Exposure to perfluorooctanesulfonate (PFOS) but not perflurorooctanoic acid (PFOA) at ppb concentration induces chronic toxicity in Daphnia carinata

Widespread environmental contamination of per- and polyfluoroalkyl substances (PFAS) is well established. Nevertheless, few studies have reported on the aquatic toxicity of PFAS, especially in indicator species such as Daphnia. In this study, the toxicity of two major PFAS, namely perfluorooctanoic acid (PFOA) and perfluorooctanesulfonate (PFOS), was investigated on water flea (Daphnia carinata) using a battery of comprehensive toxicity tests, including a 48 h acute and a 21-day chronic assays. The survival, growth, and reproduction of D. carinata were monitored over a 21-day life cycle. PFOS exhibited higher toxicity than PFOA. The 48 h LC₅₀ values (confidence interval) based on acute toxicity for PFOA and PFOS were 78.2 (54.9-105) mg L^-1 and 8.8 (6.4-11.6) mg L^-1, respectively. Chronic exposure to PFOS for 21 days displayed mortality and reproductive defects in D. carinata at a concentration as low as 0.001 mg L^-1. Genotoxicity assessment using comet assay revealed that exposure for 96 h to PFOS at 1 and 10.0 mg L^-1 significantly damaged the organism's genetic makeup. The results of this study have great implications for risk assessment of PFOS and PFOA in aquatic ecosystems, given the potential of PFOS to pose a risk to Daphnia even at lower concentrations (1 μg L^-1).

Non-targeted metabolomics of multiple human cells revealing differential toxic effects of perfluorooctanoic acid

Differences in toxic effects of contaminants among human cells are essential for evaluating their health risks to humans. In this study, non-targeted metabolomics of multiple human cell lines (A549 (lung), DLD-1 (intestine) and L-02 (liver) cells) was used to address the differential toxicity of perfluorooctanoic acid (PFOA). The number of differential metabolites (DMs) identified in the PFOA-treated A549 cells (67) was highest, followed by DLD-1 (12) and L-02 cells (10). The categorization of DMs was almost uniquely specific to each of cell lines. PFOA significantly promoted linoleic acid metabolism in L-02 cells whereas this metabolism was inhibited in the PFOA-treated A549 cells. The levels of interleukin (IL)-1β, IL-6, IL-8 and IL-13 were about 1.5 times higher in the PFOA-treated A549 and L-02 cells than in the controls. PFOA stimulated the biosynthesis of arginine and the metabolism of vitamin B6 in A549 cells. Arginine and vitamin B6 supplemented into cell culture effectively decreased the levels of IL-6 and IL-8. The inhibition of purine metabolism by PFOA resulted in the arrestation of DLD-1 cells at the G₀/G₁-phase. Our results suggest that the differential toxicity of PFOA related to exposure pathways could be elucidated by metabolic profiles specific to various human cells.

Male reproductive toxicity of perfluorooctanoate (PFOA): Rodent studies

Perfluorooctanoic acid (PFOA) is an artificial organic substance widely used for decades, which seriously threatens human health. This study aimed to identify human-relevant correlates between PFOA exposure and the male rodent reproductive system. We performed a systematic literature review of the relevant literature of PubMed, Cochrane Library databases, Web of Science and Embase from the establishment to April 2020. Studies included the effects of PFOA on the reproductive system of male rodents. The meta-analysis was performed on the basis of the following points: level of testosterone and estradiol in serum, development of reproductive organs, pathological changes of reproduction organs and parameters of semen. A series of 16 studies was enrolled in this study. The standard mean difference (SMD) for PFOA-related reproductive toxicity was summarised as -0.39 (95% confidence interval [CI]: 0.71, -0.07). The lower serum testosterone levels, decreased absolute testicular and epididymal weights, higher serum estradiol levels, elevated relative testicular and seminal vesicle weights and increased incidence of Leydig cell adenoma and percentage of abnormal sperm were observed in the exposed group compared with the control group. However, no statistical difference was found in the day of preputial separation of pups and percentage of motile sperm. In conclusion, PFOA exposure heightens the reproductive system damage in male rodents. However, many studies included in the review did not identify mechanisms by which PFOA induces changes to the male reproductive system, which is an area for additional study.

Integrated analysis of physiological, transcriptomics and metabolomics provides insights into detoxication disruption of PFOA exposure in Mytilus edulis

Perfluorooctanoic acid (PFOA), a persistent environmental contaminant, resists environmental degradation and bioaccumulates in food chains. Lots of literatures have proved that PFOA exposure could disrupt detoxifying function in a variety of organisms, however, it still remained poorly known about this in mollusk. Here, we examined physiological, transcriptomic, and metabolomic responses to PFOA in Mytilus edulis, a model organism frequently used in studies of aquatic pollution. We aimed to characterize PFOA-induced stress responses and detoxification mechanisms. PFOA exposure significantly altered antioxidant enzyme activity levels and the abundances of lipid peroxidation products. In addition, transcriptomic analysis indicated that several genes associated with oxidative stress and detoxication were differentially expressed after PFOA exposure. In combination, transcriptomic and metabolomic analyses showed that PFOA exposure disturbed several metabolic processes in M. edulis, including the lipid metabolism, amino acid metabolism, and carbohydrate metabolism etc. Molecular examination and enzymes assay of PFOA-exposed M. edulis after a 7-day depuration period still did not recover to control levels. The Pathway enrichment analysis proved that several pathways related to detoxification, such as c-Jun N-terminal kinase (JNK) and p38-dependent mitogen-activated protein kinase (MAPK) pathway, Peroxisome proliferator-activated receptor γ (PPARγ) pathway etc, were obviously affected. The present work verifies firstly PFOA disruption to molluscan detoxification and identifies the key pathways to understand the molecular mechanisms thereof. This study provides new insights into the detoxication disruption invoked in response to PFOA exposure in M. edulis.

Perfluorooctanoic acid (PFOA) exposure induces splenic atrophy via overactivation of macrophages in male mice

Perfluorooctanoic acid (PFOA), a synthetic and widely used chemical, has aroused wide public concern due to its persistence, bioaccumulation, and potential toxicity. To investigate splenic atrophy induced by PFOA, male mice were exposed to 0, 0.4, 2, or 10 mg/kg/d PFOA for 28 d. Results demonstrated that spleen weight and relative spleen weight (RSW) decreased in the 2 and 10 mg/kg/d PFOA exposure groups. Iron levels in the spleen and serum were also reduced in all PFOA exposure groups. Weighted gene co-expression network analysis (WGCNA) of 7 043 genes highlighted enrichment in cell cycle, autoimmunity, and anemia in the spleen. In addition, changes in the levels of hemoglobin, platelets, bilirubin, and heme oxygenase-1 were consistent with anemia. The ratio of total macrophages to M1 macrophages in the spleen, phagocytic ability of macrophages, and levels of cytokines such as TNF-α, IL-1β, and IL-6 all increased, thus suggesting the occurrence of autoimmune disorder. Therefore, we concluded that overactivation of macrophages may be an important reason for splenic atrophy induced by PFOA exposure.

Perfluoroalkyl Chemicals and Male Reproductive Health: Do PFOA and PFOS Increase Risk for Male Infertility?

Poly- and perfluoroalkyl substances (PFAS) are manmade synthetic chemicals which have been in existence for over 70 years. Though they are currently being phased out, their persistence in the environment is widespread. There is increasing evidence linking PFAS exposure to health effects, an issue of concern since PFAS such as perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) bioaccumulate in humans, with a half-life of years. Many epidemiological studies suggest that, worldwide, semen quality has decreased over the past several decades. One of the most worrying effects of PFOS and PFOA is their associations with lower testosterone levels, similar to clinical observations in infertile men. This review thus focuses on PFOS/PFOA-associated effects on male reproductive health. The sources of PFAS in drinking water are listed. The current epidemiological studies linking increased exposure to PFAS with lowered testosterone and semen quality, and evidence from rodent studies supporting their function as endocrine disruptors on the reproductive system, exhibiting non-monotonic dose responses, are noted. Finally, their mechanisms of action and possible toxic effects on the Leydig, Sertoli, and germ cells are discussed. Future research efforts must consider utilizing better human model systems for exposure, using more accurate PFAS exposure susceptibility windows, and improvements in statistical modeling of data to account for the endocrine disruptor properties of PFAS.

Prenatal exposure to per- and polyfluoroalkyl substances (PFAS) and neurobehavior in US children through 8 years of age: The HOME study

BACKGROUND

Studies of prenatal per- and polyfluoroalkyl substances (PFAS) and attention deficit hyperactivity disorder (ADHD)-related behaviors in children are inconsistent.

OBJECTIVES

To examine associations between maternal serum PFAS concentrations and child behavior in 241 mother-child dyads within the Health Outcomes and Measures of the Environment (HOME) Study.

METHODS

We quantified perfluorooctanoate (PFOA), perfluorooctane sulfonate (PFOS), perfluorohexane sulfonate (PFHxS), and perfluorononanoate (PFNA) in maternal serum collected during pregnancy or at delivery. We evaluated a total of 17 outcomes of child behavior using the Behavioral Assessment System for Children-2 (BASC-2) at 5 and 8 years (n = 240) and ADHD diagnostic symptoms and criteria with the Diagnostic Interview Schedule for Children-Young Child (DISC-YC) at 5 years (n = 190). We used linear mixed models and logistic regression with generalized estimating equations to assess associations between PFAS and continuous or dichotomous "at risk" BASC-2 scores; negative binomial regression to calculate incident rate ratios for counts of ADHD symptoms; and Poisson regression with robust standard errors to calculate relative risks of meeting ADHD diagnostic criteria.

RESULTS

Each ln-unit increase in PFOS, PFHxS, and PFNA was associated with higher BASC-2 scores and increased odds of "at-risk" scores for externalizing behaviors, including hyperactivity (PFOS: odds ratio [OR] 2.7, 95% confidence interval [CI] 1.2, 5.9; PFHxS: OR 2.5, 95% CI 1.5, 4.3; PFNA: OR 3.2, 95% CI 1.3, 8.0). PFHxS was also associated with internalizing problems (OR 2.0, 95% CI 1.1, 3.4) and somatization (OR 2.2, 95% CI 1.2, 4.0). PFOS and PFNA were significantly associated with 50-80% more DISC-YC symptoms and diagnostic criteria related to hyperactive-impulsive type ADHD. Prenatal PFNA was associated with increased risk of any-type ADHD.

CONCLUSIONS

Prenatal PFOS and PFNA were consistently associated with measures related to hyperactive-impulsive type ADHD across two validated assessment instruments. PFHxS was associated with increased problems with both externalizing and internalizing behaviors. No associations were noted between PFOA and child neurobehavior.

Early-life perfluorooctanoic acid exposure induces obesity in male offspring and the intervention role of chlorogenic acid

Perfluorooctanoic acid (PFOA) is an emerging organic pollutant (EOP) hazardous to human health. Effects of maternal PFOA exposure on offspring as well as the underlying mechanisms remain unclear. In this study, ICR mouse models of gestational low PFOA exposure (0.05 mg/kg/day) were established to investigate the roles on metabolic disorders of offspring. Body weight, body composition, hepatic lipid levels, transcriptome and metabolome were analyzed. Expression of genes related to lipid metabolism, inflammasome formation and gut barrier integrity were measured. Furthermore, oral administration of chlorogenic acid (CGA) (100 mg/kg/day) was performed to observe the rescue effect on lipid disorders caused by PFOA exposure. Our findings demonstrated that gestational exposure to PFOA resulted in obesity, hepatic inflammation, disorders of lipid metabolism, and disruption of gut barrier integrity in male offspring. Notably, these adverse effects were attenuated by CGA supplementation. These data suggested that PFOA exposure during early life stage induced potential risks for later onset of obesity and metabolic disorder which could be ameliorated by CGA treatment.

The Subacute Toxicity of Perfluorooctane Sulfonate and/or Perfluorooctanoic Acid and Legacy Aqueous Film-Forming Foams to Japanese Quail (Coturnix japonica) Chicks

As part of an effort to develop avian ecotoxicity information for poly- and perfluoroalkyl substances (PFAS) including perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) associated with aqueous film-forming foam (AFFF) used by the Department of Defense, the subacute toxicity of PFOS, PFOA, PFOS + PFOA, 3M AFFF, and Ansul AFFF to Japanese quail (Coturnix japonica) chicks was determined. Ten-day-old Japanese quail were administered treated feed for 5 d and then fed untreated feed for 18 d. Analyzed concentrations of PFOS, PFOA, and PFOS + PFOA ranged from 62 to 1955, 162 to 1208, and 43 + 45 to 296 + 292 mg kg feed^-1 . Analyzed concentrations of PFOS in feed containing the 3M AFFF ranged from 73 to 1399 mg kg feed^-1 , and formulated concentrations of 6:2 fluorotelomer thioamido sulfonate in feed containing the Ansul AFFF ranged from 9 to 1118 mg kg feed^-1 . Average daily doses resulting in 50% mortality at day 5 were 38 (34-43), 68 (63-74), 55 (51-59), and 130 (103-164) mg PFOS, PFOA, PFOS + PFOA, and PFOS in 3M AFFF kg body weight^-1  d^-1 . Ansul AFFF did not result in any mortalities. Dietary concentrations resulting in 50% mortality at day 5 were 351 (275-450), 496 (427-575), 398 (339-468), and 467 (390-559) mg PFOS, PFOA, PFOS + PFOA, and PFOS in 3M AFFF kg feed^-1 . Environ Toxicol Chem 2021;40:695-710. © 2020 SETAC.

Comparison of zebrafish in vitro and in vivo developmental toxicity assessments of perfluoroalkyl acids (PFAAs)

Perfluoroalkyl acids (PFAAs) are persistent environmental contaminants that are associated with various adverse health outcomes. Perfluorooctanoic acid (PFOA) is one of the most prominently detected PFAAs in the environment, which is now replaced with shorter chain carbon compounds including perfluorohexanoic acid (PFHxA) and perfluorobutyric acid (PFBA). The aim of this study was to compare the toxicity of four PFAAs as a function of chain length and head group (carboxylate versus sulfonate) with in vitro and in vivo zebrafish assessments, which were subsequently compared to other cell and aquatic models. Mortality rate increased with chain length (PFOA > PFHxA ≫ PFBA) in both whole embryo/larvae and embryonic cell models. The sulfonate group enhanced toxicity with perfluorobutane sulfonate (PFBS) showing higher toxicity than PFBA and PFHxA in both larvae and cells. Toxicity trends were similar among different aquatic models, but sensitivities varied. Discrepancies with other zebrafish studies were confirmed to be associated with a lack of neutralization of acidic pH of dosing solutions in these other investigations, demonstrating the need for rigor in reporting pH of exposure solutions in all experiments. The zebrafish embryonic cell line was also found to be similar to most other cell lines regardless of exposure length. Overall, results agree with findings in other cell lines and organisms where longer chain length and sulfonate group increase toxicity, except in investigations not neutralizing the exposure solutions for these acidic compounds.

Associations of Maternal Stress, Prenatal Exposure to Per- and Polyfluoroalkyl Substances (PFAS), and Demographic Risk Factors with Birth Outcomes and Offspring Neurodevelopment: An Overview of the ECHO.CA.IL Prospective Birth Cohorts

BACKGROUND

Infants whose mothers experience greater psychosocial stress and environmental chemical exposures during pregnancy may face greater rates of preterm birth, lower birth weight, and impaired neurodevelopment.

METHODS

ECHO.CA.IL is composed of two cohorts, Chemicals in Our Bodies (CIOB; n = 822 pregnant women and n = 286 infants) and Illinois Kids Development Study (IKIDS; n = 565 mother-infant pairs), which recruit pregnant women from San Francisco, CA and Urbana-Champaign, IL, respectively. We examined associations between demographic characteristics and gestational age, birth weight z-scores, and cognition at 7.5 months across these two cohorts using linear models. We also examined differences in biomarkers of exposure to per- and polyfluoroalkyl substances (PFAS), measured in second-trimester serum, and psychosocial stressors by cohort and participant demographics.

RESULTS

To date, these cohorts have recruited over 1300 pregnant women combined. IKIDS has mothers who are majority white (80%), whereas CIOB mothers are racially and ethnically diverse (38% white, 34% Hispanic, 17% Asian/Pacific Islander). Compared to CIOB, median levels of PFOS, a specific PFAS congener, are higher in IKIDS (2.45 ng/mL versus 1.94 ng/mL), while psychosocial stressors are higher among CIOB. Across both cohorts, women who were non-white and single had lower birth weight z-scores relative to white women and married women, respectively. Demographic characteristics are not associated with cognitive outcomes at 7.5 months.

CONCLUSIONS

This profile of the ECHO.CA.IL cohort found that mothers and their infants who vary in terms of socioeconomic status, race/ethnicity, and geographic location are similar in many of our measures of exposures and cognitive outcomes. Similar to past work, we found that non-white and single women had lower birth weight infants than white and married women. We also found differences in levels of PFOS and psychosocial stressors based on geographic location.

Perfluoroalkyl acids and their isomers, diabetes, anemia, and albuminuria: Variabilities with deteriorating kidney function

Data for US adults aged ≥20 years from National Health and Nutrition Examination Survey for the years 2003-2014 were analyzed to evaluate how adjusted (N = 8481) and unadjusted (N = 9080) levels of selected perfluoroalkyl acids (PFAA) vary across the different stages of glomerular function (GF) among those who did not have diabetes, anemia, or albuminuria as compared to those who had diabetes only, anemia only, and albuminuria only. PFAAs selected for analyses were: perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS), perfluorodecanoic acid (PFDA), perfluorohexane sulfonic acid (PFHxS), and perfluorononanoic acid (PFNA). Irrespective of GF stage, there was no noticeable evidence to suggest that adjusted levels of PFAA for those with diabetes only are any lower than those with no diabetes, no anemia, and no albuminuria. Those who had anemia only were found to have lower adjusted levels of at least PFOA, PFOS, PFDA, and PFHxS than those who had no diabetes, no anemia, and no albuminuria. These results were seen in the presence (eGFR < 60 mL/min/1.73 m²) as well as the absence of chronic kidney disease. For GF-1 (eGFR > 90 mL/min/1.73 m²), GF-2 (60 ≤ eGFR ≤ 90 mL/min/1.73 m²), and GF-3B/4 (15 < eGFR ≤ 45 mL/min/1.73 m²), those who had albuminuria only had lower adjusted levels of PFOA, PFOS, and PFHxS than those who had no diabetes, no anemia, and no albuminuria. In general, adjusted levels of those who had albuminuria only were lower than those who had anemia only at GF-3 and more often than not at GF-1 and GF-2. Rise in adjusted levels of PFAA from GF-1 to GF-3A (45 < eGFR < 60 mL/min/1.73 m²) was faster for those with anemia only than any other comparison group for the total population and females.

Perfluorooctanoic acid-induced cellular and subcellular alterations in fish hepatocytes

Liver perfluorooctanoic acid (PFOA) pathophysiology and related morphofunction disturbances were studied in common carp at the cellular and subcellular level and with box-counting fractal analysis of ultrathin sections to assess the effect of PFOA exposure on hepatocyte structure complexity and heterogeneity. Three experimental groups were investigated: unexposed; low exposure (200 ng L^-1 PFOA); high exposure (2 mg L^-1 PFOA). PFOA-exposed cells showed differences from controls at both tested concentrations, manifested mainly as cloudy swelling and reversible vacuolar degeneration. Subcellular modifications primarily involved mitochondria and secondarily endoplasmic reticulum, with evidence of increased subcellular turnover. The alterations were consistent with oxidative stress related pathophysiology. Fractal analysis discriminated exposed from unexposed fish and low from high PFOA exposure based on lacunarity and fractal dimension, respectively. The absence of irreversible organelle alterations and apoptosis/necrosis, along with the increase of cellular complexity, led to the conclusion that the patterns observed represented an adaptive recovery response.

Male reproductive toxicity involved in spermatogenesis induced by perfluorooctane sulfonate and perfluorooctanoic acid in Caenorhabditis elegans

As a persistent organic pollutant, perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) have gained increasing research attention over recent years because of their potential risk to humans and the environment. In this paper, we investigated the reproductive toxicity of these pollutants using a C. elegans model to evaluate spermatogenesis throughout the entire developmental cycle of him-5 mutant by exposing to 0.001, 0.01, and 0.1 mmol/L PFOS or PFOA for 48 h. Experimental results suggested that PFOS and PFOA exposure led to reductions in brood size, germ cell number, spermatid size, and motility, and increases in rate of malformation spermatids. Analysis of variance (ANOVA) showed that exposure to PFOS resulted in higher levels of damage than PFOA in germ cells only in 0.001 mmol/L exposure group. RT-qPCR was used to further investigate the expression of genes associated with different stages of spermatogenesis, such as mitosis and meiosis, fibrous body-membranous organelles (FB-MOs), and sperm activation. The expression levels of wee-1.3, spe-4, spe-6, and spe-17 genes were increased, while those of puf-8, spe-10, fer-1, swm-1, try-5, and spe-15 genes were decreased. Our results suggesting that PFOS or PFOA may cause spermatogenesis damage by disrupting the mitotic proliferation, meiotic entry, formation of the MOs, fusion of the MOs and plasma membrane (PM), and pseudopods. Loss-of-function studies using puf-8 and spe-10 mutants revealed spe-10 gene was specifically involved in PFOS- or PFOA-induced reproductive toxicity via regulating one or more critical palmitoylation events, while puf-8 gene was not direct target of PFOS and PFOA, and PFOS and PFOA may act on the upstream gene of puf-8, thus affecting reproductive ability. Taken together, these results demonstrate the potential adverse impact of PFOS and PFOA exposure on spermatogenesis and provide valuable data for PFC risk assessment. Grapical abstract.

Perfluoroalkyl substances and cognitive function in older adults: Should we consider non-monotonic dose-responses and chronic kidney disease?

BACKGROUND

Although potential neurotoxicity of perfluoroalkyl and polyfluoroalkyl substances (PFAS) is suggested, previous epidemiologic studies have reported a 'protective' association between serum PFAS concentration and cognition function. Poor outcome assessment, residual confounding, non-monotonic dose-responses (NMDRs), and the role of reduced kidney function in PFAS excretion may be alternative explanations of these findings.

OBJECTIVES

We examined the association of perfluoroalkyls with cognitive functions assessed using the Consortium to Establish a Registry for Alzheimer's Disease word learning and recall; the Animal Fluency; and the Digit Symbol Substitution tests.

METHODS

We included 903 adults aged ≥60 years from the National Health and Nutrition Examination Survey (NHANES) 2011-2014. We computed a composite z-score as an average of four individual cognitive z-scores and used it as the outcome. Linear and generalized additive models were used to evaluate linear and non-linear associations.

RESULTS

With the linearity assumption, perfluorooctanoate (PFOA) and perfluorononanoate (PFNA) were significantly positively associated with composite z-score after adjustment for age, sex, race/ethnicity, education, smoking, poverty-income ratio, health insurance, food security, alcohol, and physical activity. Smoothing plots suggested NMDRs, especially for perfluorooctane sulfonate (PFOS) with a U-shape dose-response. When restricting to participants without chronic kidney disease (CKD) (n = 613), the positive associations for PFOA and PFNA observed in the whole population diminished, whereas PFOS was inversely and significantly associated with composite z-score. Also, negative confounding effects of fish/seafood consumption seem to be substantial. Effect estimates of composite z-score were -0.055 (95% CI: -0.097, -0.012, P = 0.01) for a doubling increase in PFOS.

DISCUSSION

These findings suggest that the previous epidemiologic findings of a 'protective' association between PFAS and cognition may be explained by CKD, NMDRs and confounding by fish consumption. PFOS at the current population exposure level in the U.S. may be a risk factor for cognitive decline in older adults with normal kidney function.

Perfluorooctanoic acid (PFOA) inhibits the gap junction intercellular communication and induces apoptosis in human ovarian granulosa cells

Perfluorooctanoic acid (PFOA) has attracted widespread research attention as it is very stable, bioaccumulates, and causes reproductive toxicity. Data from several animal experiments and epidemiological studies indicate that female fertility may decline because of ovarian granulosa cell (GC) apoptosis as oocyte quality is positively associated with effective gap junctional intercellular communication (GJIC) between GCs. To the best of our knowledge, however, no previous trials have been conducted or reported on the effects of PFOA exposure on apoptosis induction in human GCs. Moreover, the roles of GJIC in GC survival and in the induction of apoptosis in GCs by PFOA remain unclear. To test this, we cultured human GCs in vitro and treated them with 0 μM, 0.3 μM, 3 μM, or 30 μM PFOA for 24 h. We also treated a human ovarian GC line (KGN) with various combinations of PFOA, retinoic acid (RA, 10 μM), and carbenoxolone disodium (CBX, 50 mM). Our findings showed that PFOA lowered human GC viability and increased apoptosis. The effects of CBX resemble those of PFOA. The combination of PFOA and CBX enhances the inhibition of GJIC by PFOA and promotes apoptosis. The effects of RA are the opposite to those of PFOA. The combination of RA and PFOA mitigates PFOA-induced GJIC inhibition and reduces apoptosis. The observed expression levels of apoptosis-related proteins were consistent with the aforementioned findings. Hence, our study demonstrated that PFOA may induce human ovarian GC apoptosis by inhibiting GJIC.

An assessment of serum-dependent impacts on intracellular accumulation and genomic response of per- and polyfluoroalkyl substances in a placental trophoblast model

Per- and polyfluoroalkyl substances (PFAS), a class of environmental contaminants, have been detected in human placenta and cord blood. The mechanisms driving PFAS-induced effects on the placenta and adverse pregnancy outcomes are not well understood. This study investigated the impact of perfluorooctanesulfonic acid (PFOS), perfluorooctanoic acid (PFOA), and a replacement PFAS known as hexafluoropropylene oxide dimer acid (HFPO-DA, tradename GenX) on placental trophoblasts in vitro. Several key factors were addressed. First, PFAS levels in cell culture reagents at baseline were quantified. Second, the role of supplemental media serum in intracellular accumulation of PFAS in a human trophoblast (JEG3) cell line was established. Finally, the impact of PFAS on the expression of 96 genes involved in proper placental function in JEG3 cells was evaluated. The results revealed that serum-free media (SFM) contained no detectable PFAS. In contrast, fetal bovine serum-supplemented media (SSM) contained PFNA, PFUdA, PFTrDA, and 6:2 FTS, but these PFAS were not detected internally in cells. Intracellular accumulation following 24 hr treatments was significantly higher when cultured in SFM compared to SSM for PFOS and PFOA, but not HFPO-DA. Treatment with PFAS was associated with gene expression changes (n = 32) in pathways vital to placental function, including viability, syncytialization, inflammation, transport, and invasion/mesenchymal transition. Among the most robust PFAS-associated changes were those observed in the known apoptosis-related genes, BAD and BAX. These results suggest a complex relationship between PFAS, in vitro culture conditions, and altered expression of key genes necessary for proper placentation.

Perfluorooctanoic acid induces cytotoxicity in spermatogonial GC-1 cells

Perfluorooctane acid (PFOA), a typical perfluorinated chemical, has been suggested to interfere with male reproductive function. In this study, mouse spermatogonial GC-1 cells were in vitro treated with PFOA (250, 500 or 750 μM) for 24 h to investigate the cytotoxicity of PFOA and its underlying mechanisms. Our results indicated that exposure to intermediate and high doses of PFOA suppressed the viability of GC-1 cells in a concentration-dependent manner. Furthermore, PFOA treatment markedly enhanced the generation of reactive oxygen species and malondialdehyde, with diminished activity of superoxide dismutase. Particularly, PFOA exposure evoked a decline in mitochondrial membrane potential and ATP production. Furthermore, the apoptotic index and caspase-3 activity were significantly elevated after treatment with PFOA. In addition, PFOA incubation caused an increase in LC3B-II/LC3B-I ratio. Meanwhile, PFOA resulted in an excessive accumulation of autophagosomes in the cytoplasm. Taken together, exposure to PFOA can elicit cytotoxicity to spermatogonial GC-1 cells in vitro, which may be link to the mitochondrial oxidative damage and induction of apoptosis and autophagy.

Review: Evolution of evidence on PFOA and health following the assessments of the C8 Science Panel

BACKGROUND

The C8 Science Panel was composed of three epidemiologists charged with studying the possible health effects of PFOA in a highly exposed population in the mid-Ohio Valley. The Panel determined in 2012 there was a 'probable link' (i.e., more probable than not based on the weight of the available scientific evidence) between PFOA and high cholesterol, thyroid disease, kidney and testicular cancer, pregnancy-induced hypertension, and ulcerative colitis.

OBJECTIVE

Here, former C8 Science Panel members and collaborators comment on the PFOA literature regarding thyroid disorders, cancer, immune and auto-immune disorders, liver disease, hypercholesterolemia, reproductive outcomes, neurotoxicity, and kidney disease. We also discuss developments regarding fate and transport, and pharmacokinetic models, and discuss causality assessment in cross-sectional associations among low-exposed populations.

DISCUSSION

For cancer, the epidemiologic evidence remains supportive but not definitive for kidney and testicular cancers. There is consistent evidence of a positive association between PFOA and cholesterol, but no evidence of an association with heart disease. There is evidence for an association with ulcerative colitis, but not for other auto-immune diseases. There is good evidence that PFOA is associated with immune response, but uneven evidence for an association with infectious disease. The evidence for an association between PFOA and thyroid and kidney disease is suggestive but uneven. There is evidence of an association with liver enzymes, but not with liver disease. There is little evidence of an association with neurotoxicity. Suggested reductions in birthweight may be due to reverse causality and/or confounding. Fate and transport models and pharmacokinetic models remain central to estimating past exposure for new cohorts, but are difficult to develop without good historical data on emissions of PFOA into the environment.

CONCLUSION

Overall, the epidemiologic evidence remains limited. For a few outcomes there has been some replication of our earlier findings. More longitudinal research is needed in large populations with large exposure contrasts. Additional cross-sectional studies of low exposed populations may be less informative.

Exposure to Perfluorooctanoic Acid Induces Cognitive Deficits via Altering Gut Microbiota Composition, Impairing Intestinal Barrier Integrity, and Causing Inflammation in Gut and Brain

Perfluorooctanoic acid (PFOA) is an eight-carbon perfluoroalkyl chemical and has been detected widely in many media. Although the toxic effect of PFOA has been confirmed, the influence on gut and brain has not been cleared. Male C57BL/6J mice were exposed to different concentrations (0, 0.5, 1, and 3 mg/Kg (bw)/day of PFOA for 35 days in this work. The results indicate that exposure to PFOA could damage intestinal barrier integrity and impair the synaptic structure. PFOA exposure also caused inflammation in gut and brain by increasing lipopolysaccharide, tumor necrosis factor-α, interleukin-1 beta, and cyclooxygenase-2 and decreasing interleukin-10. Interestingly, fecal microbiota transplantation treatment could attenuate a series of PFOA-induced changes to a certain extent. The results suggest that exposure to PFOA has potential deleterious effects on gut and brain, and inflammation may play an essential role in evaluating the influence induced by PFOA exposure.

Perfluorooctanoic acid activates multiple nuclear receptor pathways and skews expression of genes regulating cholesterol homeostasis in liver of humanized PPARα mice fed an American diet

Humans are exposed to per- and polyfluoroalkyl substances (PFAS) in their drinking water, food, air, dust, and by direct use of consumer products. Increased concentrations of serum total cholesterol and low density lipoprotein cholesterol are among the endpoints best supported by epidemiology. The objectives of this study were to generate a new model for examining PFAS-induced dyslipidemia and to conduct molecular studies to better define mechanism(s) of action. We tested the hypothesis that perfluorooctanoic acid (PFOA) exposure at a human-relevant level dysregulates expression of genes controlling cholesterol homeostasis in livers of mice expressing human PPARα (hPPARα). Female and male hPPARα and PPARα null mice were fed a diet based on the "What we eat in America" analysis and exposed to PFOA in drinking water (8 μM) for 6 weeks. This resulted in a serum PFOA concentration of 48 μg/ml. PFOA increased liver mass, which was associated with histologically-evident lipid accumulation. Pooled analyses of serum lipoprotein cholesterol suggest that PFOA increased serum cholesterol, particularly in male mice. PFOA induced PPARα and constitutive androstane receptor target gene expression in liver. Expression of genes in four pathways regulating cholesterol homeostasis were also measured. PFOA decreased expression of Hmgcr in a PPARα-dependent manner. PFOA decreased expression of Ldlr and Cyp7a1 in a PPARα-independent manner. Apob expression was not changed. Sex differences were evident. This novel study design (hPPARα mice, American diet, long term exposure) generated new insight on the effects of PFOA on cholesterol regulation in the liver and the role of hPPARα.

Antimicrobial activity of organic acids against Campylobacter spp. and development of combinations-A synergistic effect?

Contaminated poultry meat is considered to be the main source of human infection with Campylobacter spp., a pathogen that asymptomatically colonizes broiler chickens during fattening and contaminates carcasses during slaughter. To prevent or reduce the colonization of broiler flocks with Campylobacter spp., applying different organic acids, especially in combinations, via feed or drinking water seems to be a promising approach. However, only very few combinations of organic acids have been tested for their antibacterial efficacy against Campylobacter spp. Therefore, the in vitro susceptibility of 30 Campylobacter spp. isolates (20 C. jejuni and ten C. coli) to ten organic acids and ten combinations was determined. The testing of minimum inhibitory concentration (MIC) values was performed at pH 6.0 and 7.3 by using the broth microdilution method and included the following organic acids: Caprylic acid, sorbic acid, caproic acid, benzoic acid, ascorbic acid, propionic acid, acetic acid, formic acid, fumaric acid and tartaric acid and combinations thereof. The lowest MIC values were seen for caprylic acid (MIC range at pH 7.3: 0.5-2 mmol/L) and sorbic acid (MIC range at pH 7.3: 1-4 mmol/L). One to two dilution steps lower MIC values were determined at the lower pH value of 6.0. Furthermore, ten combinations consisting of three to five organic acids were developed. In addition to the tested antibacterial activity, other criteria were included such as approval as feed additives, reported synergistic effects and chemical properties. For nine of ten combinations, the MIC90 values of the organic acids decreased 1.25- to 241.5-fold compared to the MIC90 values for the individual substances. Furthermore, nine of ten combinations exhibited synergistic activities against two or more of the tested C. jejuni and C. coli isolates. A combination of caprylic acid, sorbic acid and caproic acid exhibited synergistic activities against the largest number of Campylobacter spp. isolates (six C. jejuni and four C. coli) with fractional inhibitory concentration (FIC) indices (∑FIC) ranging from 0.33 to 1.42. This study shows in vitro synergistic activities of different organic acids in combinations against the major Campylobacter species and could therefore be a promising basis for reducing Campylobacter spp. in vivo.

Environment occurrence of perfluoroalkyl acids and associated human health risks near a major fluorochemical manufacturing park in southwest of China

Despite China being the largest global manufacturer of perfluoroalkyl acids (PFAAs), few studies have been carried out on the environmental occurrence and associated human health risks of PFAAs emitted from manufacturing sites in China. Here, river water, tap water, soil and leaf samples were collected around a major fluorochemical manufacturing park (FMP) in the southwest of China in 2019. High ΣPFAA concentrations (sum of 12 PFAAs) of 3817 ng/L, 3254 ng/L, 322-476 ng/g dw and 23401-33749 ng/g dw were measured near the FMP in river water, tap water, soil and leaves, respectively, indicating that the FMP is a point source of PFAAs. PFOA was the predominant PFAA in all samples (58.5-98.6 %) indicating the production or use of PFOA at the FMP. PFOA concentrations in most tap water samples (> 300 ng/L in 31 of 38 samples) exceeded the U.S. EPA health advisory. Proportions of branched PFOA isomers in all samples were in 5.9-47.4 %, suggesting the production or use of PFOA manufactured by electrochemical fluorination at the FMP. It is recommended to focus more attention on branched PFOA isomers in the future because otherwise health risks may be underestimated due to their relatively high proportions in China.

Perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS), and perfluorononanoic acid (PFNA) increase triglyceride levels and decrease cholesterogenic gene expression in human HepaRG liver cells

Per- and polyfluoroalkyl substances (PFASs) are omnipresent in the environment, food chain, and humans. Epidemiological studies have shown a positive association between serum levels of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS), and increased serum cholesterol and, in some cases, also triglyceride levels. However, causality has been questioned, as animal studies, as well as a human trial, showed a decrease in serum cholesterol and no effects or a decrease in plasma triglycerides. To obtain more insight into the effects of PFASs on these processes, the present study investigated the effects of PFOA, PFOS, and perfluorononanoic acid (PFNA) on intracellular triglyceride and cholesterol levels in human HepaRG liver cells. DNA microarray analyses were performed to provide insight into underlying mechanisms. All PFASs induced an increase in cellular triglyceride levels, but had no effect on cholesterol levels. Gene set enrichment analysis (GSEA) of the microarray data indicated that gene sets related to cholesterol biosynthesis were repressed by PFOA, PFOS, and PFNA. Other gene sets commonly affected by all PFAS were related to PERK/ATF4 signaling (induced), tRNA amino-acylation (induced), amino acid transport (induced), and glycolysis/gluconeogenesis (repressed). Moreover, numerous target genes of peroxisome proliferator-activated receptor α (PPARα) were found to be upregulated. Altogether, the present study shows that PFOA, PFOS, and PFNA increase triglyceride levels and inhibit cholesterogenic gene expression in HepaRG cells. In addition, the present study indicates that PFASs induce endoplasmic reticulum stress, which may be an important mechanism underlying some of the toxic effects of these chemicals.

Exposure to per- and polyfluorinated alkyl substances in pregnant Brazilian women and its association with fetal growth

Research pertaining to exposure of humans to per- and polyfluorinated alkyl substances (PFASs) has received considerable public and regulatory attention in recent years. Although several studies have reported exposure to PFASs by populations in North America and western Europe, such information is still scarce in Latin America, including Brazil. In this study, concentrations of thirteen PFASs were determined in whole blood collected during the second trimester from 252 pregnant Brazilian women. This is a nested case-control study within the Brazilian Ribeirao Preto and Sao Luiz Birth Cohort Study (BRISA) with selected birth outcomes cases (n = 63) and matched controls (n = 189). PFASs concentrations were associated with conditions including preeclampsia, birth weight (BW), preterm birth, and intrauterine growth restriction (IUGR). Among PFASs measured, perfluorooctane sulfonate (PFOS) was found at the highest concentration (range: 1.06-106 ng mL^-1 with a median value of 3.41 ng mL^-1) which was followed by perfluorooctanoic acid (PFOA, range: 0.11-2.77 ng mL^-1 with a median value of 0.20 ng mL^-1). A significant positive association of PFOS and PFOA concentrations with fetal growth restriction (p < 0.05) was found. This is the first study to assess whole blood concentrations of PFASs and their effect on fetal growth in pregnant Brazilian women.

Association between perfluoroalkyl acids and the prevalence of hypertension among US adults

The nonlinear associations of serum perfluoroalkyl acids (PFAAs) with hypertension and blood pressure have not been addressed. Cross-sectional data from 6967 adults (age ≥ 20 years) from the 2003-2012 National Health and Nutrition Examination Survey (NHANES) were analyzed. Hypertension was defined as an average systolic blood pressure above 140 mmHg, an average diastolic blood pressure above 90 mmHg or self-reported use of prescribed medicine for diagnosed hypertension. After multivariable adjustment, compared with the lowest tertile, the odds ratios (ORs) with 95% confidence intervals (CIs) of hypertension for the highest tertile of perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS), perfluorohexane sulfonic acid (PFHxS) and perfluorononanoic acid (PFNA) were 1.32 (1.13, 1.54), 1.14 (0.97, 1.34), 1.16 (0.99, 1.36) and 1.18 (1.01, 1.37), respectively. PFOA and PFNA displayed a J-shaped relationship with the prevalence of hypertension. Furthermore, threshold effect analysis showed that the inflection point of PFOA was 1.80 ng/ml. Each 10-fold change in PFOA exhibited a 44% decrease (OR 0.56, 95%CI (0.32, 0.99)) in the odds of hypertension on the left side of the inflection point, and an 85% increase (OR 1.85, 95%CI (1.34, 2.54)) on the right side of the inflection point. Threshold effect analysis also indicated that the inflection point of PFNA was 0.53 ng/ml. Each 10-fold change in PFNA exhibited a 60% decrease (OR 0.40, 95%CI (0.18, 0.85)) in the odds of hypertension on the left side of the inflection point, and an 85% increase (OR 1.64, 95%CI (1.25, 2.14)) on the right side of the inflection point. These cross-sectional data showed a J-shaped association between perfluoroalkyl acids and hypertension.

Mechanism of immunosuppression in zebrafish (Danio rerio) spleen induced by environmentally relevant concentrations of perfluorooctanoic acid

Perfluorooctanoic acid (PFOA) has been identified as a new persistent organic pollutant. This pollutant is ubiquitous in water and environments. Although PFOA is toxic to fishes, the precise immunotoxicological mechanism remains unclear. In this study, HPLC-MS analysis proved that PFOA can accumulate in the spleen of zebrafish. As comparison of 7-day and 14-day data, the cumulative content in the spleen significantly increased by 26% even in the 0.1 mg/L PFOA-treated group. Morphological observations revealed that PFOA can damage immune cells in zebrafish spleen by inducing vacuolization, lipofuscin granule production, and mitochondrial swelling. The Toll-like receptor 2 (TLR2)/myeloid differentiation factor 88 (myd88)/NF-κB (P65) pathway can mediate the mRNA expression levels of interferon (IFN) and B cell-activating factor (BAFF); immunoglobulin (Ig) secretion is further regulated. RT-PCR results indicated that the expression levels of P65 and IFN in the 1 mg/L group after PFOA exposure for 7 d increased by 4.03- and 3.28-fold, respectively, in a dose-dependent manner compared with those of the control group. The linear correlation coefficient (r²) was analyzed, and the results indicated that the Ig-mediated pathway can be affected by PFOA. For example, the r² between IgD and P65 decreased from 0.641 (7 d) to 0.295 (14 d) after the cells were exposed to PFOA for a prolonged time; the r² between IgD and IFN increased from 0.562 (7 d) to 0.808 (14 d). The triangle plot method strongly demonstrated that increased PFOA concentration and prolonged exposure to PFOA can inhibit Ig secretion. Therefore, immune organs, particularly the spleen, of zebrafish are vulnerable to PFOA. These results can help to improve the understanding of the possible noncarcinogenic risk mechanisms induced by PFOA.

Phytotoxicity induced by perfluorooctanoic acid and perfluorooctane sulfonate via metabolomics

Poly- and perfluoroalkyl substances (PFASs) are becoming common pollutants in natural environment, while the toxic effects and defense mechanisms in agricultural plants are poorly understood. Here, lettuce exposed to either perfluorooctanoic acid (PFOA) or perfluorooctane sulfonate (PFOS) at two different concentrations (500, 5000 ng/L) in hydroponic media was investigated via metabolomics. Under the tested conditions, the growth and biomass of lettuce were not affected by PFOA and PFOS, but metabolic profiles in leaves were altered. The composition and metabolism of lipids, carbohydrates, fatty acids, amino acids and some antioxidants were regulated, compromising the nutritional quality of the plants. Key pathways in energy metabolism were disturbed by both PFOA and PFOS, including tricarboxylic acid cycle, glyoxylate and dicarboxylate metabolism and pyruvate metabolism. Amino acid metabolism, e.g., phenylalanine and tyrosine, was disturbed by PFOA. The metabolism of linoleic acid was disturbed by PFOS. The changes of antioxidants and 8-hydroxy-deoxyguanosine indicated the occurrence of oxidative stress and DNA damage under PFOA or PFOS exposure. The main defense processes against PFASs exposure in lettuce included alteration in plasma membrane, activation of antioxidant systems, increase of tolerance and repair of DNA injury. These findings help elucidate the response of plants to PFASs in a molecular-scale perspective.

Fetal bovine serum attenuating perfluorooctanoic acid-inducing toxicity to multiple human cell lines via albumin binding

Perfluorooctanoic acid (PFOA), as a typical emerging organic pollutant, can interact with serum albumin. However, it remains to characterize the binding of PFOA with serum albumin and to address the role of this interaction in related toxic effects. We aimed to characterize the interaction between PFOA and albumin for understanding the effects of this interaction on the uptake, distribution, and toxicity of PFOA in human cells. The results showed that viable cell count was significantly enhanced by addition of fetabl bovine serum (FBS) into cell culture medium with 300 μM PFOA treatment. PFOA mainly existed as complexed with FBS, at FBS concentration > 10%, which substantially reduced the absorption efficiency of all cell lines to PFOA. The majority of PFOA was accumulated in the cytosolic fraction, followed by nuclei, and mitochondria. Conclusively, our study suggests that the complexation of organic contaminants with proteins might mitigate their toxicity by reducing cellular uptake.

Managing health risks of perfluoroalkyl acids in aquatic food from a river-estuary-sea environment affected by fluorochemical industry

Substantial perfluoroalkyl acids (PFAAs) production still occurs in China, and the consumption of aquatic products is a critical exposure pathway of PFAAs in humans. In this study, specimens of 16 freshwater and 40 marine species were collected in the river-estuary-sea environment affected by a mega fluorochemical industry park in China in 2015, and the edible tissues of these organisms were analyzed for PFAA levels. Perfluorooctanoic acid (PFOA) was the dominating contaminant with an overall contribution of more than 90%, and concentrations as high as 2161 ng/g wet weight (measured in the freshwater winkle). All species with the greatest PFOA levels were benthic. The trophic magnification factor (TMF) of PFOA was 1.10 for freshwater species and 1.28 for marine species, indicating that PFOA was slightly magnifying. Analysis of carbon source indicated that freshwater species were more benthic feeding, while marine species were more pelagic feeding. Aquatic food consumption screening values of PFOA were modified according to estimated daily intake (EDI) values, which generated recommendations for limited meal categories and the do-not-eat category. Thus, this study provides recommendations for mitigating the health risks of PFAA-contaminated aquatic food, ranging from food selection to consumption frequency and proper food processing.

An acute exposure to perfluorooctanoic acid causes non-reversible plasma membrane injury in HeLa cells

Health and environmental risks regarding perfluorooctanoic acid, a well-known perfluorinated compound, are still a subject of great concern. Ubiquitous exposure and disparity of results make it difficult to determine the underlying mechanism of action, especially at the cellular level. This study proposes an experimental design to assess the reversibility of adverse effects after a one-time exposure to the compound, in comparison with other more conventional timings. Complementary endpoints including total protein content, neutral red uptake and MTT reduction tests along with division rates and microscopic observations were evaluated in HeLa cells. In addition, PFOA quantification inside the cells was performed. The cellular effects exerted after 24 h exposure to perfluorooctanoic acid are non-reversible after a 48 h recovery period. In addition, we describe for the first time the induction of plasma membrane blebbing and the activation of membrane repair mechanisms after recovery from non-cytotoxic treatments with the compound. This experimental design has provided relevant information regarding the toxicity of this perfluorinated compound, relating all the adverse effects detected to its interaction with the plasma membrane.

Accumulation and phytotoxicity of perfluorooctanoic acid and 2,3,3,3-tetrafluoro-2-(heptafluoropropoxy)propanoate in Arabidopsis thaliana and Nicotiana benthamiana

2,3,3,3-Tetrafluoro-2-(heptafluoropropoxy)propanoate (known as GenX) has been used as an alternative to perfluorooctanoic acid (PFOA) which was phased out of formulations for industrial and consumer product applications in 2015. While the effects of GenX on lab animals have been studied, little is known about its effects on plants. This study examined and compared the accumulation and toxicity of GenX and PFOA in the model plants Arabidopsis thaliana and Nicotiana benthamiana. Both plants showed reduction in biomass and root growth following exposure to PFOA or GenX in a dosage-dependent manner. The bioaccumulation factors (BFs) of GenX and PFOA were plant species-dependent, with higher BFs in A. thaliana compared to N. bethanminana. Additionally, GenX and PFOA were more readily accumulated into shoot tissues of A. thaliana than in N. bethanminana. Exposure to GenX also caused a reduction in chlorophyll content (18%) and total phenolic compounds (26%). However, GenX exposure increased superoxide dismutase activity and H2O2 content (1.6 and 2.6 folds increase, respectively) in N. benthamiana. Overall, our result suggest that GenX is bioaccumulative, and that its accumulation likely inhibits plant growth and photosynthesis as well as inducing oxidative stress.

Perfluorooctanoic acid alters progesterone activity in human endometrial cells and induces reproductive alterations in young women

Female fecundity is finely regulated by hormonal signaling, representing a potential target for endocrine-disrupting chemicals. Among the chemicals of most concern are the perfluoroalkyl substances (PFAS), widely used in consumer goods, that are associated with adverse effects on reproductive health. In this context, the endometrium clearly represents an important fertility determining factor. The aim of this study was to investigate PFAS interference on hormonal endometrial regulation. This study was performed within a screening protocol to evaluate reproductive health in high schools. We studied a cohort of 146 exposed females aged 18-21 from the Veneto region in Italy, one of the four areas worldwide heavily polluted with PFAS, and 1080 non-exposed controls. In experiments on Ishikawa cells included UV-Vis spectroscopy, microarray analysis and qPCR. We report a significant dysregulation of the genetic cascade leading to embryo implantation and endometrial receptivity. The most differentially-expressed genes upon PFOA coincubation were ITGB8, KLF5, WNT11, SULT1E1, ALPPL2 and G0S2 (all p < 0.01). By qPCR, we confirmed an antagonistic effect of PFOA on all these genes, which was reversed at higher progesterone levels. Molecular interference of PFOA on progesterone was confirmed by an increase in the intensity of absorption spectra at 250 nm in a dose-dependent manner, but not in the presence of β-estradiol. Age at menarche (+164 days, p = 0.006) and the frequency of girls with irregular periods (29.5% vs 21.5%, p = 0.022) were significantly higher in the exposed group. Our results are indicative of endocrine-disrupting activity of PFAS on progesterone-mediated endometrial function.

Effects of perfluorooctanoic acid (PFOA) on the thyroid status, vitellogenin, and oxidant-antioxidant balance in the Murray River rainbowfish

Perfluorooctanoic acid's (PFOA) widespread use, presence and persistence in the aquatic environment has led to an increasing number of studies focusing on its toxicological effects. In Australia, PFOA has been detected in the aquatic environment, however its effects on Australian native fauna are unknown. In this study, male Australian native fish Murray River rainbowfish (Melanotaenia fluviatilis) were exposed to four different concentrations of PFOA (0.01, 0.1, 1 and 10 mg L^-1). Variations in thyroid hormones (Triiodothyronine (T3)/Thyroxine (T4)) and the presence of vitellogenin were determined in plasma. Oxidative stress responses were evaluated in gills and liver. Exposure of male fish to PFOA resulted in altered T3/T4 ratios and the presence of vitellogenin in the plasma. Activities of catalase (CAT) and glutathione- S-transferase (GST) were significantly increased in the gills and significantly reduced in the liver. Lipid peroxidation was observed in both tissues showing that vital organs could not neutralize the peroxides generated by oxidative stress resulting from exposure to PFOA. In natural populations exposed to PFOA, such hormonal disturbances can have negative effects, notably through altered capacity to respond to changes in environmental conditions.

Associations of Exposure to Perfluoroalkyl Substances With Thyroid Hormone Concentrations and Birth Size

BACKGROUND

Adequate thyroid function during pregnancy is essential for optimal fetal growth. Gestational exposure to perfluoroalkyl substances (PFAS) can negatively affect birth size and disrupt maternal and neonatal thyroid function, although the interrelationship is unclear.

OBJECTIVE

We aimed to quantify the associations between maternal serum-PFAS concentrations and birth weight, birth length, and cranial circumference. We also aimed to estimate associations between PFAS and thyroid hormone (TH) concentrations, thereby elucidating whether THs potentially mediate the associations between PFAS concentrations and birth size.

METHODS

We studied a population-based prospective cohort of 172 mother-singleton pairs from the Faroe Islands. Twelve PFAS were measured in maternal serum obtained at 34 weeks of gestation. THs were measured in maternal and cord serum. Associations between PFAS concentrations and birth size and TH concentrations were estimated using multivariable linear regressions. Sex-stratified analyses along with a mediation analysis were performed to estimate potential mediating effects of THs in the association between PFAS and birth outcomes.

RESULTS

Several PFASs were negatively associated with birth weight, length, and head circumference, and a general positive association between maternal serum-PFASs and cord serum-thyroid-stimulating hormone (TSH; also known as thyrotropin) was found. For instance, a doubling in perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) was associated with a 53% (95% CI, 18%-99%) and 40% (95% CI, 8%-81%) increases in TSH concentrations, respectively. There was little evidence of sexually dimorphic associations. Overall, THs were not found to mediate associations between PFASs and birth size.

CONCLUSION

In this study, several PFASs were negatively associated with birth size and increased THs; however, this did not explain lower birth weight among children exposed to PFAS.

Dynamic growth metrics for examining prenatal exposure impacts on child growth trajectories: Application to perfluorooctanoic acid (PFOA) and postnatal weight gain

BACKGROUND

Epidemiologic studies investigating prenatal exposures in relation to growth typically rely on cumulative growth measures such as weight or BMI. However, less is known about how prenatal exposure may impact other aspects of growth dynamics, including timing and velocity.

OBJECTIVES

To describe and apply a nonlinear growth model previously used in other health science fields to characterize postnatal growth trajectories for use in environmental epidemiology studies.

METHODS

We used a double logistic function to model child weight trajectories from birth to 5.5 years using data from the Swedish Environmental Longitudinal Mother and Child, Asthma and Allergy (SELMA) study. From this, we approximated several infant growth metrics: 1) duration of time needed to complete 90% of the infant growth spurt (Δt₁), 2) the maximum growth rate in infancy or infant peak growth velocity (PGV), 3) the age at infant PGV (δ₁), a measure of growth tempo, and 4) the weight plateau at the end of the infant growth spurt (α₁). We assessed these metrics in relation to prenatal perfluorooctanoic acid (PFOA) exposure among 1334 mother-child pairs, and differences between boys and girls.

RESULTS

Average estimated infant PGV and its timing (δ₁) were 0.68 kg/month and 3.4 months, respectively. Mean infant growth spurt duration (Δt₁) was 13 months, ending at an average weight plateau (α₁) of 8.2 kg. Higher prenatal PFOA concentrations were related to a longer duration of infant growth (Δt₁: 0.06; 95% CI = 0.01, 0.11). PGV was not impacted, but higher prenatal PFOA concentrations were significantly related to delayed infant PGV (δ₁: 0.58; 95% CI = 0.17, 0.99) and a higher post-spurt weight plateau (α₁: 0.81; 95% CI = 0.21, 1.41). After adjusting for false discovery, results were only significant for δ₁ and α₁. We observed a significant interaction by sex for the association with δ₁, and stratified analyses revealed the association was only significant among girls.

CONCLUSION

Model-derived growth metrics were consistent with published growth standards. This novel application of nonlinear growth modeling enabled detection of altered infant growth dynamics in relation to prenatal PFOA exposure. Our results may help describe how PFOA yields lower birthweights, but higher weight later in childhood. Future applications may characterize adolescent growth or additional metrics of biological interest.

Omics approach reveals perturbation of metabolism and phenotype in Caenorhabditis elegans triggered by perfluorinated compounds

Perfluorinated compounds (PFCs) are widely used in consumer products because of their remarkable endurance. However, their distinct stability prolongs degradation, resulting in bioaccumulation in the environment which is a severe environmental issue. Perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) are principal constituents in the PFCs. In this study, the potential toxic effects of PFOS and PFOA were evaluated by adopting an in vivo animal model, Caenorhabditis elegans (C. elegans). The uptake of PFCs was confirmed by the quantification of internal concentration in C. elegans. Metabolomics and lipidomics were applied along with reproduction assay and reactive oxygen species (ROS) assay. In the C. elegans exposed to PFOS and PFOA, amino acids including phenylalanine, tyrosine, and tryptophan, were significantly affected. Also, various species that belong to glycerophospholipids and triacylglycerol were perturbed in the exposed groups. The alteration patterns of the lipidome in PFOS and PFOA treated C. elegans were significantly different. Additionally, dichlorodihydrofluorescein diacetate (H₂DCFDA)-based ROS assay revealed increased internal ROS in PFOS (1.5 fold, p-value = 0.0067) and PFOA (1.46 fold, p-value = 0.0253) groups. Decrease in reproduction was confirmed in PFOS (0.53 fold, p-value < 0.0001) and PFOA (0.69 fold, p-value = 0.0003) by counting progeny. Collectively, our findings suggest that exposure to PFCs in C. elegans leads to perturbation of various phenotypes as well as crucial amino acid and lipid metabolism.

Evaluation of Maternal, Embryo, and Placental Effects in CD-1 Mice following Gestational Exposure to Perfluorooctanoic Acid (PFOA) or Hexafluoropropylene Oxide Dimer Acid (HFPO-DA or GenX)

BACKGROUND

Perfluorooctanoic acid (PFOA) is a poly- and perfluoroalkyl substance (PFAS) associated with adverse pregnancy outcomes in mice and humans, but little is known regarding one of its replacements, hexafluoropropylene oxide dimer acid (HFPO-DA, referred to here as GenX), both of which have been reported as contaminants in drinking water.

OBJECTIVES

We compared the toxicity of PFOA and GenX in pregnant mice and their developing embryo-placenta units, with a specific focus on the placenta as a hypothesized target.

METHODS

Pregnant CD-1 mice were exposed daily to PFOA (0, 1, or 5mg/kg) or GenX (0, 2, or 10mg/kg) via oral gavage from embryonic day (E) 1.5 to 11.5 or 17.5 to evaluate exposure effects on the dam and embryo-placenta unit. Gestational weight gain (GWG), maternal clinical chemistry, maternal liver histopathology, placental histopathology, embryo weight, placental weight, internal chemical dosimetry, and placental thyroid hormone levels were determined.

RESULTS

Exposure to GenX or PFOA resulted in increased GWG, with increase in weight most prominent and of shortest latency with 10mg/kg/d GenX exposure. Embryo weight was significantly lower after exposure to 5mg/kg/d PFOA (9.4% decrease relative to controls). Effect sizes were similar for higher doses (5mg/kg/d PFOA and 10mg/kg/d GenX) and lower doses (1mg/kg/d PFOA and 2mg/kg/d GenX), including higher maternal liver weights, changes in liver histopathology, higher placental weights and embryo-placenta weight ratios, and greater incidence of placental abnormalities relative to controls. Histopathological features in placentas suggested that PFOA and GenX may exhibit divergent mechanisms of toxicity in the embryo-placenta unit, whereas PFOA- and GenX-exposed livers shared a similar constellation of adverse pathological features.

CONCLUSIONS

Gestational exposure to GenX recapitulated many documented effects of PFOA in CD-1 mice, regardless of its much shorter reported half-life; however, adverse effects toward the placenta appear to have compound-specific signatures. https://doi.org/10.1289/EHP6233.

Ecological risk assessment for perfluorooctanoic acid in soil using a species sensitivity approach

Perfluorooctanoic acid (PFOA) is one of the persistent organic pollutants that has been listed in Annex A of the Stockholm Convention and has attracted attention owing to its endocrine-disrupting properties. However, there is currently little information available regarding the soil ecotoxicity of PFOA and the associated ecological risks. Accordingly, in this study, we sought to assess the soil ecological risk of PFOA based on a probabilistic approach using data obtained from multispecies bioassays and soil toxicity assessments, from which we generated soil species sensitivity distributions and estimated soil protective concentrations for PFOA. Using the latter distributions, we also undertook a probabilistic ecological risk assessment. On the basis of acute and chronic toxicity estimates obtained from bioassays involving eight soil-associated organisms from six diverse taxonomic groups, we could deduce that PFOA poses a negligible risk to soil ecosystems. However, we also found that this chemical may be more toxic than some of the established endocrine-disrupting chemicals such as bisphenol A, nonylphenol, and methylparaben, thereby indicating that further in-depth studies would be necessary to obtain a better understanding of the toxic potential of this chemical in the soil environment.

Metabolomic analysis reveals metabolic alterations of human peripheral blood lymphocytes by perfluorooctanoic acid

Perfluorooctanoic acid (PFOA) is a dispersive persistent organic pollutant in the environment. Accumulating reports suggest that PFOA is toxic to human lymphocytes; however, the toxicological effects of PFOA on these cells remain largely unclear. In this study, ultra-performance liquid chromatography (UPLC)-based metabolomic analysis was employed to identify metabolites in human peripheral blood lymphocytes and to assess the metabolic alterations caused by PFOA exposure. Our comparative metabolomic analysis results demonstrated that PFOA treatment could increase the level of organic acids and reduce the level of lipid molecules. Kyoto Encyclopedia of Genes and Genomes (KEGG) annotation further highlighted the fact that the PFOA treatment interfered with the metabolism of amino acids, carbohydrates and lipids, which may lead to disruption of the immune system.

Tissue distribution of 14C-labelled perfluorooctanoic acid in adult mice after 1-5 days of dietary exposure to an experimental dose or a lower dose that resulted in blood levels similar to those detected in exposed humans

Perfluorooctanoic acid (PFOA), a global environmental pollutant detected in both wildlife and human populations, has several pathophysiological effects in experimental animals, including hepatotoxicity, immunotoxicity, and developmental toxicity. However, details concerning the tissue distribution of PFOA, in particular at levels relevant to humans, are lacking, which limits our understanding of how humans, and other mammals, may be affected by this compound. Therefore, we characterized the tissue distribution of ¹⁴C-PFOA in mice in the same manner as we earlier examined its analogues perfluorooctanesulfonate (PFOS) and perfluorobutanesulfonate (PFBS) in order to allow direct comparisons. Following dietary exposure of adult male C57/BL6 mice for 1, 3 or 5 days to a low dose (0.06 mg/kg/day) or a higher experimental dose (22 mg/kg/day) of ¹⁴C-PFOA, both scintillation counting and whole-body autoradiography revealed the presence of PFOA in most of the 19 different tissues examined, demonstrating its ability to leave the bloodstream and enter tissues. There were no differences in the pattern of tissue distribution with the low and high dose and the tissue-to-blood ratios were similar. At both doses, PFOA levels were highest in the liver, followed by blood, lungs and kidneys. The body compartments estimated to contain the largest amounts of PFOA were the liver, blood, skin and muscle. In comparison with our identical studies on PFOS and PFBS, PFOA reached considerably higher tissue levels than PFBS, but lower than PFOS. Furthermore, the distribution of PFOA differed notably from that of PFOS, with lower tissue-to-blood ratios in the liver, lungs, kidneys and skin.

Investigations on the phytotoxicity of perfluorooctanoic acid in Arabidopsis thaliana

Environmental contamination by perfluorooctanoic acid (PFOA) has raised concerns for years. Yet, little information on its phytotoxic effects and underlying mechanisms in higher plants is available. To this end, comparative analyses of the responses to PFOA exposure between shoots and roots in the model plant species Arabidopsis thaliana were performed at the physiological and molecular levels. Our results showed that PFOA exposure reduced Arabidopsis biomass in a dose-related manner, and shoot growth was more sensitive to PFOA than root growth. Consistently, PFOA accumulation and the levels of several metal elements, including Zn, Ca, Cu, and K, in addition to Fe, were more substantially affected in the shoots than in the roots. Transcriptomic analysis further showed that the shoot transcriptional profile was distinguishable from that of roots upon PFOA exposure. Nevertheless, some overlapping genes were present between the shoots and roots, mainly including transporter genes, Fe-deficiency-responsive genes, and oxidative stress-related genes. More importantly, a comparative analysis of ROS-associated genes in combination with other oxidative stress assays pointed out that PFOA triggered certain oxidative stress-associated events more strongly in shoots than in roots. Overall, the results demonstrated that PFOA exposure caused alterations in PFOA distribution, metal element balance, reconfiguration of transcriptomes, and induction of oxidative stress in a tissue-dependent manner in Arabidopsis thaliana.

Hyfraxinic Acid, a Phytotoxic Tetrasubstituted Octanoic Acid, Produced by the Ash (Fraxinus excelsior L.) Pathogen Hymenoscyphus fraxineus Together with Viridiol and Some of Its Analogues

A new tetrasubstituted octanoic acid, named hyfraxinic acid (1), was isolated together with known 1-deoxyviridiol (2), viridiol (3), nodulisporiviridin M (4), and demethoxyviridiol (5) from the organic extract of Hymenoscyphus fraxineus responsible for ash (Fraxinus excelsior L.) dieback in Europe. Hyfraxinic acid (1) was characterized, using spectroscopic methods, as 2,4-dihydroxy-7-methyl-6-methyleneoctanoic acid. Furthermore, the advanced Mosher method was used to determine the absolute configuration (3R) of 1-deoxyviridiol. Nodulisporiviridin M (4) was isolated for the first time from H. fraxineus. The phytotoxicity of each compound was tested by a leaf puncture assay on Celtis australis L., Quercus suber L., Hedera elix L., Juglans regia L., and Fraxinus angustifolia L. leaves. Compounds 1, 3, and 5 exhibited remarkable phytotoxicity on all plants tested, inducing necrotic lesions at concentrations of 1.0 and 0.5 mg/mL, while compounds 2 and 4 were found to be inactive in this bioassay. These results could contribute to a deeper understanding of the pathogenicity of H. fraxineus.

Evaluation of morpho-physiological traits and contaminant accumulation ability in Lemna minor L. treated with increasing perfluorooctanoic acid (PFOA) concentrations under laboratory conditions

There is increasing concern about the effects of releasing emerging contaminants (i.e. endocrine-disrupting chemicals, pharmaceuticals, personal-care products and flame retardants) into the environment. Particular attention is being paid to perfluoroalkyl substances (PFAS) because of their persistence and bioaccumulation, especially in the aquatic environment. In this paper, we present results of a study aimed at evaluating the effects of different perfluorooctanoic acid (PFOA) concentrations (2, 20 and 200 μg/L) on morpho-physiological traits in Lemna minor L. plants. The accumulation of PFOA in the plant's tissues was also monitored. L. minor was selected as a model plant for ecotoxicological studies, and we performed a seven-day assay for this investigation. The results highlight the lack of inhibitory effects on biometric parameters such as mean frond area, total frond number, multiplication rate, doubling time of frond number and average specific growth rate, for each of tested PFOA concentrations. Also, at photosynthetic level, physiological measurements showed that chlorophyll content and electron transport rate (ETR) were not affected by the exposure to PFOA. Remarkably, the chlorophyll fluorescence images, used for the first time in a study on PFOA, evidenced no impairment to the photosynthetic efficiency, measured by the maximum quantum yield of photosystem II (PSII) photochemistry (Fv/Fm), the quantum efficiency of PSII photochemistry (ΦPSII) and the non-photochemical quenching (NPQ) over the leaf surface of PFOA-treated plants, in comparison to control. Quantification of PFOA in the growth medium at the end of the seven-day test revealed no statistically different concentrations in plates with or without L. minor plants. We detected increasing PFOA accumulation in plant tissues, in accordance with the PFOA concentrations in the medium. Therefore, the L. minor plants were capable of taking up and accumulating PFOA. The ecological impact of the environmentally relevant PFOA concentrations tested in this work on biological organisms of the aquatic environment is discussed.

Perfluorooctanoic Acid Exposure Assessment on Common Carp Liver through Image and Ultrastructural Investigation

Perfluorooctanoic acid (PFOA) poses particular concern as an emerging pollutant in both surface and ground waters. Fish, as a natural inhabitant of these waters and being highly representative of vertebrates, represents an ideal animal model to assess the toxic effects of PFOA. Hereby, liver microscopic texture was comparatively evaluated in individuals of common carp subchronically exposed to PFOA using grayscale differential box counting, a fractal analysis method. Furthermore, liver cytoplasmic glycogen areas and ultrastructure were also evaluated and compared to the image analysis findings. Redundancy Analysis was performed to assess, in summary, how much the variation of fractal dimension and lacunarity was explained by the concentration of PFOA in liver, the mass of liver and the number of proliferating cell nuclear antigen (PCNA)-immunoreactive nuclei. Treatment group ordination was better determined by fractal dimension than lacunarity. Interestingly, a significant complexity increase was associated with the modification of liver microscopic texture due to PFOA exposure. This complexity increase was related to "cloudy swelling", possibly representing a primarily adaptive strategy against PFOA challenge, rather than a slight, reversible form of degeneration as traditionally proposed. The occurrence of endoplasmic reticulum stress, unfolded protein reaction and hormetic response was proposed and discussed.

A mortality study on male subjects exposed to polyfluoroalkyl acids with high internal dose of perfluorooctanoic acid

OBJECTIVES

The aim of the present study was to examine the association between exposure to polyfluoroalkyl substances (PFASs) and mortality (1970-2018) in a cohort of 462 male employees who had worked at least six months before 2009 for a factory (14,658 person-years; 107 deaths, average follow-up time 31.7 years), which had been producing perfluorooctanoic acid (PFOA), perfluorooctanesulfonyl fluoride (PFOS) and other chemicals since 1968.

METHODS

Employees were classified as follows: 1) by probability of exposure to PFASs; 2) by tertiles of PFOA serum concentrations. In a fraction (n = 120) of workers measurements of internal PFOA serum concentration were used to predict a cumulative serum PFOA concentration of each cohort member. Mortality rates were compared to that of the regional population using the standardized mortality ratio (SMR), and to that of the workers of a nearby metalworking factory in terms of risk ratio (RR), across categories of probability of PFASs exposure and tertiles of cumulative serum PFOA concentrations.

RESULTS

Internal PFOA serum concentration among 120 workers in the 2000-2013 period was very high (Geometric Mean: 4048 ng/mL; range 19-91,900 ng/mL). The mortality of the chemical cohort was increased for liver cancer (SMR: 2.32; CI: 1.11-4.87), malignant neoplasm of lymphatic and haematopoietic tissue (SMR: 2.26; CI: 1.08-4.73). In the comparison with the cohort of workers from the metalworking factory, the RRs for mortality of the cohort were increased for overall mortality (RR: 1.42; CI: 1.12-1.79), diabetes (RR: 5.95; CI: 1.08-32.8), liver cancer (RR: 6.69; CI: 1.71-26.2) and liver cirrhosis (RR: 3.87; CI: 1.18-12.7). Mortality for these causes increased in association with probability of PFASs exposure and with tertiles of cumulative PFOA serum concentrations.

CONCLUSION

The present is a small observational study with limited control over confounding factors. The cohort showed increased mortality for all causes and subjects in the highest cumulative internal dose of PFOA had a statistically significant increase for mortality of liver cancer, liver cirrhosis, diabetes, malignant neoplasms of lymphatic and haematopoietic tissue in both comparisons. Toxicological studies on PFOA and PFOS provide support for causality for the observed association with the risk for liver cirrhosis and liver cancer.

Acute and chronic effects of perfluoroalkyl substance mixtures on larval American bullfrogs (Rana catesbeiana)

Discovery of elevated concentrations of perfluoroalkyl substances (PFAS) in ground and surface waters globally has heightened concern over their potential adverse health effects. The effects of PFAS are known largely from acute toxicity studies of single PFAS compounds in model organisms, while little is understood concerning effects of mixtures on wildlife. To address this gap, we examined the acute and chronic effects of two of the most common PFAS (perfluorooctanesulfonic acid [PFOS] and perfluorooctanoic acid [PFOA]) and their mixtures on survival, growth, and development of American bullfrog (Rana catesbeiana) tadpoles. In 96 h acute toxicity tests, PFOS was 10X more toxic than PFOA and effects of the two chemicals in combination appeared additive. The effects of PFOS, PFOA, and their interaction varied by the sublethal endpoint under consideration in a 72 d exposure. Effects of PFAS on tadpole mass and developmental stage were largely driven by PFOS and there was no evidence of interactions suggesting deviations from additivity. However, for snout-vent length, reductions in length in mixture treatments were greater than expected based on the effects of the two chemicals independently (i.e. non-additivity). Further, effects on snout-vent length in single chemical exposures were only observed with PFOA. Our results highlight the importance of assessing combined effects of PFAS co-occurring in the environment and suggest caution in extrapolating the effects of acute toxicity studies to more environmentally relevant exposures. Future studies examining effects of environmentally relevant mixtures on wildlife will be essential for effective environmental risk assessment and management.

In vitro and in silico modeling of perfluoroalkyl substances mixture toxicity in an amphibian fibroblast cell line

Poly and perfluoroalkyl substances (PFAS) are a large group of emerging organic pollutants that can persist in the environment and bioaccumulate in biota. They are found in complex mixtures, and although the exact number of PFAS is unknown, it has been estimated to be in the thousands. The objective of this study was two-fold. First, we examined the cytotoxicity of PFAS singly and in binary mixtures using an amphibian fibroblast cell line. Second, we used this experimental data to develop quantitative structure-activity relationship (QSAR) models for single and binary mixtures. We tested the cytotoxicity of four common PFAS: perfluorooctane sulfonate (PFOS); perfluorooctanoic acid (PFOA); perfluorohexane sulfonate (PFHxS); and perfluorohexanoic acid (PFHxA). PFOS was the most toxic and PFHxA the least cytotoxic. Binary mixtures allowed for the construction of isobolograms to test for additivity, synergism, or antagonism. Using this data, QSAR modeling was used for predicting the toxicity of 24 single and 1380 binary mixtures (theoretically generated). Overall, our experimental and modeling results showed that mixtures were approximately additive, with the exception of PFOS and PFOA, which were found to be weakly synergistic. This data shows that certain mixtures of PFAS may have increased toxicity potential above what the simple sum of PFAS concentrations would suggest. More studies are needed that test the toxicity of PFAS mixtures.

Associations of Perfluoroalkyl and Polyfluoroalkyl Substances With Incident Diabetes and Microvascular Disease

OBJECTIVE

Perfluoroalkyl and polyfluoroalkyl substances (PFASs) are suspected endocrine disruptors widely detected across populations. We examine the extent to which PFASs are associated with diabetes incidence and microvascular disease. Secondarily, we tested whether a lifestyle intervention modifies associations and decreases concentrations.

RESEARCH DESIGN AND METHODS

We analyzed data from a prospective cohort of 957 participants from the Diabetes Prevention Program (DPP) trial and Diabetes Prevention Program Outcomes Study (DPPOS). At baseline, participants were randomized to an intensive lifestyle intervention of diet, physical activity, and behavior modification or a placebo medication. We quantified plasma concentrations of six PFASs at baseline and 2 years after randomization. Participants were monitored for ∼15 years, repeatedly tested for diabetes, and evaluated for microvascular disease at the end of the follow-up.

RESULTS

A doubling in baseline branched perfluorooctanoic acid concentration was associated with a 14% increase in diabetes risk for the placebo (hazard ratio [HR] 1.14, 95% CI 1.04, 1.25) but not in the lifestyle intervention group (HR 1.01, 95% CI 0.92, 1.11, P interaction = 0.11). Mean change in plasma baseline branched perfluorooctanoic acid concentration was greater for the placebo (0.96 ng/mL; 95% CI 0.71, 1.22) compared with the lifestyle intervention group (0.31 ng/mL; 95% CI 0.14, 0.48) 2 years after randomization. Each doubling in N-ethyl-perfluorooctane sulfonamido acetic acid was associated with 17% greater odds of prevalent microvascular disease (OR 1.17, 95% CI 1.05, 1.31), and a similar association was observed for perfluorodimethylhexane sulfonic acid (OR 1.18, 95% CI 1.04, 1.35), regardless of treatment.

CONCLUSIONS

Some plasma PFASs were associated with diabetes and microvascular disease. Our results suggest that exercise and diet may attenuate the diabetogenic association of PFASs.

Prenatal perfluorooctanoic acid exposure is associated with early onset atopic dermatitis in 5-year-old children

Atopic dermatitis (AD) is the most common childhood skin disease and the first step of atopic march. Perfluoroalkyl substance (PFAS) exposure is associated with atopic diseases, including AD. However, whether PFAS exposure is related to earlier AD onset remains unclear. We aimed to investigate the association between prenatal PFAS exposure and earlier onset of AD in children in a 5-year follow-up study. From 2001 to 2005, 1264 mother-infant pairs were recruited from eight Taiwanese maternity hospitals. PFAS levels were analyzed from cord blood. Information on children's health status, including AD occurrence, was obtained via phone interviews at multiple time points. Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) concentrations were measured by ultra-high performance liquid chromatography/tandem mass spectrometry. Cox proportional hazards models assessed associations between prenatal PFAS exposure and early onset AD. Overall, 863 mother-infant pairs with complete measurements were recruited. The prevalence of physician-diagnosed AD before 5 years of age was 7.1%. PFOA and PFOS concentrations were grouped based on whether they were above the 75th percentile. PFOA exposure was positively associated with earlier onset of AD (Kaplan-Meier estimate, p = 0.014). In the Cox model, after adjusting for sex, family income, parental atopy, breast feeding, and maternal age at childbirth, significance was observed in children above the upper quartile (≥75th) of the PFOA group (hazard ratio: 1.89; 95% confidence interval, 1.10-3.16). Our findings suggested that children with higher prenatal PFOA exposure have a higher risk of earlier AD development. Minimizing early life PFAS exposure may help inhibit AD development.