Prenatal window of susceptibility to perfluorooctane sulfonate-induced neonatal mortality in the Sprague-Dawley rat

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

Production of per- and polyfluoroalkyl substances (PFAS) has shifted from long-chain perfluoroalkyl acids to short-chain compounds and those with ether bonds in the carbon chain. Next-generation perfluoroalkylether PFAS include HFPO-DA ("GenX chemicals"), Nafion Byproducts, and the PFOx homologous series that includes perfluoro-3,5,7,9-butaoxadecanoic acid (PFO4DA) and perfluoro-3,5,7,9,11-pentaoxadodecanoic acid (PFO5DoA). PFO4DA and PFO5DoA have been detected in serum and/or tissues from humans and wildlife proximal to contamination point sources. However, toxicity data are extremely limited, with no in vivo developmental toxicology data. To address these data gaps, pregnant Sprague-Dawley rats were exposed via oral gavage to vehicle, PFO4DA, or PFO5DoA across a series of doses (0.1 to 62.5 mg/kg/day) from gestation day (GD) 18-22. Hepatic transcriptomics were assayed in dams and fetuses, and serum metabolomics in dams. These data were overlaid with serum PFO4DA and PFO5DoA concentrations to perform dose-response modeling. Both dams and fetuses exhibited dose-responsive disruption of hepatic gene expression in response to PFO4DA or PFO5DoA, with fetal expression disrupted at lower doses than dams. Several differentially expressed genes were upregulated by every dose of PFO5DoA in both maternal and fetal samples, including genes encoding enzymes that hydrolyze acyl-coA to free fatty acids. Maternal serum metabolomics revealed PFO4DA exposure did not induce significant changes at any tested dose, whereas PFO5DoA exposure resulted in dose-dependent differential metabolite abundance for 149 unique metabolites. Multi-omics pathway analyses of integrated maternal liver transcriptomics and serum metabolomics revealed significant convergent changes as low as 3 mg/kg/d PFO4DA and 0.3 mg/kg/d PFO5DoA exposure. Overall, transcriptomic and metabolomic effects of PFO4DA and PFO5DoA appear consistent with other carboxylic acid PFAS, with primary changes related to lipid metabolism, bile acids, cholesterol, and cellular stress. Importantly, PFO5DoA exposure more potently induced changes in maternal and fetal hepatic gene expression and maternal circulating metabolites, despite high structural similarity. Further, we report in vitro PPARα and PPARγ receptor activation for both compounds as putative molecular mechanisms. This work demonstrates the potential developmental toxicity of alternative moiety perfluoroethers and highlights the developing liver as particularly vulnerable to transcriptomic disruption. Synopsis: Developmental exposure to fluoroether carboxylic acids PFO4DA and PFO5DoA result in differential impacts on hepatic transcriptome in dams and offspring and circulating metabolome in dams, with PFO5DoA exhibiting higher potency than PFO4DA.

Developmental PFOS exposure alters lung inflammation and barrier integrity in juvenile mice

Emerging epidemiological evidence indicates perfluorooctane sulfonic acid (PFOS) is increasingly associated with asthma and respiratory viral infections. Animal studies suggest PFOS disrupts lung development and immuno-inflammatory responses, but little is known about the potential consequences on respiratory health and disease risk. Importantly, PFOS exposure during the critical stages of lung development may increase disease risk later in life. Thus, we hypothesized that developmental PFOS exposure will affect lung inflammation and alveolar/airway development in a sex-dependent manner. To address this knowledge gap, timed pregnant Balb/cJ dams were orally dosed with a PFOS (1.0 or 2.0 mg/kg/d) injected mealworm or a vehicle control daily from gestational day (GD) 0.5 to postnatal day (PND) 21, and offspring were sacrificed at PND 22-23. PFOS-exposed male offspring displayed increased alveolar septa thickness. Occludin was also downregulated in the lungs after PFOS exposure in mice, indicative of barrier dysfunction. BALF macrophages were significantly elevated at 2.0 mg/kg/d PFOS in both sexes compared with vehicles, whereas BALF cytokines (TNF-α, IL-6, KC, MIP-1α, MIP-1β, and MCP-1) were suppressed in PFOS-exposed male offspring compared with vehicle controls. Multiplex nucleic acid hybridization assay showed male-specific downregulation of cytokine gene expression in PFOS-exposed mice compared with vehicle mice. Overall, these results demonstrate PFOS exposure exhibits male-specific adverse effects on lung development and inflammation in juvenile offspring, possibly predisposing them to later-in-life respiratory disease. Further research is required to elucidate the mechanisms underlying the sex-differentiated pulmonary toxicity of PFOS.

Caspase-3/GSDME dependent pyroptosis contributes to offspring lung injury induced by gestational PFOS exposure via PERK/ATF4 signaling

Perfluorooctane sulfonate (PFOS) is widely used in industry and consumer products. Previous studies have showed that PFOS gestational exposure is associated with offspring lung damage in rat. However, the underlying mechanisms remain poorly understood. In this study, we investigated the role of gasdermin E (GSDME) in lung injury of offspring and its underlying mechanisms using in vivo and in vitro approaches. Pregnant SD rats were exposed to PFOS (1 mg/kg BW/d) between gestational day 12-18, and the lung tissue of the offspring was evaluated on postnatal day 7. PFOS treated animals exhibited alveolar septal thickening and inflammation-related damages, with an increased expression of GSDME in alveolar type II epithelial cells (AECII). Furthermore, in vitro experiments demonstrated that PFOS exposure (with 225 μM and up) upregulated the caspase-3/GSDME signaling pathway in AECII. Also, ultrastructure analysis revealed significant changes in the endoplasmic reticulum (ER) structure in PFOS-induced pyroptotic cells, which is consistent with the ER stress detected in these cells. Additionally, PFOS exposure led to increased expression of ER stress-related proteins, including p-PERK, p-eIF2α, ATF4, and CHOP. Subsequently, using specific inhibitors, we found that the PERK/ATF4 pathway acted as an upstream signal regulating GSDME-dependent pyroptosis. Overall, our findings show that GSDME-dependent pyroptosis plays a crucial role in the lung injury induced by gestational PFOS exposure, and the PERK/ATF4 pathway may function as a possible mediator of this process.

A Review: Per- and Polyfluoroalkyl Substances-Biological Degradation

Per- and polyfluoroalkyl substances (PFASs), highly stable synthetic organic compounds with multiple carbon-fluorine bonds, are emerging as environmental contaminants, toxic, bioaccumulative, and environmentally persistent. PFASs are strongly resistant to biological and chemical degradation, and therefore PFASs present a challenge to researchers and scientists for a better understanding and application of remediation methods and biodegradation of PFASs and have become subject to strict government regulations. The review summarizes the recent knowledge of bacterial and fungal degradation of PFASs, as well as the enzymes involved in the processes of transformation/degradation of PFASs.

Health Risk Exposure Assessment of Migration of Perfluorooctane Sulfonate and Perfluorooctanoic Acid from Paper and Cardboard in Contact with Food under Temperature Variations

Perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) are extensively used in food-contact paper and cardboard. However, they may migrate from food-contact materials to food, and the migration rate may be increased at elevated temperatures. In addition, there is a positive association of PFOS/PFOA levels with total cholesterol. Therefore, this study aims to assess the human health risk of increased total cholesterol associated with long-term exposure to PFOS and PFOA migration from food-contact paper and cardboard under temperature variation scenarios in adults. An exposure assessment was performed using an uptake dose model to estimate the uptake doses of PFOS and PFOA for the high-, intermediate-, and low-exposure scenarios. Benchmark dose (BMD) modeling was conducted to describe the dose-response relationships between PFOS/PFOA and total cholesterol levels. Finally, a margin of exposure (MOE) approach was used to characterize the risk. The results of the exposure assessment showed that PFOS and PFOA uptake doses in the high-exposure scenarios were around one and two orders of magnitude greater than those in the intermediate- and low-exposure scenarios, respectively. Under high-exposure scenarios, the uptake levels of hundredth-percentile PFOS and PFOA at high temperatures may raise health concerns (MOE < 1). This study provides a methodology to assess the health risks associated with exposure to migration of food contaminants from various types of paper and cardboard that come into contact with food.

1α,25-dihydroxyvitamin D3 supplementation alleviates perfluorooctanesulfonate acid-induced reproductive injury in male mice: Modulation of Nrf2 mediated oxidative stress response

Perfluorooctanesulfonate acid (PFOS) is a typical persistent organic pollutant that widely exists in the environment. To clarify the toxic effects and mechanisms of PFOS and to find effective intervention strategies have been attracted global attention. Here, we investigated the effects of PFOS on the male reproductive system and explored the potential protective role of 1α,25-dihydroxyvitamin D₃ (1α,25(OH)₂ D₃ ). Our results showed that 1α,25(OH)₂ D₃ intervention significantly improved PFOS-induced sperm quality decline and testicular damage. Moreover, 1α,25(OH)₂ D₃ aggrandized the total antioxidant capacity. Furthermore, after PFOS exposure, the transcription factor nuclear factor erythroid-related factor 2 (Nrf2) was adaptively increased together with its target genes, such as HO-1, NQO1, and SOD2. Meanwhile, 1α,25(OH)₂ D₃ ameliorated PFOS-induced augment of Nrf2 and target genes. These findings indicated that 1α,25(OH)₂ D₃ might attenuate PFOS-induced reproductive injury in male mice via Nrf2-mediated oxidative stress.

Reproductive and developmental toxicity of perfluorooctane sulfonate (PFOS) in the white-footed mouse (Peromyscus leucopus)

Concerns about per- and polyfluoroalkyl substances (PFAS) stem from their ubiquitous presence in the environment, bioaccumulation, resistance to degradation, and toxicity. Previously, toxicity data relevant to ecological risk assessment has largely been aquatic, terrestrial invertebrates, or avian in origin. In this study, repeated oral exposures of perfluorooctane sulfonate (PFOS) were administered to white-footed mice (Peromyscus leucopus) to evaluate effects on reproduction and development. Prenatal exposure to high doses of PFOS caused neonatal mortality, though growth and development were unaffected by low doses. Additionally, parental (P) generation animals exhibited increased liver:body weight, increased hepatocyte cytoplasmic vacuolization, and decreased serum thyroxine (T4) levels. Total litter loss was selected as the protective critical effect in this study resulting in a benchmark dose low (BMDL) of 0.12 mg/kg-d PFOS. Importantly, PFOS exposure has been linked to reduced adult recruitment in myriad species and at similar thresholds to this study. Similarities in critical/toxicologic effects across taxa may add confidence in risk assessments at sites with multiple taxa or environments.

Tissue distribution of sodium p-perfluorous nonenoxybenzene sulfonate (OBS) in mice via oral exposure

Environmental risks caused by emerging per- and polyfluoroalkyl substances (PFASs) have attracted increasing attention. As an important substitute for perfluorooctane sulfonate (PFOS), sodium p-perfluorous nonenoxybenzene sulfonate (OBS) is widely used as a firefighting foam additive and oil recovery agent in China. This study reported the tissue distribution of OBS in KM mice that were administered a dose of OBS at 10 µg/day via daily oral gavage for 7, 14, or 28 days. During exposure, gender-based differences were observed in body weight changes and tissue distribution of OBS. Liver exhibited the highest concentrations (males: 12.57 ± 1.80 µg/g; females: 11.80 ± 5.32 µg/g) and tissue/blood ratios and contributed more than 50% to the whole-body burden of OBS in both male and female mice, showing its ability to enrich PFASs. Furthermore, there were certain differences in the distribution characteristics of the three OBS isomers. Based on its bioaccumulation potential and widespread use, further studies are required on the human exposure risks of OBS.

Prenatal PFAS and psychosocial stress exposures in relation to fetal growth in two pregnancy cohorts: Applying environmental mixture methods to chemical and non-chemical stressors

BACKGROUND

Prenatal exposure to individual per‑ and poly‑fluoroalkyl substances (PFAS) and psychosocial stressors have been associated with reductions in fetal growth. Studies suggest cumulative or joint effects of chemical and non-chemical stressors on fetal growth. However, few studies have examined PFAS and non-chemical stressors together as a mixture, which better reflects real life exposure patterns. We examined joint associations between PFAS, perceived stress, and depression, and fetal growth using two approaches developed for exposure mixtures.

METHODS

Pregnant participants were enrolled in the Chemicals in Our Bodies cohort and Illinois Kids Development Study, which together make up the ECHO.CA.IL cohort. Seven PFAS were previously measured in 2nd trimester maternal serum samples and were natural log transformed for analyses. Perceived stress and depression were assessed using self-reported validated questionnaires, which were converted to t-scores using validated methods. Quantile g-computation and Bayesian kernel machine regression (BKMR) were used to assess joint associations between PFAS, perceived stress and depression t-scores and birthweight z-scores (N = 876).

RESULTS

Individual PFAS, depression and perceived stress t-scores were negatively correlated with birthweight z-scores. Using quantile g-computation, a simultaneous one quartile increase in all PFAS, perceived stress and depression t-scores was associated with a slight reduction in birthweight z-scores (mean change per quartile increase = -0.09, 95% confidence interval = -0.21,0.03). BKMR similarly indicated that cumulative PFAS and stress t-scores were modestly associated with lower birthweight z-scores. Across both methods, the joint association appeared to be distributed across multiple exposures rather than due to a single exposure.

CONCLUSIONS

Our study is one of the first to examine the joint effects of chemical and non-chemical stressors on fetal growth using mixture methods. We found that PFAS, perceived stress, and depression in combination were modestly associated were lower birthweight z-scores, which supports prior studies indicating that chemical and non-chemical stressors are jointly associated with adverse health outcomes.

Global Exposure to Per- and Polyfluoroalkyl Substances and Associated Burden of Low Birthweight

Low birthweight (LBW) is a worldwide public health concern, while the global burden of LBW attributable to endocrine-disrupting chemicals, such as per- and polyfluoroalkyl substances (PFAS), has not yet been evaluated. Here, we established a large dataset for the biomonitoring of seven representative congeners of PFAS by examining data from 2325 publications. Global exposure to perfluorooctanesulfonic acid (PFOS) was the highest, followed by perfluorohexanesulfonic acid (PFHxS) and perfluorooctanoic acid (PFOA). Spatiotemporal exposure to PFAS varied considerably, with daily intake estimated in the range of 0.01-1.7 ng/kg/day. Moreover, decreasing trends in PFOS, PFHxS, and PFOA exposure were noted in most regions of the world over the past two decades, but such trends were not observed for other PFAS with long carbon chains, especially in East Asia. Furthermore, we estimated that human exposure to PFOA contributed to approximately 461,635 (95% confidence interval: 57,418 to 854,645) cases per year of LBW during the past two decades, predominantly from Asian regions. Although our estimation may be constrained by uncertainties from the dose-response curve and data availability, this study has unveiled that PFAS might be a contributor to global LBW prevalence during 2000-2019, supporting continuous actions to mitigate PFAS contamination.

Developmental toxicity of Nafion byproduct 2 (NBP2) in the Sprague-Dawley rat with comparisons to hexafluoropropylene oxide-dimer acid (HFPO-DA or GenX) and perfluorooctane sulfonate (PFOS)

Nafion byproduct 2 (NBP2) is a polyfluoroalkyl ether sulfonic acid that was recently detected in surface water, drinking water, and human serum samples from monitoring studies in North Carolina, USA. We orally exposed pregnant Sprague-Dawley rats to NBP2 from gestation day (GD) 14-18 (0.1-30 mg/kg/d), GD17-21, and GD8 to postnatal day (PND) 2 (0.3-30 mg/kg/d) to characterize maternal, fetal, and postnatal effects. GD14-18 exposures were also conducted with perfluorooctane sulfonate (PFOS) for comparison to NBP2, as well as data previously published for hexafluoropropylene oxide-dimer acid (HFPO-DA or GenX). NBP2 produced stillbirth (30 mg/kg), reduced pup survival shortly after birth (10 mg/kg), and reduced pup body weight (10 mg/kg). Histopathological evaluation identified reduced glycogen stores in newborn pup livers and hepatocyte hypertrophy in maternal livers at ≥ 10 mg/kg. Exposure to NBP2 from GD14-18 reduced maternal serum total T₃ and cholesterol concentrations (30 mg/kg). Maternal, fetal, and neonatal liver gene expression was investigated using RT-qPCR pathway arrays, while maternal and fetal livers were also analyzed using TempO-Seq transcriptomic profiling. Overall, there was limited alteration of genes in maternal or F1 livers from NBP2 exposure with significant changes mostly occurring in the top dose group (30 mg/kg) associated with lipid and carbohydrate metabolism. Metabolomic profiling indicated elevated maternal bile acids for NBP2, but not HFPO-DA or PFOS, while all three reduced 3-indolepropionic acid. Maternal and fetal serum and liver NBP2 concentrations were similar to PFOS, but ∼10-30-fold greater than HFPO-DA concentrations at a given maternal oral dose. NBP2 is a developmental toxicant in the rat, producing neonatal mortality, reduced pup body weight, reduced pup liver glycogen, reduced maternal thyroid hormones, and altered maternal and offspring lipid and carbohydrate metabolism similar to other studied PFAS, with oral toxicity for pup loss that is slightly less potent than PFOS but more potent than HFPO-DA.

Effects of gestational exposure to perfluorooctane sulfonate on the lung development of offspring rats

Perfluorooctane sulfonate (PFOS) is a man-made fluorosurfactant widely used in industry and consumer products. Previous studies with rats suggested that gestational exposure to PFOS may affect the lung development in the offspring. The mechanism, however, is still unknown. In the present study, we have exposed 24 pregnant SD rats from gestational day 12-18 to different doses of PFOS (0, 1 or 5 mg/kg BW/day). The lungs of the offspring were analyzed at postnatal days 1, 3, 7 and 14. PFOS treatment appeared to reduce the alveolar numbers, resulting in simplified alveolar structure and thickened alveolar septa. Also, PFOS treated animals had increased lung inflammation with up-regulated inflammasome associated proteins NLRP3, ASC, Caspase-1 and GSDMD and increased inflammatory cytokines IL-18 and IL-1β. At the same time, HIF-1α and VEGFA were significantly down-regulated. Since HIF-1α and VEGFA are critical factors promoting alveolar development and pulmonary angiogenesis, these results suggested that PFOS may also affect lung development by inhibiting HIF-1α and VEGFA expression. Our results here indicate that gestational exposure to PFOS may affect lung development in the offspring with pathological characteristics similar to bronchopulmonary dysplasia (BPD), a severe lung developmental defect. The results also suggest that environmental factors such as PFOS may contribute to the increasing incidence of developmental lung diseases, such as BPD, by elevating lung inflammation and inhibiting lung development.

Hexafluoropropylene oxide-dimer acid (HFPO-DA or GenX) alters maternal and fetal glucose and lipid metabolism and produces neonatal mortality, low birthweight, and hepatomegaly in the Sprague-Dawley rat

Hexafluoropropylene oxide dimer acid (HFPO-DA or GenX) is an industrial replacement for the straight-chain perfluoroalkyl substance (PFAS), perfluorooctanoic acid (PFOA). Previously we reported maternal, fetal, and postnatal effects from gestation day (GD) 14-18 oral dosing in Sprague-Dawley rats. Here, we further evaluated the perinatal toxicity of HFPO-DA by orally dosing rat dams with 1-125 mg/kg/d (n = 4 litters per dose) from GD16-20 and with 10-250 mg/kg/d (n = 5) from GD8 - postnatal day (PND) 2. Effects of GD16-20 dosing were similar to those previously reported for GD14-18 dosing and included increased maternal liver weight, altered maternal serum lipid and thyroid hormone concentrations, and altered expression of peroxisome proliferator-activated receptor (PPAR) pathway genes in maternal and fetal livers. Dosing from GD8-PND2 produced similar effects as well as dose-responsive decreased pup birth weight (≥30 mg/kg), increased neonatal mortality (≥62.5 mg/kg), and increased pup liver weight (≥10 mg/kg). Histopathological evaluation of newborn pup livers indicated a marked reduction in glycogen stores and pups were hypoglycemic at birth. Quantitative gene expression analyses of F1 livers revealed significant alterations in genes related to glucose metabolism at birth and on GD20. Maternal serum and liver HFPO-DA concentrations were similar between dosing intervals, indicating rapid clearance, however dams dosed GD8 - PND2 had greater liver weight and gestational weight gain effects at lower doses than GD16-20 dosing, indicating the importance of exposure duration. Comparison of neonatal mortality dose-response curves between HFPO-DA and previously published perfluorooctane sulfonate (PFOS) data indicated that, based on serum concentration, the potency of these two PFAS are similar in the rat. Overall, HFPO-DA is a developmental toxicant in the rat and the spectrum of adverse effects is consistent with prior PFAS toxicity evaluations, such as PFOS and PFOA.

Treatment train approaches for the remediation of per- and polyfluoroalkyl substances (PFAS): A critical review

Per- and polyfluoroalkyl substances (PFAS) have recently drawn great attention due to their ubiquitous presence in aquatic environments and potential toxicity to human health and the environment. A number of recent studies have demonstrated that "passive" removal approaches, such as adsorption, filtration, and reverse osmosis or "active" degradation technologies, such as enhanced photolysis, electrochemical oxidation, and sonochemical destruction, are all able to individually conduct remedial measures for PFAS contamination at some level. However, drawbacks, specifically high energy consumption, low cost-efficiency, and extreme operating conditions, are commonly observed from these studies which significantly suppress the future for commercialization of these innovative technologies. Since 2015, a new trend of PFAS remediation has emerged that uses multiple synergetic technologies simultaneously (known as treatment train processes) to effectively achieve in-situ remediation of PFAS. This paper provides new insight of the recently reported treatment train studies selected from approximately 150 different publications with regards to the remediation of PFAS and discusses their innovative designs, remediation performances, present limits, and possible improvements. Based on a comprehensive review of the current treatment train studies, this review work proposes a new design that consists of three individual technologies, namely, nanofiltration, electrochemical anodic oxidation, and electro-Fenton degradation, to maximize economic and environmental benefits of PFAS remedial measures.

The long-term rapid increase in incidence of adenocarcinoma of the kidney in the USA, especially among younger ages

BACKGROUND

We previously observed a rapid increase in the incidence of renal cell carcinoma (RCC) in men and women between 1935 and 1989 in the USA, using data from the Connecticut Tumor Registry. This increase appeared to be largely explained by a positive cohort effect, but no population-based study has been conducted to comprehensively examine age-period-cohort effects by histologic types for the past decade.

METHODS

We calculated age-adjusted and age-specific incidence rates of the two major kidney-cancer subtypes RCC and renal urothelial carcinoma, and conducted an age-period-cohort analysis of 114 138 incident cases of kidney cancer reported between 1992 and 2014 to the Surveillance, Epidemiology, and End Results programme.

RESULTS

The age-adjusted incidence rates of RCC have been increasing consistently in the USA among both men and women (from 12.18/100 000 in 1992-1994 to 18.35/100 000 in 2010-2014 among men; from 5.77/100 000 in 1992-1994 to 8.63/100 000 in 2010-2014 among women). Incidence rates generally increased in successive birth cohorts, with a continuing increase in rates among the younger age groups (ages 0-54 years) in both men and women and among both Whites and Blacks. These observations were confirmed by age-period-cohort modelling, which suggested an increasing birth-cohort trend for RCC beginning with 1955 birth cohorts, regardless of the assumed value for the period effect for both men and women and for Whites and Blacks.

CONCLUSIONS

Known risk factors for kidney cancer may not fully account for the observed increasing rates or the birth-cohort pattern for RCC, prompting the need for additional etiologic hypotheses (such as environmental exposures) to investigate these descriptive patterns.

SAM targeting methylation by the methyl donor, a novel therapeutic strategy for antagonize PFOS transgenerational fertilitty toxicity

DNA methylation have been suggested as possible mediators of long-term health effects of environmental stressors. This study aimed to evaluate the potential therapy of methylation of S-adenosyl-l-methionine (SAM) on PFOS induced trangeneral reproductive toxicity. In this study, postnatal 5d Sprague Dawley rats were randomly divided into four groups: control, PFOS, PFOS + SAM, and PFOS + Decitabine (DAC). The F0 rats were exposed to 5 mg/kg PFOS and SAM or DAC until PND60. The development of the offsprings were monitored without PFOS exposure. The fertility in F0, F1 rats, and change in F1 testes were observed. The results were as follows. The significant increase in F0 pregnancy rate, and survival rate in F1 offspring in PFOS + SAM relative to PFOS group were observed. Changes of birth weights and physical development in F1 offspring with SAM were approached as a corresponding variation of the control after the deparation period. No pregnant in F1 maternal rats in the PFOS and DAC groups were found, but pregnant in the SAM group. Significantly decrease in the percentage of abnormal seminiferous tubules and increase in expression of promyelocytic leukemia zinc finger (PLZF+) spermatogonial stem cells in F1 testis compared with the PFOS group. Taken together, Methyl donor SAM improve PLZF + spermatogonia stem cell proliferation, attenuate damage in testicular tissue structure, which subsequently improve the transgenerational growth retard and infertility induced by PFOS chronic stress.

Adverse Maternal, Fetal, and Postnatal Effects of Hexafluoropropylene Oxide Dimer Acid (GenX) from Oral Gestational Exposure in Sprague-Dawley Rats

BACKGROUND

Hexafluoropropylene oxide dimer acid [(HFPO-DA), GenX] is a member of the per- and polyfluoroalkyl substances (PFAS) chemical class, and elevated levels of HFPO-DA have been detected in surface water, air, and treated drinking water in the United States and Europe.

OBJECTIVES

We aimed to characterize the potential maternal and postnatal toxicities of oral HFPO-DA in rats during sexual differentiation. Given that some PFAS activate peroxisome proliferator-activated receptors (PPARs), we sought to assess whether HFPO-DA affects androgen-dependent development or interferes with estrogen, androgen, or glucocorticoid receptor activity.

METHODS

Steroid receptor activity was assessed with a suite of in vitro transactivation assays, and Sprague-Dawley rats were used to assess maternal, fetal, and postnatal effects of HFPO-DA exposure. Dams were dosed daily via oral gavage during male reproductive development (gestation days 14-18). We evaluated fetal testes, maternal and fetal livers, maternal serum clinical chemistry, and reproductive development of F1 animals.

RESULTS

HFPO-DA exposure resulted in negligible in vitro receptor activity and did not impact testosterone production or expression of genes key to male reproductive development in the fetal testis; however, in vivo exposure during gestation resulted in higher maternal liver weights ([Formula: see text]), lower maternal serum thyroid hormone and lipid profiles ([Formula: see text]), and up-regulated gene expression related to PPAR signaling pathways in maternal and fetal livers ([Formula: see text]). Further, the pilot postnatal study indicated lower female body weight and lower weights of male reproductive tissues in F1 animals.

CONCLUSIONS

HFPO-DA exposure produced multiple effects that were similar to prior toxicity evaluations on PFAS, such as perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA), but seen as the result of higher oral doses. The mean dam serum concentration from the lowest dose group was 4-fold greater than the maximum serum concentration detected in a worker in an HFPO-DA manufacturing facility. Research is needed to examine the mechanisms and downstream events linked to the adverse effects of PFAS as are mixture-based studies evaluating multiple PFAS. https://doi.org/10.1289/EHP4372.

Perfluoroalkyl acid exposure induces protective mitochondrial and endoplasmic reticulum autophagy in lung cells

Wide application of perfluoroalkyl acids (PFAAs) has raised great concerns on their side-effects on human health. PFAAs have been shown to accumulate mainly in the liver and cause hepatotoxicity. However, PFAAs can also deposit in lung tissues through air-borne particles and cause serious pulmonary toxicity. But the underlying mechanisms are still largely unknown. Autophagy is a type of programmed cell death parallel to necrosis and apoptosis, and may be involved in the lung toxicity of PFAAs. In this study, lung cancer cells, A549, were employed as the model to investigate the effects of three PFAAs with different carbon chain lengths on cell autophagy. Through Western blot analysis on LC3-I/II ratio of cells exposed to non-cytotoxic concentration (200 µM) and cytotoxic concentration (350 µM), we found concentration-dependent increase of autophagosomes in cells, which was further confirmed by TEM examination on ultra-thin section of cells and fluorescence imaging on autophagosomes in live cells. The abundance of p62 increased with the PFAAs concentration indicating the blockage of autophagy flux. Furthermore, we identified the mitochondrial autophagy (mitophagy) and endoplasmic reticulum autophagy (ER-phagy) morphologically as the major types of autophagy, suggesting the disruption on mitochondria and ERs. These organelle damages were confirmed by the overgeneration of ROS, hyperpolarization of mitochondrial membrane potential, as well as the up-regulation of ER-stress-related proteins, ATF4 and p-IRE1. Further analysis on the signaling pathways showed that PFAAs activated the MAPK pathways and inhibited the PI3K/Akt pathway, with potencies following the order of PFDA > PFNA > PFOA. Anti-oxidant (NAC) treatment did not rescue cells from death, indicating that oxidative stress is not the reason of cytotoxicity. Inhibition of autophagy by Atg5 siRNA and chloroquine even increased the toxicity of PFAAs, suggesting that PFAAs-autophagy was induced as the secondary effects of organelle damages and played a protective role during cell death.

Reproductive and developmental toxicity of potassium perfluorohexanesulfonate in CD-1 mice

Potassium perfluorohexanesulfonate (K⁺PFHxS) was evaluated for reproductive/developmental toxicity in CD-1 mice. Up to 3 mg/kg-d K⁺PFHxS was administered (n = 30/sex/group) before mating, for at least 42 days in F₀ males, and for F₀ females, through gestation and lactation. F₁ pups were directly dosed with K⁺PFHxS for 14 days after weaning. There was an equivocal decrease in live litter size at 1 and 3 mg/kg-d, but the pup-born-to-implant ratio was unaffected. Adaptive hepatocellular hypertrophy was observed, and in 3 mg/kg-d F₀ males, it was accompanied by concomitant decreased serum cholesterol and increased alkaline phosphatase. There were no other toxicologically significant findings on reproductive parameters, hematology/clinical pathology/TSH, neurobehavioral effects, or histopathology. There were no treatment-related effects on postnatal survival, development, or onset of preputial separation or vaginal opening in F₁ mice. Consistent with previous studies, our data suggest that the potency of PFHxS is much lower than PFOS in rodents.

Perfluoroalkyl substance exposure and urine CC16 levels among asthmatics: A case-control study of children

BACKGROUND

Studies have reported an association between serum perfluoroalkyl substances (PFASs) and asthma. However, few studies have examined the possible associations between PFASs and the 16-kDa club cell secretory protein (Clara) (CC16) level, a prominent biomarker of asthma, among adolescents.

METHODS

We recruited a total of 231 asthmatic children and 225 non-asthmatic controls in the Genetic and Biomarkers study for Childhood Asthma (GBCA) in northern Taiwan from 2009 to 2010. Structured questionnaires were administered by face-to-face interview. Urine CC16 was determined by an enzyme-link immunoassay kit. Multiple general linear models were employed to examine the associations between PFASs and urinary CC16 levels.

RESULTS

Asthmatic participants had significantly higher serum PFAS concentrations overall than the healthy controls. After adjusting for confounding factors, urinary CC16 was significantly, negatively associated with PFASs, especially PFOS, PFOA, PFDA and PFNA, and especially among males, as follows: PFOS (β = -0.003, 95% confidence interval [CI]: -0.004, -0.002), PFOA (β = -0.045, 95% CI: -0.086, -0.004), and PFHxA (β = -0.310, 95% CI: -0.455, -0.165) among asthmatic boys, and PFDA (β = -0.126, 95%CI: -0.241, -0.012) and PFNA (β = -0.329, 95% CI: -0.526, -0.132) among non-asthmatic boys. Among girls, PFDA (β = -0.088, 95% CI: -0.172, -0.004), was the only PFAS significantly associated with CC16. Significant interaction effects (p < 0.15) on CC16 levels were found between asthma and PFOS, PFOA, PFBS and PFHxA in all participants.

CONCLUSION

Our overall results showed that serum PFASs were significantly, inversely associated with CC16 levels. Associations were stronger among males.

Exposure to PFOA and PFOS and fetal growth: a critical merging of toxicological and epidemiological data

Toxicological and epidemiological evidence on the association between perfluorooctanoic acid (PFOA) or perfluorooctane sulfonic acid (PFOS) and birth/fetal weight was assessed. An extensive search for toxicological information in rats and mice, and a systematic search for epidemiological evidence were conducted. The linear regression coefficient (LRC) of birth weight (BrthW) on PFOA/PFOS was considered, and separate random effects meta-analyses for untransformed (i.e. not mathematically transformed) and log-transformed values were performed. Toxicological evidence: PFOA: 12 studies (21 datasets) in mice showed statistically significant lower birth/fetal weights from 5 mg/kg body weight per day. PFOS: most of the 13 studies (19 datasets) showed lower birth/fetal weights following in utero exposure. Epidemiological evidence: Sixteen articles were considered. The pooled LRC for a 1 ng/mL increase in untransformed PFOA (12 studies) in maternal plasma/serum was -12.8 g (95% CI -23.2; 2.4), and -27.1 g (95% CI -50.6; -3.6) for an increase of 1 log_e ng/mL PFOA (nine studies). The pooled LRC for untransformed PFOS (eight studies) was -0.92 g (95%CI -3.4; 1.6), and for an increase of 1 log_e ng/mL was -46.1(95% CI -80.3; -11.9). No consistent pattern emerged for study location or timing of blood sampling.

CONCLUSIONS

Epidemiological and toxicological evidence suggests that PFOA and PFOS elicit a decrease in BrthW both in humans and rodents. However, the effective animal extrapolated serum concentrations are 10²-10³ times higher than those in humans. Thus, there is no quantitative toxicological evidence to support the epidemiological association, thus reducing the biological plausibility of a causal relationship.

Differential toxicity between perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA)

Perfluoroalkyl substances (PFASs) are persistent environmental contaminants. Perfluorooctane sulfonate (PFOS) and Perfluorooctanoic acid (PFOA) are representatives of PFASs. Recently, the U.S. Environmental Protection Agency (US EPA) set the health advisory level as 70 parts per trillion for lifetime exposure to PFOS and PFOA from drinking water, based on the EPA's 2016 Health Effects Support Documents. Then, a monograph on PFOA was made available online by the International Agency for Research on Cancer, where the agency classified PFOA as "possibly carcinogenic to humans" (Group 2B). The distinction between PFOS and PFOA, however, may not be easily understood from the above documents. This paper discussed differential toxicity between PFOS and PFOA focusing on neurotoxicity, developmental toxicity and carcinogenicity, mainly based on these documents. The conclusions are as follows: Further mechanistic studies may be necessary for ultrasonic-induced PFOS-specific neurotoxicity. To support the hypothesis for PFOS-specific neonatal death that PFOS interacts directly with components of natural lung surfactant, in vivo studies to relate the physicochemical effects to lung collapse may be required. PFOA-induced DNA damage secondary to oxidative stress may develop to mutagenicity under the condition where PFOA-induced apoptosis is not sufficient to remove the damaged cells. A study to find whether PFOA induces apoptosis in normal human cells may contribute to assessment of human carcinogenicity. Studies for new targets such as hepatocyte nuclear factor 4α (HNF4α) may help clarify the underlying mechanism for PFOA-induced carcinogenicity.

Multigenerational effect of perfluorooctane sulfonate (PFOS) on the individual fitness and population growth of Daphnia magna

We investigated the multigenerational effect of PFOS to individual fitness (e.g., body weight, acetylcholinesterase and glutathione S-transferase) and population growth (e.g., offspring number and time to first brood) of Daphnia magna during continuous and discontinuous exposures. The intrinsic rate of population growth was also calculated. In the continuous exposure, population growth-related adverse effects were detected during all test periods, and the adverse effect tended to be weaker in later generations. On the other hand, individual fitness-related adverse effects were observed from F1 not in F0 and deteriorated as the generation number increased. These results imply that individual fitness worsens although the population growth is restored in later generations. Upon discontinuous exposure, a few but significant adverse effects were observed during the non-exposure period and highest effects were detected during the re-exposure period. This encourages the study of different exposure scenarios, which may result in unexpected and higher PFOS toxicity. Consequently, this study confirms adverse effects of PFOS to Daphnia magna in multigenerational period and supports reasons for studies linking individual fitness changes to population dynamics and covering diverse exposure scenarios to evaluate the risk of PFOS in a water environment.

Perfluorooctane sulfonate exposure causes gonadal developmental toxicity in Caenorhabditis elegans through ROS-induced DNA damage

Perfluorooctane sulfonate (PFOS), a common persistent organic pollutant, has been reported to show potential developmental toxicity in many animal studies. However, little was known about its effects on reproductive tissues, especially in the germ line. In the present study, Caenorhabditis elegans was used as an in vivo experimental model to study the developmental toxicity caused by PFOS exposure, especially in the gonads. Our results showed that PFOS exposure significantly retarded gonadal development, as shown by the increased number of worms that remained in the larval stages after hatched L1-stage larvae were exposed to PFOS for 72 h. Investigation of germ line proliferation following PFOS exposure showed that the number of total germ cells reduced in a dose-dependent manner when L1-stage larvae were exposed to 0-25.0 μM PFOS. PFOS exposure induced transient mitotic cell cycle arrest and apoptosis in the germ line. Quantification of DNA damage in proliferating germ cells and production of reactive oxygen species (ROS) showed that distinct foci of HUS-1:GFP and ROS significantly increased in the PFOS-treated groups, whereas the decrease in mitotic germ cell number and the enhanced apoptosis induced by PFOS exposure were effectively rescued upon addition of dimethyl sulfoxide (DMSO) and mannitol (MNT). These results suggested that ROS-induced DNA damage might play a pivotal role in the impairment of gonadal development indicated by the reduction in total germ cells, transient mitotic cell cycle arrest, and apoptosis.

Effects of Environmental Exposures on Fetal and Childhood Growth Trajectories

Delayed fetal growth and adverse birth outcomes are some of the greatest public health threats to this generation of children worldwide because these conditions are major determinants of mortality, morbidity, and disability in infancy and childhood and are also associated with diseases in adult life. A number of studies have investigated the impacts of a range of environmental conditions during pregnancy (including air pollution, endocrine disruptors, persistent organic pollutants, heavy metals) on fetal and child development. The results, while provocative, have been largely inconsistent. This review summarizes up to date epidemiologic studies linking major environmental pollutants to fetal and child development and suggested future directions for further investigation.

Prenatal exposure to PFOS caused mitochondia-mediated apoptosis in heart of weaned rat

Perfluorooctanyl sulfonate (PFOS), a cardiac toxicity compound, has been widely detected in the environment and in organisms. However, the toxic mechanism is not clear. Our previous study indicated that prenatal PFOS exposure led to swollen mitochondrial with vacuolar structure and loss of cristae in offsping's heart. The purpose of this study was to investigate the effect of PFOS on the apoptosis in developing heart and mitochondria-mediated apoptosis pathway. Pregnant Sprague-Dawley (SD) rats were exposed to PFOS at doses of 0.1, 0.6, and 2.0 mg/kg-d and 0.05% Tween 80 as control by gavage from gestation day 2 (GD 2) to GD 21. Apoptosis, as well as expression of apoptosis related genes associated with mitochondrial-mediated apoptosis pathway, including p53, bcl-2, bax, cytochrome c, caspase-9, and caspase-3 were analyzed in heart tissues from weaned (postnatal day 21, PND 21) offspring. The results showed that prenatal PFOS exposure resulted in apoptosis in the offspring's heart. The mRNA and protein expression levels of p53, bax, cytochrome c, caspase-9, and caspase-3 in the offspring's heart were enhanced in various PFOS-treated groups, meanwhile, the bcl-2 expression levels were decreased. Our results indicated that prenatal PFOS exposure induced the apoptosis of weaned offspring rat heart tissue via mitochondria-mediated apoptotic pathway.

Perfluoroalkyl and polyfluoroalkyl substances and human fetal growth: a systematic review

BACKGROUND

Exposure to perfluoroalkyl and polyfluoroalkyl substances (PFASs) is ubiquitous in most regions of the world. The most commonly studied PFASs are perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA). Animal studies indicate that maternal PFAS exposure is associated with reduced fetal growth. However, the results of human studies are inconsistent.

OBJECTIVES

To summarize the evidence of an association between exposure to PFASs, particularly PFOS and PFOA, and human fetal growth.

METHODS

Systematic literature searches were performed in MEDLINE and EMBASE. We included original studies on pregnant women with measurements of PFOA or PFOS in maternal blood during pregnancy or the umbilical cord and associations with birth weight or related outcomes according to the PFAS level. Citations and references from the included articles were investigated to locate more relevant articles. Study characteristics and results were extracted to structured tables. The completeness of reporting as well as the risk of bias and confounding were assessed.

RESULTS

Fourteen studies were eligible. In utero PFOA exposure was associated with decreased measures of continuous birth weight in all studies, even though the magnitude of the association differed and many results were statistically insignificant. PFOS exposure and birth weight were associated in some studies, while others found no association.

CONCLUSIONS

Higher PFOS and PFOA concentrations were associated with decreased average birth weight in most studies, but only some results were statistically significant. The impact on public health is unclear, but the global exposure to PFASs warrants further investigation.

Chronic exposure to perfluorinated compounds: Impact on airway hyperresponsiveness and inflammation

Emerging epidemiological evidence reveals a link between lung disease and exposure to indoor pollutants such as perfluorinated compounds (PFCs). PFC exposure during critical developmental stages may increase asthma susceptibility. Thus, in a murine model, we tested the hypothesis that early life and continued exposure to two ubiquitous household PFCs, perfluorooctanoic acid (PFOA) and perflurooctanesulfonic acid (PFOS), can induce lung dysfunction that exacerbates allergen-induced airway hyperresponsiveness (AHR) and inflammation. Balb/c mice were exposed to PFOA or PFOS (4 mg/kg chow) from gestation day 2 to 12 wk of age by feeding pregnant and nursing dams, and weaned pups. Some pups were also sensitized and challenged with ovalbumin (OVA). We assessed lung function and inflammatory cell and cytokine expression in the lung and examined bronchial goblet cell number. PFOA, but not PFOS, without the OVA sensitization/challenge induced AHR concomitant with a 25-fold increase of lung macrophages. PFOA exposure did not affect OVA-induced lung inflammatory cell number. In contrast, PFOS exposure inhibited OVA-induced lung inflammation, decreasing total cell number in lung lavage by 68.7%. Interferon-γ mRNA in the lung was elevated in all PFC-exposed groups. Despite these effects, neither PFOA nor PFOS affected OVA-induced AHR. Our data do not reveal PFOA or PFOS exposure as a risk factor for more severe allergic asthma-like symptoms, but PFOA alone can induce airway inflammation and alter airway function.

An in-vitro investigation of the effect of perfluorooctane sulphonate on cell lines of embryonic origin

Fluorinated organic compounds, such as perfluorooctane sulfonate, are stable chemicals with a wide range of industrial applications. The potential toxicity of perfluorooctane sulfonate is not well characterized, and even less known are the mechanisms underlying its toxic effects. Perfluorooctane sulfonate change of inner mitochondrial membrane permeability has been implicated as a potential mechanism of toxicity. In this study, we research that perfluorooctane sulfonate effects the expression of Apaf1 and Caspase3 genes in the amnion and fetal lung cell line that initiate the cells to undergo apoptosis. The expression of Caspase3 and Apaf1 was determined by using quantitative RT-PCR. In the study there is significant increase in expression of Caspase3 and Apaf1 in amnion and fetal lung cell line exposed to high dose (p < 0.001, p = 0.004). Also there is significant increase in cell lines exposed for a long period of time to perfluorooctane sulfonate (p = 0.001). But no significant increase was seen in the low doses and exposed for a short period of time. In conclusion, apoptotic gene expression is increase in cells exposed perfluorooctane sulfonate by dose dependent manner was determined. So this work is the first study examines the apoptotic effects of perfluorooctane sulfonate in human embryonic cells it will lead the way to the other topical studies.

Prenatal exposures to perfluorinated chemicals and anthropometry at 7 years of age

Fetal exposure to the perfluoroalkyl acids, perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA), has been associated with lower birth weight and lower weight and body mass index (weight (kg)/height (m)(2)) in early infancy. It is, however, unclear if exposure to prenatal PFOS and PFOA has a lasting influence on growth. We estimated the associations between the maternal plasma level of PFOS or PFOA and the children's body mass index, waist circumference, and risk of overweight at 7 years of age. A total of 1,400 women were randomly selected from the Danish National Birth Cohort among those who provided blood samples early in pregnancy and gave birth to liveborn singletons in 1996-2002. Weight and height information at 7 years was available for 811 children. Multiple linear and logistic regression models were used for analyses. Maternal PFOS and PFOA concentrations were overall inversely but nonsignificantly associated with the children's body mass index, waist circumference, and risk of overweight at 7 years of age. In conclusion, plasma levels of PFOS and PFOA in pregnant women did not seem to have any appreciable influence on their children's anthropometry at this point in childhood.

Glucose and lipid homeostasis in adult rat is impaired by early-life exposure to perfluorooctane sulfonate

Perfluorooctane sulfonate (PFOS), which belongs to the degradation product of many perfluorinated compounds, is on the list of persistent organic pollutants (POPs) and is currently detected in both wildlife and humans. The consequence of gestational and lactational exposure to PFOS on prediabetes effect in offspring was investigated in rats in the present study. Maternal rats were treated with vehicle, 0.5 mg/kg/day or 1.5 mg/kg/day PFOS respectively from gestation day 0 to postnatal day 21. The glucose and lipid metabolism effects were investigated on the offspring in adulthood. The gestational and lactational exposure to PFOS led to low body weight from birth to weaning, and evoked signs of a prediabetic state, with elevated fasting serum insulin and leptin level, impaired glucose tolerance, though the fasting serum glucose and glycosylated serum protein level were normal. Abnormal lipid homeostasis was also observed by the phenomenon of hepatic steatosis and increased gonadal fat pad weight. However, the circulating serum level of fasting triglyceride and cholesterol level were no different from controls. Our results suggested that developmental exposure to PFOS may contribute to glucose and lipid metabolic disorder in adulthood.

In vitro microarray analysis identifies genes in acute-phase response pathways that are down-regulated in the liver of chicken embryos exposed in ovo to PFUdA

Perfluoroundecanoic acid (PFUdA) is one of the most highly detected perfluoroalkyl compounds in wild bird tissues and eggs. Although PFUdA does not affect hatching success, many PFCs are known to impair post-hatch development and survival. Here we use microarrays to survey the transcriptional response of cultured chicken embryonic hepatocytes (CEH) to PFUdA for potential targets of PFUdA action that could lead to developmental deficiencies in exposed birds. At 1 μM and 10 μM PFUdA significantly altered the expression of 346 and 676 transcripts, respectively (fold-change>1.5, p<0.05, false discovery rate-corrected). Using functional, pathway and interactome analysis we identified several potentially important targets of PFUdA exposure, including the suppression of the acute-phase response (APR). We then measured the expression of five APR genes, fibrinogen alpha (fga), fibrinogen gamma (fgg), thrombin (f2), plasminogen (plg), and protein C (proC), in the liver of chicken embryos exposed in ovo to PFUdA. The expression of fga, f2, and proC were down-regulated in embryo livers (100 or 1000 ng/g, p<0.1) as predicted from microarray analysis, whereas fibrinogen gamma (fgg) was up-regulated and plg was not significantly affected. Our results demonstrate the utility of CEH coupled with transcriptome analysis as an in vitro screening tool for identifying novel effects of toxicant exposure. Additionally, we identified APR suppression as a potentially important and environmentally relevant target of PFUdA. These findings suggest in ovo exposure of birds to PFUdA may lead to post-hatch developmental deficiencies, such as impaired inflammatory response.

Circulating maternal perfluoroalkyl substances during pregnancy in the C8 Health Study

Perfluoroalkyl substances are manmade chemicals used in many consumer products and have become ubiquitous in the environment. Animal studies and a limited number of human studies have demonstrated developmental effects in offspring exposed to perfluoroalkyl substances in utero, but the implications of timing of in utero exposure have not been systematically investigated. The present study investigated variation in perfluorocarbon levels of 9952 women of childbearing age who had been exposed to perfluorooctanoic acid (PFOA) in drinking water contaminated by industrial waste. An analysis of variance with contrast was performed to compare the levels of PFOA and perfluorooctanesulfonic acid (PFOS) in pregnant and nonpregnant women overall and during each trimester of pregnancy. We found that pregnant women had lower circulating PFOA and PFOS concentrations in peripheral blood than nonpregnant women and that PFOA levels were consistently lower throughout all trimesters for pregnancy, suggesting transfer to the fetus at an early stage of gestation. These results are discussed in the context of the endocrine-disrupting properties of perfluoroalkyl substances that have been characterized in animal and human studies. Our conclusion is that further, systematic study of the potential implications of intrauterine perfluorocarbon exposure during critical periods of fetal development is urgently needed.

Chronic PFOS exposures induce life stage-specific behavioral deficits in adult zebrafish and produce malformation and behavioral deficits in F1 offspring

Perfluorooctane sulfonic acid (PFOS) is an organic contaminant that is ubiquitous in the environment. Few studies have assessed the behavioral effects of chronic PFOS exposure in aquatic organisms. The present study defined the behavioral effects of varying life span chronic exposures to PFOS in zebrafish. Specifically, zebrafish were exposed to control or 0.5 µM PFOS during 1 to 20, 21 to 120, or 1 to 120 d postfertilization (dpf). Exposure to PFOS impaired the adult zebrafish behavior mode under the tapping stimulus. The movement speed of male and female fish exposed for 1 to 120 dpf was significantly increased compared with control before and after tapping, whereas in the groups exposed for 1 to 20 and 21 to 120 dpf, only the males exhibited elevated swim speed before tapping. Residues of PFOS in F1 embryos derived from parental exposure for 1 to 120 and 21 to 120 dpf were significantly higher than control, and F1 embryos in these two groups also showed high malformation and mortality. The F1 larvae of parental fish exposed to PFOS for 1 to 20 or 21 to 120 dpf exhibited a higher swimming speed than control larvae in a light-to-dark behavior assessment test. The F1 larvae derived from parental fish exposed to PFOS for 1 to 120 dpf showed a significantly lower speed in the light period and a higher speed in the dark period compared with controls. Although there was little PFOS residue in embryos derived from the 1- to 20-dpf parental PFOS-exposed group, the adverse behavioral effects on both adult and F1 larvae indicate that exposure during the first 21 dpf induces long-term neurobehaviorial toxicity. The authors' findings demonstrate that chronic PFOS exposure during different life stages adversely affects adult behavior and F1 offspring morphology, behavior, and survival.

Perfluorinated compounds in umbilical cord blood and adverse birth outcomes

Background

Previous animal studies have shown that perfluorinated compounds (PFCs) have adverse impacts on birth outcomes, but the results have been inconclusive in humans. We investigated associations between prenatal exposure to perfluorooctanoic acid (PFOA), perfluorooctyl sulfonate (PFOS), perfluorononanoic acid (PFNA), and perfluoroundecanoic acid (PFUA) and birth outcomes.

Methods

In total, 429 mother-infant pairs were recruited from the Taiwan Birth Panel Study (TBPS). Demographic data were obtained by interviewing mothers using a structured questionnaire and birth outcomes were extracted from medical records. Cord blood was collected for PFOA, PFOS, PFNA, and PFUA analysis by ultra-high-performance liquid chromatography/tandem mass spectrometry.

Results

The geometric mean (standard deviation) levels of PFOA, PFOS, PFNA, and PFUA in cord blood plasma were 1.84 (2.23), 5.94 (1.95), 2.36(4.74), and 10.26 (3.07) ng/mL, respectively. Only PFOS levels were found to be inversely associated with gestational age, birth weight, and head circumference [per ln unit: adjusted β (95% confidence interval, CI) = −0.37 (−0.60, −0.13) wks, −110.2 (−176.0, −44.5) gm and −0.25 (−0.46, −0.05) cm]. Additionally, the odds ratio of preterm birth, low birth weight, and small for gestational age increased with PFOS exposure [per ln unit: adjusted odds ratio (OR) (95%CI) = 2.45 (1.47, 4.08), 2.61(0.85, 8.03) and 2.27 (1.25, 4.15)]. When PFOS levels were divided into quartiles, a dose-response relation was observed. However, PFOA, PFNA, and PFUA were not observed to have any convincing impact on birth outcomes.

Conclusions

An adverse dose-dependent association was observed between prenatal PFOS exposure and birth outcomes. However, no associations were found for the other examined PFCs.

Transcription of genes involved in fat metabolism in chicken embryos exposed to the peroxisome proliferator-activated receptor alpha (PPARα) agonist GW7647 or to perfluorooctane sulfonate (PFOS) or perfluorooctanoic acid (PFOA)

Perfluoroalkyl acids (PFAAs) such as perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) are developmental toxicants in various animal classes, including birds. Both compounds interact with peroxisome proliferator-activated receptors (PPARs), but it is not known whether activation of PPARs is involved in their embryo toxicity in birds. We exposed chicken embryos via egg injection at a late developmental stage to GW7647, a potent PPARα agonist in mammals, and to PFOS or PFOA. Mortality was induced by PFOS and PFOA but not by GW7647. Transcripts of a number of genes activated by PPARα agonists in mammals were analyzed in liver and kidney of 18-day-old embryos. Several of the genes were induced in both liver and kidney following exposure to GW7647. Treatment with PFOA resulted in induction of acyl-coenzyme A oxidase mRNA in liver, whereas none of the genes were significantly induced by PFOS treatment. No up-regulation of gene transcription was found in kidney following treatment with PFOS or PFOA. Principal component analysis showed that PFOA caused an mRNA expression pattern in liver more similar to the pattern induced by GW7647 than PFOS did. Our findings do not support that the embryo mortality by PFOS and PFOA in chicken embryos involves PPARα activation.

Gene expression profiling in fetal rat lung during gestational perfluorooctane sulfonate exposure

Perfluorooctane sulfonate (PFOS) is a persistent environmental contaminant found in the tissues of humans and wildlife. It has been reported that gestational exposure to PFOS causes neonatal death of rats. However, the mechanism is still unclear. In this study, we investigated the effects of gestational PFOS exposure on the gene expression profiling of fetal rat lung at pseudoglandular stage. Adult Sprague Dawley dams were dosed orally from gestational day 12-18 with 0 (control), 5 mg/kg/day or 20 mg/kg/day PFOS. Animals were euthanized on day 18.5, fetal lung samples were collected for histochemical staining and RNA profiling analysis. PFOS did not cause apparent microscopic changes of fetal lungs. Gene expression profiling revealed that PFOS dose-dependently up-regulated the expression of 21 (5 mg/kg) and 43 (20 mg/kg) genes. These genes include five PPARα target genes (Acot1, Hmgcs2, Fabp4, Fabp1 and Myh7), and 4 of them are involved in lipid metabolism. The other genes were primarily included in the categories of cytoskeletal structure (Tpm1, Tnnt2, Actn3, Myoz2, Tmod1, and Mfap5), extracellular matrix (Ckm, Lum, Tnnc1, Art3, Dcn, Col17a1, Aspn, Ctsk, Itm2a, Spock2 and Orm1), transporting (Cox8h, Cox6a2 and Scnn1a) and secreted proteins (Scgb3a1, Nppb and Spp1). Our study demonstrates that in utero PFOS exposure resulted in the alteration of a set of genes which are involved in significant cytoskeletal, extracellular matrix remodeling, lipid metabolism and secreted proteins in the fetal rat lung.

Abnormal development of motor neurons in perfluorooctane sulphonate exposed zebrafish embryos

Perfluorooctane sulfonate (PFOS) is an environmental organic pollutant, the potential neurotoxicity of which is causing great concern in fish. In the present study, we examined the effects of PFOS on motor neurons, and investigated the potential toxicological mechanisms oxidative stress in zebrafish embryos. Six-hour post-fertilization (hpf) zebrafish embryos were exposed to 1.0 mg/L PFOS, then we examined the expression of alpha-tubulin, proliferating cell nuclear antigen (PCNA), cyclin-dependent kinase 5 (CDK5), and peroxiredoxin 2 (PRX2) after PFOS exposure until 120 hpf. The results showed that PFOS increased alpha-tubulin in the coccygeal spinal cord (CSC) at 96 hpf, whereas decreased alpha-tubulin in the brain and spinal cord at 120 hpf. PCNA expression was highly increased in CSC and abdomen compared with control at 96 and 120 hpf after PFOS exposure. In addition, PFOS exposure caused CDK5 expression to be highly increased in brain region following by down-regulation of PRX2 expression at 96 hpf. These results indicated that, at least in part, the effect on motor neurons induced by PFOS was mediated by dynamically interfering with the expression of alpha-tubulin and PCNA. Furthermore, PFOS-induced toxicity was associated with oxidative stress by deregulating CDK5 and PRX2.

Effects of environmentally-relevant levels of perfluorooctane sulfonate on clinical parameters and immunological functions in B6C3F1 mice

In the first part of a series of studies to account for perfluorooctane sulfonate (PFOS)-induced sheep red blood cell (SRBC)-specific immunoglobulin M (IgM) antibody suppression in mice, a survey of clinical and immunotoxicological endpoints was examined. Adult female B₆C₃F₁ mice were exposed orally for 28 days to a total administered dose (TAD) of 0, 0.1, 0.5, 1, or 5 mg PFOS/kg. Uterus wet weight was significantly decreased compared with control at the 5 mg/kg dose. No indications of wasting syndrome, malnutrition, alteration of thyroid homeostasis, or signs of overt toxicity were observed. Numbers of splenic CD19+/CD21⁻, CD19+/CD21+, B220+/CD40+, CD4+/CD154⁻, CD4+/CD154+, and MHC-II+ cells were not altered. Additionally, ex vivo interleukin-4 (IL-4), IL-5, and IL-6 production by in vitro anti-CD3- or phorbol myristate acetate-stimulated CD4+ T-cells was not affected. Ex vivo IL-6 production by B-cells was significantly increased by in vitro stimulation with either anti-CD40 or lipopolysaccharide. Increased IL-6 production by B-cells was the most sensitive endpoint assessed resulting in alterations at the lowest dose tested (0.1 mg/kg TAD) following anti-CD40 stimulation. Further studies are required to characterize effects on inflammatory markers such as IL-6 at environmentally relevant concentrations of PFOS and to determine the key events associated with PFOS-induced IgM suppression to address potential human health risks.

Structure-activity relationship assessment of four perfluorinated chemicals using a prolonged zebrafish early life stage test

Perfluorinated compounds (PFCs) are a group of anthropogenic chemicals containing diverse functional groups and chain lengths. They are known to be persistent and bioaccumulative explaining their worldwide environmental presence. The toxicological information on these chemicals is still incomplete and insufficient to assess their environmental impact and structure-activity relationship. In the present study, the developmental effects of PFOS (perfluorooctane sulfonate, C8), PFOA (perfluorooctanoic acid, C8), PFBS (perfluorobutane sulfonate, C4) and PFBA (perfluorobutanoic acid, C4) were evaluated in zebrafish embryos (Danio rerio). The different chain lengths and functional groups of the selected chemicals made it possible to determine the structure-activity relationship of these compounds. PFCs with longer chain lengths (C8) tend to be more toxic than PFCs with shorter chain lengths (C4). Comparison based on the functional groups of compounds with the same chain length indicates that PFCs with a sulfonate group have a larger toxic potential than the ones with a carboxyl group. Furthermore, exposure to the different PFCs resulted in some general effects, such as deformations of the tail and an uninflated swim bladder, as well as in more specific effects which might be related to the structure of the tested chemicals. Oedemas and effects on length could only be detected in 8-carbon PFCs while malformations of the head were a more specific action of the sulfonated PFCs. Effects on hatching rate and success were found in PFOA exposed embryos and heart rates were affected after exposure to PFOS, PFOA and PFBS.

Developmental effects of perfluorononanoic Acid in the mouse are dependent on peroxisome proliferator-activated receptor-alpha

Perfluorononanoic acid (PFNA) is one of the perfluoroalkyl acids found in the environment and in tissues of humans and wildlife. Prenatal exposure to PFNA negatively impacts survival and development of mice and activates the mouse and human peroxisome proliferator-activated receptor-alpha (PPARα). In the current study, we used PPARα knockout (KO) and 129S1/SvlmJ wild-type (WT) mice to investigate the role of PPARα in mediating PFNA-induced in vivo effects. Pregnant KO and WT mice were dosed orally with water (vehicle control: 10 ml/kg), 0.83, 1.1, 1.5, or 2 mg/kg PFNA on gestational days (GDs) 1–18 (day of sperm plug = GD 0). Maternal weight gain, implantation, litter size, and pup weight at birth were unaffected in either strain. PFNA exposure reduced the number of live pups at birth and survival of offspring to weaning in the 1.1 and 2 mg/kg groups in WT. Eye opening was delayed (mean delay 2.1 days) and pup weight at weaning was reduced in WT pups at 2 mg/kg. These developmental endpoints were not affected in the KO. Relative liver weight was increased in a dose-dependent manner in dams and pups of the WT strain at all dose levels but only slightly increased in the highest dose group in the KO strain. In summary, PFNA altered liver weight of dams and pups, pup survival, body weight, and development in the WT, while only inducing a slight increase in relative liver weight of dams and pups at 2 mg/kg in KO mice. These results suggest that PPARα is an essential mediator of PFNA-induced developmental toxicity in the mouse.

Perfluorinated compounds, polychlorinated biphenyls, and organochlorine pesticide contamination in composite food samples from Dallas, Texas, USA

OBJECTIVES

The objective of this article is to extend our previous studies of persistent organic pollutant (POP) contamination of U.S. food by measuring perfluorinated compounds (PFCs), organochlorine pesticides, and polychlorinated biphenyls (PCBs) in composite food samples. This study is part of a larger study reported in two articles, the other of which reports levels of polybrominated diphenyl ethers and hexabromocyclododecane brominated flame retardants in these composite foods [Schecter et al. 2010. Polybrominated diphenyl ethers (PBDEs) and hexabromocyclodecane (HBCD) in composite U.S. food samples, Environ Health Perspect 118:357-362].

METHODS

In this study we measured concentrations of 32 organochlorine pesticides, 7 PCBs, and 11 PFCs in composite samples of 31 different types of food (310 individual food samples) purchased from supermarkets in Dallas, Texas (USA), in 2009. Dietary intake of these chemicals was calculated for an average American.

RESULTS

Contamination varied greatly among chemical and food types. The highest level of pesticide contamination was from the dichlorodiphenyltrichloroethane (DDT) metabolite p,p -dichlorodiphenyldichloroethylene, which ranged from 0.028 ng/g wet weight (ww) in whole milk yogurt to 2.3 ng/g ww in catfish fillets. We found PCB congeners (28, 52, 101, 118, 138, 153, and 180) primarily in fish, with highest levels in salmon (PCB-153, 1.2 ng/g ww; PCB-138, 0.93 ng/g ww). For PFCs, we detected perfluorooctanoic acid (PFOA) in 17 of 31 samples, ranging from 0.07 ng/g in potatoes to 1.80 ng/g in olive oil. In terms of dietary intake, DDT and DDT metabolites, endosulfans, aldrin, PCBs, and PFOA were consumed at the highest levels.

CONCLUSION

Despite product bans, we found POPs in U.S. food, and mixtures of these chemicals are consumed by the American public at varying levels. This suggests the need to expand testing of food for chemical contaminants.