Effects of perfluorooctane sulfuric acid on placental PRL-family hormone production and fetal growth retardation in mice

Per- and polyfluoroalkyl substances (PFAS) and hypertensive disorders of Pregnancy- integration of epidemiological and mechanistic evidence

BACKGROUND

Hypertensive disorders of pregnancy (HDP) remain a significant global health burden despite medical advancements. HDP prevalence appears to be rising, leading to increased maternal and fetal complications, mortality, and substantial healthcare costs. The etiology of HDP are complex and multifaceted, influenced by factors like nutrition, obesity, stress, metabolic disorders, and genetics. Emerging evidence suggests environmental pollutants, particularly Per- and polyfluoroalkyl substances (PFAS), may contribute to HDP development.

OBJECTIVE

This review integrates epidemiological and mechanistic data to explore the intricate relationship between PFAS exposure and HDP.

EPIDEMIOLOGICAL EVIDENCE

Studies show varying degrees of association between PFAS exposure and HDP, with some demonstrating positive correlations, particularly with preeclampsia. Meta-analyses suggest potential fetal sex-specific differences in these associations.

MECHANISTIC INSIGHTS

Mechanistically, PFAS exposure appears to disrupt vascular hemodynamics, placental development, and critical processes like angiogenesis and sex steroid regulation. Experimental studies reveal alterations in the renin-angiotensin system, trophoblast invasion, oxidative stress, inflammation, and hormonal dysregulation - all of which contribute to HDP pathogenesis. Elucidating these mechanisms is crucial for developing preventive strategies.

THERAPEUTIC POTENTIAL

Targeted interventions such as AT2R agonists, caspase inhibitors, and modulation of specific microRNAs show promise in mitigating adverse outcomes associated with PFAS exposure during pregnancy.

KNOWLEDGE GAPS AND FUTURE DIRECTIONS

Further research is needed to comprehensively understand the full spectrum of PFAS-induced placental alterations and their long-term implications for maternal and fetal health. This knowledge will be instrumental in developing effective preventive and therapeutic strategies for HDP in a changing environmental landscape.

Preconception and/or preimplantation exposure to a mixture of environmental contaminants altered fetoplacental development and placental function in a rabbit model

Pregnant women are daily exposed to environmental contaminants, including endocrine disruptors that can impact the offspring's health. This study aimed to evaluate the effects of maternal oral exposure to a mixture of contaminants at a dose mimicking women's exposure, during folliculogenesis and/or preimplantation period (FED and ED groups, respectively) on the fetoplacental phenotype in a rabbit model. The mixture (DEHP, pp'DDE, β-HCH, HCB, BDE-47, BPS, PFOS, PFOA) was defined based on data from HELIX and INMA cohorts. FED and ED females or unexposed females (control) were inseminated, their embryos were collected and transferred to unexposed control recipient rabbits at 80 h post-insemination. The effects of maternal FED and ED exposure were evaluated on fetoplacental growth and development by ultrasound, fetoplacental biometry, fetal metabolism, placental structure and function. The results demonstrated that the mixture weakly affected ultrasound measurements, as only placental volume increased significantly in FED vs ED. Analysis of placental structure demonstrated that the volume fraction of the maternal blood space was increased in FED vs control. Pre- and/or periconception exposure did not affect biometric at the end of gestation, but affected FED fetal biochemistry. Plasma triglyceride concentration was reduced compared to control. However, total cholesterol, urea, ASAT and ALAT in fetal blood were affected in both exposed groups. Multiple factor analysis, including biometric, biochemical, and stereological datasets, indicated that the three groups were significantly different. Additionally, several placental genes were differentially expressed between groups, compared two by two, in a sex-specific manner, with more difference in females than in males. The differentially expressed genes were involved in lipid, cholesterol, and drug/xenobiotic metabolism in both sexes. These results indicate that maternal exposure to environmental contaminants during crucial developmental windows only mildly impaired fetoplacental development but disturbed fetal blood biochemistry and placental gene expression with potential long-term effects on offspring phenotype.

Impact of Gestational Exposure to Individual and Combined Per- and Polyfluoroalkyl Substances on a Placental Structure and Efficiency: Findings from the Ma'anshan Birth Cohort

Prenatal exposure to perfluoroalkyl and polyfluoroalkyl substances (PFASs) is inevitable among pregnant women. Nevertheless, there is a scarcity of research investigating the connections between prenatal PFAS exposure and the placental structure and efficiency. Based on 712 maternal-fetal dyads in the Ma'anshan Birth Cohort, we analyzed associations between individual and mixed PFAS exposure and placental measures. We repeatedly measured 12 PFAS in the maternal serum during pregnancy. Placental weight, scaling exponent, chorionic disc area, and disc eccentricity were used as the outcome variables. Upon adjusting for confounders and implementing corrections for multiple comparisons, we identified positive associations between branched perfluorohexane sulfonate (br-PFHxS) and 6:2 chlorinated polyfluorinated ether sulfonate (6:2 Cl-PFESA) with placental weight. Additionally, a positive association was observed between br-PFHxS and the scaling exponent, where a higher scaling exponent signified reduced placental efficiency. Based on neonatal sex stratification, female infants were found to be more susceptible to the adverse effects of PFAS exposure. Mixed exposure modeling revealed that mixed PFAS exposure was positively associated with placental weight and scaling exponent, particularly during the second and third trimesters. Furthermore, br-PFHxS and 6:2 Cl-PFESA played major roles in the placental measures. This study provides the first epidemiological evidence of the relationship between prenatal PFAS exposure and placental measures.

The Role of Endocrine Disrupting Chemicals in Gestation and Pregnancy Outcomes

Endocrine disrupting chemicals (EDCs) are exogenous substances widely disseminated both in the environment and in daily-life products which can interfere with the regulation and function of the endocrine system. These substances have gradually entered the food chain, being frequently found in human blood and urine samples. This becomes a particularly serious issue when they reach vulnerable populations such as pregnant women, whose hormones are more unstable and vulnerable to EDCs. The proper formation and activity of the placenta, and therefore embryonic development, may get seriously affected by the presence of these chemicals, augmenting the risk of several pregnancy complications, including intrauterine growth restriction, preterm birth, preeclampsia, and gestational diabetes mellitus, among others. Additionally, some of them also exert a detrimental impact on fertility, thus hindering the reproductive process from the beginning. In several cases, EDCs even induce cross-generational effects, inherited by future generations through epigenetic mechanisms. These are the reasons why a proper understanding of the reproductive and gestational alterations derived from these substances is needed, along with efforts to establish regulations and preventive measures in order to avoid exposition (especially during this particular stage of life).

Maternal serum per- and polyfluoroalkyl substances during pregnancy and breastfeeding duration

Per- and polyfluoroalkyl substances (PFAS) are endocrine-disrupting chemicals that may affect breastfeeding duration. We examined associations between maternal PFAS concentrations during pregnancy and breastfeeding cessation. We investigated potential effect modification by parity status.

Methods

Among 555 women enrolled in the Healthy Start study (2009-2014), we quantified maternal serum concentrations of 5 PFAS during mid- to late-pregnancy (mean 27 weeks of gestation). Participants self-reported their breastfeeding practices through 18-24 months postnatally. Among all participants and stratified by parity, we estimated associations between maternal PFAS concentrations and breastfeeding discontinuation by 3 and 6 months, using Poisson regression, and breastfeeding duration, using Cox regression.

Results

Median PFAS concentrations were similar to those in the general US population. Associations between PFAS and breastfeeding duration differed by parity status. After adjusting for covariates, among primiparous women, associations between PFAS and breastfeeding cessation by 3 and 6 months were generally null, with some inverse associations. Among multiparous women, there were positive associations between perfluorohexane sulfonate, perfluorooctane sulfonate, perfluorooctanoate (PFOA), and perfluorononanoate and breastfeeding cessation by 3 and 6 months. For example, per ln-ng/mL increase in PFOA, the risk ratio for breastfeeding discontinuation by 6 months was 1.45 (95% confidence interval, 1.18, 1.78). Hazard ratios reflected similar patterns between PFAS and breastfeeding duration.

Conclusions

Among primiparous women, we did not find evidence for associations between PFAS concentrations and breastfeeding duration. In contrast, among multiparous women, PFAS serum concentrations were generally inversely associated with breastfeeding duration, though estimates may be biased due to confounding by unmeasured previous breastfeeding.

Perfluorooctane sulfonic acid modulates expression of placental steroidogenesis-associated genes and hormone levels in pregnant rats

Perfluorooctane sulfonate (PFOS) is a widespread and persistent chemical in the environment. Reports show that PFOS is a potential endocrine disruptor; however, the possible effects of PFOS on placental endocrine function are unclear. This study aimed to investigate the endocrine-disrupting effects of PFOS on the placenta in pregnant rats and its potential mechanism. Pregnant rats from gestational days 4-20 were exposed to 0, 10, and 50 μg/mL PFOS through drinking water followed by analysis of various biochemical parameters. PFOS dose-dependently decreased fetal and placental weight in both sexes, with a specific decrease in weight of labyrinth but not junctional layer. Plasma progesterone (↑166%), aldosterone (↑201%), corticosterone (↑205%), testosterone (↑45%), luteinizing hormone (↑49%) levels were significantly increased, while estradiol (↓27%), prolactin (↓28%) and hCG (↓62%) levels were reduced in groups exposed to higher doses of PFOS. Real-time quantitative reverse transcriptase-polymerase chain reaction analysis revealed a significant increase in mRNA levels of placental steroid biosynthesis enzymes, including Cyp11A1 and 3β-HSD1 in male placenta and StAR, Cyp11A1, 17β-HSD1 and 17β-HSD3 in female placenta of PFOS dams. Cyp19A1 expression in ovaries was significantly decreased in PFOS dams. mRNA levels for placental steroid metabolism enzyme UGT1A1 increased in male but not in female placenta of PFOS dams. These results suggest that the placenta is a target tissue of PFOS and PFOS-induced dysregulation in steroid hormone production might be related to the altered expression of hormone biosynthesis and metabolism enzyme genes in the placenta. This hormone disruption might affect maternal health and fetal growth.

Effects of melamine and cyanuric acid on placental and fetal development in rats

Melamine or cyanuric acid alone has low toxicity, but combined exposure to melamine and cyanuric acid was reported to cause unexpected toxicological effects. This study investigated the potential effects and toxic mechanism of combined exposure to melamine and cyanuric acid on placental and fetal development in rats. Exposure to melamine and cyanuric acid caused maternal toxicity manifested by increased abnormal symptoms and decreased body weight gain. Developmental toxic effects included a decrease in placental and fetal weights with increased fetal deaths and post-implantation loss. Melamine and cyanuric acid induced oxidative stress in the developing placenta and fetus. The placentas from rats treated with melamine and cyanuric acid showed shortening of the placental layers with histological changes, decreased cell proliferation, increased apoptotic changes, and decreased insulin-like growth factor (IGF)/IGF-binding proteins (IGFBPs) and placental lactogen (PL) expression levels. Fetuses from melamine- and cyanuric acid-treated dams showed increased apoptotic changes and suppressed cellular proliferation in their livers and vertebrae. Consequently, combined exposure to melamine and cyanuric acid resulted in high levels of oxidative stress and impaired placental development associated with impairment of the IGF/IGFBP and PL systems, resulting in increased apoptotic changes and reduced fetal cell proliferation.

Effects of maternal urban particulate matter SRM 1648a exposure on birth outcomes and offspring growth in mice

The association between exposure to particulate matter (PM) during pregnancy and abnormal birth outcomes is still inconclusive. This study aims to provide more evidence for this public health concern by investigating birth outcomes and the growth of offspring in mice exposed to PM during pregnancy. C57BL/6 J pregnant mice were exposed to PM via nasal drip at three doses or solvent control. The dam weight gain was recorded during pregnancy. The number of pups, pup weight, and placental weight were recorded at embryonic day 18.5 (E18.5) necropsy. For mice that gave birth naturally, we calculated the gestation length and measured the body weight of offspring once a week from the 1st to the 6th week after birth. The results showed that there were no significant differences in maternal body weight gain, conception rate, pregnancy duration, and litter size among different groups. There were no significant differences in fetal weight, placental weight, and fetal/placental weight ratio at E18.5. Weight gain in offspring was reduced after birth. The average body weight of offspring in the high-dose group was significantly lower than that in the control group at weeks 5 in female pups. There were no significant differences in the body weight of male offspring among groups from 1st to the 6th. Together, our study indicated that maternal exposure to PM did not significantly impact birth outcomes of C57BL/6 J mice but affected growth trajectories in offspring after birth in a dose- and fetal sex-dependent manner.

Per- and Polyfluoroalkyl Substances and Breastfeeding as a Vulnerable Function: A Systematic Review of Epidemiological Studies

Milk formation in the breast during breastfeeding is a complex hormonally regulated process, potentially sensitive to the effects of endocrine-disrupting chemical exposures. The environmental chemicals, per- and polyfluoroalkyl substances (PFAS) are known endocrine disruptors. PFAS exposure have been associated with insufficient mammary gland development in mice and reduced breastfeeding duration in humans. The aim of this review was to gather the epidemiological evidence on the association between PFAS exposure and breastfeeding duration. Using PubMed and Embase, we performed a systematic literature search (on 23 January 2023) to identify epidemiological studies examining the association between maternal PFAS exposure and breastfeeding duration. Animal studies, reviews, and non-English studies were excluded. The risk of bias was assessed using the risk of bias in non-randomized studies of exposures tool. Estimates describing the association between PFAS exposure and the duration of breastfeeding were identified, and the data were synthesized separately for each type of PFAS and for the duration of exclusive and total breastfeeding. Six studies with between 336 and 2374 participants each were identified. PFAS exposure was assessed in serum samples (five studies) or based on residential address (one study). Five out of six studies found shorter total duration of breastfeeding with higher PFAS exposure. The most consistent associations were seen for perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), and perfluorononanoic acid (PFNA). The finding of a potential causal association between PFAS exposure and breastfeeding duration is in agreement with findings from experimental studies.

Pregnancy Exposure to Perfluoroalkyl Substances and Associations With Prolactin Concentrations and Breastfeeding in the Odense Child Cohort

CONTEXT

Human exposure to perfluoroalkyl substances (PFAS) has been associated with reduced duration of breastfeeding, although not consistently so, and mechanisms by which PFAS might affect breastfeeding are unknown.

OBJECTIVE

To examine the association between early pregnancy serum-PFAS concentrations and breastfeeding termination and to elucidate the potential role of serum-prolactin concentrations in pregnancy.

MATERIALS AND METHODS

Pregnant women from the Odense Child Cohort provided blood samples for analysis of 5 major PFAS (n = 1300) and prolactin concentrations (n = 924). They subsequently provided information about the duration of breastfeeding in questionnaires at 3 and 18 months postpartum, and a subgroup also provided breastfeeding information via weekly cell phone text messages. Associations between serum-PFAS concentrations and breastfeeding termination were analyzed using Cox regressions, while linear regression was used to assess associations between serum-PFAS and prolactin concentrations.

RESULTS

Increased serum concentrations of perfluorooctane sulfonic acid, perfluorooctanoic acid, perfluorononanoic acid, and ∑PFAS were associated with a 16% (95% CI: 4%-30%), 14% (95% CI: 2%-26%), 14% (95% CI: 3%-27%), and 20% (95% CI: 6%-36%), respectively, increased risk of terminating breastfeeding at any given time after childbirth. Serum-PFAS concentrations were not associated with serum-prolactin concentrations.

CONCLUSIONS

These findings are of public health importance due to the global exposures to PFAS. Because breastfeeding is crucial to promote both child health and maternal health, adverse PFAS effects on the ability to breastfeed may have long-term health consequences.

LncRNA MEG3 alleviates PFOS induced placental cell growth inhibition through its derived miR-770 targeting PTX3

Perfluorooctane sulfonic acid (PFOS) is a persistent environmental pollutant. Exposure to PFOS has been associated with abnormal fetal development. The long non-coding RNA (lncRNA) has been showed to play a role in fetal growth restriction (FGR), preeclampsia (PE) and other pregnancy complications. Whether the lncRNA contributes to PFOS-induced toxicity in the placenta remains unknown. In this study, we investigated the function of lncRNA MEG3 and its derived miR-770 in PFOS-induced placental toxicity. Pregnant mice received gavage administration of different concentrations of PFOS (0.5, 2.5, and 12.5 mg/kg/day) from GD0 to GD17, and HTR-8/SVneo cells were treated with PFOS in the concentrations of 0, 10^-1, 1, 10 μM. We found that expression levels of miR-770 and its host gene MEG3 were reduced in mice placentas and HTR-8/SVneo cells with exposure of PFOS. A significant hypermethylation was observed at MEG3 promoter in placentas of mice gestational-treated with PFOS. We also confirmed that MEG3 and miR-770 overexpression alleviated the cell growth inhibition induced by PFOS. Furthermore, PTX3 (Pentraxin 3) was identified as the direct target of miR-770 and it was enhanced after PFOS exposure. In summary, our results suggested that MEG3 alleviate PFOS-induced placental cell inhibition through MEG3/miR-770/PTX3 axis.

The impact of perfluoroalkyl substances on pregnancy, birth outcomes and offspring development: A review of data from mouse models1

Per- and polyfluoroalkyl substances (PFASs) such as perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) are persistent in the environment and bioaccumulate in wildlife and humans, potentially causing adverse health effects at all stages of life. Studies from human pregnancy have shown that exposure to these contaminants are associated with placental dysfunction and fetal growth restriction; however, studies in humans are confounded by genetic and environmental factors. Here, we synthesize the available results from mouse models of pregnancy to show the causal effects of prenatal exposure to PFOA and PFOS on placental and fetal development and on neurocognitive function and metabolic disorders in offspring. We also propose gaps in the present knowledge and provide suggestions for future research studies.

Endocrine disrupting chemicals (EDCs) and placental function: Impact on fetal brain development

Pregnancy is a critical time of vulnerability for the development of the fetal brain. Exposure to environmental pollutants at any point in pregnancy can negatively impact many aspects of fetal development, especially the organization and differentiation of the brain. The placenta performs a variety of functions that can help protect the fetus and sustain brain development. However, disruption of any of these functions can have negative impacts on both the pregnancy outcome and fetal neurodevelopment. This review presents current understanding of how environmental exposures, specifically to endocrine disrupting chemicals (EDCs), interfere with placental function and, in turn, neurodevelopment. Some of the key differences in placental development between animal models are presented, as well as how placental functions such as serving as a xenobiotic barrier and exchange organ, immune interface, regulator of growth and fetal oxygenation, and a neuroendocrine organ, could be vulnerable to environmental exposure. This review illustrates the importance of the placenta as a modulator of fetal brain development and suggests critical unexplored areas and possible vulnerabilities to environmental exposure.

PFOS Inhibited Normal Functional Development of Placenta Cells via PPARγ Signaling

Perfluorooctane sulfonic acid (PFOS), a persistent environmental pollutant, has adverse effects on gestation pregnancy. Peroxisome proliferator-activated receptor γ (PPARγ) is involved in angiogenesis, metabolic processes, anti-inflammatory, and reproductive development. However, the function of PPARγ in PFOS evoked disadvantageous effects on the placenta remain uncertain. Here, we explored the role of PPARγ in PFOS-induced placental toxicity. Cell viability, cell migration, angiogenesis, and mRNA expression were monitored by CCK-8 assay, wound healing assay, tube formation assay, and real-time PCR, respectively. Activation and overexpression of PPARγ were conducted by rosiglitazone or pcDNA-PPARγ, and inhibition and knockdown of PPARγ were performed by GW9662 or si-PPARγ. Results revealed that PFOS decreased cell growth, migration, angiogenesis, and increased inflammation in human HTR-8/SVneo and JEG-3 cells. Placenta diameter and fetal weight decreased in mice treated with PFOS (12.5 mg/kg). In addition, rosiglitazone or pcDNA-PPARγ rescued cell proliferation, migration, angiogenesis, and decreased inflammation induced by PFOS in HTR8/SVneo and JEG-3 cells. Furthermore, GW9662 or si-PPARγ exacerbated the inhibition of cell viability, migration, angiogenesis, and aggravated inflammation induced by PFOS in HTR-8/SVneo and JEG-3 cells. Meanwhile, the results of mRNA expression level were consistent with the cell representation. In conclusion, our findings revealed that PFOS induced placenta cell toxicity and functional damage through PPARγ pathway.

Human biomonitoring (HBM)-II values for perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) - Description, derivation and discussion

For evaluation of internal exposure to harmful substances, the Human Biomonitoring Commission of the German Environment Agency (HBM Commission) develops toxicologically justified assessment values (HBM-I and HBM-II). The HBM-I value corresponds to the concentration of a compound in human biological material below which no adverse health effects are expected to occur. Consequently, no action is required when the HBM-I value is not exceeded (HBM-Commission, 1996). In 2016, the HBM Commission developed HBM-I values of 2 ng PFOA/mL and 5 ng PFOS/mL in blood serum or plasma, respectively. A detailed delineation of supporting arguments was published in April 2018 (HBM-Commission, 2018). In contrast to the HBM-I, the HBM-II value corresponds to the concentration in human biological material which, when exceeded, may lead to health impairment which is considered as relevant to exposed individuals (HBM-Commission, 1996, HBM-Commission, 2014). HBM-II VALUES FOR PFOA AND PFOS: On September 17, 2019, the HBM Commission of the German Environment Agency established the following HBM-II values: Women at child-bearing age: 5 ng PFOA/mL blood plasma; 10 ng PFOS/mL blood plasma; All other population groups: 10 ng PFOA/mL blood plasma; 20 ng PFOS/mL blood plasma.

Risk to human health related to the presence of perfluoroalkyl substances in food

The European Commission asked EFSA for a scientific evaluation on the risks to human health related to the presence of perfluoroalkyl substances (PFASs) in food. Based on several similar effects in animals, toxicokinetics and observed concentrations in human blood, the CONTAM Panel decided to perform the assessment for the sum of four PFASs: PFOA, PFNA, PFHxS and PFOS. These made up half of the lower bound (LB) exposure to those PFASs with available occurrence data, the remaining contribution being primarily from PFASs with short half-lives. Equal potencies were assumed for the four PFASs included in the assessment. The mean LB exposure in adolescents and adult age groups ranged from 3 to 22, the 95th percentile from 9 to 70 ng/kg body weight (bw) per week. Toddlers and 'other children' showed a twofold higher exposure. Upper bound exposure was 4- to 49-fold higher than LB levels, but the latter were considered more reliable. 'Fish meat', 'Fruit and fruit products' and 'Eggs and egg products' contributed most to the exposure. Based on available studies in animals and humans, effects on the immune system were considered the most critical for the risk assessment. From a human study, a lowest BMDL 10 of 17.5 ng/mL for the sum of the four PFASs in serum was identified for 1-year-old children. Using PBPK modelling, this serum level of 17.5 ng/mL in children was estimated to correspond to long-term maternal exposure of 0.63 ng/kg bw per day. Since accumulation over time is important, a tolerable weekly intake (TWI) of 4.4 ng/kg bw per week was established. This TWI also protects against other potential adverse effects observed in humans. Based on the estimated LB exposure, but also reported serum levels, the CONTAM Panel concluded that parts of the European population exceed this TWI, which is of concern.

Placenta Disrupted: Endocrine Disrupting Chemicals and Pregnancy

Endocrine disrupting chemicals (EDCs) are chemicals that can interfere with normal endocrine signals. Human exposure to EDCs is particularly concerning during vulnerable periods of life, such as pregnancy. However, often overlooked is the effect that EDCs may pose to the placenta. The abundance of hormone receptors makes the placenta highly sensitive to EDCs. We have reviewed the most recent advances in our understanding of EDC exposures on the development and function of the placenta such as steroidogenesis, spiral artery remodeling, drug-transporter expression, implantation and cellular invasion, fusion, and proliferation. EDCs reviewed include those ubiquitous in the environment with available human biomonitoring data. This review also identifies critical gaps in knowledge to drive future research in the field.

Exposure to PFAS and small for gestational age new-borns: A birth records study in Veneto Region (Italy)

BACKGROUND

Perfluoroalkylated substances (PFAS) in serum are inversely associated with fetal growth. Small for gestational age (SGA) is a measure based on birth weight and gestational age at birth and represents a good indicator of fetal growth but it has been used only in a small number of studies. We examined the association between PFAS exposure and the risk of severe SGA in a PFAS contaminated area in the Veneto Region (North-East of Italy).

METHODS

A retrospective cohort study has been developed including all singleton live births reported in the Veneto Region Birth Registry between 2003 and 2018 to mothers living in the contaminated and in a control area. We estimated the association between mothers' area of residence and severe SGA using crude RR (and 95% CI) and stepwise logistic regression, including all the maternal characteristics.

RESULTS

The study included 105,114 singleton live births. The occurence of severe SGA was 3.44% in the contaminated area and 2.67% in the control area. The multivariate analysis confirmed that living in the contaminated area significantly increased the odds of severe SGA (adjusted OR 1.27 (95% C.I. 1.16, 1.39)).

CONCLUSIONS

The findings suggest that living in a contaminated area by PFAS plays a role in affecting fetal growth and support the hypothesis that PFAS exposure is a risk factor for SGA. Individual data on exposure are needed to confirm the direct association.

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

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

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

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

Changes in gene expression following long-term in vitro exposure of Macaca mulatta trophoblast stem cells to biologically relevant levels of endocrine disruptors

Trophoblast stem cells (TSCs) are crucial for embryo implantation and placentation. Environmental toxicants that compromise TSC function could impact fetal viability, pregnancy, and progeny health. Understanding the effects of low, chronic EDC exposures on TSCs and pregnancy is a priority in developmental toxicology. Differences in early implantation between primates and other mammals make a nonhuman primate model ideal. We examined effects of chronic low-level exposure to atrazine, tributyltin, bisphenol A, bis(2-ethylhexyl) phthalate, and perfluorooctanoic acid on rhesus monkey TSCs in vitro by RNA sequencing. Pathway analysis of affected genes revealed negative effects on cytokine signaling related to anti-viral response, most strongly for atrazine and tributyltin, but shared with the other three EDCs. Other affected processes included metabolism, DNA repair, and cell migration. Low-level chronic exposure of primate TSCs to EDCs may thus compromise trophoblast development in vivo, inhibit responses to infection, and negatively affect embryo implantation and pregnancy.

Regulation of Placental Development and Its Impact on Fetal Growth-New Insights From Mouse Models

The placenta is the chief regulator of nutrient supply to the growing embryo during gestation. As such, adequate placental function is instrumental for developmental progression throughout intrauterine development. One of the most common complications during pregnancy is insufficient growth of the fetus, a problem termed intrauterine growth restriction (IUGR) that is most frequently rooted in a malfunctional placenta. Together with conventional gene targeting approaches, recent advances in screening mouse mutants for placental defects, combined with the ability to rapidly induce mutations in vitro and in vivo by CRISPR-Cas9 technology, has provided new insights into the contribution of the genome to normal placental development. Most importantly, these data have demonstrated that far more genes are required for normal placentation than previously appreciated. Here, we provide a summary of common types of placental defects in established mouse mutants, which will help us gain a better understanding of the genes impacting on human placentation. Based on a recent mouse mutant screen, we then provide examples on how these data can be mined to identify novel molecular hubs that may be critical for placental development. Given the close association between placental defects and abnormal cardiovascular and brain development, these functional nodes may also shed light onto the etiology of birth defects that co-occur with placental malformations. Taken together, recent insights into the regulation of mouse placental development have opened up new avenues for research that will promote the study of human pregnancy conditions, notably those based on defects in placentation that underlie the most common pregnancy pathologies such as IUGR and pre-eclampsia.

Shorter duration of breastfeeding at elevated exposures to perfluoroalkyl substances

The aim of this study was to determine whether maternal exposure to persistent perfluoroalkyl substances (PFASs) affect the capability to breastfeed. In two Faroese birth cohorts (N=1130), concentrations of five PFASs were measured in maternal serum during pregnancy or two weeks after term. Duration of breastfeeding was assessed by questionnaire and clinical interview. In adjusted linear regression models, a doubling of maternal serum PFASs was associated with a reduction in duration of both total and exclusive breastfeeding, most pronounced for perfluorooctane sulfonic acid (PFOS) where a doubling was associated with a reduction in total breastfeeding of 1.4 (95% CI: 0.6; 2.1) months and perfluorooctanoic acid (PFOA) where a doubling was associated with a reduction in exclusive breastfeeding of 0.5 (0.3; 0.7) months. The associations were evident among both primiparous and multiparous women, and thus cannot be explained by confounding from previous breastfeeding.