Perfluoroalkyl Chemicals, Menstrual Cycle Length, and Fecundity: Findings from a Prospective Pregnancy Study

Effects of Per- and Polyfluoroalkylated Substances on Female Reproduction

Per- and poly-fluoroalkylated substances (PFAS) are a large group of chemicals that persist both in the environment and in the body. Legacy PFAS, e.g., perfluorooctanoic acid and perfluorooctane sulfonic acid, are implicated as endocrine disruptors and reproductive and developmental toxicants in epidemiological and animal model studies. This review describes female reproductive outcomes of reported studies and includes where associative relationships between PFAS exposures and female reproductive outcomes have been observed as well as where those are absent. In animal models, studies in which PFAS are documented to cause toxicity and where effects are lacking are described. Discrepancies exist in both human and animal studies and are likely attributable to human geographical contamination, developmental status, duration of exposure, and PFAS chemical identity. Similarly, in animal investigations, the model used, exposure paradigm, and developmental status of the female are important and vary widely in documented studies. Taken together, support for PFAS as reproductive and developmental toxicants exists, although the disparity in study conditions and human exposures contribute to the variation in effects noted.

Associations of per- and polyfluoroalkyl substances with uterine leiomyomata incidence and growth: a prospective ultrasound study

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) are endocrine-disrupting chemicals used in commercial and consumer products.

OBJECTIVE

We evaluated PFAS exposure in relation to incidence and growth of uterine leiomyomata (UL), hormone-dependent neoplasms that are associated with severe gynecologic morbidity.

METHODS

We studied 1158 participants in the Study of Environment, Lifestyle, and Fibroids, a Detroit-based prospective cohort study of Black females aged 23-35 years at enrollment (2010-2012). At enrollment and four subsequent visits during 10 years of follow-up, participants attended in-person clinic visits, completed questionnaires, provided non-fasting blood samples, and underwent ultrasound for UL detection. We quantified 7 PFAS in baseline plasma samples using mass spectrometry. We used Cox regression and probit Bayesian kernel machine regression to estimate individual and joint effects of PFAS on UL incidence. We fit linear mixed models to estimate effects of individual PFAS on UL growth. We stratified by parity, an important route of PFAS elimination and determinant of UL.

RESULTS

In individual PFAS analyses, we observed inverse associations for perfluorodecanoate (PFDA; ≥0.3 vs. <0.2 ng/ml: hazard ratio [HR] = 0.74; 95% confidence interval [CI]: 0.54-1.00) and perfluoroundecanoate (detected vs. non-detected: HR = 0.78; 95% CI: 0.61-1.01) and a weak positive association for perfluorohexane sulfonate (≥1 vs. <0.6 ng/ml: HR = 1.17; 95% CI: 0.85-1.61), while perfluorooctane sulfonate, perfluorooctanoate, perfluorononanoate (PFNA), and 2-N-methyl-perfluorooctane sulfonamido acetate (MeFOSAA) showed little association with UL incidence. The PFAS mixture was inversely associated with UL incidence, a finding driven by MeFOSAA and PFDA; however, PFNA was positively associated with UL incidence. The inverse association for PFDA and positive association for PFNA were stronger among nulliparous participants. Most PFAS showed slight inverse associations with UL growth.

IMPACT STATEMENT

In this prospective ultrasound study of 1158 Black females aged 23-35 years at enrollment, we conducted a mixtures analysis to account for co-pollutant confounding and interaction. MeFOSAA and PFDA concentrations were inversely associated with UL incidence, while PFNA concentrations were positively associated with UL incidence. Concentrations of most PFAS were associated with decreased UL growth. This study contributes data to the sparse literature on PFAS exposure and UL development.

Phthalate metabolites in urine and follicular fluid in relation to menstrual cycle characteristics in women seeking fertility assistance

BACKGROUND

Phthalates have been shown to disrupt the estrous cycle in animal studies. However, epidemiological research investigating their associations with menstrual cycle characteristics is limited.

OBJECTIVE

To explore the relationships between phthalate exposure and menstrual cycle characteristics among women seeking fertility assistance.

METHODS

We determined the levels of eight phthalate metabolites in both follicular fluid (FF) and urine specimens collected from 441 women in the Tongji Reproductive and Environmental (TREE) cohort, using high-performance liquid chromatography and tandem mass spectrometry. Information about menstrual cycle parameters was obtained through a questionnaire. The impacts of individual and joint exposure to phthalates on menstrual cycle characteristics were assessed using multivariable linear regression, Poisson regression, and quantile g-computation approaches.

RESULTS

After adjusting for relevant covariates, we found that per log10-unit increase in mono(2-ethylhexyl) phthalate (MEHP) level in urine specimens was associated with a decrease of 0.20 days (95 % CI: -0.37, -0.03) in bleeding duration. We also observed that mono(2-ethyl-5-carboxypentyl) phthalate (MECPP) and the sum of di(2-ethylhexyl) phthalate (DEHP) metabolites (∑DEHP) concentrations in FF samples were inversely related to cycle length [β = -1.92 (95 % CI: -3.10, -0.75) and -1.87 (95 % CI: -3.56, -0.19), respectively]. However, we generally observed null associations between phthalate metabolites and irregular cycle, dysmenorrhea, hypomenorrhea, or cycle length variation. Furthermore, we also found that phthalate metabolite mixtures in FF and urine were generally unrelated to menstrual cycle characteristics.

CONCLUSION

Our findings suggest that some DEHP metabolites in FF and urine are inversely associated with menstrual cycle length and menstrual bleeding duration in women attending a fertility center.

Exposure to select PFAS and PFAS mixtures alters response to platinum-based chemotherapy in endometrial cancer cell lines

BACKGROUND

Exposure to per- and poly-fluoroalkyl substances (PFAS) has been associated with significant alterations in female reproductive health. These include changes in menstrual cyclicity, timing of menarche and menopause, and fertility outcomes, as well as increased risk of endometriosis, all of which may contribute to an increased risk of endometrial cancer. The effect of PFAS on endometrial cancer cells, specifically altered treatment response and biology, however, remains poorly studied. Like other gynecologic malignancies, a key contributor to lethality in endometrial cancer is resistance to chemotherapeutics, specifically to platinum-based agents that are used as the standard of care for patients with advanced-stage and/or recurrent disease.

OBJECTIVES

To explore the effect of environmental exposures, specifically PFAS, on platinum-based chemotherapy response and mitochondrial function in endometrial cancer.

METHODS

HEC-1 and Ishikawa endometrial cancer cells were exposed to sub-cytotoxic nanomolar and micromolar concentrations of PFAS/PFAS mixtures and were treated with platinum-based chemotherapy. Survival fraction was measured 48-h post-chemotherapy treatment. Mitochondrial membrane potential was evaluated in both cell lines following exposure to PFAS ± chemotherapy treatment.

RESULTS

HEC-1 and Ishikawa cells displayed differing outcomes after PFAS exposure and chemotherapy treatment. Cells exposed to PFAS appeared to be less sensitive to carboplatin, with instances of increased survival fraction, indicative of platinum resistance, observed in HEC-1 cells. In Ishikawa cells treated with cisplatin, PFAS mixture exposure significantly decreased survival fraction. In both cell lines, increases in mitochondrial membrane potential were observed post-PFAS exposure ± chemotherapy treatment.

DISCUSSION

Exposure of endometrial cancer cell lines to PFAS/PFAS mixtures had varying effects on response to platinum-based chemotherapies. Increased survival fraction post-PFAS + carboplatin treatment suggests platinum resistance, while decreased survival fraction post-PFAS mixture + cisplatin exposure suggests enhanced therapeutic efficacy. Regardless of chemotherapy sensitivity status, mitochondrial membrane potential findings suggest that PFAS exposure may affect endometrial cancer cell mitochondrial functioning and should be explored further.

Association of per- and polyfluoroalkyl substance exposure with metabolic syndrome and its components in adults and adolescents

Per- and polyfluoroalkyl substances (PFAS) are widespread contaminants, but few studies have explored the relationship between PFAS and levels of metabolic syndrome (MetS) in the population. The available evidence of an association is also conflicting. We selected adults and adolescents with complete PFAS data from the National Health and Nutrition Examination Survey conducted between 2003 and 2018. We analyzed the association between PFAS and MetS using multivariate logistic regression models and evaluated potential nonlinear relationships with restricted cubic spline models. Additionally, we employed weighted quantile sum (WQS) regressions to uncover the multiple exposure effects and relative weights of each PFAS. Finally, we conducted a series of sensitivity analyses to test the robustness of our findings. In this population-based study, we analyzed data from a total of 4,973 adults, aged 20-85 years, and 1,381 adolescents, aged 12-19 years. Using fully adjusted multivariate logistic regression models, we found that serum levels of perfluorodecanoate (PFDA) [0.65 (0.50, 0.85)] and total PFAS [0.92 (0.85, 0.99)] were negatively associated with the prevalence of MetS in adults. Similarly, in adolescents, we observed negative correlations between the prevalence of MetS and levels of PFDA [0.55 (0.38, 0.80)], perfluorooctanoic acid (PFOA) [0.62 (0.39, 1.00)], perfluorooctane sulfonic acid (PFOS) [0.59 (0.36, 0.96)], and total PFAS [0.61 (0.37, 0.99)]. Additionally, our study identified statistically significant negative associations between serum levels of PFAS and certain components of MetS, primarily elevated fasting glucose and lower high-density lipoprotein cholesterol. Our study found that PFAS was associated with a lower prevalence of MetS in both adults and adolescents, offering new insights into the relationship between PFAS and metabolic health. Interestingly, however, we observed conflicting findings across the components of MetS. Specifically, we observed that PFAS had a negative correlation with some metrics and a positive correlation with others. These conflicting results point to a complex interplay between PFAS and various metrics of metabolic health.

Hepatic and ovarian effects of perfluorooctanoic acid exposure differ in lean and obese adult female mice

Obesity and overweight cause poor oocyte quality, miscarriage, infertility, polycystic ovarian syndrome, and offspring birth defects and affects 40% and 20% of US women and girls, respectively. Perfluorooctanoic acid (PFOA), a per- and poly-fluoroalkyl substance (PFAS), is environmentally persistent and has negative female reproductive effects including endocrine disruption, oxidative stress, altered menstrual cyclicity, and decreased fertility in humans and animal models. PFAS exposure is associated with non-alcoholic fatty liver disease which affects ∼24-26% of the US population. This study investigated the hypothesis that PFOA exposure impacts hepatic and ovarian chemical biotransformation and alters the serum metabolome. At 7 weeks of age, female lean, wild type (KK.Cg-a/a) or obese (KK.Cg-Ay/J) mice received saline (C) or PFOA (2.5 mg/Kg) per os for 15 d. Hepatic weight was increased by PFOA exposure in both lean and obese mice (P < 0.05) and obesity also increased liver weight (P < 0.05) compared to lean mice. The serum metabolome was also altered (P < 0.05) by PFOA exposure and differed between lean and obese mice. Exposure to PFOA altered (P < 0.05) the abundance of ovarian proteins with roles in xenobiotic biotransformation (lean - 6; obese - 17), metabolism of fatty acids (lean - 3; obese - 9), cholesterol (lean - 8; obese - 11), amino acids (lean - 18; obese - 19), glucose (lean - 7; obese - 10), apoptosis (lean - 18; obese - 13), and oxidative stress (lean - 3; obese - 2). Use of qRT-PCR determined that exposure to PFOA increased (P < 0.05) hepatic Ces1 and Chst1 in lean but Ephx1 and Gstm3 in obese mice. Also, obesity basally increased (P < 0.05) Nat2, Gpi and Hsd17b2 mRNA levels. These data identify molecular changes resultant from PFOA exposure that may cause liver injury and ovotoxicity in females. In addition, differences in toxicity induced by PFOA exposure occurs in lean and obese mice.

Mixtures of per- and poly-fluoroalkyl substances (PFAS) reduce the in vitro activation of human T cells and basophils

In the last decades, per- and poly-fluoroalkyl substances (PFAS), widely used industrial chemicals, have been in the center of attention because of their omnipotent presence in water and soils worldwide. Although efforts have been made to substitute long-chain PFAS towards safer alternatives, their persistence in humans still leads to exposure to these compounds. PFAS immunotoxicity is poorly understood as no comprehensive analyses on certain immune cell subtypes exist. Furthermore, mainly single entities and not PFAS mixtures have been assessed. In the present study we aimed to investigate the effect of PFAS (short-chain, long-chain and a mixture of both) on the in vitro activation of primary human immune cells. Our results show the ability of PFAS to reduce T cells activation. In particular, exposure to PFAS affected T helper cells, cytotoxic T cells, Natural Killer T cells, and Mucosal associated invariant T (MAIT) cells, as assessed by multi-parameter flow cytometry. Furthermore, the exposure to PFAS reduced the expression of several genes involved in MAIT cells activation, including chemokine receptors, and typical proteins of MAIT cells, such as GZMB, IFNG and TNFSF15 and transcription factors. These changes were mainly induced by the mixture of both short- and long-chain PFAS. In addition, PFAS were able to reduce basophil activation induced by anti-FcεR1α, as assessed by the decreased expression of CD63. Our data clearly show that the exposure of immune cells to a mixture of PFAS at concentrations mimicking real-life human exposure resulted in reduced cell activation and functional changes of primary innate and adaptive human immune cells.

Photodynamic Priming Overcomes Per- and Polyfluoroalkyl Substance (PFAS)-Induced Platinum Resistance in Ovarian Cancer†

Per- and polyfluoroalkyl substances (PFAS) are widespread environmental contaminants linked to adverse outcomes, including for female reproductive biology and related cancers. We recently reported, for the first time, that PFAS induce platinum resistance in ovarian cancer, potentially through altered mitochondrial function. Platinum resistance is a major barrier in the management of ovarian cancer, necessitating complementary therapeutic approaches. Photodynamic therapy (PDT) is a light-based treatment modality that reverses platinum resistance and synergizes with platinum-based chemotherapy. The present study is the first to demonstrate the ability of photodynamic priming (PDP), a low-dose, sub-cytotoxic variant of PDT, to overcome PFAS-induced platinum resistance. Comparative studies of PDP efficacy using either benzoporphyrin derivative (BPD) or 5-aminolevulinic acid-induced protoporphyrin IX (PpIX) were conducted in two human ovarian cancer cell lines (NIH:OVCAR-3 and Caov-3). BPD and PpIX are clinically approved photosensitizers that preferentially localize to, or are partly synthesized in, mitochondria. PDP overcomes carboplatin resistance in PFAS-exposed ovarian cancer cells, demonstrating the feasibility of this approach to target the deleterious effects of environmental contaminants. Decreased survival fraction in PDP + carboplatin treated cells was accompanied by decreased mitochondrial membrane potential, suggesting that PDP modulates the mitochondrial membrane, reducing membrane potential and re-sensitizing ovarian cancer cells to carboplatin.

The effects of perfluoroalkyl and polyfluoroalkyl substances on female fertility: A systematic review and meta-analysis

OBJECTIVE

The reproductive toxicity of perfluoroalkyl and polyfluoroalkyl substances (PFAS) has been verified in both animal and in vitro experiments, however, the association between PFAS and female fertility remains contradictory in population studies. Therefore, in this systematic review and meta-analysis, we evaluated the effects of PFAS on female fertility based on population evidence.

METHODS

Electronic searches of the Web of Science, PubMed, The Cochrane Library, and Embase databases were conducted (from inception to March 2022) to collect observational studies related to PFAS and female fertility. Two evaluators independently screened the literature, extracted information and evaluated the risk of bias for the included studies, meta-analysis was performed using R software.

RESULTS

A total of 5468 records were searched and 13 articles fully met the inclusion criteria. Meta-analysis showed that perfluorooctanoic acid (PFOA) exposure was negatively associated with the female fecundability odds ratio (FOR = 0.88, 95% confidence interval (Cl) [0.78; 0.98]) and positively associated with the odds ratio for infertility (OR = 1.33, 95%Cl [1.03; 1.73]). Perfluorooctane sulfonate (PFOS) exposure was negatively associated with the fecundability odds ratio (FOR = 0.94, 95% CI [0.90; 0.98]). Pooled effect values for perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), and perfluorohexane sulfonate (PFHxS) exposure did not find sufficient evidence for an association with female fertility.

CONCLUSION

Based on the evidence provided by the current study, increased levels of PFAS exposure are associated with reduced fertility in women, this was characterized by a reduction in fecundability odds ratio and an increase in odds ratio for infertility. This finding could partially explain the decline in female fertility and provide insight into risk assessment when manufacturing products containing PFAS.

Insights into the Dermal Absorption, Deposition, and Elimination of Poly- and Perfluoroalkyl Substances in Rats: The Importance of Skin Exposure

Humans are frequently exposed to poly- and perfluoroalkyl substances (PFASs) via direct skin contact with personal care and consumer products containing them. Here, we used a rat model to estimate the dermal penetration efficiency of 15 representative PFASs. After 144 h post-dosing, 4.1-18.0 and 5.3-15.1% of the applied PFASs in the low (L) and high (H) groups, respectively, were absorbed into the rats. PFAS absorption and permeation were parabolically associated with the perfluorinated carbon chain length (C_F), peaking for perfluoroheptanoic acid (PFHpA). The lipid-rich stratum corneum of the skin barrier substantially suppressed the penetration of less hydrophobic short-chain PFASs, whereas the water-rich viable epidermis and dermis served as obstacles to hydrophobic long-chain PFAS permeation. However, the renal clearance (CL_renal) of the target PFAS decreased with increasing C_F, suggesting that urinary excretion is crucial to eliminate less hydrophobic short-chain PFASs. Notably, the peak times of PFASs in the systemic circulation of rats (8-72 h) were remarkably longer than those after oral administration (1-24 h). These results suggest that dermal penetration can be long-lasting and contribute considerably to the body burden of PFASs, especially for those with moderate hydrophobicity due to their favorable skin permeation and unfavorable urinary excretion.

The effects of endocrine-disrupting chemicals on ovarian- and ovulation-related fertility outcomes

Exposure to endocrine-disrupting chemicals (EDCs) is unavoidable, which represents a public health concern given the ability of EDCs to target the ovary. However, there is a large gap in the knowledge about the impact of EDCs on ovarian function, including the process of ovulation. Defects in ovulation are the leading cause of infertility in women, and EDC exposures are contributing to the prevalence of infertility. Thus, investigating the effects of EDCs on the ovary and ovulation is an emerging area for research and is the focus of this review. The effects of EDCs on gametogenesis, uterine function, embryonic development, and other aspects of fertility are not addressed to focus on ovarian- and ovulation-related fertility issues. Herein, findings from epidemiological and basic science studies are summarized for several EDCs, including phthalates, bisphenols, per- and poly-fluoroalkyl substances, flame retardants, parabens, and triclosan. Epidemiological literature suggests that exposure is associated with impaired fecundity and in vitro fertilization outcomes (decreased egg yield, pregnancies, and births), while basic science literature reports altered ovarian follicle and corpora lutea numbers, altered hormone levels, and impaired ovulatory processes. Future directions include identification of the mechanisms by which EDCs disrupt ovulation leading to infertility, especially in women.

Association between Perfluoroalkyl and Polyfluoroalkyl Substances and Women's Infertility, NHANES 2013-2016

Perfluoroalkyl and polyfluoroalkyl substances (PFASs) are widely used in consumer products. However, the role of PFAS in infertility is still poorly understood. A total of 788 women from the 2013-2016 nationally representative NHANES were included to explore the association between PFAS exposure and self-reported infertility. Six PFAS, including PFDE, PFNA, PFHxS, n-PFOA, n-PFOS, and Sm-PFOS, were detected by online SPE-HPLC-TIS-MS/MS. We used the generalized linear regression model (GLM), generalized additive models (GAM), and Bayesian kernel machine regression (BKMR) to assess the single effects, non-linear relationships, and mixed effects on women's infertility, respectively. The prevalence of self-reported infertility was 15.54% in this study. In GLM, n-PFOA showed a negative association with self-reported infertility in women for the Q3 (OR: 0.396, 95% CI: 0.119, 0.788) and Q4 (OR: 0.380, 95% CI: 0.172-0.842) compared with Q1 (p for trend = 0.013). A negative trend was also observed in n-PFOS and ∑PFOS (p for trend < 0.05). In GAM, a non-linear relationship was revealed in Sm-PFOS, which exhibits a U-shaped relationship. The BKMR model indicated that there might be a joint effect between PFAS and women's infertility, to which PFNA contributed the highest effect (PIP = 0.435). Moreover, age stratification analysis showed a different dose-response curve in under and above 35 years old. Women under the age of 35 have a more noticeable U-shaped relationship with infertility. Therefore, the relatively low level of mixed PFAS exposure was negatively associated with self-reported infertility in women in general, and the impact of PFAS on infertility may vary among women of different age groups. Further studies are needed to determine the etiological relationship.

PFOA-Induced Ovotoxicity Differs Between Lean and Obese Mice With Impacts on Ovarian Reproductive and DNA Damage Sensing and Repair Proteins

Perfluorooctanoic acid (PFOA) is an environmentally persistent perfluoroalkyl substance that is widely used in consumer products. Exposure to PFOA is associated with reproductive and developmental effects including endocrine disruption, delayed puberty in girls, and decreased fetal growth. In the United States, obesity affects 40% of women and 20% of girls, with higher rates in minority females. Obesity causes infertility, poor oocyte quality, miscarriage, and offspring defects. This study proposed that PFOA exposure would impact estrous cyclicity, ovarian steroid hormones, and the ovarian proteome and further hypothesized that obesity would impact PFOA-induced ovotoxicity. Female wild type (KK.Cg-a/a; lean) or KK.Cg-Ay/J mice (obese) received saline (CT) or PFOA (2.5 mg/kg) per os for 15 days beginning at 7 weeks of age. There were no effects on food intake, body weight, estrous cyclicity, serum progesterone, and heart, spleen, kidney, or uterus weight (p > .05). Ovary weight was decreased (p < .05) by PFOA exposure relative to vehicle control-treated mice in lean but not obese mice. Liquid chromatography-tandem mass spectrometry was performed on isolated ovarian protein and PFOA exposure altered the ovarian abundance of proteins involved in DNA damage sensing and repair pathways and reproduction pathways (p < .05) differentially in lean and obese mice. The data suggest that PFOA exposure alters ovary weight and differentially targets ovarian proteins in lean and obese females in ways that might reduce female fecundity.

Endocrine disrupting chemicals impact on ovarian aging: Evidence from epidemiological and experimental evidence

Endocrine-disrupting chemicals (EDCs) are ubiquitous in daily life, but their harmful effects on the human body have not been fully explored. Recent studies have shown that EDCs exposure could lead to infertility, menstrual disorder and menopause, resulting in subsequent effects on female health. Therefore, it is of great significance to clarify and summarize the impacts of EDCs on ovarian aging for explaining the etiology of ovarian aging and maintaining female reproductive health. Here in this review, we focused on the impacts of ten typical environmental contaminants on the progression of ovarian aging during adult exposure, including epidemiological data in humans and experimental models in rodents, with their clinical phenotypes and underlying mechanisms. We found that both persistent (polychlorinated biphenyls, perfluoroalkyl and polyfluoroalkyl substances) and non-persistent (phthalates) EDCs exposure could increase an overall risk of ovarian aging, leading to the diminish of ovarian reserve, decline of fertility or fecundity, irregularity of the menstrual cycle and an earlier age at menopause, and/or premature ovarian insufficiency/failure in epidemiological studies. Among these, the loss of follicles can also be validated in experimental studies of some EDCs, such as BPA, phthalates, parabens and PCBs. The underlying mechanisms may involve the impaired ovarian follicular development by altering receptor-mediated pro-apoptotic pathways, inducing signal transduction and cell cycle arrest and epigenetic modification. However, there were inconsistent results in the impacts on fertility/fecundity, menstrual/estrous cycle and hormone changes response to different EDCs, and differences between human and animal studies. Our review summarizes the current state of knowledge on ovarian disrupters, highlights their risks to ovarian aging and identifies knowledge gaps in humans and animals. We therefore propose that females adopt healthy lifestyle changes to minimize their exposure to both persistent and non-persistent chemicals, that have the potential damage to their reproductive function.

Multi- and Transgenerational Effects of Developmental Exposure to Environmental Levels of PFAS and PFAS Mixture in Zebrafish (Danio rerio)

Per- and polyfluoroalkyl substances (PFASs) are ubiquitous in the environment and are tied to myriad health effects. Despite the phasing out of the manufacturing of two types of PFASs (perfluorosulfonic acid (PFOS) and perfluorooctanoic acid (PFOA)), chemical composition renders them effectively indestructible by ambient environmental processes, where they thus remain in water. Exposure via water can affect both human and aquatic wildlife. PFASs easily cross the placenta, exposing the fetus at critical windows of development. Little is known about the effects of low-level exposure during this period; even less is known about the potential for multi- and transgenerational effects. We examined the effects of ultra-low, very low, and low-level PFAS exposure (7, 70, and 700 ng/L PFOA; 24, 240, 2400 ng/L PFOS; and stepwise mixtures) from 0–5 days post-fertilization (dpf) on larval zebrafish (Danio rerio) mortality, morphology, behavior and gene expression and fecundity in adult F0 and F1 fish. As expected, environmentally relevant PFAS levels did not affect survival. Morphological abnormalities were not observed until the F1 and F2 generations. Behavior was affected differentially by each chemical and generation. Gene expression was increasingly perturbed in each generation but consistently showed lipid pathway disruption across all generations. Dysregulation of behavior and gene expression is heritable, even in larvae with no direct or indirect exposure. This is the first report of the transgenerational effects of PFOA, PFOS, and their mixture in terms of zebrafish behavior and untargeted gene expression.

Select Per- and Polyfluoroalkyl Substances (PFAS) Induce Resistance to Carboplatin in Ovarian Cancer Cell Lines

Per- and polyfluoroalkyl substances (PFAS) are ubiquitous environmental contaminants associated with adverse reproductive outcomes including reproductive cancers in women. PFAS can alter normal ovarian function, but the effects of PFAS on ovarian cancer progression and therapy response remain understudied. Ovarian cancer is the most lethal gynecologic malignancy, and a major barrier to effective treatment is resistance to platinum-based chemotherapy. Platinum resistance may arise from exposure to external stimuli such as environmental contaminants. This study evaluated PFAS and PFAS mixture exposures to two human ovarian cancer cell lines to evaluate the ability of PFAS exposure to affect survival fraction following treatment with carboplatin. This is the first study to demonstrate that, at sub-cytotoxic concentrations, select PFAS and PFAS mixtures increased survival fraction in ovarian cancer cells following carboplatin treatment, indicative of platinum resistance. A concomitant increase in mitochondrial membrane potential, measured by the JC-1 fluorescent probe, was observed in PFAS-exposed and PFAS + carboplatin-treated cells, suggesting a potential role for altered mitochondrial function that requires further investigation.

An Epidemiologic Review of Menstrual Blood Loss as an Excretion Route for Per- and Polyfluoroalkyl Substances

PURPOSE OF REVIEW

Menstrual blood loss, a common physiologic occurrence, provides an excretion route for per- and polyfluoroalkyl substances (PFAS) since these chemicals are bound to proteins in blood. To increase awareness of this relationship in environmental epidemiology, we reviewed the available epidemiologic data on menstrual bleeding and PFAS concentrations.

RECENT FINDINGS

Initial epidemiologic studies reported generally higher PFAS concentrations in men, menopausal women, and those with a history of hysterectomy compared to premenopausal women. Although subsequent studies investigating menstrual cycle characteristics observed somewhat discrepant results for menstrual irregularity and cycle length, consistent associations have been observed between heavy menstrual bleeding and lower PFAS concentrations. This review highlights the important role of menstrual bleeding on the excretion of PFAS. Given the high prevalence of menstrual bleeding in the population and the implications for environmental epidemiology, we provide recommendations to move this field forward.

Environmental factors in declining human fertility

A severe decline in child births has occurred over the past half century, which will lead to considerable population declines, particularly in industrialized regions. A crucial question is whether this decline can be explained by economic and behavioural factors alone, as suggested by demographic reports, or to what degree biological factors are also involved. Here, we discuss data suggesting that human reproductive health is deteriorating in industrialized regions. Widespread infertility and the need for assisted reproduction due to poor semen quality and/or oocyte failure are now major health issues. Other indicators of declining reproductive health include a worldwide increasing incidence in testicular cancer among young men and alterations in twinning frequency. There is also evidence of a parallel decline in rates of legal abortions, revealing a deterioration in total conception rates. Subtle alterations in fertility rates were already visible around 1900, and most industrialized regions now have rates below levels required to sustain their populations. We hypothesize that these reproductive health problems are partially linked to increasing human exposures to chemicals originating directly or indirectly from fossil fuels. If the current infertility epidemic is indeed linked to such exposures, decisive regulatory action underpinned by unconventional, interdisciplinary research collaborations will be needed to reverse the trends.

Per- and poly-fluoroalkyl substances (PFAS) and female reproductive outcomes: PFAS elimination, endocrine-mediated effects, and disease

Per- and poly-fluoroalkyl substances (PFAS) are widespread environmental contaminants frequently detected in drinking water supplies worldwide that have been linked to a variety of adverse reproductive health outcomes in women. Compared to men, reproductive health effects in women are generally understudied while global trends in female reproduction rates are declining. Many factors may contribute to the observed decline in female reproduction, one of which is environmental contaminant exposure. PFAS have been used in home, food storage, personal care and industrial products for decades. Despite the phase-out of some legacy PFAS due to their environmental persistence and adverse health effects, alternative, short-chain and legacy PFAS mixtures will continue to pollute water and air and adversely influence women's health. Studies have shown that both long- and short-chain PFAS disrupt normal reproductive function in women through altering hormone secretion, menstrual cyclicity, and fertility. Here, we summarize the role of a variety of PFAS and PFAS mixtures in female reproductive tract dysfunction and disease. Since these chemicals may affect reproductive tissues directly or indirectly through endocrine disruption, the role of PFAS in breast, thyroid, and hypothalamic-pituitary-gonadal axis function are also discussed as the interplay between these tissues may be critical in understanding the long-term reproductive health effects of PFAS in women. A major research gap is the need for mechanism of action data - the targets for PFAS in the female reproductive and endocrine systems are not evident, but the effects are many. Given the global decline in female fecundity and the ability of PFAS to negatively impact female reproductive health, further studies are needed to examine effects on endocrine target tissues involved in the onset of reproductive disorders of women.

Menstrual cycle length and modern living: a review

PURPOSE OF REVIEW

The aim of this review is to evaluate biological, life history, environmental, and lifestyle factors and exposures that cause variability in menstrual cycle length (MCL).

RECENT FINDINGS

Recent literature has detailed a number of factors that influence MCL, with particular emphasis placed on novel environmental exposures, such as air pollution and endocrine disrupting chemicals.

SUMMARY

MCL varies widely in response to intrinsic and extrinsic inputs and is a useful predictor of reproductive health and fecundability.

VIDEO ABSTRACT

http://links.lww.com/COE/A28.

Endocrine disrupting chemicals: Impacts on human fertility and fecundity during the peri-conception period

It is becoming increasingly difficult to avoid exposure to man-made endocrine disrupting chemicals (EDCs) and environmental toxicants. This escalating yet constant exposure is postulated to partially explain the concurrent decline in human fertility that has occurred over the last 50 years. Controversy however remains as to whether associations exist, with conflicting findings commonly reported for all major EDC classes. The primary aim of this extensive work was to identify and review strong peer-reviewed evidence regarding the effects of environmentally-relevant EDC concentrations on adult male and female fertility during the critical periconception period on reproductive hormone concentrations, gamete and embryo characteristics, as well as the time to pregnancy in the general population. Secondly, to ascertain whether individuals or couples diagnosed as sub-fertile exhibit higher EDC or toxicant concentrations. Lastly, to highlight where little or no data exists that prevents strong associations being identified. From the greater than 1480 known EDCs, substantial evidence supports a negative association between exposure to phthalates, PCBs, PBDEs, pyrethroids, organochloride pesticides and male fertility and fecundity. Only moderate evidence exists for a negative association between BPA, PCBs, organochloride pesticides and female fertility and fecundity. Overall fewer studies were reported in women than men, with knowledge gaps generally evident for both sexes for all the major EDC classes, as well as a paucity of female fertility studies following exposure to parabens, triclosans, dioxins, PFAS, organophosphates and pyrethroids. Generally, sub-fertile individuals or couples exhibit higher EDC concentrations, endorsing a positive association between EDC exposure and sub-fertility. This review also discusses confounding and limiting factors that hamper our understanding of EDC exposures on fertility and fecundity. Finally, it highlights future research areas, as well as government, industry and social awareness strategies required to mitigate the negative effects of EDC and environmental toxicant exposure on human fertility and fecundity.

Per- and Polyfluoroalkyl Substance Toxicity and Human Health Review: Current State of Knowledge and Strategies for Informing Future Research

Reports of environmental and human health impacts of per- and polyfluoroalkyl substances (PFAS) have greatly increased in the peer-reviewed literature. The goals of the present review are to assess the state of the science regarding toxicological effects of PFAS and to develop strategies for advancing knowledge on the health effects of this large family of chemicals. Currently, much of the toxicity data available for PFAS are for a handful of chemicals, primarily legacy PFAS such as perfluorooctanoic acid and perfluorooctane sulfonate. Epidemiological studies have revealed associations between exposure to specific PFAS and a variety of health effects, including altered immune and thyroid function, liver disease, lipid and insulin dysregulation, kidney disease, adverse reproductive and developmental outcomes, and cancer. Concordance with experimental animal data exists for many of these effects. However, information on modes of action and adverse outcome pathways must be expanded, and profound differences in PFAS toxicokinetic properties must be considered in understanding differences in responses between the sexes and among species and life stages. With many health effects noted for a relatively few example compounds and hundreds of other PFAS in commerce lacking toxicity data, more contemporary and high-throughput approaches such as read-across, molecular dynamics, and protein modeling are proposed to accelerate the development of toxicity information on emerging and legacy PFAS, individually and as mixtures. In addition, an appropriate degree of precaution, given what is already known from the PFAS examples noted, may be needed to protect human health. Environ Toxicol Chem 2021;40:606-630. © 2020 SETAC.

Endocrine Disruptor Potential of Short- and Long-Chain Perfluoroalkyl Substances (PFASs)-A Synthesis of Current Knowledge with Proposal of Molecular Mechanism

Endocrine disruptors are a group of chemical compounds that, even in low concentrations, cause a hormonal imbalance in the body, contributing to the development of various harmful health disorders. Many industry compounds, due to their important commercial value and numerous applications, are produced on a global scale, while the mechanism of their endocrine action has not been fully understood. In recent years, per- and polyfluoroalkyl substances (PFASs) have gained the interest of major international health organizations, and thus more and more studies have been aimed to explain the toxicity of these compounds. PFASs were firstly synthesized in the 1950s and broadly used in the industry in the production of firefighting agents, cosmetics and herbicides. The numerous industrial applications of PFASs, combined with the exceptionally long half-life of these substances in the human body and extreme environmental persistence, result in a common and chronic exposure of the general population to their action. Available data have suggested that human exposure to PFASs can occur during different stages of development and may cause short- or/and long-term health effects. This paper synthetizes the current literature reports on the presence, bioaccumulation and, particularly, endocrine toxicity of selected long- and short-chain PFASs, with a special emphasis on the mechanisms underlying their endocrine actions.

Persistent organic pollutants and couple fecundability: a systematic review

BACKGROUND

Despite increasing regulation, exposure to persistent organic pollutants (POPs) remains a serious public health concern due to their accumulation in the environment and ability to biomagnify up the food chain. POPs are associated with endocrine-disrupting effects including adverse reproductive outcomes that could affect fecundability, i.e. the capacity to conceive a pregnancy, quantified as time to pregnancy (TTP).

OBJECTIVE AND RATIONALE

Results of epidemiologic studies that examine the impact of various chemical classes of POPs on TTP have not been synthesised. We undertook a systematic review to summarise the strength of evidence for associations of four common groups of POPs with couple fecundability and to identify gaps and limitations in the literature in order to inform policy decisions and future research.

SEARCH METHODS

We performed an electronic search of literature published between 1 January 2007 and 6 August 2019 in MEDLINE, EMBASE.com, Global Health, DART/TOXLINE and POPLINE. We included empirical research papers that examined human exposure to organochlorine (OC) pesticides, brominated flame retardants, polychlorinated organic compounds and/or per- and polyfluoroalkyl substances (PFAS) and considered TTP or fecundability as an outcome. Standardised forms for screening, data extraction and study quality were developed using DistillerSR software, and all reviews were completed in duplicate. We used the Newcastle-Ottawa Scale to assess risk of bias and devised additional quality metrics based on specific methodological features of fecundability studies.

OUTCOMES

The search returned 4573 articles, and 28 papers from 19 different studies met inclusion criteria. Among them, four studies measured TTP prospectively, three had data on participants' prenatal exposure, three examined associations in both male and female partners and one focused exclusively on males. Analyses varied widely in terms of exposure characterisation, precluding a meta-analytic approach. Evidence was strongest for adverse associations of female exposure to polychlorinated biphenyls with TTP, with some additional support for associations of female exposure to polybrominated diphenyl ethers and PFAS with longer TTP. Our review provided little or no support for associations between female exposure to OC pesticides or male exposure to any of the POP groups and TTP.

WIDER IMPLICATIONS

Evidence suggests that female exposure to at least some POPs may reduce fecundability. Although many of these chemicals are no longer in production, they are still detectable in human biosamples because of their persistence in the environment. Replacement chemicals that are being introduced as older ones are restricted may have similar reproductive consequences. Future studies should examine these newer POPs, assess interactions between POPs and other chemical and non-chemical exposures, investigate how POPs are distributed in and metabolised by the human body and focus on populations that may be disproportionately exposed.

Early life exposure to per- and polyfluoroalkyl substances (PFAS) and latent health outcomes: A review including the placenta as a target tissue and possible driver of peri- and postnatal effects

Per- and polyfluoroalkyl substances (PFAS) are ubiquitous drinking water contaminants of concern due to mounting evidence implicating adverse health outcomes associated with exposure, including reduced kidney function, metabolic syndrome, thyroid disruption, and adverse pregnancy outcomes. PFAS have been produced in the U.S. since the 1940s and now encompass a growing chemical family comprised of diverse chemical moieties, yet the toxicological effects have been studied for relatively few compounds. Critically, exposures to some PFAS in utero are associated with adverse outcomes for both mother and offspring, such as hypertensive disorders of pregnancy (HDP), including preeclampsia, and low birth weight. Given the relationship between HDP, placental dysfunction, adverse health outcomes, and increased risk for chronic diseases in adulthood, the role of both developmental and lifelong exposure to PFAS likely contributes to disease risk in complex ways. Here, evidence for the role of some PFAS in disrupted thyroid function, kidney disease, and metabolic syndrome is synthesized with an emphasis on the placenta as a critical yet understudied target of PFAS and programming agent of adult disease. Future research efforts must continue to fill the knowledge gap between placental susceptibility to environmental exposures like PFAS, subsequent perinatal health risks for both mother and child, and latent health effects in adult offspring.

Perfluoroalkyl and polyfluoroalkyl substances (PFAS) and their effects on the ovary

BACKGROUND

Perfluoroalkyl and polyfluoroalkyl substances (PFAS) are found widespread in drinking water, foods, food packaging materials and other consumer products. Several PFAS have been identified as endocrine-disrupting chemicals based on their ability to interfere with normal reproductive function and hormonal signalling. Experimental models and epidemiologic studies suggest that PFAS exposures target the ovary and represent major risks for women's health.

OBJECTIVE AND RATIONALE

This review summarises human population and toxicological studies on the association between PFAS exposure and ovarian function.

SEARCH METHODS

A comprehensive review was performed by searching PubMed. Search terms included an extensive list of PFAS and health terms ranging from general keywords (e.g. ovarian, reproductive, follicle, oocyte) to specific keywords (including menarche, menstrual cycle, menopause, primary ovarian insufficiency/premature ovarian failure, steroid hormones), based on the authors' knowledge of the topic and key terms.

OUTCOMES

Clinical evidence demonstrates the presence of PFAS in follicular fluid and their ability to pass through the blood-follicle barrier. Although some studies found no evidence associating PFAS exposure with disruption in ovarian function, numerous epidemiologic studies, mostly with cross-sectional study designs, have identified associations of higher PFAS exposure with later menarche, irregular menstrual cycles, longer cycle length, earlier age of menopause and reduced levels of oestrogens and androgens. Adverse effects of PFAS on ovarian folliculogenesis and steroidogenesis have been confirmed in experimental models. Based on laboratory research findings, PFAS could diminish ovarian reserve and reduce endogenous hormone synthesis through activating peroxisome proliferator-activated receptors, disrupting gap junction intercellular communication between oocyte and granulosa cells, inducing thyroid hormone deficiency, antagonising ovarian enzyme activities involved in ovarian steroidogenesis or inhibiting kisspeptin signalling in the hypothalamus.

WIDER IMPLICATIONS

The published literature supports associations between PFAS exposure and adverse reproductive outcomes; however, the evidence remains insufficient to infer a causal relationship between PFAS exposure and ovarian disorders. Thus, more research is warranted. PFAS are of significant concern because these chemicals are ubiquitous and persistent in the environment and in humans. Moreover, susceptible groups, such as foetuses and pregnant women, may be exposed to harmful combinations of chemicals that include PFAS. However, the role environmental exposures play in reproductive disorders has received little attention by the medical community. To better understand the potential risk of PFAS on human ovarian function, additional experimental studies using PFAS doses equivalent to the exposure levels found in the general human population and mixtures of compounds are required. Prospective investigations in human populations are also warranted to ensure the temporality of PFAS exposure and health endpoints and to minimise the possibility of reverse causality.

Environmental & occupational exposure & female reproductive dysfunction

All individuals are exposed to certain chemical, physical, biological, environmental as well as occupational factors. The data pertaining to role of these factors on female reproduction are scanty as compared to male. The available data suggest the adverse effects of certain toxicants, viz., metals such as lead, cadmium and mercury, pesticides such as bis(4-chlorophenyl)-1,1,1-trichloroethane and organic solvent such as benzene, toluene and ionizing radiation on the female reproductive system affecting directly the organ system or impacting in directly through hormonal impairments, molecular alterations, oxidative stress and DNA methylation impairing fertility as well as pregnancy and its outcomes. Thus, there is a need for awareness and prevention programme about the adverse effects of these factors and deterioration of female reproductive health, pregnancy outcome and offspring development as some of these chemicals might affect the developing foetus at very low doses by endocrine disruptive mechanism.

Menstrual cycle characteristics as determinants of plasma concentrations of perfluoroalkyl substances (PFASs) in the Norwegian Mother and Child Cohort (MoBa study)

INTRODUCTION

Perfluoroalkyl substances (PFASs) are fluorinated organic compounds that have been used in a variety of industrial and consumer applications. Menstruation is implicated as a possible route of elimination for PFASs in women. The overall purpose of this study was to examine menstrual cycle characteristics as determinants of plasma PFAS concentrations in women.

METHODS

Our study sample consisted of 1977 pregnant women from the Norwegian Mother and Child Cohort (MoBa) study. The women were asked about menstrual cycle regularity in the year before the pregnancy and typical menstrual cycle length as well as other demographic and reproductive characteristics in a questionnaire completed during the pregnancy. Blood samples were collected around 17-18 weeks gestation and PFAS concentrations were measured in plasma. We examined the association between menstrual cycle characteristics and seven PFASs (perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), perfluoroundecanoic acid (PFUnDA), perfluorohexane sulfonate (PFHxS), perfluoroheptane sulfonate (PFHpS), and perfluorooctane sulfonate (PFOS)) using multiple linear regression, adjusted for age, pre-pregnancy body mass index, smoking, education, income, parity, oral contraceptive use, inter-pregnancy interval, and breastfeeding duration.

RESULTS

Irregular cycles were not associated with PFAS concentrations. Overall, we found no evidence of associations between menstrual cycle length and PFAS concentrations. In subgroup analyses we found some evidence, among parous women, of decreased PFHpS and PFOS with short menstrual cycles; we also found, among recent OC users (in the 12 months before the questionnaire) increased PFNA and PFUnDA with long cycle length. Limitations of our study include misclassification of menstrual cycle characteristics, small sample sizes in the sub-group analyses, and a lack of information on duration and volume of menses.

CONCLUSIONS

In the entire study sample, we found little evidence of menstrual cycle characteristics as determinants of PFAS concentrations. However, we observed some associations between cycle length and PFAS concentrations with some select PFAS compounds in subgroup analyses.

Oral contraceptive use as a determinant of plasma concentrations of perfluoroalkyl substances among women in the Norwegian Mother and Child Cohort (MoBa) study

OBJECTIVE

Because oral contraceptives (OC) tends to lessen menstrual fluid loss - a route of excretion for perfluoroalkyl substances (PFASs) - we hypothesized that such use would be positively associated with PFAS concentrations.

METHODS

This analysis was based on the Norwegian Mother and Child Cohort (MoBa) study. We included 1090 women from two previous substudies of women enrolled from 2003 to 2007. Characteristics of OC use were obtained at baseline: use in the past 12months, duration and recency of use, age at first use. We examined log-transformed plasma concentrations of seven PFASs (perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), perfluoroundecanoic acid (PFUnDA), perfluorohexane sulfonate (PFHxS), perfluoroheptane sulfonate (PFHpS), and perfluorooctane sulfonate (PFOS)). Linear regression analyses, adjusted for maternal age, menstrual cycle length, parity, and education, were used to examine whether OC use characteristics were determinants of PFAS concentrations.

RESULTS

Except for PFDA and PFUnDA, women who used OCs in the 12months preceding the baseline interview had 12.9-35.7% higher PFAS concentrations than never OC users. To a lesser extent, past OC use was positively associated with PFASs (estimates ranged from 7.2-32.1%). Compared with never users, using OCs for 10 or more years was associated with increased PFAS concentrations, except for PFDA and PFUnDA (estimates for other PFASs ranged from 18.9-46.2%). We observed little effect of age at first OC use.

CONCLUSIONS

This analysis shows that characteristics of OC use, and duration of use in particular, may be important considerations when investigating relationships between women's reproductive outcomes and PFASs.