Umbilical cord blood levels of perfluoroalkyl acids and polybrominated flame retardants

Systematic evidence mapping of potential correlates of exposure for per- and poly-fluoroalkyl substances (PFAS) based on measured occurrence in biomatrices and surveys of dietary consumption and product use

Per- and poly-fluoroalkyl substances (PFAS) are widely observed in environmental media and often are found in indoor environments as well as personal-care and consumer products. Humans may be exposed through water, food, indoor dust, air, and the use of PFAS-containing products. Information about relationships between PFAS exposure sources and pathways and the amounts found in human biomatrices can inform source-contribution assessments and provide targets for exposure reduction. This work collected and collated evidence for correlates of PFAS human exposure as measured through sampling of biomatrices and surveys of dietary consumption and use of consumer products and articles. A systematic evidence mapping approach was applied to perform a literature search, conduct title-abstract and full-text screening, and to extract primary data into a comprehensive database for 16 PFAS. Parameters of interest included: sampling dates and locations, cohort descriptors, PFAS measured in a human biomatrix, information about food consumption in 11 categories, use of products/articles in 11 categories, and reported correlation values (and their statistical strength). The literature search and screening process yielded 103 studies with information for correlates of PFAS exposures. Detailed data were extracted and compiled on measures of PFAS correlations between biomatrix concentrations and dietary consumption and other product/article use. A majority of studies (61/103; 59%) were published after 2015 with few (8/103; 8%) prior to 2010. Studies were most abundant for dietary correlates (n = 94) with fewer publications reporting correlate assessments for product use (n = 56), while some examined both. PFOA and PFOS were assessed in almost all studies, followed by PFHxS, PFNA, and PFDA which were included in >50% of the studies. No relevant studies included PFNS or PFPeS. Among the 94 studies of dietary correlates, significant correlations were reported in 83% of the studies for one or more PFAS. The significant dietary correlations most commonly were for seafood, meats/eggs, and cereals/grains/pulses. Among the 56 studies of product/article correlates, significant correlations were reported in 70% of the studies. The significant product/article correlations most commonly were for smoking/tobacco, cosmetics/toiletries, non-stick cookware, and carpet/flooring/furniture and housing. Six of 11 product/article categories included five or fewer studies, including food containers and stain- and water-resistant products. Significant dietary and product/article correlations most commonly were positive. Some studies found a mix of positive and negative correlations depending on the PFAS, specific correlate, and specific response level, particularly for fats/oils, dairy consumption, food containers, and cosmetics/toiletries. Most of the significant findings for cereals/grains/pulses were negative correlations. Substantial evidence was found for correlations between dietary intake and biomatrix levels for several PFAS in multiple food groups. Studies examining product/article use relationships were relatively sparse, except for smoking/tobacco, and would benefit from additional research. The resulting database can inform further assessments of dietary and product use exposure relationships and can inform new research to better understand PFAS source-to-exposure relationships. The search strategy should be extended and implemented to support living evidence review in this rapidly advancing area.

Using in vitro data to derive acceptable exposure levels: A case study on PBDE developmental neurotoxicity

BACKGROUND

Current acceptable chemical exposure levels (e.g., tolerable daily intake) are mainly based on animal experiments, which are costly, time-consuming, considered non-ethical by many, and may poorly predict adverse outcomes in humans.

OBJECTIVE

To evaluate a method using human in vitro data and biological modeling to calculate an acceptable exposure level through a case study on 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) developmental neurotoxicity (DNT).

METHODS

We reviewed the literature on in vitro assays studying BDE-47-induced DNT. Using the most sensitive endpoint, we derived a point of departure using a mass-balance in vitro disposition model and benchmark dose modeling for a 5% response (BMC05) in cells. We subsequently used a pharmacokinetic model of gestation and lactation to estimate administered equivalent doses leading to four different metrics of child brain concentration (i.e., average prenatal, average postnatal, average overall, and maximum concentration) equal to the point of departure. The administered equivalent doses were translated into tolerable daily intakes using uncertainty factors. Finally, we calculated biomonitoring equivalents for maternal serum and compared them to published epidemiological studies of DNT.

RESULTS

We calculated a BMC05 of 164 μg/kg of cells for BDE-47 induced alteration of differentiation in neural progenitor cells. We estimated administered equivalent doses of 0.925-3.767 μg/kg/day in mothers, and tolerable daily intakes of 0.009-0.038 μg/kg/day (composite uncertainty factor: 100). The lowest derived biomonitoring equivalent was 19.75 ng/g lipids, which was consistent with reported median (0.9-23 ng/g lipids) and geometric mean (7.02-26.9 ng/g lipids) maternal serum concentrations from epidemiological studies.

CONCLUSION

This case study supports using in vitro data and biological modeling as a viable alternative to animal testing to derive acceptable exposure levels.

The Association between Prenatal Exposure to Per- and Polyfluoroalkyl Substances and Respiratory Tract Infections in Preschool Children: A Wuhan Cohort Study

This study investigates the association between prenatal exposure to per- and polyfluoroalkyl substances (PFASs) and the incidence and frequency of respiratory tract infections (RTIs) in preschool children. We selected 527 mother-infant pairs from Wuhan Healthy Baby Cohort (WHBC), China. Ten PFASs were measured in umbilical cord serum, and we collected data on common RTIs in preschool children aged 4 years through a questionnaire. Associations of single PFASs with the incidence and frequency of RTIs were analyzed via Logistic regression and Poisson regression, while the collective effect was assessed by weighted quantile sum (WQS) regression. Furthermore, stratified and interaction analyses were performed to evaluate if there were sex-specific associations. We found a positive correlation between perfluorododecanoic acid (PFDoDA) and the incidence of tonsillitis, with several PFASs also showing positive associations with its frequency. Moreover, perfluorotridecanoic acid (PFTrDA) showed a positive link with the frequency of common cold. The results of WQS regression revealed that after adjusting for other covariates, PFASs mixture showed a positive association with the incidence of tonsillitis, the frequency of common cold, and episodes. In particular, perfluoroundecanoic acid (PFUnDA), PFDoDA, PFTrDA, perfluorodecanoic acid (PFDA) and 8:2 chlorinated polyfluorinated ether sulfonic acid (8:2 Cl-PFESA) had the most significant impact on this combined effect. The results suggest that both single and mixed exposures to PFASs may cause RTIs in preschool children. However, there was no statistically significant interaction between different PFASs and sex.

Sex-specific associations between legacy and novel per- and polyfluoroalkyl substances and telomere length in newborns in Wuhan, China: Mixture and single pollutant associations

Telomere length (TL) at birth predicts later life TL and is related to health. Prenatal exposure to environmental pollutants might affect TL, but the associations between intrauterine per- and polyfluoroalkyl substances (PFASs) exposure and neonatal TL remained inconclusive. This study aimed to explore the single pollutant and mixture associations between legacy and novel PFASs and TL in newborns. In 908 mother-newborn pairs from Wuhan, China, thirteen PFASs were measured in cord serum, and TL was determined in cord leukocytes. Weighted quantile sum (WQS) regression and generalized linear model (GLM) were utilized to analyze the associations between PFASs mixture and single PFASs and TL in newborns. Furthermore, stratified and interaction analyses were performed to evaluate if there were sex-specific associations. The concentrations of perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), and 6:2 chlorinated polyfluorinated ether sulfonate (6:2 Cl-PFESA) ranked the highest (geometric mean, 4.12, 1.61, and 0.77 ng/mL, respectively) among the 13 measured PFASs. Each unit increase in WQS index of PFASs mixture was associated with -5.19 % change (95% CI, -9.44, -0.73) of neonatal TL, and 8:2 Cl-PFESA contributed most (32.59 %) to the mixture association. In stratified analyses by neonatal sex, PFOS (-4.73 % change, 95% CI, -8.40, -0.93 for per doubling concentration) and 8:2 Cl-PFESA (-4.52 % change, 95% CI, -8.20, -0.70) were negatively associated with neonatal TL in male newborns, but no significant association appeared in females. In summary, intrauterine exposure to PFASs in mixture was associated with shorter neonatal TL, and the negative associations of 8:2 Cl-PFESA and PFOS with neonatal TL were observed only in boys. Future risk assessments are needed to pay more attention to the health effects of novel PFASs.

Perfluorooctanoic acid promotes pancreatic β cell dysfunction and apoptosis through ER stress and the ATF4/CHOP/TRIB3 pathway

Perfluorooctanoic acid (PFOA), a widely used chemical substance, causes an increased risk of human type 2 diabetes (T2D), but its underlying mechanism is not well elucidated. The aim of the present study was to investigate whether PFOA regulates the functions of pancreatic β cells, which are specialized for the biosynthesis and secretion of insulin. The treatment of the mouse pancreatic β cell line (MIN6 cells) with PFOA caused a time- and dose-dependent inhibition of cell viability in CCK-8 assays. Annexin V/PI and TUNEL staining results confirmed that exposure to a high PFOA dose (500 μM) promoted apoptosis of β cells, while a low dose (300 μM) had no effects on β cell survival. PFOA treatment, even at a low dose, diminished glucose-stimulated insulin secretion (GSIS) in both primary islet perfusion and MIN6 cell experiments. RNA-sequencing data showed significantly increased expression of endoplasmic reticulum (ER) stress-associated genes, with tribbles homolog 3 (Trib3) ranking first among the altered genes. The activation of ER stress pathways was verified by qRT-PCR assays, and the ATF4/CHOP/TRIB3 pathway contributed to PFOA-induced β cell damage. The inhibition of TRIB3 expression significantly protected MIN6 cells from PFOA-induced GSIS defects and apoptosis by ameliorating ER stress. These findings reveal a link between ER stress and PFOA-induced β cell defects, opening up a new set of questions about the pathogenesis of T2D due to environmental chemicals.

Perfluorooctanoic acid (PFOA) exposure affects early embryonic development and offspring oocyte quality via inducing mitochondrial dysfunction

Perfluorooctanoic acid (PFOA) is a synthetic perfluorinated compound that is extensively used as an integral surfactant in commercial production. Owing to its hydrophilicity and persistence, PFOA can accumulate in living organisms and induce severe disease in animals and humans. It has been reported that PFOA exposure can affect ovarian function and induce reproductive toxicity; however, the effects and potential mechanism of PFOA exposure during gestation on early embryonic development and offspring remain unclear. This study found that PFOA exposure in vitro disrupted spindle assembly and chromosome alignment during the first cleavage of early mouse embryos, which impacted early embryonic cleavage and blastocyst formation. Moreover, PFOA exposure caused mitochondrial dysfunction and oxidative stress by inducing aberrant Ca²⁺ levels, liquid drops(LDs), and mitochondrial membrane potential in the 2-cell stage. Furthermore, we found that PFOA exposure resulted in DNA damage, autophagy, and apoptosis in 2-cell stage by inhibiting SOD2 function. Gestational exposure to PFOA significantly increased ovarian apoptosis and disrupted follicle development in F1 offspring. In addition, oocyte maturation competence was decreased in F1 offspring. Finally, single-cell transcriptome analysis revealed that PFOA-induced oocyte deterioration was caused by mitochondrial dysfunction and apoptosis in the F1 offspring. In summary, our results indicated that gestational exposure to PFOA had potential toxic effects on ovarian function and led to a higher incidence of meiotic defects in F1 female offspring.

Leveraging Systematic Reviews to Explore Disease Burden and Costs of Per- and Polyfluoroalkyl Substance Exposures in the United States

Accelerating evidence confirms the contribution of per- and polyfluoroalkyl substances (PFAS) to disease burden and disability across the lifespan. Given that policy makers raise the high cost of remediation and of substituting PFAS with safer alternatives in consumer products as barriers to confronting adverse health outcomes associated with PFAS exposure, it is important to document the costs of inaction even in the presence of uncertainty. We therefore quantified disease burdens and related economic costs due to legacy PFAS exposures in the US in 2018. We leveraged systematic reviews and used meta-analytic inputs whenever possible, identified previously published exposure-response relationships, and calculated PFOA- and PFOS-attributable increases in 13 conditions. These increments were then applied to census data to determine total annual PFOA- and PFOS-attributable cases of disease, from which we calculated economic costs due to medical care and lost productivity using previously published cost-of-illness data. We identified PFAS-attributable disease costs in the US of $5.52 billion across five primary disease endpoints shown to be associated with PFAS exposure in meta-analyses. This estimate represented the lower bound, with sensitivity analyses revealing as much as $62.6 billion in overall costs. While further work is needed to assess probability of causation and establish with greater certainty effects of the broader category of PFAS, the results confirm further that public health and policy interventions are still necessary to reduce exposure to PFOA and PFOS and their endocrine-disrupting effects. This study demonstrates the large potential economic implications of regulatory inaction.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12403-022-00496-y.

The relationship between multiple perfluoroalkyl substances and cardiorespiratory fitness in male adolescents

Exposure to perfluoroalkyl substances (PFASs) is associated with a number of adverse health outcomes. However, the relationship between mixed and individual PFAS exposure and cardiorespiratory fitness (CRF) in adolescents remains unclear. We used cross-sectional data from 491 teenagers (aged 13-19 years) from the 2003-2004 National Health and Nutrition Examination Survey (NHANES) and examined the association between mixed PFAS exposure and CRF via weighted quantile sum (WQS) regression. Maximal oxygen consumption (VO2max) was used to evaluate CRF. Multivariate linear regression was performed to investigate the relationship between each PFAS and VO2max as well as the relationship between PFAS exposure and the inflammation parameters and blood lipid content. Mediation analyses were performed to investigate possible explanations of the risk of low CRF due to PFAS exposure. The results showed that for males, mixed PFAS exposure was negatively related to VO2max (beta =  - 0.80, 95% CI: - 1.53 to - 0.10, P = 0.028) and that of the PFASs, perfluorononanoic acid (PFNA) had the greatest influence on VO2max. In the individual PFAS analysis, PFNA was negatively related to VO2max in male adolescents (beta =  - 1.49, 95% CI: - 2.65 to - 0.32, P = 0.013). Additionally, significant relationships among serum PFNA levels and total cholesterol and the white blood cell (WBC) count were found. Mediation analyses revealed that WBC count accounted for 24.18% of the variation between PFNA level and CRF. The present results provide epidemiological evidence that exposure to PFASs, mainly PFNA, is negatively associated with CRF, possibly via alterations in WBC count.

Killing two birds with one stone: Pregnancy is a sensitive window for endocrine effects on both the mother and the fetus

Pregnancy is a complex process requiring tremendous physiological changes in the mother in order to fulfill the needs of the growing fetus, and to give birth, expel the placenta and nurse the newborn. These physiological modifications are accompanied with psychological changes, as well as with variations in habits and behaviors. As a result, this period of life is considered as a sensitive window as impaired functional and physiological changes in the mother can have short- and long-term impacts on her health. In addition, dysregulation of the placenta and of mechanisms governing placentation have been linked to chronic diseases later-on in life for the fetus, in a concept known as the Developmental Origin of Health and Diseases (DOHaD). This concept stipulates that any change in the environment during the pre-conception and perinatal (in utero life and neonatal) period to puberty, can be "imprinted" in the organism, thereby impacting the health and risk of chronic diseases later in life. Pregnancy is a succession of events that is regulated, in large part, by hormones and growth factors. Therefore, small changes in hormonal balance can have important effects on both the mother and the developing fetus. An increasing number of studies demonstrate that exposure to endocrine disrupting compounds (EDCs) affect both the mother and the fetus giving rise to growing concerns surrounding these exposures. This review will give an overview of changes that happen during pregnancy with respect to the mother, the placenta, and the fetus, and of the current literature regarding the effects of EDCs during this specific sensitive window of exposure.

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.

The use of in vitro methods in assessing human health risks associated with short-chain perfluoroalkyl and polyfluoroalkyl substances (PFAS)

Perfluoroalkyl and polyfluoroalkyl substances (PFAS) are a large class of industrial chemicals with a ubiquitous and persistent presence in the environment. Of the thousands of PFAS used by consumers and industry, very few have been thoroughly characterized for potential adverse effects. This is especially true for the novel short-chain (C < 8) alternatives that replaced legacy PFAS. Perfluoroalkyl and polyfluoroalkyl substances have revealed inconsistencies in the toxicokinetics predicted by animal models and empirical findings in humans. To adequately assess the possible health effects of short-chain PFAS, there is a need for robust aggregated data sets on the mechanistic underpinnings and physiochemical properties of these alternatives. Acquiring relevant data on the health effects of short-chain PFAS can be achieved through high-throughput methods supported by in vitro human cell-based models. This review briefly summarizes some of the toxicity data obtained using human cells in vitro, discusses the advantages and limitations of cell-based models, and provides insights on potential solutions to challenges presented with the use of these methods for use in safety assessments.

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.

Prenatal exposure and transplacental transfer of perfluoroalkyl substance isomers in participants from the upper and lower reaches of the Yangtze River

Data on gestational exposure characteristics and transplacental transfer are quite limited for perfluoroalkyl substance (PFAS) isomers, especially those from large-scale comparative studies. To fill this gap, we examined isomers of perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), and perfluorohexane sulfonic acid (PFHxS) in matched maternal and cord serum from Mianyang and Hangzhou, which are located in the upper and lower reaches of the Yangtze River, China, respectively. These data were compared with those from our previous study on Wuhan in the middle reach. The average ΣPFAS concentration increased from upstream to downstream (Mianyang (4.44 ng/mL) < Wuhan (9.88 ng/mL) < Hangzhou (19.72 ng/mL)) and may be related to the per capita consumption expenditure of each city. The ln-transformed PFAS concentrations showed significant differences between Mianyang and Hangzhou after adjusting confounding factors (p < 0.05). The percentages of linear PFOS and PFOA in maternal and cord serum from these cities all exceeded those in electrochemical fluorination products. The isomer profiles of PFASs in maternal and cord serum might be greatly influenced by local production processes of PFASs and residents' dietary habits. The transplacental transfer efficiencies decreased significantly with increasing concentrations in maternal serum for ΣPFAS, ΣPFOS, ΣPFOA, ΣPFHxS, n-PFOS, iso-PFOS, 4m-PFOS, 1m-PFOS, n-PFOA, n-PFHxS, and br-PFHxS (Spearman rank correlation coefficients (r) = 0.373-0.687, p < 0.01). These findings support an understanding of the regional characteristics in maternal exposure to PFASs along the Yangtze River, isomeric profiles of PFASs in these regions, and the transplacental transfer processes of PFAS isomers.

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

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

Identifying Risk Factors for Levels of Per- and Polyfluoroalkyl Substances (PFAS) in the Placenta in a High-Risk Pregnancy Cohort in North Carolina

Prenatal exposure to per- and polyfluoroalkyl substances (PFAS), a ubiquitous class of chemicals, is associated with adverse outcomes such as pre-eclampsia, low infant birth weight, and later-life adiposity. The objectives of this study were to examine PFAS levels in the placenta and identify sociodemographic risk factors in a high-risk pregnancy cohort (n = 122) in Chapel Hill, North Carolina. Of concern, PFOS, PFHxS, PFHpS, and PFUnA were detected above the reporting limit in 99, 75, 55, and 49% of placentas, respectively. Maternal race/ethnicity was associated with significant differences in PFUnA levels. While the data from this high-risk cohort did not provide evidence for an association with hypertensive disorders of pregnancy, fetal growth, or gestational age, the prevalence of detectable PFAS in the placenta suggests a need to biomonitor for exposure to PFAS during pregnancy. Future research should investigate factors underlying the differences in PFAS levels in association with a mother's race/ethnicity, as well as potential effects on pregnancy and child health.

Review of the environmental prenatal exposome and its relationship to maternal and fetal health

Environmental chemicals comprise a major portion of the human exposome, with some shown to impact the health of susceptible populations, including pregnant women and developing fetuses. The placenta and cord blood serve as important biological windows into the maternal and fetal environments. In this article we review how environmental chemicals (defined here to include man-made chemicals [e.g., flame retardants, pesticides/herbicides, per- and polyfluoroalkyl substances], toxins, metals, and other xenobiotic compounds) contribute to the prenatal exposome and highlight future directions to advance this research field. Our findings from a survey of recent literature indicate the need to better understand the breadth of environmental chemicals that reach the placenta and cord blood, as well as the linkages between prenatal exposures, mechanisms of toxicity, and subsequent health outcomes. Research efforts tailored towards addressing these needs will provide a more comprehensive understanding of how environmental chemicals impact maternal and fetal health.

Maternal urinary levels of trichloroacetic acid and association with adverse pregnancy outcomes

The current study aimed to determine the association between trichloroacetic acid (TCAA) levels and adverse pregnancy outcomes among third-trimester pregnant women who were exposed to chlorinated drinking water. A total of 205 pregnant women who participated in the disinfection by-products exposure and adverse pregnancy outcome study in South Africa were randomly asked to participate in this study by providing their morning urine sample voids. Samples were analysed for urinary creatinine and TCAA. Furthermore, participants gave individual data using a structured questionnaire. The mean (median) concentration of creatinine-adjusted urinary TCAA was 2.34 (1.95) μg/g creatinine. Elevated levels of creatinine-adjusted TCAA concentrations showed an increased risk of premature birth, small for gestational age (SGA) and low birth weight. There was no significant statistical correlation observed between creatinine-adjusted TCAA concentrations and the total volume of cold water ingested among the study population. No statistically significant association was observed between creatinine-adjusted urinary TCAA and premature birth, SGA and low birth weight newborns among the study subjects. However, the urinary TCAA concentrations identified in this study suggest potential health risks towards women and foetus. Therefore, further studies are warranted to prevent further adverse pregnancy outcomes.

Prediction of maternal and foetal exposures to perfluoroalkyl compounds in a Spanish birth cohort using toxicokinetic modelling

Prenatal exposures to perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) have been associated with child health outcomes, but many of these associations remain poorly characterized. The aim of this work was to provide new indicators of foetal exposure for the Spanish INMA birth cohort. First, a pregnancy and lactation physiologically based pharmacokinetic (PBPK) model was calibrated in a population framework to provide quantitative estimates for the PFOA and PFOS placental transfers in humans. The estimated distributions indicated that PFOA crosses the placental barrier at a rate three times higher than PFOS and shows a higher variability between mothers. The PBPK model was then used to back-calculate the time-varying daily intakes of the INMA mothers corrected for their individual history from a spot maternal concentration. We showed the importance of accounting for the mothers' history as different dietary intakes can result in similar measured concentrations at one time point. Finally, the foetal exposure was simulated in target organs over pregnancy using the PBPK model and the estimated maternal intakes. We showed that the pattern of PFOA and PFOS exposures varies greatly among the foetuses. About a third has levels of either one compound always higher than the levels of the other compound. The other two thirds showed different ranking of PFOA and PFOS in terms of concentrations in the target organs. Our simulated foetal exposures bring additional information to the measured maternal spot concentrations and can help to better characterize the prenatal exposure in target organs during windows of susceptibility.

Developing novel in vitro methods for the risk assessment of developmental and placental toxicants in the environment

During pregnancy, the placenta is critical for the regulation of maternal homeostasis and fetal growth and development. Exposures to environmental chemicals during pregnancy can be detrimental to the health of the placenta and therefore adversely impact maternal and fetal health. Though research on placental-derived developmental toxicity is expanding, testing is limited by the resources required for traditional test methods based on whole animal experimentation. Alternative strategies utilizing in vitro methods are well suited to contribute to more efficient screening of chemical toxicity and identification of biological mechanisms underlying toxicity outcomes. This review aims to summarize methods that can be used to evaluate toxicity resulting from exposures during the prenatal period, with a focus on newer in vitro methods centered on placental toxicity. The following key aspects are reviewed: (i) traditional test methods based on animal developmental toxicity testing, (ii) in vitro methods using monocultures and explant models, as well as more recently developed methods, including co-cultures, placenta-on-a-chip, and 3-dimensional (3D) cell models, (iii) endpoints that are commonly measured using in vitro designs, and (iv) the translation of in vitro methods into chemical evaluations and risk assessment applications. We conclude that findings from in vitro placental models can contribute to the screening of potentially hazardous chemicals, elucidation of chemical mechanism of action, incorporation into adverse outcome pathways, estimation of doses eliciting toxicity, derivation of extrapolation factors, and characterization of overall risk of adverse outcomes, representing key components of chemical regulation in the 21^st century.

Three contaminated sites in southern Italy. The Neonatal Environment and Health Outcomes cohort: protocol for a longitudinal birth cohort study

INTRODUCTION

Exposure to environmental contaminants during pregnancy is one of the determinants of child's future health outcomes. The effect of environmental pollution on pregnant women living in heavily polluted areas is of special interest and, in this context, the Neonatal Environment and Health Outcomes (NEHO) cohort will focus on the investigation of (1) toxicants transferred from the environment to the mother and from the mother to the developing fetus and (2) the influence of toxicants on pregnancy outcomes, fetal development and health status during infancy. Because the human placenta is positioned at the interface between the maternal/external environment and the embryo, it can be considered a highly informative matrix regarding many key pregnancy events that can shape infant's future health.

METHODS AND ANALYSIS

The NEHO cohort will enrol an estimated total of 800 pregnant women in three selected National Priority Contaminated Sites in southern Italy. Epidemiological data, concerning maternal health status, lifestyle and pregnancy, are obtained through questionnaires provided to the mother starting from the last 2 months of pregnancy. At delivery, maternal blood, umbilical cord blood and placenta tissue are collected to assess contaminant levels and to clarify how toxicants interact with the placental domain. Furthermore, placental transcriptome is studied in order to explore the interferences of toxicants on the role of the placenta in maternal/fetal interplay. Regular follow-up is planned at 6, 12 and 24 months.

ETHICS AND DISSEMINATION

The study has been approved by all the Ethics Committees of the three National Priority Contaminated Sites involved: the Ethics Committee of the University Hospitals of Messina (18 September 2017, n. 9/2017); the Ethics Committee 'Catania 2' (11 July 2017, n. 38/2017/CECT2); the Ethics Committee of the Region of Calabria (20 July 2017, n. 173). Findings will be disseminated in the scientific community and on a regional basis for appropriate policy actions.

Socio-Economic Status and Health: Evaluation of Human Biomonitored Chemical Exposure to Per- and Polyfluorinated Substances across Status

Research on the environment, health, and well-being nexus (EHWB) is shifting from a silo toward a systemic approach that includes the socio-economic context. To disentangle further the complex interplay between the socio-exposome and internal chemical exposure, we performed a meta-analysis of human biomonitoring (HBM) studies with internal exposure data on per-and polyfluoroalkyl substances (PFASs) and detailed information on risk factors, including descriptors of socio-economic status (SES) of the study population. PFASs are persistent in nature, and some have endocrine-disrupting properties. Individual studies have shown that HBM biomarker concentrations of PFASs generally increase with SES indicators, e.g., for income. Based on a meta-analysis (five studies) of the associations between PFASs and SES indicators, the magnitude of the association could be estimated. For the SES indicator income, changes in income were expressed by a factor change, which was corrected by the Gini coefficient to take into account the differences in income categories between studies, and the income range between countries. For the SES indicator education, we had to conclude that descriptors ( Collapse

Key Words

• HBM
• HBM4EU
• PFAS
• SES
• education
• health inequity
• human biomonitoring
• income
• socio-economic status

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MESH Headings

• Environmental Exposure
• Environmental Monitoring
• Environmental Pollutants/adverse effects
• Fluorocarbons/adverse effects
• Health Status
• Humans
• Risk Factors
• Social Class

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Affiliation(s)

Jurgen Buekers Flemish Institute for Technological Research (VITO)-Sustainable Health, 2400 Mol, Belgium.
Ann Colles Flemish Institute for Technological Research (VITO)-Sustainable Health, 2400 Mol, Belgium.
Christa Cornelis Flemish Institute for Technological Research (VITO)-Sustainable Health, 2400 Mol, Belgium.
Bert Morrens Sociology Department, University of Antwerp (UA), 2000 Antwerpen, Belgium.
Eva Govarts Flemish Institute for Technological Research (VITO)-Sustainable Health, 2400 Mol, Belgium.
Greet Schoeters Flemish Institute for Technological Research (VITO)-Sustainable Health, 2400 Mol, Belgium.

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Concentrations of endocrine disrupting chemicals in newborn blood spots and infant outcomes in the upstate KIDS study

BACKGROUND

Novel methodologies to quantify infant exposures to endocrine disrupting chemicals (EDCs) for population-based studies are needed.

OBJECTIVES

We used newborn dried blood spots to quantify three EDCs and their associations with infant outcomes in the Upstate KIDS Cohort.

METHODS

We measured bisphenol A (BPA), perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) in 2071 singleton and 1040 twin infants born to mothers in New York State. We log transformed concentrations after rescaling by their standard deviations and modeled each in relation to gestational age, birthweight, length, head circumference and Ponderal Index (PI) using linear regression techniques. All models were adjusted for maternal age, body mass index, education, infertility treatment and parity. Generalized estimating equations with robust standard errors were used to assess the associations for twins.

RESULTS

Chemicals were largely quantified above the limits of detection (>99% for PFOS and PFOA; 90% for BPA). Overall, we observed no significant associations between PFASs and birth size irrespective of plurality of birth. However, among twins, BPA was associated with decreases in gestational age (adjusted β = -0.09 weeks; 95% Confidence Interval (CI): -0.16, -0.02) and birthweight (adjusted β = -32.52 g; 95% CI: -60.99, -4.05), head circumference (adjusted β = -0.18 cm; 95% CI: -0.38, -0.02) and increased PI in singletons (adjusted β = 0.02 cm; 95% CI: 0.004, 0.04).

CONCLUSION

We observed negative associations between BPA and birth size in twins. Our findings demonstrate the feasibility of newborn dried blood spots for quantifying neonatal exposure at the population level.

Perfluoroalkyl and polyfluoroalkyl substances in matched parental and cord serum in Shandong, China

BACKGROUND

Perfluoroalkyl and polyfluoroalkyl substances (PFASs) have been widely detected in different populations. However, limited data is available about exposure among family members.

OBJECTIVES

To investigate the PFASs levels in parents and their newborns and to understand their correlation and health implications of in utero exposure to PFASs.

METHODS

Ten PFASs were measured in matched parental and cord serum (N = 369 families) from a birth cohort in Shandong, one of the regions seriously polluted by PFASs in China. The correlation of PFASs levels within families was examined. A questionnaire survey on maternal factors and risk assessment using the hazard quotients (HQs) approach based on maternal PFASs levels was conducted.

RESULTS

Within a family, the father had the highest levels of all PFASs. Among the 10 PFASs, perfluorooctanoic acid (PFOA) was the highest, with 103.38, 42.83, and 34.67 ng/ml in paternal, maternal and cord serum, respectively. PFASs levels were positively correlated among family members (r = 0.14-0.91, p < 0.01). Maternal age, body mass index (BMI); smoking history; and intake of fish, milk, poultry, vegetables and tap water were significantly related to PFASs concentrations in cord serum. Twenty-seven (7.3%) HQ values exceeded 1 for both PFOA and the sum of PFOA and perfluorooctane sulfonate (PFOS), indicating potential concern for developmental toxicity in the local newborns.

CONCLUSIONS

PFASs, and especially PFOA levels were extremely high and positively correlated between parents, indicating heavy pollution in this region and common sources of exposure. In utero exposure to PFASs might pose potential concern for developmental toxicity in the local newborns.

PFOA is associated with diabetes and metabolic alteration in US men: National Health and Nutrition Examination Survey 2003-2012

Exposure to perfluoroalkyl substances (PFAS) is associated with a range of adverse health effects. However, it remains unclear whether PFAS at environmentally relevant exposure levels are related to diabetes and metabolite concentrations in adults. Using cross-sectional data from 7904 adults (age≥20years) in the 2003-2012 National Health and Nutrition Examination Survey (NHANES), we examined the association of PFAS with the prevalence of diabetes and metabolite concentrations. A multivariate logistic regression was applied to investigate the associations of diabetes prevalence with serum perfluorooctanoate (PFOA), perfluorooctane sulfonate (PFOS), perfluorohexane sulfonate (PFHxS) and perfluorononanoate (PFNA) levels. A multivariate generalised linear regression was further performed to investigate the associations between PFAS exposure and some metabolites. We identified a strong positive association between serum PFOA and diabetes prevalence in men with an adjusted model (OR: 2.66, 95% CI: 1.63-4.35; P for trend=0.001). No significant association between serum PFOA and diabetes prevalence was observed in women (OR: 1.47, 95% CI: 0.88-2.46; P for trend=0.737). Furthermore, diabetes was not related to PFOS, PFHxS and PFNA, regardless of gender. In the gender-stratified generalised linear models, men and women with the highest PFOA levels demonstrated a 1.43% (95% CI: 0.62%-2.34%) and a 1.07% (95% CI: 0.27%-1.97%) greater increase in serum total cholesterol (P for trend=0.006 and 0.001) compared to those with the lowest PFOA levels. There were no significant associations between serum PFOA and other metabolites. These results provide epidemiological evidence that environment-related levels of serum PFOA may be positively associated with the prevalence of diabetes in men and with total cholesterol in adults. Further clinical and animal studies are urgently needed to elucidate putative causal relationships and shed light on the potential mode of action involved.

Recent developments in polyfluoroalkyl compounds research: a focus on human/environmental health impact, suggested substitutes and removal strategies

Between the late 1940s and early 1950s, humans manufactured polyfluoroalkyl compounds (PFCs) using electrochemical fluorination and telomerisation technologies, whereby hydrogen atoms are substituted by fluorine atoms, thus conferring unnatural and unique physicochemical properties to these compounds. Presently, there are wide ranges of PFCs, and owing to their bioaccumulative properties, they have been detected in various environmental matrices and in human sera. It has thus been suggested that they are hazardous. Hence, this review aims at highlighting the recent development in PFC research, with a particular focus on perfluorooctanoate (PFOA) and perfluorooctane sulfonate (PFOS), the most studied and predominantly found PFCs in various environmental matrices, although recent reports have included perfluorobutane sulfonate (PFBS), which was previously regarded as innocuously harmless, when compared to its counterparts, PFOA and PFOS. As such, proper investigations are thus required for a better understanding of short-chain PFC substitutes, which have been suggested as suitable replacements to long-chained PFCs, although these substitutes have also been suggested to pose various health risks comparable to those associated with long-chain PFCs. Similarly, several novel technologies, such as PFC reduction using zero-valent iron, including removal at point of use, adsorption and coagulation, have been proposed. However, regardless of how efficient removers some of these techniques have proven to be, short-chain PFCs remain a challenge to overcome for scientists, in this regard.

Exposure to modern, widespread environmental endocrine disrupting chemicals and their effect on the reproductive potential of women: an overview of current epidemiological evidence

Growing evidence indicates that exposure to widespread, environmental contaminants called endocrine disruptors (EDCs) negatively affects animal and human reproductive health and has been linked to several diseases including infertility. This review aims to evaluate the impact of environmental exposure to endocrine disrupting chemicals [phthalates, parabens, triclosan, bisphenol A (BPA), organochlorine (PCBs) and perfluorinated (PFCs) compounds] on the reproductive potential among women, by reviewing most recently published literature. Epidemiological studies focusing on EDCs exposure and reproductive potential among women for the last 16 years were identified by a search of the PUBMED, MEDLINE, EBSCO and TOXNET literature databases. The results of the presented studies show that exposure to EDCs impacts the reproductive potential in women, measured by ovarian reserve and by assisted reproductive technology outcomes. Exposure to environmental endocrine disrupting chemicals decrease: (i) oestradiol levels (BPA); (ii) anti-Müllerian hormone concentrations (PCBs); (iii) antral follicle count (BPA, parabens, phthalates); (iv) oocyte quality (BPA, triclosan, phthalates, PCBs); (v) fertilization rate (PFCs, PCBs); (vi) implantation (BPA, phthalates, PCBs); (vii) embryo quality (triclosan, PCBs, BPA); (viii) rate of clinical pregnancy and live births (parabens, phthalates). The studies were mostly well-designed and used prospective cohorts with the exposure assessment based on the biomarker of exposure. Considering the suggested health effects, more epidemiological data is urgently needed to confirm the presented findings.

Polybrominated diphenyl ethers (flame retardants) in mother-infant pairs in the Southeastern U.S

Polybrominated diphenyl ethers (PBDEs) are commonly used flame retardants in foams, building material, electronics, and textiles. These chemicals leach into the environment, where they persist, and are found today in virtually every population worldwide. Several studies in recent years have detected the presence of PBDEs in maternal and infant samples. However, few of these studies were conducted in the U.S., and few examined paired or matched mother blood-cord blood samples. We analyzed serum from 10 mother-infant pairs for the presence of PBDEs in a patient population in the Southeastern U.S. Out of 35 measured PBDE congeners, five (BDE-28, -47, -99, -100, and -153) were present, with detection frequencies of 65-100 %. The total PBDE concentrations in maternal and infant sera were highly correlated (r² = 0.710, p = 0.0043). The levels of BDE-47, -99, and -100 and of total PBDEs were higher in the infant cord sera when compared with those in maternal sera (p < 0.017), suggesting that fetuses and neonates might have higher circulating concentrations of these potentially neurotoxic and endocrine disrupting chemicals compared with their mothers. The primary focus henceforward should be whether there are any deleterious effects from exposure to these chemicals on human health.

Isomers of perfluorooctanesulfonate (PFOS) in cord serum and birth outcomes in China: Guangzhou Birth Cohort Study

Prior investigations on the associations of polyfluoroalkyl substances (PFASs) with fetal growth are mixed. Moreover, little research has accrued pertaining to the association between isomers of PFASs with gestational age and birth weight. To address this gap and present novel information, we conducted a study including 321 pairs of mothers and their infants recruited from Guangzhou, China. High performance liquid chromatography-mass spectrometry was utilized to analyze isomers of perfluorooctanesulfonate (PFOS), perfluorooctanoate (PFOA) along with other PFAS levels in cord serum samples. Mothers' and infants' characteristics were gathered from medical records. The resulting data revealed that higher PFOS, PFOA and isomers of PFOS were associated with lower birth weight. Per ln-unit (ng/mL) increase in cord serum total branched PFOS isomers was associated with a 126.3g (95% CI: -195.9, -56.8) reduction in the weight of infants at birth, while an ln-unit (ng/mL) increase of serum linear PFOS isomers (n-PFOS) was associated with a 57.2g (95% CI: -103.1, -11.3) reduction in the weight of infants at birth upon the subsequent adjustment for potential confounding variables. Notably, the association between cord PFAS level and birth weight was more pronounced in male infants. Furthermore, a positive association among branched PFOS isomers (1m-PFOS and 3+4+5m-PFOS) and gestational age was found. No associations could be found among other PFASs in conjunction with gestational age or birth weight. In conclusion, this investigation suggests that higher PFAS concentrations are associated with lower birth weight, and branched PFOS isomers show greater impact on infant birth weight than linear PFOS.

Environmental chemicals and preterm birth: Biological mechanisms and the state of the science

PURPOSE OF REVIEW

Preterm birth is a significant worldwide health problem of uncertain origins. The extant body of literature examining environmental contaminant exposures in relation to preterm birth is extensive but results remain ambiguous for most organic pollutants, metals and metalloids, and air pollutants. In the present review we examine recent epidemiologic studies investigating these associations, and identify recent advances and the state of the science. Additionally, we highlight biological mechanisms of action in the pathway between chemical exposures and preterm birth, including inflammation, oxidative stress, and endocrine disruption, that deserve more attention in this context.

RECENT FINDINGS

Important advances have been made in the study of the environment and preterm birth, particularly in regard to exposure assessment methods, exploration of effect modification by co-morbidities and exposures, and in identification of windows of vulnerability during gestation. There is strong evidence for an association between maternal exposure to some persistent pesticides, lead, and fine particulate matter, but data on other contaminants is sparse and only suggestive trends can be noted with the current data.

SUMMARY

Beyond replicating current findings, further work must be done to improve understanding of mechanisms underlying the associations observed between environmental chemical exposures and preterm birth. By examining windows of vulnerability, disaggregating preterm birth by phenotypes, and measuring biomarkers of mechanistic pathways in these epidemiologic studies we can improve our ability to detect associations with exposure, provide additional evidence for causality in an observational setting, and identify opportunities for intervention.

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

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

CONCLUSIONS

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

Occurrence of perfluoroalkyl substances in cord serum and association with growth indicators in newborns from Beijing

Perfluoroalkyl substances (PFASs), a group of environmental pollutants, persistently exist in the environment. To investigate the associations between PFASs levels in cord serum and birth weight, birth length and ponderal index, we measured PFASs in cord serum samples from 170 infants from Feb. 2012 to Jun. 2012 in Beijing, China. The mean concentrations in cord serum samples for perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS), perfluorohexane sulfonic acid (PFHxS), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA) and perfluoroundecanoic acid (PFUnA) were 1.285 ng/mL, 1.228 ng/mL, 0.230 ng/mL, 0.224 ng/mL, 0.100 ng/mL and 0.085 ng/mL, respectively. First-born children had slightly higher exposure levels of PFHxS (p < 0.001) and PFOA (p = 0.03) than second-born or third-born children. The spearman correlation coefficients with gestation time were individually 0.160 (p = 0.038) for PFHxS and 0.202 (p = 0.008) for PFOA. Both univariate and multivariate linear regression analysis showed that the exposure levels of PFASs had no statistically significant associations with birth weight, birth length or ponderal index in the present population. For male infants, we observed that PFHxS positively correlated with birth length, but the levels of PFUnA were negatively associated with birth length.

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

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

Maternal exposure to perfluoroalkyl acids measured in whole blood and birth outcomes in offspring

Perfluoralkyl and polyfluoralkyl substances have been measured in plasma and serum of pregnant women as a measure of prenatal exposure. Increased concentrations of individual perfluoroalkyl acids (PFAAs), (typically perfluorooctanoic acid (PFOA) and perfluoroctane sulfonate (PFOS) have been reported to be associated with reductions in birth weight and other birth outcomes. We undertook a study of 14 PFAAs in whole blood (including PFOS, PFHxS, PFHpA, PFOA, PFNA, PFDA and PFUnDA) from 98 pregnant women in Western Australia from 2008 to 2011. Median concentrations (in μg/L) were: PFOS 1.99; PFHxS 0.33; PFOA 0.86; PFNA 0.30; PFDA 0.12 and PFUnDA 0.08. Infants born to women with the highest tertile of PFHxS exposure had an increased odds of being <95% of their optimal birth weight (OR 3.5, 95% CI 1.1-11.5). Conversely, maternal blood concentrations of PFUnDA were associated with non-significant increases in average birth weight (+102g, 95% CI -41, 245) and significant increases in proportion of optimal birth weight (+4.7%, 95% CI 0.7, 8.8) per ln-unit change. This study has reported a range of PFAAs in the whole blood of pregnant women and suggests that PFHxS and PFUnDA may influence foetal growth and warrant further attention. Additional studies are required to identify the sources of PFAA exposure with a view to prevention, in addition to further studies investigating the long term health effects of these ubiquitous chemicals.

Environmental influences on reproductive health: the importance of chemical exposures

Chemical exposures during pregnancy can have a profound and life-long impact on human health. Because of the omnipresence of chemicals in our daily life, there is continuous contact with chemicals in food, water, air, and consumer products. Consequently, human biomonitoring studies show that pregnant women around the globe are exposed to a variety of chemicals. In this review we provide a summary of current data on maternal and fetal exposure, as well as health consequences from these exposures. We review several chemical classes, including polychlorinated biphenyls, perfluoroalkyl substances, polybrominated diphenyl ethers, phenols, phthalates, pesticides, and metals. Additionally, we discuss environmental disparities and vulnerable populations, and future research directions. We conclude by providing some recommendations for prevention of chemical exposure and its adverse reproductive health consequences.

Perfluoroalkyl Acids in Maternal Serum and Indices of Fetal Growth: The Aarhus Birth Cohort

BACKGROUND

Previous studies indicated an association between intrauterine exposure to perfluorooctane sulfonate (PFOS) or perfluorooctanoate (PFOA) and lower birth weight. However, these perfluoroalkyl acids (PFAAs) have to some extent been substituted by other compounds on which little is known.

OBJECTIVES

We investigated the association between specific PFAAs and birth weight, birth length, and head circumference at birth.

METHODS

We studied 1,507 mothers and their children from the Aarhus Birth Cohort (2008-2013). Nulliparous women were included during pregnancy, and serum levels of 16 PFAAs were measured between 9 and 20 completed gestational weeks (96% within 13 weeks). For compounds with quantifiable values in > 50% of samples (7 compounds), we report the associations with birth weight, birth length, and head circumference at birth determined by multivariable linear regression.

RESULTS

Estimated mean birth weights were lower among women with serum perfluorohexane sulfonate, perfluoroheptane sulfonate, and PFOS concentrations above the lowest exposure quartile, but we found no consistent monotonic dose-response patterns. These associations were stronger when the population was restricted to term births (n = 1,426). For PFOS, the birth weight estimates for the highest versus lowest quartile were -50 g (95% CI: -123, 23 g) in all births and -62 g (95% CI: -126, 3 g) in term births. For the other PFAAs, the direction of the associations was inconsistent, and no overall association with birth weight was apparent. No PFAAs were associated with birth length or head circumference at birth.

CONCLUSIONS

Overall, we did not find strong or consistent associations between PFAAs and birth weight or other indices of fetal growth, though estimated mean birth weights were lower among those with exposures above the lowest quartile for some compounds.

CITATION

Bach CC, Bech BH, Nohr EA, Olsen J, Matthiesen NB, Bonefeld-Jørgensen EC, Bossi R, Henriksen TB. 2016. Perfluoroalkyl acids in maternal serum and indices of fetal growth: the Aarhus Birth Cohort. Environ Health Perspect 124:848-854; http://dx.doi.org/10.1289/ehp.1510046.

Cumulative Chemical Exposures During Pregnancy and Early Development

Industrial and consumer product chemicals are widely used, leading to ubiquitous human exposure to the most common classes. Because these chemicals may affect developmental milestones, exposures in pregnant women and developing fetuses are of particular interest. In this review, we discuss the prevalence of chemical exposures in pregnant women, the chemical class-specific relationships between maternal and fetal exposures, and the major sources of exposures for six chemical classes of concern: phthalates, phenols, perfluorinated compounds (PFCs), flame retardants, polychlorinated biphenyls (PCBs), and organochlorine pesticides (OCs). Additionally, we describe the current efforts to characterize cumulative exposures to synthetic chemicals during pregnancy. We conclude by highlighting gaps in the literature and discussing possible applications of the findings to reduce the prevalence of cumulative exposures during pregnancy.

Postnatal exposure to PFOS, but not PBDE 99, disturb dopaminergic gene transcription in the mouse CNS

The CNS of breast feeding infants and toddlers may be exposed to persistent organic pollutants via lactational transfer. Here, 10 days old mice were exposed to single oral doses of either PFOS, PBDE99 or vehicle control and were examined for changes in dopaminergic gene transcription in CNS tissue collected at 24h or 2 months post exposure.qPCR analyses of brain tissue from mice euthanized 24h post exposure revealed that PFOS affected transcription of Dopamine receptor-D5 (DRD5) in cerebral cortex and Tyrosine hydroxylase (TH) in the hippocampus. At 2 months of age, mice neonatally exposed to PFOS displayed decreased transcription of Dopamine receptor-D2 (DRD2) and TH in hippocampus. No significant changes in any of the tested genes were observed in PBDE99 exposed mice. This indicates that PFOS, but not PBDE99, affects the developing cerebral dopaminergic system at gene transcriptional level in cortex and hippocampus, which may account for some of the mechanistic effects behind the aetiology of neuropsychiatric disorders.

More signs of neurotoxicity of surfactants and flame retardants - Neonatal PFOS and PBDE 99 cause transcriptional alterations in cholinergic genes in the mouse CNS

Maternally and lactionally transferred persistent organic pollutants may interfere with CNS development. Here, 10-day-old male mice were exposed to single oral doses of PFOS (perflourooctanosulphonate) or PBDE 99 (2,2',4,4',5-penta-bromodiphenyl ether), and examined for changes in cholinergic gene transcription in the CNS 24h and 7 weeks later. 24h after exposure qPCR analyses revealed decreased transcription of nAChR-β2 and AChE in cortex, and increased mAChR-5 in hippocampus of PFOS treated mice. Neonatal PFOS treatment altered spontaneous behaviour at 2 months of age but did not affect gene transcription in adults. At 2 months of age neonatally PBDE 99 treated mice had altered spontaneous behaviour, and cortical transcription of AChE, nAChR-α4, nAChR-β2 and mAChR-5 were elevated. Our results indicate that PFOS and PBDE 99 affects the developing central cholinergic system by altering gene transcription in cortex and hippocampus, which may in part account for mechanisms causing changes in spontaneous behaviour.

Maternal exposure to perfluorinated chemicals and reduced fecundity: the MIREC study

STUDY QUESTION

What is the effect of maternal exposure to perfluorooctane sulfonate (PFOS), perflurooctanoic acid (PFOA) and perfluorohexane sulfonate (PFHxS) on female fecundity?

SUMMARY ANSWER

Increasing concentrations of PFOA or PFHxS in maternal plasma were associated with reduced fecundability and infertility.

WHAT IS KNOWN ALREADY

Perfluorinated chemicals (PFCs) are a group of synthetic compounds used in industrial production. There is a concern about the effect of PFCs on fecundity, as measured by time-to-pregnancy (TTP). Although some recent studies suggest that increasing concentrations of PFCs may decrease fecundity, divergence in the methodological approaches used to evaluate this association have prevented firm conclusions being reached.

STUDY DESIGN, SIZE, DURATION

The Maternal-Infant Research on Environmental Chemicals (MIREC) Study is a cohort study of 2,001 women recruited before 14 weeks of gestation in 10 cities across Canada between 2008 and 2011.

PARTICIPANTS/MATERIALS, SETTING, METHODS

A questionnaire was administered and medical chart data and biospecimens were collected from participants. After excluding women who withdrew, those for whom data were incomplete, those whose pregnancies followed birth control failure, and accounting for male fertility, 1743 participants remained. TTP was defined as the number of months of unprotected intercourse needed to become pregnant in the current pregnancy, as self-reported in the first trimester of pregnancy. Plasma concentrations of PFOA, PFOS and PFHxS measured in the first trimester were considered as a surrogate of preconception exposure. Fecundability odds ratios (FORs) were estimated using Cox proportional hazard models for discrete time. FOR < 1 denote a longer TTP and FORs >1 denote a shorter TTP. The odds of infertility (TTP > 12 months or infertility treatment in the index pregnancy) were estimated using logistic regression. Each chemical concentration (ng/ml) was log-transformed and divided by its SD.

MAIN RESULTS AND THE ROLE OF CHANCE

The cumulative probabilities of pregnancy at 1, 6 and 12 months were 0.42 (95% confidence interval (CI) 0.40-0.45), 0.81 (95% CI 0.79-0.83) and 0.90 (95% CI 0.89-0.92), respectively. The mean maternal age was 32.8 (SD 5.0) years. The geometric means (ng/ml) of PFOA, PFOS and PFHxS were 1.66 (95% CI 1.61-1.71), 4.59 (95% CI 4.46-4.72) and 1.01 (95% CI 0.97-1.05), respectively. After adjustment for potential confounders, PFOA and PFHxS were associated with a 11 and 9% reduction in fecundability per one SD increase (FOR = 0.89; 95% CI 0.83-0.94; P < 0.001 for PFOA and FOR = 0.91; 95% CI 0.86-0.97; P = 0.002 for PFHxS), while no significant association was observed for PFOS (FOR = 0.96; 95% CI 0.91-1.02; P = 0.17). In addition, the odds of infertility increased by 31% per one SD increase of PFOA (odds ratio (OR) = 1.31; 95% CI 1.11-1.53; P = 0.001) and by 27% per one SD increase of PFHxS (OR = 1.27; 95% CI 1.09-1.48; P = 0.003), while no significant association was observed for PFOS (OR = 1.14; 95% CI 0.98-1.34; P = 0.09).

LIMITATIONS, REASONS FOR CAUTION

Women with the highest concentrations of PFCs might have been excluded from the study if there is a causal association with infertility. The MIREC study did not assess concentrations of PFCs in males, semen quality, menstrual cycle characteristics or intercourse frequency.

WIDER IMPLICATIONS OF THE FINDINGS

Our results add to the evidence that exposure to PFOA and PFHxS, even at lower levels than previously reported, may reduce fecundability.

STUDY FUNDING/COMPETING INTERESTS

The MIREC study is supported by the Chemicals Management Plan of Health Canada, the Canadian Institutes for Health Research (CIHR, grant no. MOP - 81285) and the Ontario Ministry of the Environment. M.P.V. was supported by a CIHR Fellowship Award, and a CIHR-Quebec Training Network in Perinatal Research (QTNPR) Ph.D. scholarship. W.D.F. is supported by a CIHR Canada Research Chair. There are no conflicts of interest to declare.

Preconception maternal and paternal exposure to persistent organic pollutants and birth size: the LIFE study

BACKGROUND

Persistent organic pollutants (POPs) are developmental toxicants, but the impact of both maternal and paternal exposures on offspring birth size is largely unexplored.

OBJECTIVE

We examined associations between maternal and paternal serum concentrations of 63 POPs, comprising five major classes of pollutants, with birth size measures.

METHODS

Parental serum concentrations of 9 organochlorine pesticides, 1 polybrominated biphenyl (PBB), 7 perfluoroalkyl chemicals (PFCs), 10 polybrominated diphenyl ethers (PBDEs), and 36 polychlorinated biphenyls (PCBs) were measured before conception for 234 couples. Differences in birth weight, length, head circumference, and ponderal index were estimated using multiple linear regression per 1-SD increase in natural log-transformed (ln-transformed) chemicals. Models were estimated separately for each parent and adjusted for maternal age, maternal prepregnancy body mass index (kilograms per meter squared) and other confounders, and all models included an interaction term between infant sex and each chemical.

RESULTS

Among girls (n = 117), birth weight was significantly lower (range, 84-195 g) in association with a 1-SD increase in ln-transformed maternal serum concentrations of DDT, PBDE congeners 28 and 183, and paternal serum concentrations of PBDE-183 and PCB-167. Among boys (n = 113), maternal (PCBs 138, 153, 167, 170, 195, and 209 and perfluorooctane sulfonamide) and paternal (PCBs 172 and 195) serum concentrations of several POPs were statistically associated with lower birth weight (range, 98-170 g), whereas paternal concentrations of PBDEs (66, 99) were associated with higher birth weight. Differences in offspring head circumference, length, and ponderal index were also associated with parental exposures.

CONCLUSIONS

Preconceptional maternal and paternal concentrations of several POPs were associated with statistically significant differences in birth size among offspring.

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

BACKGROUND

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

The Navigation Guide - evidence-based medicine meets environmental health: integration of animal and human evidence for PFOA effects on fetal growth

BACKGROUND

The Navigation Guide is a novel systematic review method to synthesize scientific evidence and reach strength of evidence conclusions for environmental health decision making.

OBJECTIVE

Our aim was to integrate scientific findings from human and nonhuman studies to determine the overall strength of evidence for the question "Does developmental exposure to perfluorooctanoic acid (PFOA) affect fetal growth in humans?"

METHODS

We developed and applied prespecified criteria to systematically and transparently a) rate the quality of the scientific evidence as "high," "moderate," or "low"; b) rate the strength of the human and nonhuman evidence separately as "sufficient," "limited," "moderate," or "evidence of lack of toxicity"; and c) integrate the strength of the human and nonhuman evidence ratings into a strength of the evidence conclusion.

RESULTS

We identified 18 epidemiology studies and 21 animal toxicology studies relevant to our study question. We rated both the human and nonhuman mammalian evidence as "moderate" quality and "sufficient" strength. Integration of these evidence ratings produced a final strength of evidence rating in which review authors concluded that PFOA is "known to be toxic" to human reproduction and development based on sufficient evidence of decreased fetal growth in both human and nonhuman mammalian species.

CONCLUSION

We concluded that developmental exposure to PFOA adversely affects human health based on sufficient evidence of decreased fetal growth in both human and nonhuman mammalian species. The results of this case study demonstrate the application of a systematic and transparent methodology, via the Navigation Guide, for reaching strength of evidence conclusions in environmental health.