Two-generation reproduction and cross-foster studies of perfluorooctanesulfonate (PFOS) in rats

Regulation of Perfluorooctanoic Acid (PFOA) and Perfluorooctane Sulfonic Acid (PFOS) in Drinking Water: A Comprehensive Review

Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) are receiving global attention due to their persistence in the environment through wastewater effluent discharges and past improper industrial waste disposal. They are resistant to biological degradation and if present in wastewater are discharged into the environment. The US Environmental Protection Agency (USEPA) issued drinking water Health Advisories for PFOA and PFOS at 70 ng/L each and for the sum of the two. The need for an enforceable primary drinking water regulation under the Safe Drinking Water Act (SDWA) is currently being assessed. The USEPA faces stringent legal constraints and technical barriers to develop a primary drinking water regulation for PFOA and PFOS. This review synthesizes current knowledge providing a publicly available, comprehensive point of reference for researchers, water utilities, industry, and regulatory agencies to better understand and address cross-cutting issues associated with regulation of PFOA and PFOS contamination of drinking water.

Derivation of a chronic reference dose for perfluorohexane sulfonate (PFHxS) for reproductive toxicity in mice

Perfluorohexane sulfonate (PFHxS) is a six-carbon perfluoroalkyl sulfonic acid that was used as an industrial surfactant, but is now found as an environmental contaminant worldwide. In addition to its use as an industrial surfactant, it is a legacy contaminant from the use of aqueous film-forming foams. Despite its widespread occurrence in the environment and evidence of biological activity associated with PFHxS and similar perfluoroalkyl sulfonic acids in rodents, there is no oral toxicity value currently available from the IRIS Database. To derive an oral reference dose (RfD) for PFHxS, available toxicity studies were reviewed using a weight-of-evidence approach. A 42-day mouse reproductive study was chosen as the critical study for the derivation of the oral RfD. Benchmark dose modeling was utilized to derive a point of departure (POD) for a reduction in litter size. A 95% lower confidence limit on the benchmark dose (BMDL) of 13,900 ng/mL (serum PFHxS) was modeled for a reduction in litter size. An oral RfD for PFHxS of 4.0 ng/kg/d was calculated by conversion of the BMDL to a human equivalent oral dose using a human half-life adjusted dosimetric conversion factor and the application of a total uncertainty factor of 300. Additional research is needed to better characterize the toxicity associated with oral exposure to PFHxS and refine the development of toxicity values.

Occurrence and tissue distribution of perfluoroalkyl substances (PFASs) in sharks and rays from the eastern Mediterranean Sea

Persistent organic pollutants (POPs), including Perfluoroalkyl substances (PFASs), enter into the marine ecosystem, raising questions on possible adverse effects caused to the health of marine organisms and especially of top predators. Thus, there is an urge to assess the occurrence and the tissue distribution of PFASs in apex predators. To this end, the current study examines concentrations and distribution of 15 PFASs among 85 samples of different tissues from 9 shark and ray species collected in Greece. The results showed a similar PFAS pattern among the different tissues, with long carbon chain PFASs being the most frequently detected compounds. PFTrDA was the most predominant compound in terms of concentration and frequency of detection, followed by PFUnDA and PFOS. PFTrDA concentrations ranged between < LOQ and 27.1 ng/g ww, while PFUnDA and PFOS levels ranged from <LOQ to 16.0 and < LOQ to 21.6 ng/g ww, respectively. Regarding their frequency of detection, PFTrDA and PFUnDA were detected in 98% and 91% of the samples, respectively, while PFOS was detected in 79%. ΣPFAS concentrations in each analysed tissue ranged from 0.3 to 85 ng/g ww, with the latter being detected in the liver of angular roughshark (Oxynotus centrina). On average, PFASs were found to be accumulated in tissues in the following order: gonads > heart > liver ≈ gills > muscle. Relative contribution (%) of individual compounds to ΣPFAS concentration varied among the different shark tissues, and also among the different shark species. No correlation between PFASs levels in tissues and sharks' gender, length and geographical origin was observed.

Neurodevelopmental and Metabolomic Responses from Prenatal Coexposure to Perfluorooctanesulfonate (PFOS) and Methylmercury (MeHg) in Sprague-Dawley Rats

Methylmercury (MeHg) and perfluorooctanesulfonate (PFOS) are major contaminants of human blood that are both common in dietary fish, thereby raising questions about their combined impact on human development. Here, pregnant Sprague-Dawley rats ingested a daily dose, from gestational day 1 through to weaning, of either 1 mg/kg bw PFOS (PFOS-only), 1 mg/kg MeHg (MeHg-only), a mixture of 0.1 mg/kg PFOS and 1 mg/kg MeHg (Low-Mix), or of 1 mg/kg of PFOS and 1 mg/kg MeHg (High-Mix). Newborns were monitored for physical milestones and reflexive developmental responses, and in juveniles the spontaneous activity, anxiety, memory, and cognition were assessed. Targeted metabolomics of 199 analytes was applied to sectioned brain regions of juvenile offspring. Newborns in the High-Mix group had decreased weight gain as well as delayed reflexes and innate behavioral responses compared to controls and individual chemical groups indicating a toxicological interaction on early development. In juveniles, cumulative mixture effects increased in a dose-dependent manner in tests of anxiety-like behavior. However, other developmental test results suggested antagonism, as PFOS-only and MeHg-only juveniles had increased hyperactivity and thigmotaxic behavior, respectively, but fewer effects in Low-Mix and High-Mix groups. Consistent with these behavioral observations, a pattern of antagonism was also observed in neurochemicals measured in rat cortex, as PFOS-only and MeHg-only juveniles had altered concentrations of metabolites (e.g., lipids, amino acids, and biogenic amines), while no changes were evident in the combined exposures. The cortical metabolites altered in PFOS-only and MeHg-only exposed groups are involved in inhibitory and excitatory neurotransmission. These proof-of-principle findings at relatively high doses indicate the potential for toxicological interaction between PFOS and MeHg, with developmental-stage specific effects. Future mixture studies at lower doses are warranted, and prospective human birth cohorts should consider possible confounding effects from PFOS and mercury exposure on neurodevelopment.

Bayesian evaluation of a physiologically based pharmacokinetic (PBPK) model for perfluorooctane sulfonate (PFOS) to characterize the interspecies uncertainty between mice, rats, monkeys, and humans: Development and performance verification

A challenge in the risk assessment of perfluorooctane sulfonate (PFOS) is the large interspecies differences in its toxicokinetics that results in substantial uncertainty in the dosimetry and toxicity extrapolation from animals to humans. To address this challenge, the objective of this study was to develop an open-source physiologically based pharmacokinetic (PBPK) model accounting for species-specific toxicokinetic parameters of PFOS. Considering available knowledge about the toxicokinetic properties of PFOS, a PBPK model for PFOS in mice, rats, monkeys, and humans after intravenous and oral administrations was created. Available species-specific toxicokinetic data were used for model calibration and optimization, and independent datasets were used for model evaluation. Bayesian statistical analysis using Markov chain Monte Carlo (MCMC) simulation was performed to optimize the model and to characterize the uncertainty and interspecies variability of chemical-specific parameters. The model predictions well correlated with the majority of datasets for all four species, and the model was validated with independent data in rats, monkeys, and humans. The model was applied to predict human equivalent doses (HEDs) based on reported points of departure in selected critical toxicity studies in rats and monkeys following U.S. EPA's guidelines. The lower bounds of the model-derived HEDs were overall lower than the HEDs estimated by U.S. EPA (e.g., 0.2 vs. 1.3 μg/kg/day based on the rat plasma data). This integrated and comparative analysis provides an important step towards improving interspecies extrapolation and quantitative risk assessment of PFOS, and this open-source model provides a foundation for developing models for other perfluoroalkyl substances.

Longitudinal analysis reveals early-pregnancy associations between perfluoroalkyl sulfonates and thyroid hormone status in a Canadian prospective birth cohort

Serum perfluoroalkyl acids (PFAAs) have been linked to disruption of maternal thyroid hormone homeostasis, but results have varied between studies which we hypothesized was due to timing of the thyroid hormone measurements, variability in PFAA isomer patterns, or presence of other stressors. In a longitudinal study design, we investigated the time-dependency of associations between PFAA isomers and thyroid hormones during pregnancy and post-partum while considering thyroid peroxidase antibody (TPOAb) status and mercury (Hg) co-exposure. In participants of a prospective Canadian birth cohort (n = 494), free thyroxine (FT4), free triiodothyronine (FT3), thyroid stimulating hormone (TSH) and TPOAb were quantified in maternal plasma collected in each trimester and 3-months postpartum, and 25 PFAAs (15 linear and 10 branched) and Hg were quantified in samples collected during the second trimester. Perfluorohexane sulfonate (PFHxS) and total branched isomers of perfluorooctane sulfonate (PFOS) were positively associated with TSH in mixed-effect models, with strongest associations early in gestation. Throughout pregnancy and post-partum, PFHxS was inversely associated with FT4, consistent with elevated TSH, while Hg was inversely associated with FT3. In TPOAb-positive women, negative associations were found between PFUnA and FT4, and 1m-PFOS and TSH, supporting previous studies that thyroid disorder could increase susceptibility to PFAA-mediated hormone dysregulation. Hg did not confound associations but was a significant interaction term, revealing further positive associations between PFOS isomers (∑3m+4m-PFOS) and TSH. Higher perfluoroalkyl sulfonate exposures were associated with higher TSH and/or lower FT4, strongly suggestive that PFHxS and branched PFOS isomers are risk factors for subclinical maternal hypothyroidism. Isomer-specific analysis is important in future studies, as crude measures of 'total-PFOS' masked the associations of branched isomers. A concerning result was for PFHxS which had consistent negative associations with FT4 at all time points and a positive association with TSH in early pregnancy when fetal development is most sensitive to disruption.

Breastfeeding as a Predictor of Serum Concentrations of Per- and Polyfluorinated Alkyl Substances in Reproductive-Aged Women and Young Children: A Rapid Systematic Review

PURPOSE OF REVIEW

Per- and polyfluorinated alkyl substances (PFASs) are synthetic chemicals widely detected in human serum, and at low levels in breast milk. We conducted a rapid systematic review on breastfeeding practices and serum concentrations of PFASs-specifically PFOS and PFOA-among reproductive-aged women and young children using the Navigation Guide systematic review methodology.

RECENT FINDINGS

We included 14 studies examining associations between breastfeeding and PFASs in infants/toddlers or pregnant/postnatal women. Breastfeeding was significantly associated with lower PFASs exposure among women and higher PFASs exposure among children. We concluded there was "sufficient" evidence supporting an association between breastfeeding and serum PFASs concentrations among women, and "limited" evidence of an association among children due to issues with sample size, confounding, and exposure assessment. These findings reinforce that lactation is an important excretion route of PFASs for women, and that breast milk may be an important exposure pathway for young children.

The derivation of a Reference Dose (RfD) for perfluorooctane sulfonate (PFOS) based on immune suppression

Exposure to perfluorooctane sulfonate (PFOS) is ubiquitous in populations and environments worldwide. Its long half-life in humans, indefinite persistence in the environment, and awareness of its widespread presence in drinking water make the human health assessment of PFOS a priority. While developmental, endocrine, and hepatic effects, and increased serum cholesterol are among the outcomes resulting from PFOS exposure, immunosuppression has also consistently emerged as an adverse effect. An in-depth review of the relevant scientific literature on the toxicology of PFOS has identified immunosuppression as a sensitive endpoint for PFOS toxicity. Here, we focus specifically on that endpoint and provide a detailed derivation of a Reference Dose (RfD) of 1.8 × 10^-6 mg/kg/day for chronic human exposure to PFOS. This RfD is based on decreased plaque-forming cell (PFC) response in mice, an endpoint that reflects suppression of the immune response to a foreign antigen. We additionally identify two endpoints in the epidemiology literature, decreased vaccine response and increased incidence of childhood infections, that are associated with PFOS exposure and that are consistent with and support the decreased PFC response endpoint from animal studies. We provide a weight of evidence analysis integrating the evidence from animal and epidemiology endpoints. Finally, we compare this RfD to the PFOS RfD derived by the United States Environmental Protection Agency (USEPA) Office of Water based on a developmental endpoint. Based on this comparison, and given our assessment, the USEPA RfD does not provide sufficient protection against the adverse health effects of PFOS. The RfD derived herein is intended to be public health protective and appropriately minimizes PFOS exposure based on available evidence.

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.

Neonatal and juvenile exposure to perfluorooctanoate (PFOA) and perfluorooctane sulfonate (PFOS): Advance puberty onset and kisspeptin system disturbance in female rats

Perfluorooctanoate (PFOA) and perfluorooctane sulfonate (PFOS) are widespread and persistent chemicals in the environment, and limited data about their effects on puberty development are available. In order to explore the effects of neonatal and juvenile PFOA/PFOS exposure on puberty maturation, female rats were injected with PFOA or PFOS at 0.1, 1 and 10 mg/kg/day during postnatal day (PND) 1-5 or 26-30. The day of vaginal opening (VO) and first estrus were significantly advanced in 10 mg/kg PFOA, 1 and 10 mg/kg PFOS groups after neonatal and juvenile exposure. Besides, neonatal PFOA/PFOS exposure increased body weight and anogenital distance (AGD) in a non-dose-dependent manner. Estradiol and luteinizing hormone levels were also increased with more frequent occurrences of irregular estrous cycles in 0.1 and 1 mg/kg PFOA/PFOS exposure groups. Although no altered ovarian morphology was observed, follicles numbers were reduced in neonatal groups. Kiss1, Kiss1r and ERα mRNA expressions were downregulated after two periods' exposure in the hypothalamic anteroventral periventricular (AVPV) and arcuate (ARC) nuclei. PFOA/PFOS exposure also suppressed kisspeptin fiber intensities, especially at the high dose. In conclusion, neonatal and juvenile are critical exposure periods, during which puberty maturation may be vulnerable to environmental exposure of PFOA/PFOS, and kisspeptin system plays a key role during these processes.

Risk to human health related to the presence of perfluorooctane sulfonic acid and perfluorooctanoic acid in food

The European Commission asked EFSA for a scientific evaluation on the risks to human health related to the presence of perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) in food. Regarding PFOS and PFOA occurrence, the final data set available for dietary exposure assessment contained a total of 20,019 analytical results (PFOS n = 10,191 and PFOA n = 9,828). There were large differences between upper and lower bound exposure due to analytical methods with insufficient sensitivity. The CONTAM Panel considered the lower bound estimates to be closer to true exposure levels. Important contributors to the lower bound mean chronic exposure were 'Fish and other seafood', 'Meat and meat products' and 'Eggs and egg products', for PFOS, and 'Milk and dairy products', 'Drinking water' and 'Fish and other seafood' for PFOA. PFOS and PFOA are readily absorbed in the gastrointestinal tract, excreted in urine and faeces, and do not undergo metabolism. Estimated human half-lives for PFOS and PFOA are about 5 years and 2-4 years, respectively. The derivation of a health-based guidance value was based on human epidemiological studies. For PFOS, the increase in serum total cholesterol in adults, and the decrease in antibody response at vaccination in children were identified as the critical effects. For PFOA, the increase in serum total cholesterol was the critical effect. Also reduced birth weight (for both compounds) and increased prevalence of high serum levels of the liver enzyme alanine aminotransferase (ALT) (for PFOA) were considered. After benchmark modelling of serum levels of PFOS and PFOA, and estimating the corresponding daily intakes, the CONTAM Panel established a tolerable weekly intake (TWI) of 13 ng/kg body weight (bw) per week for PFOS and 6 ng/kg bw per week for PFOA. For both compounds, exposure of a considerable proportion of the population exceeds the proposed TWIs.

Environmental Chemicals in Breast Milk and Formula: Exposure and Risk Assessment Implications

BACKGROUND

Human health risk assessment methods have advanced in recent years to more accurately estimate risks associated with exposure during childhood. However, predicting risks related to infant exposures to environmental chemicals in breast milk and formula remains challenging.

OBJECTIVES

Our goal was to compile available information on infant exposures to environmental chemicals in breast milk and formula, describe methods to characterize infant exposure and potential for health risk in the context of a risk assessment, and identify research needed to improve risk analyses based on this type of exposure and health risk information.

METHODS

We reviewed recent literature on levels of environmental chemicals in breast milk and formula, with a focus on data from the United States. We then selected three example publications that quantified infant exposure using breast milk or formula chemical concentrations and estimated breast milk or formula intake. The potential for health risk from these dietary exposures was then characterized by comparison with available health risk benchmarks. We identified areas of this approach in need of improvement to better characterize the potential for infant health risk from this critical exposure pathway.

DISCUSSION

Measurements of chemicals in breast milk and formula are integral to the evaluation of risk from early life dietary exposures to environmental chemicals. Risk assessments may also be informed by research investigating the impact of chemical exposure on developmental processes known to be active, and subject to disruption, during infancy, and by analysis of exposure-response data specific to the infant life stage. Critical data gaps exist in all of these areas.

CONCLUSIONS

Better-designed studies are needed to characterize infant exposures to environmental chemicals in breast milk and infant formula as well as to improve risk assessments of chemicals found in both foods. https://doi.org/10.1289/EHP1953.

Internal concentrations of perfluorobutane sulfonate (PFBS) comparable to those of perfluorooctane sulfonate (PFOS) induce reproductive toxicity in Caenorhabditis elegans

Perfluorobutane sulfonate (PFBS) is considered a less-toxic replacement for perfluorooctane sulfonate (PFOS), with multiple applications in industrial and consumer products. Previous studies comparing their toxicity generally used similar exposure levels, without taking internal concentrations into account. The current study compared the reproductive toxicity of PFOS and PFBS, at similar internal concentrations, to Caenorhabditis elegans (C. elegans). PFBS was much less bioaccumulative than PFOS. The 48-h median lethal concentrations (LC₅₀) for PFOS and PFBS were 1.4 μM (95% confidence interval [CI]: 1.1-1.6) and 794 μM (95% CI: 624-1009), respectively. Egg production and brood number of C. elegans decreased markedly following exposure to 0.1 μM PFOS or 1000 or 1500 μM PFBS. Germ-cell apoptosis and production of reactive oxygen species increased significantly following exposure to 2 μM PFOS or 500 or 1000 μM PFBS. Expression of the antioxidant genes sod-3, ctl-2, and gst-4 and the pro-apoptotic genes egl-1 and ced-13 was altered significantly following PFOS and PFBS exposure. These findings indicate that both chemicals exert reproductive toxicity in C. elegans, probably owing to germ-cell apoptosis resulting from elevated levels of reactive oxygen species. The vastly different exposure concentrations of PFBS and PFOS used in this study produced similar internal concentrations, leading to the reproductive toxicities observed.

Chlorinated Polyfluoroalkylether Sulfonates Exhibit Similar Binding Potency and Activity to Thyroid Hormone Transport Proteins and Nuclear Receptors as Perfluorooctanesulfonate

Chlorinated polyfluoroalkylether sulfonates (Cl-PFAESs) have been used as perfluorooctanesulfonate (PFOS) alternatives in the chrome plating industry for years. Although Cl-PFAESs have become ubiquitous environmental contaminants, knowledge on their toxicological mechanism remains very limited. We compared potential thyroid hormone (TH) disruption effects of Cl-PFAESs and PFOS via the mechanisms of competitive binding to TH transport proteins and activation of TH receptors (TRs). Fluorescence binding assays revealed that 6:2 Cl-PFAES, 8:2 Cl-PFAES and F-53B (a mixture of 6:2 and 8:2 Cl-PFAES) all interacted with a TH transport protein transthyretin (TTR), with 6:2 Cl-PFAES showing the highest affinity. It was also found that the chemicals interacted with TRs, with the affinity following the order of 6:2 Cl-PFAES > PFOS > 8:2 Cl-PFAES. In reporter gene assays the chemicals exhibited agonistic activity toward TRs, with the potency of 6:2 Cl-PFAES comparable to that of PFOS. The chemicals also promoted GH3 cell proliferation, with 6:2 Cl-PFAES displaying the highest potency. Molecular docking and molecular dynamic simulation revealed that both Cl-PFAESs fit into the ligand binding pockets of TTR and TRs with the binding modes similar to PFOS. Collectively, our results demonstrate that Cl-PFAESs might cause TH disruption effects through competitive binding to transport proteins and activation of TRs.

The serum concentrations of perfluoroalkyl compounds were inversely associated with growth parameters in 2-year old children

The relationship between the serum concentrations of perfluoroalkyl compounds (PFCs) and growth parameters was investigated in 2-year-old Korean children. The study included 361 children aged 2years (192 boys and 169 girls; 22-27months), born at term appropriate-for-gestational-age, who visited between 2012 and 2013. Growth parameters of height and weight, and serum samples were collected from 2-year-old children. Four PFCs (perfluorohexane sulfonic acid [PFHxS], perfluorooctane sulfonic acid [PFOS], perfluorooctanoic acid [PFOA], and perfluorononanoic acid [PFNA]), perfluorodecanoic acid (PFDA), perfluoroundecanoic acid (PFUnDA), and perfluoroheptanoic acid (PFHpA) were detected in >99, 93.4, 89.8, and 74.2% of the serum samples, respectively. The duration of breastfeeding was positively associated with the serum concentrations of ln-transformed PFHxS, PFOS, PFHpA, PFOA, PFNA, PFDA, and PFUnDA (all P<0.001). Height at 2years of age was inversely related to PFHxS, PFOS, PFOA, PFNA, and PFDA concentrations (adjusted β per ln unit [95% confidence interval, CI]: -0.84 [-1.26, -0.42], -0.77 [-1.27, -0.15], -0.91 [-1.36, -0.47], -0.48 [-1.40, -0.51], and -0.44 [-0.77, -0.10] cm, respectively), after adjusting for age, sex, and midparental height. Weight at 2years of age was inversely associated with PFNA (adjusted β per ln unit [95% CI]: -0.32 [-0.48, -0.15] kg), after adjusting for age, sex, and parental BMI. In conclusion, the serum concentrations of PFCs were inversely associated with growth parameters in 2-year-old children.

Prenatal Perfluorooctyl Sulfonate Exposure and Alu DNA Hypomethylation in Cord Blood

BACKGROUND

Perfluoroalkyl substances (PFASs) are stable and persistent in the environment, animals, and humans. PFASs can penetrate placenta and affect fetal growth. We investigated associations between prenatal exposure to perfluorooctanoic acid (PFOA), perfluorooctyl sulfonate (PFOS), perfluorononanoic acid (PFNA), and perfluoroundecanoic acid (PFUA) and global methylation levels. Specific Aims and Methods: The study used the subjects from Taiwan Birth Panel birth cohort study, including all pregnant women who gave birth between July 2004 and June 2005 in four hospitals in Taipei city and New Taipei City. A total of 363 mother-infant pairs were included in the final analyses. PFOA, PFOS, PFNA, and PFUA were measured by UPLC-MS/MS in cord blood. LINE-1 and Alu repeated elements from cord blood was used to represent global DNA methylation levels. Multivariable regression models were used to adjust potential confounders.

RESULTS

After controlling for potential confounders, each unit increase in the natural log-transformed PFOS exposure was associated with an adjusted OR of 1.72 (95% CI: 1.03, 2.88) for low Alu methylation level when dichotomized methylation level by medium. No significant effects between PFOA, PFNA, PFUA and methylation levels in the multivariable regression models were observed.

CONCLUSIONS

Our findings suggest that prenatal PFOS exposure may be associated with low Alu methylation level.

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.

Simultaneous determination of (N-ethyl perfluorooctanesulfonamido ethanol)-based phosphate diester and triester and their biotransformation to perfluorooctanesulfonate in freshwater sediments

While (N-ethyl perfluorooctanesulfonamido ethanol)-based phosphates (SAmPAPs) have been proposed as a group of perfluorooctanesulfonate (PFOS) precursors, investigation of their occurrence and fate has been limited to SAmPAP diester. In this study, SAmPAP diester and triester were simultaneously determined in freshwater sediment from Taihu Lake using a newly developed UPLC-MS/MS method, and their biotransformation to PFOS in lake sediment was investigated. SAmPAP diester and triester were detected in sediments with a detection frequency of 56% and 88%, and their mean concentrations were 0.24 ± 0.11 ng/g dry weight (dw) and 0.12 ± 0.03 ng/g dw, respectively. The SAmPAP diester/triester ratio in sediment was 1.1 ± 4.2, much lower than that (6.7) observed in the technical product, and the positive correlation was found between the concentrations of SAmPAP diester and PFOS in sediments (r² = 0.45, p = 0.01), suggesting that SAmPAP diester would be biotransformed to PFOS in the lake sediment. The microbial degradation test in the lake sediments further clarified that SAmPAP diester was biodegraded to PFOS, but SAmPAP triester was highly recalcitrant to microbial degradation. This study suggests that the occurrence of SAmPAP diester in freshwater lake sediments may be an important precursor of PFOS.

Elevation of intracellular calcium and oxidative stress is involved in perfluorononanoic acid–induced neurotoxicity

Perfluorononanoic acid (PFNA) is one of the major perfluorinated compounds found in both biological and abiotic samples and has recently been demonstrated to cause neurobehavioral defects in mammals. In this study, pheochromocytoma-12 (PC12) cells were exposed to various doses of PFNA to explore the cytotoxicity of PFNA to neurons and the possible mechanisms underlying these effects. The results showed that exposure to PFNA dose-dependently decreased the viability of PC12 cells and increased the release of lactate dehydrogenase into cell culture media. Exposure to PFNA increased the malondialdehyde content and decreased the total antioxidant capacity and glutathione peroxidase activity in PC12 cell culture supernatants. Exposure to PFNA increased the intracellular calcium level and upregulated the Ca2+/calmodulin-dependent protein kinase II (CaMKII) expression in PC12 cells. PFNA also decreased Bcl-2 expression and increased Bax expression in PC12 cells. These results suggested that exposure to PFNA elevated the intracellular calcium level and activated the CaMKII signaling pathway, which may aggravate oxidative stress in PC12 cells and lead to cell damage or cell apoptosis.

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.

Issues raised by the reference doses for perfluorooctane sulfonate and perfluorooctanoic acid

On 25th May 2016, the U.S. EPA released reference doses (RfDs) for Perfluorooctane Sulfonate (PFOS) and Perfluorooctanoic Acid (PFOA) of 20ng/kg/day, which were much more conservative than previous values. These RfDs rely on the choices of animal point of departure (PoD) and the toxicokinetics (TK) model. At this stage, considering that the human evidence is not strong enough for RfD determination, using animal data may be appropriate but with more uncertainties. In this article, the uncertainties concerning RfDs from the choices of PoD and TK models are addressed. Firstly, the candidate PoDs should include more critical endpoints (such as immunotoxicity), which may lead to lower RfDs. Secondly, the reliability of the adopted three-compartment TK model is compromised: the parameters are not non-biologically plausible; and this TK model was applied to simulate gestation and lactation exposures, while the two exposure scenarios were not actually included in the model structure.

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.

Oral perfluorooctane sulfonate (PFOS) lessens tumor development in the APCmin mouse model of spontaneous familial adenomatous polyposis

Background

Colorectal cancer is the second most common cause of cancer deaths for both men and women, and the third most common cause of cancer in the U.S. Toxicity of current chemotherapeutic agents for colorectal cancer, and emergence of drug resistance underscore the need to develop new, potentially less toxic alternatives. Our recent cross-sectional study in a large Appalachian population, showed a strong, inverse, dose–response association of serum perfluorooctane sulfonate (PFOS) levels to prevalent colorectal cancer, suggesting PFOS may have therapeutic potential in the prevention and/or treatment of colorectal cancer. In these preliminary studies using a mouse model of familial colorectal cancer, the APC^min mouse, and exposures comparable to those reported in human populations, we assess the efficacy of PFOS for reducing tumor burden, and evaluate potential dose–response effects.

Methods

At 5–6 weeks of age, APC^min mice were randomized to receive 0, 20, 250 mg PFOS/kg (females) or 0, 10, 50 and 200 mg PFOS/kg (males) via their drinking water. At 15 weeks of age, gastrointestinal tumors were counted and scored and blood PFOS levels measured.

Results

PFOS exposure was associated with a significant, dose–response reduction in total tumor number in both male and female mice. This inverse dose–response effect of PFOS exposure was particularly pronounced for larger tumors (r² for linear trend = 0.44 for males, p’s <0.001).

Conclusions

The current study in a mouse model of familial adenomatous polyposis offers the first experimental evidence that chronic exposure to PFOS in drinking water can reduce formation of gastrointestinal tumors, and that these reductions are both significant and dose-dependent. If confirmed in further studies, these promising findings could lead to new therapeutic strategies for familial colorectal cancer, and suggest that PFOS testing in both preventive and therapeutic models for human colorectal cancer is warranted.

Perfluoroalkyl and polyfluoroalkyl substances in cord blood of newborns in Shanghai, China: Implications for risk assessment

Perfluoroalkyl and polyfluoroalkyl substances (PFASs) are commonly used in industrial applications and consumer products, and their potential health impacts are of concern, especially for vulnerable population like fetuses. However, in utero exposure to PFASs and health implications are far from fully characterized in China. To fill in the gap, we analyzed 10 PFASs in cord plasma samples (N=687) collected in Shanghai between 2011 and 2012, one of the regions widely polluted with PFASs in China. A questionnaire survey on maternal and diet-related factors was conducted. Except for perfluoroheptanoic acid (PFHpA) and perfluorooctane sulfonamide (PFOSA), all other PFASs were detected in ˃90% of the samples. Perfluorooctanoic acid (PFOA) was the most predominant PFAS (median value: 6.96ng/mL), followed by perfluorooctane sulfonate (PFOS) (2.48ng/mL). PFOA and PFOS combined contributed to 80% of the total PFASs. The final multiple regression models showed that maternal factors including maternal age, body mass index, gestational age, economic status and educational level as well as consumption of fish and wheat were significantly related with concentrations of PFASs in cord blood. The risk assessment using the hazard quotients (HQs) approach on the basis of plasma PFAS levels indicated no potential concern for developmental toxicity in the local newborns. The results demonstrate the unique profiles of local prenatal exposure to PFASs, suggesting that PFOA has been the primary human exposure due to its widespread use and pollution. Special attention to high PFOA exposure and confirmation of potential determinants should be taken as a priority in the future plan for risk management and actions in this area.

Perfluorooctane sulfonate-induced testicular toxicity and differential testicular expression of estrogen receptor in male mice

Perfluorooctane sulfonate (PFOS, CAS#1763-23-1) causes male reproductive toxicities, but the underlying mechanisms are still unclear. In this study, 0, 0.5 and 10mg/kg/day PFOS were given by oral gavage to adult mice for 5 weeks. In the 10mg/kg group, serum testosterone levels decreased significantly. Sperm counts declined which might be associated with the decreased proliferation and increased apoptosis of germ cells. In relation to increased apoptosis, bax, cleaved caspase-9 and cleaved caspase-3 levels elevated significantly, indicating that PFOS induced germ cell apoptosis by activating the mitochondrial pathway. In addition, the increase in levels of testicular estrogen receptor (ER) β was observed in both 0.5 and 10mg/kg group, whereas a decrease in ERα expression was only observed in 10mg/kg group. These results suggested that the alterations in testicular ERs expression, together with decreased proliferation and increased apoptosis of germ cells, might be involved in PFOS-induced testicular toxicity.

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.

The expression of several reproductive hormone receptors can be modified by perfluorooctane sulfonate (PFOS) in adult male rats

This study was undertaken to evaluate the possible role of several reproductive hormone receptors on the disruption of the hypothalamic-pituitary-testis (HPT) axis activity induced by perfluorooctane sulfonate (PFOS). The studied receptors are the gonadotropin-releasing hormone receptor (GnRHr), luteinizing hormone receptor (LHr), follicle-stimulating hormone receptor (FSHr), and the androgen receptor (Ar). Adult male rats were orally treated with 1.0; 3.0 and 6.0 mg of PFOS kg(-1) d(-1) for 28 days. In general terms, PFOS can modify the relative gene and protein expressions of these receptors in several tissues of the reproductive axis. At the testicular level, apart from the expected inhibition of both gene and protein expressions of FSHr and Ar, PFOS also stimulates the GnRHr protein and the LHr gene expression. The receptors of the main hormones involved in the HPT axis may have an important role in the disruption exerted by PFOS on this axis.

Developmental perfluorooctane sulfonate exposure results in tau hyperphosphorylation and β-amyloid aggregation in adults rats: Incidence for link to Alzheimer's disease

With regard to the defects of the cognitive function observed after developmental exposure to perfluorooctane sulfonate (PFOS), and earlier studies on the developmental neurotoxicology, the aim of this study was to investigate the role of developmental PFOS exposure in neurodegenerative disorders in later life. Two pathological hallmarks of Alzheimer's disease (AD), Tau hyperphosphorylation and β-amyloid (Aβ) aggregation, were examined. SD rats were exposed to PFOS during only prenatal and/or postnatal period. Tau mRNA and protein levels were elevated by PFOS exposure. The phosphorylation of Tau at S199, T231 and S396 sites were also increased. Besides, PFOS exposure increased the Aβ1-42 levels, as well as the amyloid precursor protein (APP) regulation. The prenatal PFOS exposure caused alterations in the involved proteins at comparable levels with the postnatal and both prenatal and postnatal exposure. Thus, it has raised some evidence that early PFOS exposure can affect processes linked to neurodegeneration, enhancing the AD pathological risk. And PFOS exposures in early life may be of particular etiologic importance of neurodegenerative diseases.

Perfluorooctane Sulfonate Plasma Half-Life Determination and Long-Term Tissue Distribution in Beef Cattle (Bos taurus)

Perfluorooctane sulfonate (PFOS) is used in consumer products as a surfactant and is found in industrial and consumer waste, which ends up in wastewater treatment plants (WWTPs). PFOS does not breakdown during WWTP processes and accumulates in the biosolids. Common practices include application of biosolids to pastures and croplands used for feed, and as a result, animals such as beef cattle are exposed to PFOS. To determine plasma and tissue depletion kinetics in cattle, 2 steers and 4 heifers were dosed with PFOS at 0.098 mg/kg body weight and 9.1 mg/kg, respectively. Plasma depletion half-lives for steers and heifers were 120 ± 4.1 and 106 ± 23.1 days, respectively. Specific tissue depletion half-lives ranged from 36 to 385 days for intraperitoneal fat, back fat, muscle, liver, bone, and kidney. These data indicate that PFOS in beef cattle has a sufficiently long depletion half-life to permit accumulation in edible tissues.

Perfluoroalkyl substances measured in breast milk and child neuropsychological development in a Norwegian birth cohort study

Perfluoroalkyl substances (PFASs) are chemicals with potential neurotoxic effects although the current evidence is still limited. This study investigated the association between perinatal exposure to perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) and neuropsychological development assessed at 6, 12 and 24 months. We measured PFOS and PFOA in breast milk samples collected one month after delivery by mothers of children participating in the HUMIS study (Norway). Cognitive and psychomotor development was measured at 6 and at 24 months using the Ages and Stages Questionnaire (ASQ-II). Behavioral development was assessed using the infant-toddler symptom checklist (ITSC) at 12 and at 24 months. Weighted logistic regression and weighted negative binomial regression models were applied to analyze the associations between PFASs and ASQ-II and ITSC, respectively. The median concentration of PFOS was 110 ng/L, while the median for PFOA was 40 ng/L. We did not detect an increased risk of having an abnormal score in ASQ-II at 6 months or 24 months. Moreover, no consistent increase in behavioral problems assessed at 12 and 24 months by ITSC questionnaire was detected. We observed no association between perinatal PFOS and PFOA exposure and early neuropsychological development. Further longitudinal studies are needed to confirm the effects of these compounds on neuropsychological development in older children.

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.

Toxicity and DNA methylation changes induced by perfluorooctane sulfonate (PFOS) in sea urchin Glyptocidaris crenularis

Perfluorooctane sulfonate (PFOS) is an ubiquitous persistent organic pollutant, which can be bioaccumulated and cause adverse effects on organisms. However, there is very limited information about the toxic effects of PFOS to marine organisms and its mechanisms. Therefore, in the present study, adult sea urchins Glyptocidaris crenularis were exposed to PFOS for 21 d, followed by a 7-d depuration period, in order to investigate the toxicity of PFOS to sea urchin and its potential epigenetic mechanisms. Sea urchins dropped spines, and lowered down the motor ability and feeding ability after the PFOS exposure. Superoxide dismutase activities in supernatant of coelomic fluid of sea urchin increased firstly and then dropped down, while the change of the catalase activity took an opposite trend during the exposure period. They both approached to the corresponding activity of the control after the depuration period. The DNA methylation polymorphism, methylation rate and demethylation rate in sea urchin gonad all increased following the prolonged exposure time, and then decreased after the depuration period. The demethylation rates were lower than the corresponding methylation rates, therefore methylation events were dominant during the whole experimental period. This might suggest that sea urchin have strong self-protection mechanisms and can survive from the PFOS exposure presented in this study. Further efforts are needed to more precisely investigate the DNA methylation effects of PFOS and the self-protection mechanism of sea urchin.

Temporal trends of perfluorooctanesulfonate isomer and enantiomer patterns in archived Swedish and American serum samples

Human perfluorooctanesulfonate (PFOS) body burdens are attributable to both direct PFOS and indirect PFOS precursor (PreFOS) exposure. The relative importance of these two pathways has been estimated, but the relative temporal trajectory of exposure to PFOS and PreFOS has not been examined. Here, two hypothesized biomarkers of PreFOS exposure, PFOS isomer profiles (quantified as percent branched PFOS, %br-PFOS) and chiral 1m-PFOS enantiomer fractions (1m-PFOS EF) were analyzed in archived human serum samples of individual American adults (1974-2010) and pooled samples of Swedish primiparous women (1996-2010). After correcting for potential confounders, significant correlations between %br-PFOS and 1m-PFOS EFs were observed in American samples and in Swedish samples for the 1996-2000 period, supporting the hypothesis that both %br-PFOS and 1m-PFOS EF are biomarkers of PreFOS exposure. Significant trends of increasing %br-PFOS, from 2000 to 2010, and increasingly non-racemic 1m-PFOS EFs, from 1996 to 2000, were detected in Swedish samples. No statistically significant trend for %br-PFOS or 1m-PFOS EF was observed in American samples, but American males had significantly higher %br-PFOS and significantly lower 1m-PFOS EF (i.e. more non-racemic) than females, and a similar significant difference was shown in the older age group, relative to the younger age group. These temporal trends in %br-PFOS and 1m-PFOS EF are not easily explained and the results highlight uncertainties about how humans are exposed to PFOS.

Perfluorochemicals and human semen quality: the LIFE study

BACKGROUND

The relation between persistent environmental chemicals and semen quality is evolving, although limited data exist for men recruited from general populations.

OBJECTIVES

We examined the relation between perfluorinated chemicals (PFCs) and semen quality among 501 male partners of couples planning pregnancy.

METHODS

Using population-based sampling strategies, we recruited 501 couples discontinuing contraception from two U.S. geographic regions from 2005 through 2009. Baseline interviews and anthropometric assessments were conducted, followed by blood collection for the quantification of seven serum PFCs (perfluorosulfonates, perfluorocarboxylates, and perfluorosulfonamides) using tandem mass spectrometry. Men collected a baseline semen sample and another approximately 1 month later. Semen samples were shipped with freezer packs, and analyses were performed on the day after collection. We used linear regression to estimate the difference in each semen parameter associated with a one unit increase in the natural log-transformed PFC concentration after adjusting for confounders and modeling repeated semen samples. Sensitivity analyses included optimal Box-Cox transformation of semen quality end points.

RESULTS

Six PFCs [2-(N-methyl-perfluorooctane sulfonamido) acetate (Me-PFOSA-AcOH), perfluorodecanoate (PFDeA), perfluorononanoate (PFNA), perfluorooctane sulfonamide (PFOSA), perfluorooctane sulfonate (PFOS), and perfluorooctanoic acid (PFOA)] were associated with 17 semen quality end points before Box-Cox transformation. PFOSA was associated with smaller sperm head area and perimeter, a lower percentage of DNA stainability, and a higher percentage of bicephalic and immature sperm. PFDeA, PFNA, PFOA, and PFOS were associated with a lower percentage of sperm with coiled tails.

CONCLUSIONS

Select PFCs were associated with certain semen end points, with the most significant associations observed for PFOSA but with results in varying directions.

Effects of developmental perfluorooctane sulfonate exposure on spatial learning and memory ability of rats and mechanism associated with synaptic plasticity

The present study aims to explore the effects of perfluorooctane sulfonate (PFOS) on cognitive function in developing rats and the underlying mechanism associated with synaptic plasticity. Pregnant Wistar rats were fed with 0, 5, and 15 mg/L of PFOS via drinking water during gestation and lactation. Offspring were exposed to PFOS on prenatal and/or postnatal days by cross-fostering. Spatial learning and memory abilities were tested from postnatal day (PND) 35. We also analyzed the expression pattern of the synaptic plasticity-related genes and proteins in the hippocampus on PND7 and PND35. Results revealed that PFOS exposure reduced the spatial learning and memory abilities of the offspring, particularly of those with prenatal exposure. Meanwhile, protein levels of growth-associated protein-43, neural cell adhesion molecule 1, nerve growth factor, and brain-derived neurotrophic factor decreased on PND35, which are involved in the formation of synaptic plasticity. In contrast, significant increase in gap-43, ncam1, and bdnf genes on the mRNA level was observed on PND7, possibly due to the post-transcriptional mechanism. Results of both behavioral effects and molecular endpoints suggested the high risk of prenatal PFOS exposure. The decline of spatial learning and memory abilities induced by developmental PFOS exposure was closely related to synaptic plasticity.

Elucidating the molecular basis of adverse health effects from exposure to anthropogenic polyfluorinated compounds using toxicoproteomic approaches

Linear, short-chain polyfluorinated and perfluorinated alkyl compounds, often referred to as PFCs, have been in worldwide use as surfactants and polymer precursors for decades, and environmental dispersal of these highly persistent compounds represents a public health threat. Whereas ubiquitous low-level exposure to these compounds has been demonstrated in human populations from around the world, the exact mechanisms of toxicity and their toxic potency remain subject to investigation and scientific dispute. As with other environmental exposures, a major hurdle for gaining a better understanding of their human health impacts is the limited utility of cell culture and animal models serving as convenient, yet imperfect proxies to human physiology and disease. The present communication provides a brief overview of the current understanding of potential health effects of PFC exposure and examines how new toxicoproteomic methodologies can provide insight into the molecular mechanism of PFC exposure. Furthermore, we showcase an exemplary data set to illustrate how toxicoproteomic, population-wide studies might overcome limitations of animal models to more fully understand the metabolism and effects of PFCs and other environmental stressors where it matters most, in human populations experiencing real-world, chronic, low-level exposures.

Persistent organic pollutants measured in maternal serum and offspring neurodevelopmental outcomes--a prospective study with long-term follow-up

Fetal exposure to persistent organic pollutants (POPs) has been linked to adverse neurodevelopment, but few studies have had follow-up beyond childhood. The purpose of this study was to examine the association of maternal serum concentrations of two perfluoroalkyl acids (perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS)), polychlorinated biphenyls (PCBs), dichlorodiphenyldichloroethylene (p,p'-DDE) and hexachlorobenzene (HCB) with offspring behavioural and affective disorders and scholastic achievement in a prebirth cohort study with 20 years of follow up. Between 1988 and 1989 pregnant women (n=965) were recruited for the prebirth Danish Fetal Origins 1988 (DaFO88) Cohort in Aarhus, Denmark. Perfluoroalkyl acids, PCBs, p,p'-DDE, and HCB were quantified in serum from week 30 of gestation (n=876 for perfluoroalkyl acids/872 for PCBs, p,p'-DDE, HCB). Offspring were followed up through national registries until 2011. We evaluated associations between maternal serum concentrations of these POPs and offspring neurodevelopmental outcomes, defined as: first admission diagnosis or prescription of medication until age >20 for (1) ADHD; (2) depression; and (3) scholastic achievement defined as mean grade on a standardized written examination given in the 9th grade (final exams of compulsory school in Denmark). Maternal concentrations of organochlorine substances and perfluoroalkyl acids were higher than present day levels. During the follow-up period there were 27 (3.1%) cases of ADHD and 104 (11.9%) cases of depression; the mean scholastic achievement was 6.7 (SD 2.3). Overall we found no association for maternal levels of any of the measured pollutants with offspring behavioural and affective disorders or with scholastic achievement. Our analyses based on biomarkers from a cohort of over 800 pregnant women with long-term close to complete follow-up through national registries showed little evidence of a programming effect of PFOA, PFOS, PCBs, p,p'-DDE, and HCB in relation to clinically and functionally relevant offspring neurodevelopmental outcomes.

Early life perfluorooctanesulphonic acid (PFOS) exposure impairs zebrafish organogenesis

As a persistent organic contaminant, perfluorooctanesulphonic acid (PFOS) has been widely detected in the environment, wildlife, and humans. The present study revealed that zebrafish embryos exposed to 16 μM PFOS during a sensitive window of 48-96 hour post-fertilization (hpf) disrupted larval morphology at 120 hpf. Malformed zebrafish larvae were characterized by uninflated swim bladder, less developed gut, and curved spine. Histological and ultrastructural examination of PFOS-exposed larvae showed structural alterations in swim bladder and gut. Whole genome microarray was used to identify the early transcripts dysregulated following exposure to 16 μM PFOS at 96 hpf. In total, 1278 transcripts were significantly misexpressed (p<0.05) and 211 genes were changed at least two-fold upon PFOS exposure in comparison to the vehicle-exposed control group. A PFOS-induced network of perturbed transcripts relating to swim bladder and gut development revealed that misexpression of genes were involved in organogenesis. Taken together, early life stage exposure to PFOS perturbs various molecular pathways potentially resulting in observed defects in swim bladder and gut development.

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.

Organic contaminants in bats: trends and new issues

Exposure to contaminants, often pesticides, has been implicated as a major factor contributing to decreases in bat populations. Bats provide essential ecosystem services and a sustained, thriving population is vital for ecosystem health. Understanding issues threatening their survival is crucial for their protection and conservation. This paper provides the first review for 12years on organic pollutants in bats and aims to investigate trends and any new issues impacting bat resilience. Organochlorine (OC) pesticides have been reported most often, especially in the older literature, with the dichlorodiphenyltrichloroethane (DDT) metabolite, dichlorodiphenyldichloroethylene (DDE), present at highest concentrations in tissues analyzed. The OC pesticide concentrations reported in bat tissues have declined significantly since the late 1970s, presumably as a result of restrictions in use. For example, DDE study mean concentrations over time periods 1970-1980, 1981-1999 and 2000-2013 ranged from 2.6-62, 0.05-2.31, 0.08-0.19ppm wet weight, respectively. Exposure, however, still occurs from remaining residues, many years after the compounds have been actively used. In recent years (2000-2013), a range of other organic chemicals have been reported in bat tissues including brominated flame retardants (polybrominated diphenyl ether at a mean concentration of 2.9ppm lipid weight) and perfluorinated compounds (perfluorooctanyl sulfonate at a mean concentration 0.09ppm wet weight). The persistent organic compounds concentrate in tissues with higher fat content notably back-depot fat. Numerous factors influence exposure, residues detected and concentrations in different individuals, species and tissues which must be understood to provide meaningful assessment of the impacts of exposure. Exposure can lead to not only acute and lethal impacts, but also physiological sub-lethal and chronic effects, often linked to the annual cycle of fat deposition and withdrawal. Current challenges for bat conservation include collation of a more extensive and standardized database of bat exposure, especially to current use pesticides and emerging contaminants, and better prediction and definition of toxicity end points notably for the sub-lethal effects. Understanding sub-lethal effects will be of greater importance for sustaining populations in the longer-term.