias melastigma). The fish were exposed to these substances for 28 days (0.2 μg/L), followed by a clearance period of 14 days. The depuration constant (k_d) of PFECHS [0.103 ± 0.009 day^-1 (mean ± standard deviation)] was reported for the first time. Among the six studied tissues, the highest concentrations of 6:2 Cl-PFESA, 8:2 Cl-PFESA, and PFECHS were found in the liver [1540, 1230, and 188 ng (g of wet weight)^-1, respectively] on day 28 while the longest residence times were found in the eyes (t_1/2 values of 21.7 ± 4.3, 23.9 ± 1.5, and 17.3 ± 0.8 days, respectively). No significant positive correlation was found between the bioconcentration factors of the studied PFASs and the phospholipid or protein contents in different tissues of the studied fish. Potential metabolites of Cl-PFESAs, i.e., their hydrogen-substituted analogues (H-PFESAs), were identified by time-of-flight mass spectrometry. However, the biotransformation rates were low (<0.19%), indicating the poor capacity of marine medaka to metabolize Cl-PFESAs to H-PFESAs.

Extraction and Matrix Cleanup Method for Analyzing Novel Per- and Polyfluoroalkyl Ether Acids and Other Per- and Polyfluoroalkyl Substances in Fruits and Vegetables

Per- and polyfluoroalkyl ether acids (PFEAs) are a subclass of per- and polyfluoroalkyl substances (PFAS) that are detected with increasing frequency in environmental matrices. Diet can be an important route of PFEA exposure, but the presence of PFEAs in food is poorly understood. Extraction methods for food samples exist for traditionally studied PFAS, but their suitability for PFEAs and other novel PFAS remains unknown. In this study, an extraction and matrix cleanup method was developed to quantify 45 PFAS, including 13 PFEAs, 3 perfluoroalkane sulfonamides, and 6 fluorotelomer carboxylic acids in 10 types of fruits and vegetables. Homogenized samples were extracted with basic methanol, and resulting extracts were diluted with water and cleaned up using solid-phase extraction with weak anion-exchange cartridges. The method was validated by performing spike-recovery experiments at spike levels of 1 ng/g in all 10 matrices and 0.1 ng/g in 2 matrices. For PFAS without a corresponding isotopically labeled internal standard (IS), adopting an IS with a similar chromatographic retention time generated the most accurate recoveries. Dependent upon the matrix, recoveries of 38-44 PFAS (including 10-13 PFEAs) fell within 50-150% for samples spiked at 1 ng/g. Recoveries of 40 and 38 PFAS in blueberries and corn, respectively, fell within 50-150% for samples spiked at 0.1 ng/g. Method quantification limits (MQLs) of PFAS in pure solvents were determined as the lowest calibration level with an accuracy between 70 and 130%. To compensate for matrix effects, a matrix factor was applied on the basis of the analyte response in different matrices relative to the pure solvent. The MQLs of 45 PFAS (including 13 PFEAs) in 10 matrices ranged from 0.025 to 0.25 ng/g. Overall, this method is capable of sensitively quantifying 45 PFAS in many fruits and vegetables.

Human exposure to F-53B in China and the evaluation of its potential toxicity: An overview

Chlorinated polyfluoroalkyl ether sulfonic acid (Cl-PFESAs, trade name F-53B), an alternative to perfluorooctane sulfonate (PFOS), has been widely used as a mist suppressant in the Chinese electroplating industry since the 1970 s. Due to greater restrictions on PFOS globally in recent years, the production and use of F-53B correspondingly increased, consequently causing more emissions into the environment. In China, an increasing number of studies report frequent detection and broad exposure to F-53B in the natural environment, various wildlife and the human body. In human blood, the detection rate of F-53B is almost 80%, accounting for 8.69 to 28% of ∑per- and polyfluoroalkyl substances (PFASs). F-53B is the most biopersistent PFAS in humans to date, with a half-life of 15.3 years. In addition, F-53B displays protein binding affinity and high human placental permeability. Recently, some epidemiological studies have reported the health risks associated with F-53B in humans, including abnormal serum lipid metabolism, vascular dysfunction, endocrine disorders and even adverse birth outcomes. Various in vivo and in vitro studies have demonstrated the toxicity of F-53B, such as hepatotoxicity, interference effects on the endocrine system, as well as reproductive and developmental toxicity. Our aims are to review studies on human F-53B exposure levels, trends and associated health effects; evaluate the potential toxicity; and predict directions for future research.

Prenatal Exposure to Per- and Polyfluoroalkyl Substances and Facial Features at 5 Years of Age: A Study from the Danish National Birth Cohort

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) are widespread persistent pollutants. Evidence regarding neurodevelopmental effects of PFAS have been mixed. The relation between PFAS exposure and anatomical markers that have been suggested to correlate with fetal brain development have not been studied.

OBJECTIVES

We investigated the association between prenatal PFAS exposures and three craniofacial features in children measured at 5 years of age.

METHODS

Measures of palpebral fissure length (PFL), philtrum groove, and upper-lip thickness were generated from standardized digital facial photographs from 656 children in the Danish National Birth Cohort. PFL was classified into two groups (shorter; normal), and the philtrum (grooved; smooth; normal) and upper-lip (thick; thin; normal) measures into three groups each. Six PFAS were measured in maternal plasma (median=8 gestational wk). Multinomial logistic regression was used to estimate the odds ratio (OR) and 95% confidence interval (CI) for each facial feature using the normal group as the reference according to log2-PFAS concentration (in nanograms per milliliter) or PFAS tertiles, adjusting for potential confounders, including maternal alcohol intake and smoking. Stratified analyses by maternal alcohol intake or child's sex were performed.

RESULTS

Prenatal exposure to each PFAS was associated with elevated odds for a shorter PFL, with the strongest association observed for perfluorodecanoic acid (PFDA; per doubling OR=2.02; 95% CI: 1.11, 3.70). Some nonlinear associations were found for philtrum measures: the second tertile of PFDA and perfluorononanoic acid were associated with grooved philtrum, whereas the second tertile of perfluoroheptane sulfonate with smooth philtrum. The associations between PFAS exposure and a shorter PFL were stronger among mothers who consumed alcohol in the first trimester, some sex-specific associations were noted for philtrum and upper-lip measures.

DISCUSSION

Prenatal PFAS exposures might influence fetal craniofacial development. A larger study is needed to replicate the potential modifying effects observed for alcohol exposure and to clarify whether associations of craniofacial markers observed reflect specific neurologic deficits. https://doi.org/10.1289/EHP9478.

Legacy and emerging poly- and perfluorochemicals in seawater and sediment from East China Sea

Following the global phase out of perfluorooctane sulfate (PFOS), chlorinated polyfluoroalkyl ether sulfonates (Cl-PFAESs) and p-perfluorous nonenoxybenzenesulfonate (PFNOBS) have emerged as novel PFOS substitutes. However, until now, limited data is available on their occurrence and environmental behaviors in the marine environment. Here, seawater and sediment samples were collected from East China Sea and analyzed for Cl-PFAESs, PFNOBS, and perfluoroalkyl acids (PFAAs; including their branched isomers) to investigate their concentrations, potential sources, and sediment-seawater partitioning behaviors. Perfluorooctanoate (PFOA) and PFOS were consistently the predominant PFAAs in seawaters and sediments. Branched PFOA and PFOS isomers were consistently much less frequently detected in sediments than that in seawaters. Linear PFOA contributed 92-95% of total PFOA in seawaters, suggesting the great contribution of telomerization PFOA. 6:2 Cl-PFAES was detected in all seawaters (concentration, 0.58-47 pg/L) and in the majority of sediments (<LOD-28 pg/g). PFNOBS was observed in 46% of seawater samples (concentration, <LOD-5.2 pg/L) and 66% of sediment samples (<LOD-1.7 pg/g). Spatial distribution trend suggested the riverine input as an important source of PFAAs and 6:2 Cl-PFAES in this sampling area. 6:2 Cl-PFAES (log K_oc, 2.6 ± 0.36) and PFNOBS (2.7 ± 0.33) had comparable mean log-transformed sediment-seawater partitioning coefficients (log K_oc) to PFOA (2.5 ± 0.32) or PFOS (2.8 ± 0.49), indicating their long-range transport potential in global oceans with ocean currents. Overall, this study provides the first data on occurrence and partitioning behaviors of 6:2 Cl-PFAES and PFNOBS in the marine environment.

Lipid metabolism disorders effects of 6:2 chlorinated polyfluorinated ether sulfonate through Hsa-miRNA-532-3p/Acyl-CoA oxidase 1(ACOX1) pathway

6:2 Chlorinated polyfluorinated ether sulfonate (6:2 Cl-PFESA), an alternative product of perfluorooctane sulfonate (PFOS), has been frequently detected in various environmental, wildlife, and human samples. A few studies revealed the hepatotoxicity of 6:2 Cl-PFESA in animals, but the underlying toxicity mechanisms remain largely unknown. In this study, we investigated the lipid metabolism disorders of 6:2 Cl-PFESA through miRNA-gene interaction mode in Huh-7 cells. Our results showed that 6:2 Cl-PFESA significantly promoted cellular lipid accumulation and increased the expression of Acyl-CoA oxidase 1 (ACOX1), with the lowest effective concentrations (LOECs) of 3 μM. In silico analysis showed that hsa-miR-532-3p is a potential miRNA molecule targeting ACOX1. Fluorescent-based RNA electrophoretic mobility shift assay (FREMSA) and ACOX1-mediated luciferase reporter gene assays showed that hsa-miR-532-3p could directly bind to ACOX1 and inhibit its transcription activity. Besides, 6:2 Cl-PFESA decreased the expression of hsa-miR-532-3p in the PPARα-independent manner. Overexpression of hsa-miR-532-3p promoted 6:2 Cl-PFESA-induced cellular lipid accumulation and decreased the ACOX1 production in Huh-7 cells. Taken together, at human exposure relevant concentrations, 6:2 Cl-PFESA might upregulate the expression levels of ACOX1 through downregulating hsa-miR-532-3p, and disturbed lipid homeostasis in Huh-7 cells, which revealed a novel epigenetic mechanism of 6:2 Cl-PFESA-induced hepatic lipid toxic effects.

A Review of Per- and Polyfluorinated Alkyl Substance Impairment of Reproduction

In this review article, we compiled peer-reviewed literature describing PFAS exposure and reproductive effects in animals and humans. The aim was to compare environmental occurrence and effects of the most prominent long-chain PFAS compounds and their short-chain replacements. Long-chain PFAS compounds are known to persist in the environment due to their chemical stability, and also known to bioaccumulate; hence, these compounds are being replaced globally. Indeed, PFOA and PFOS are considered long-chain "forever pollutants," and thus the potential reproductive risk may continue for decades. Much less is known about their short-chain replacements despite the fact that they becoming more widespread in the environment. Short-chain PFAS are generally less bioaccumulative than long-chain, but they are more mobile and persistent in aquatic ecosystems. The three most prominent of these are commonly referred to as GenX, ADONA and F53B. The short-chain PFAS have similar physical and chemical properties as their predecessors; however, because they are relatively new, much less is known about the potential to disrupt reproduction. Indeed, high-quality epidemiological studies are needed to determine associations between short-chain PFAS exposure and effects on reproductive health. However, epidemiological evidence is mounting that long-chain PFAS exposure is associated with reproductive effects (i.e., decrease in fertility, reduced fetal growth and birth weight, pregnancy-induced hypertension and preeclampsia, thyroid hormone disruption during pregnancy, and preterm birth). Evidence from animal models and human cell lines indicates that short-chain PFAS similarly affect reproductive endpoints; however, epidemiological studies are scarce and inconsistent. Although short-chain PFAS have been quantified in drinking water and sediment worldwide, most of these studies did not focus on quantitation of GenX, ADONA, and F53B. There are also many other short-chain PFAS byproducts of manufacturing that have yet to be identified and studied. When sum total concentration of long- and short-chain PFAS are considered, the concentration rises by an order or magnitude or greater, as will the risk of exposure and subsequent reproductive effects.

Varied thyroid disrupting effects of perfluorooctanoic acid (PFOA) and its novel alternatives hexafluoropropylene-oxide-dimer-acid (GenX) and ammonium 4,8-dioxa-3H-perfluorononanoate (ADONA) in vitro

Due to its potential adverse effects on human health, perfluorooctanoic acid (PFOA), one of the once widely used legacy per- and polyfluoroalkyl substances (PFASs), has been recently replaced by its novel alternatives including hexafluoropropylene-oxide-dimer-acid (GenX) and ammonium 4,8-dioxa-3H-perfluorononanoate (ADONA). These alternative PFASs are detected in water and exposed workers. PFASs can enter organs like thyroids, however, it is yet unknown whether the new alternatives are safer than PFOA. In the current study, we compared the thyroid disrupting effects of PFOA and its alternatives GenX and ADONA in vitro with both rat thyroid cell line FRTL5 and primary normal human thyroid (NHT) cells. Cells were exposed to ascendant doses of PFOA, GenX or ADONA for various incubation time and cell viability was assessed by WST-1 assay and LDH assay. The proliferation rate of survived cells was determined by crystal violet-based cell proliferation assay and MTT assay. The gene expression of thyroid hormone regulation-related genes in thyroid cells after exposure was quantified by RT-PCR and Western blot. Our data showed that both PFOA and GenX reduced thyroid cell viability in both dose and time dependent manner, with GenX being more toxic than PFOA at the same condition. Similarly, the proliferation rate of cells survived exposure to PFOA and GenX was considerably impaired, with GenX showing more profound adverse effect than PFOA. Unlike PFOA and GenX, ADONA showed no apparent adverse effects on the viability and proliferation of both thyroid cell types. Gene expression data revealed that all three PFASs altered gene expression in both thyroid cells and the altered gene expression seemed to be PFAS and cell type dependent. Taken together, our data reveal that the thyroid disrupting effects is increased in the order of GenX > PFOA > ADONA. Our findings will be beneficial for the guidance of the future usage of PFASs and development of better alternatives.

Exposure to legacy and novel perfluoroalkyl substance disturbs the metabolic homeostasis in pregnant women and fetuses: A metabolome-wide association study

BACKGROUND

Perfluoroalkyl substances (PFASs) exist extensively and several of these have been verified to be toxic. Prenatal exposure to PFASs has attracted much attention. Metabolome-wide association analyses can be used to explore the toxicity mechanisms of PFASs by identifying associated biomarkers.

OBJECTIVES

To evaluate associations between the metabolites in maternal and cord serum and internal exposure to several common PFASs.

METHODS

Paired maternal and cord serum samples were collected from 84 pregnant women who gave birth between 2015 and 2016. Seven legacy and two novel PFASs were measured. A nontarget metabolomic method and an iterative metabolite annotation based on metabolic pathways were applied to characterize the metabolic profiles. Linear regression adjusted with the false discovery rate and covariates was used to indicate the associations.

RESULTS

A total of 279 features in maternal serum and 338 features in cord serum were identified as metabolites associated with PFAS exposure. Perfluorooctanoic acid (PFOA) and perfluorohexane sulfonic acid (PFHxS) were two PFASs associated with more metabolites, while the two novel chlorinated polyfluorinated ether sulfonic acids (Cl-PFESAs) showed less relevance to the metabolome. With pathway enrichment analysis, we found that three fatty acid metabolisms and retinol metabolism were correlated with PFAS exposure in maternal blood, and that sterol metabolism showed the correlation in both maternal serum and cord serum.

CONCLUSIONS

We identified metabolites and pathways in pregnant women and fetuses associated with the exposure to several PFAS, indicating a promising application for metabolome-wide association studies. Additional research is needed to confirm causation.

Maternal exposure of mice to sodium p-perfluorous nonenoxybenzene sulfonate causes endocrine disruption in both dams and offspring

The toxicity of certain novel perfluoroalkyl substances (PFCs) has attracted increasing attention. However, the toxic effects of sodium p-perfluorous nonenoxybenzene sulfonate (OBS) on the endocrine system have not been elucidated. In this study, OBS was added to the drinking water during the pregnancy and lactation of the healthy female mice at dietary levels of 0.0 mg/L (CON), 0.5 mg/L (OBS-L), and 5.0 mg/L (OBS-H). OBS exposure during the pregnancy and lactation resulted in the presence of OBS residues in the placenta and fetus. We also analyzed physiological and biochemical parameters and gene expression levels in mice of the F0 and F1 generations after maternal OBS exposure. The total serum cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) levels were significantly increased in female mice of the F0 generation. The androgen levels in the serum and the ovarian mRNA levels of androgen receptor (AR) also tended to increase after maternal OBS exposure in the F0 generation mice. Moreover, maternal OBS exposure altered the mRNA expression of endocrine-related genes in male mice of F1 generation. Notably, the serum TC and LDL-C levels were significantly increased in 8-weeks-old male mice of the F1 generation, and the serum high-density lipoprotein cholesterol (HDL-C) levels were decreased in 24-week-old male mice of the F1 generation. These results indicated that maternal OBS exposure can interfere with endocrine homeostasis in the F0 and F1 generations. Therefore, exposure to OBS during pregnancy and lactation has the potential toxic effects on the dams and male offspring, which cannot be overlooked.