Thyroid cancer and endocrine disruptive chemicals: a case-control study on per-fluoroalkyl substances and other persistent organic pollutants.

Objective: The aim was to evaluate the possible association between some endocrine disruptive chemicals and thyroid cancer (TC) in an Italian case-control cohort. Methods: We enrolled 112 TC patients and 112 sex- and age-matched controls without known thyroid diseases. Per- and poly-fluoroalkyl substances (PFAS), poly-chlorinated biphenyls (PCBs), and dichlorodiphenyltrichloroethane (4,4'-DDT and 4,4'-DDE) were measured in the serum by liquid or gas chromatography-mass spectrometry. Unconditional logistic regression, Bayesan kernel machine regression and weighted quantile sum models were used to estimate the association between TC and pollutants' levels, considered individually or as mixture. BRAFV600E mutation was assessed by standard methods. Results: The detection of perfluorodecanoic acid (PFDA) was positively correlated to TC (OR = 2.03, 95% CI: 1.10-3.75, P = 0.02), while a negative association was found with perfluorohexanesulfonic acid (PFHxS) levels (OR = 0.63, 95% CI: 0.41-0.98, P = 0.04). Moreover, perfluorononanoic acid (PFNA) was positively associated with the presence of thyroiditis, while PFHxS and perfluorooctane sulfonic acid (PFOS) with higher levels of presurgical thyroid-stimulating hormone (TSH). PFHxS, PFOS, PFNA, and PFDA were correlated with less aggressive TC, while poly-chlorinated biphenyls (PCB-105 and PCB-118) with larger and more aggressive tumors. Statistical models showed a negative association between pollutants' mixture and TC. BRAF V600E mutations were associated with PCB-153, PCB-138, and PCB-180. Conclusion: Our study suggests, for the first time in a case-control population, that exposure to some PFAS and PCBs associates with TC and some clinical and molecular features. On the contrary, an inverse correlation was found with both PFHxS and pollutants' mixture, likely due to a potential reverse causality.

The associations between maternal and fetal exposure to endocrine-disrupting chemicals and asymmetric fetal growth restriction: a prospective cohort study.

Recent evidence has revealed associations between endocrine-disrupting chemicals (EDCs) and placental insufficiency due to altered placental growth, syncytialization, and trophoblast invasion. However, no epidemiologic study has reported associations between exposure to EDCs and asymmetric fetal growth restriction (FGR) caused by placenta insufficiency. The aim of this study was to evaluate the association between EDC exposure and asymmetric FGR. This was a prospective cohort study including women admitted for delivery to the Maternal Fetal Center at Seoul St. Mary's Hospital between October 2021 and October 2022. Maternal urine and cord blood samples were collected, and the levels of bisphenol-A (BPA), monoethyl phthalates, and perfluorooctanoic acid in each specimen were analyzed. We investigated linear and non-linear associations between the levels of EDCs and fetal growth parameters, including the head circumference (HC)/abdominal circumference (AC) ratio as an asymmetric parameter. The levels of EDCs were compared between fetuses with and without asymmetric FGR. Of the EDCs, only the fetal levels of BPA showed a linear association with the HC/AC ratio after adjusting for confounding variables (ß = 0.003, p < 0.05). When comparing the normal growth and asymmetric FGR groups, the asymmetric FGR group showed significantly higher maternal and fetal BPA levels compared to the normal growth group (maternal urine BPA, 3.99 µg/g creatinine vs. 1.71 µg/g creatinine [p < 0.05]; cord blood BPA, 1.96 µg/L vs. -0.86 µg/L [p < 0.05]). In conclusion, fetal exposure levels of BPA show linear associations with asymmetric fetal growth patterns. High maternal and fetal exposure to BPA might be associated with asymmetric FGR.

Association of Combined Per- and Polyfluoroalkyl Substances and Metals with Chronic Kidney Disease.

Background: Exposure to environmental pollutants such as metals and Per- and Polyfluoroalkyl Substances (PFAS) has become common and increasingly associated with a decrease in the estimated Glomerular Filtration Rate (eGFR), which is a marker often used to measure chronic kidney disease (CKD). However, there are limited studies involving the use of both eGFR and the urine albumin creatinine ratio (uACR), which are more comprehensive markers to determine the presence of CKD and the complexity of pollutant exposures and response interactions, especially for combined metals and PFAS, which has not been comprehensively elucidated. Objective: This study aims to assess the individual and combined effects of perfluorooctanoic acid (PFOA), perfluorooctanesulfonic acid (PFOS), Cadmium (Cd), Mercury (Hg), and Lead (Pb) exposure on CKD using data from the National Health and Nutritional Examination Survey (NHANES) 2017-2018. Methods: We employed the use of bivariate logistic regression and Bayesian Kernel Machine Regression (BKMR) in our analysis of the data. Results: Logistic regression results revealed a positive association between PFOA and CKD. Our BKMR analysis revealed a non-linear and bi-phasic relationship between the metal exposures and CKD. In our univariate exposure-response function plot, Cd and Hg exhibited a U and N-shaped interaction, which indicated a non-linear and non-additive relationship with both low and high exposures associated with CKD. In addition, the bivariate exposure-response function between two exposures in a mixture revealed that Cd had a U-shaped relationship with CKD at different quantiles of Pb, Hg, PFOA, and PFOS, indicating that both low and high levels of Cd is associated with CKD, implying a non-linear and complex biological interaction. Hg's interaction plot demonstrated a N-shaped association across all quantiles of Cd, with the 75th quantile of Pb and the 50th and 75th quantiles of PFOA and PFOS. Furthermore, the PIP results underscored Cd's consistent association with CKD (PIP = 1.000) followed by Hg's (PIP = 0.9984), then PFOA and PFOS with a closely related PIP of 0.7880 and 0.7604, respectively, and finally Pb (PIP = 0.6940), contributing the least among the five environmental pollutants on CKD, though significant. Conclusions: Our findings revealed that exposure to environmental pollutants, particularly Hg and Cd, are associated with CKD. These findings highlight the need for public health interventions and strategies to mitigate the cumulative effect of PFAS and metal exposure and elucidate the significance of utilizing advanced statistical methods and tools to understand the impact of environmental pollutants on human health. Further research is needed to understand the mechanistic pathways of PFAS and metal-induced kidney injury and CKD, and longitudinal studies are required to ascertain the long-term impact of these environmental exposures.

Association between per- and polyfluoroalkyl substances exposure and risk of diabetes: a systematic review and meta-analysis.

BACKGROUND: Emerging evidence suggests that per- and polyfluoroalkyl substances (PFAS) are endocrine disruptors and may contribute to the etiology of diabetes. OBJECTIVES: This study aimed to systematically review the epidemiological evidence on the associations of PFAS with mortality and morbidity of diabetes and to quantitatively evaluate the summary effect estimates of the existing literature. METHODS: We searched three electronic databases for epidemiological studies concerning PFAS and diabetes published before April 1, 2022. Summary odds ratio (OR), hazard ratio (HR), or ß and their 95% confidence intervals (CIs) were respectively calculated to evaluate the association between PFAS and diabetes using random-effects model by the exposure type, and dose-response meta-analyses were also performed when possible. We also assessed the risk of bias of the studies included and the confidence in the body of evidence. RESULTS: An initial literature search identified 1969 studies, of which 22 studies were eventually included. The meta-analyses indicated that the observed statistically significant PFAS-T2DM associations were consistent in cohort studies, while the associations were almost non-significant in case-control and cross-sectional studies. Dose-response meta-analysis showed a "parabolic-shaped" association between perfluorooctanoate acid (PFOA) exposure and T2DM risk. Available evidence was rated with "low" risk of bias, and the level of evidence for PFAS and incident T2DM was considered "moderate". CONCLUSIONS: Our findings suggest that PFAS exposure may increase the risk of incident T2DM, and that PFOA may exert non-monotonic dose-response effect on T2DM risk. Considering the widespread exposure, persistence, and potential for adverse health effects of PFAS, further cohort studies with improvements in expanding the sample size, adjusting the covariates, and considering different types of PFAS exposure at various doses, are needed to elucidate the putative causal associations and potential mode of action of different PFAS on diabetes. IMPACT STATEMENT: A growing body of evidence suggests that per- and polyfluoroalkyl substances (PFAS) are endocrine disruptors and may contribute to the development of diabetes. However, epidemiological evidence on the associations of PFAS and diabetes is inconsistent. We performed this comprehensive systematic review and meta-analysis to quantitatively synthesize the evidence. The findings of this study suggest that exposure to PFAS may increase diabetes risk among the general population. Reduced exposure to these "forever and everywhere chemicals" may be an important preventative approach to reducing the risk of diabetes across the population.

Exposure to Perfluoro-Octanoic Acid Associated With Upstream Uncoupling of the Insulin Signaling in Human Hepatocyte Cell Line.

Perfluoro-alkyl substances (PFAS) are chemical pollutants with prevalent stability and environmental persistence. Exposure to PFAS, particularly perfluoro-octanoic acid (PFOA), has been associated with increased diabetes-related cardiovascular mortality in subjects residing areas of high environmental contamination, however the exact pathogenic mechanism remains elusive. Here we used HepG2 cells, an in vitro model of human hepatocyte, to investigate the possible role of PFOA exposure in the alteration of hepatic glucose metabolism. HepG2 cells were exposed for 24 hours to PFOA at increasing concentration from 0 to 1000 ng/mL and then stimulated with 100 nm Insulin (Ins). The consequent effect on glycogen synthesis, glucose uptake and Glut-4 glucose transporter translocation was then evaluated by, respectively, Periodic Acid Schiff (PAS) staining, 2-deoxyglucose (2-DG) uptake assay and immunofluorescence. Exposure to PFOA was associated with reduced glycogen synthesis and glucose uptake, at concentration equal or greater than, respectively, 0,1 ng/mL and 10 ng/mL, with parallel impaired membrane translocation of Glut-4 upon Ins stimulation. Western blot analysis showed early uncoupling of Insulin Receptor (InsR) activation from the downstream Akt and GSK3 phosphorylation. Computational docking analysis disclosed the possible stabilizing effect of PFOA on the complex between InsR and GM3 ganglioside, previously shown to be associated with the low grade chronic inflammation-related insulin resistance. Consistently, long term treatment with glucosyl-ceramide synthase inhibitor PDMP was able to largely restore glycogen synthesis, glucose uptake and Glut-4 translocation upon Ins stimulation in HepG2 exposed to PFOA. Our data support a novel pathogenic mechanism linking exposure to PFOA to derangement of hepatocyte cell metabolism.

Why is elevation of serum cholesterol associated with exposure to perfluoroalkyl substances (PFAS) in humans? A workshop report on potential mechanisms.

Serum concentrations of cholesterol are positively correlated with exposure to perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) in humans. The associated change in cholesterol is small across a broad range of exposure to PFOA and PFOS. Animal studies generally have not indicated a mechanism that would account for the association in humans. The extent to which the relationship is causal is an open question. Nonetheless, the association is of particular importance because increased serum cholesterol has been considered as an endpoint to derive a point of departure in at least one recent risk assessment. To gain insight into potential mechanisms for the association, both causal and non-causal, an expert workshop was held Oct 31 and Nov 1, 2019 to discuss relevant data and propose new studies. In this report, we summarize the relevant background data, the discussion among the attendees, and their recommendations for further research.

Octanoic acid a major component of widely consumed medium-chain triglyceride ketogenic diet is detrimental to bone.

Octanoic acid is a medium-chained saturated fatty acid found abundantly in the ketogenic dietary supplements containing medium chained triglycerides (MCT) along with decanoic acid. The MCT ketogenic diet is commonly consumed for weight loss but has also showcased neuroprotective potential against neurodegenerative disorders. However, recent clinical findings have reported a critical disadvantage with the long-term consumption of ketogenic diet i.e. bone loss. The following study was employed to investigate whether the two major components of MCT diet also possess bone loss potential as observed with classical ketogenic diet. Swiss albino mice aged between 10 and 12 weeks, were divided into 3 treatment groups that were administered with oral suspensions of octanoic acid, decanoic acid and a combination of both for 4 weeks. Bone specific markers, microarchitectural parameters, using micro computed tomography, and biomechanical strength were analyzed. Remarkably deleterious alterations in the trabecular bone microarchitecture, and on bone markers were observed in the octanoic acid treated groups. Our results suggest significant negative effects on bone health by octanoic acid. These findings require further investigation and validation in order to provide significant clinically relevant data to possibly modify dietary composition of the MCT ketogenic diet.

Fluorine detection in the lung tissue of a worker with interstitial pulmonary fibrosis and long-term occupational exposure to polytetrafluoroethylene and perfluorooctanoic acid.

Exposure to polytetrafluoroethylene (PTFE), a compound used in nonstick cookware coating and a variety of other applications, is known to cause acute lung injury and granulomatous pneumonitis. It is uncertain whether PTFE and compounds used in its manufacture, such as perfluorooctanoic acid (PFOA), cause chronic lung disease. Here we report a case of interstitial pulmonary fibrosis in a 71-year-old man who died following a brief illness clinically suspected to be acute respiratory distress syndrome. He had a 25-year history of occupational exposure to PTFE and PFOA. At postmortem examination, the lungs demonstrated diffuse alveolar damage (DAD) superimposed on interstitial pulmonary fibrosis. The interstitial fibrosis lacked fibroblast foci and exhibited basilar and subpleural accentuation with focal microscopic honeycombing. Within the fibrotic lung parenchyma were scattered giant cells containing birefringent translucent particles. Scanning electron microscopy and energy-dispersive x-ray spectroscopy (SEM-EDS) were performed. A majority of the birefringent particles demonstrated a prominent peak for fluorine by EDS analysis. This is the first report to document the presence of fluorine, an elemental constituent of PTFE and PFOA, in fibrotic lung tissue. Careful evaluation of other individuals with long-term exposure to PTFE and/or PFOA appears warranted to better elucidate the spectrum of pulmonary disease associated with these compounds.

Internal exposure to perfluoroalkyl substances (PFASs) and biological markers in 101 healthy 1-year-old children: associations between levels of perfluorooctanoic acid (PFOA) and vaccine response.

Perfluoroalkyl substances (PFASs) are a complex group of man-made chemicals with high stability and mobility leading to ubiquitous environmental contamination and accumulation in the food chain. In human serum/plasma samples, perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) are the lead compounds. They are immunotoxic in experimental animals, and epidemiological studies provided evidence of a diminished production of vaccine antibodies in young children. However, information on children of the first year of age is missing but relevant, as they have a relatively high exposure if breastfed, and may have a higher susceptibility as their immune system is developing. In a cross-sectional study with 101 healthy 1-year-old children, internal levels of persistent organic pollutants and a broad panel of biological parameters were investigated at the end of the 1990s. Additional analysis of PFASs resulted in plasma levels (mean ± SD) of PFOA and PFOS of 3.8 ± 1.1 and 6.8 ± 3.4 µg/L, respectively, in the 21 formula-fed children, and of 16.8 ± 6.6 and 15.2 ± 6.9 µg/L in the 80 children exclusively breastfed for at least 4 months. The study revealed significant associations between levels of PFOA, but not of PFOS, and adjusted levels of vaccine antibodies against Haemophilus influenza type b (Hib, r = 0.32), tetanus (r = 0.25) and diphtheria (r = 0.23), with no observed adverse effect concentrations (NOAECs) determined by fitting a 'knee' function of 12.2, 16.9 and 16.2 µg/L, respectively. The effect size (means for PFOA quintiles Q1 vs. Q5) was quantified to be - 86, - 54 and - 53%, respectively. Furthermore, levels of PFOA were inversely associated with the interferon gamma (IFNÉ£) production of ex-vivo lymphocytes after stimulation with tetanus and diphtheria toxoid, with an effect size of - 64 and - 59% (means Q1 vs. Q5), respectively. The study revealed no influence of PFOA and PFOS on infections during the first year of life and on levels of cholesterol. Our results confirmed the negative associations of PFAS levels and parameters of immune response observed in other epidemiological studies, with high consistency as well as comparable NOAECs and effects sizes for the three vaccine antibodies investigated, but for PFOA only. Due to reduction of background levels of PFASs during the last 20 years, children in Germany nowadays breastfed for a long duration are for the most part not expected to reach PFOA levels at the end of the breastfeeding period above the NOAECs determined.

Perfluoroalkyl substances and likelihood of stroke in persons with and without diabetes.

OBJECTIVE: The main objective of this study is to evaluate the relationship of perfluoroalkyl substances with stroke and any modifying influence of diabetes. METHODS: Data on 3921 adults aged ⩾20 years with and 44,285 without diabetes were drawn from the C8 Health Project. Four perfluoroalkyl substances were investigated: perfluorohexane sulphate, C8 - perfluorooctanoic acid, perfluoroctane sulfonate and perfluorononaoic acid. RESULTS: There were 238 cases of stroke among those with and 643 among those without diabetes. In analyses controlled for age, sex, race, diabetes duration, body mass index, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, C-reactive protein, kidney function and a history of smoking, a history of stroke was significantly inversely associated with serum perfluorohexane sulphate (odds ratio = 0.75, 0.64-0.88) and perfluoroctane sulfonate (odds ratio = 0.81, 0.70-0.90), but not perfluorooctanoic acid (odds ratio = 1.04, 0.94-1.15) or perfluorononaoic acid (odds ratio = 0.89, 0.70-1.14) among those with diabetes. Perfluoroalkyl substances demonstrated no association with stroke among those without diabetes (p interaction = 0.006 and 0.01 for perfluorohexane sulphate and perfluorooctanoic acid, respectively). CONCLUSION: In this large cross-sectional study, serum levels of perfluorohexane sulphate and perfluoroctane sulfonate were inversely associated with stroke among those with diabetes. Although mechanisms and implications for this diabetes-specific inverse relationship need to be further explored, our data suggest that perfluoroalkyl substances do not increase risk of stroke among persons with or without diabetes.

Maternal serum levels of perfluoroalkyl substances in early pregnancy and offspring birth weight.

BACKGROUND: Perfluoroalkyl substances (PFASs) are widespread, bioaccumulating, and persistent and show placental transfer. Emerging research indicates associations between prenatal exposure and low birth weight. The aim of this study was to assess the associations between first trimester exposure to PFASs and birth weight (BW) in the Swedish Environmental, Longitudinal, Mother and child, Asthma and allergy (SELMA) study and examine whether associations differ between girls and boys. METHODS: Eight PFASs were analyzed in maternal serum (median: 10 weeks of pregnancy). Associations between prenatal PFAS exposure and birth outcomes with BW, BW for gestational age, and birth small for gestational age (SGA) were assessed in 1533 infants, adjusted for potential confounders and stratified by sex. RESULTS: Increased maternal perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), and perfluoroundecanoic acid (PFUnDA) were associated with lower BW, lower BW for gestational age, and SGA birth. Associations were significant only in girls, where prenatal exposure in the upper quartile was associated with a 93-142-g lower BW when compared with that of the lowest quartile exposure. The associations were not mediated by effects on gestational age. CONCLUSIONS: We found associations between prenatal exposure for five different PFASs and birth weight, with more pronounced associations in girls than in boys.

Making the invisible visible: results of a community-led health survey following PFAS contamination of drinking water in Merrimack, New Hampshire.

BACKGROUND: In March 2016, citizens of Merrimack, New Hampshire, learned that their public water supply was contaminated with perfluorooctanoic acid (PFOA). A subsequent state-led investigation revealed widespread contamination of both public and private well water with PFOA and several related chemicals, broadly termed per- and polyfluoroalkyl substances (PFAS). This research examines the local response to PFAS contamination of the public water system and well water in Merrimack and the results from the health survey administered by a local advocacy group, Merrimack Citizens for Clean Water (MCFCW). METHODS: MCFCW designed and implemented a community health survey (n = 596) representing 213 households exposed to PFAS through drinking water. The surveys were conducted in the summer of 2017. Respondents used an online survey platform to report demographic information, exposure sources, and health conditions. Logistic regression was used to analyze the community-based health survey results . RESULTS: There were several important associations that warrant further investigation and more immediate attention, especially: 1) elevated incidence of developmental, autoimmune and kidney disorders among those under 18 years of age; 2) elevated levels of health concerns, multiple health concerns, autoimmune disorders, and reproductive disorders among women, 3) elevated levels of health concerns, multiple health conditions, cardiovascular, respiratory, reproductive, and liver disorders in those with industrial occupational exposures, and; 4) elevated incidence of health concerns, cardiovascular, and developmental disorders among those who have been living in Merrimack for a long time versus newer residents. CONCLUSIONS: The limitations inherent in the study design warrant caution in interpreting the results, however the associations found in this study merit further investigation. This health survey highlights foremost the critical gap in information-lack of access to blood testing, medical monitoring and physician guidance of PFAS-exposed residents. This study provides a model for conducting community-based health studies to advocate for pathways to state supported biomonitoring and medical monitoring for those exposed to industrial toxins and to take into consideration the human health burden in shaping the future of chemical regulation.

Guideline levels for PFOA and PFOS in drinking water: the role of scientific uncertainty, risk assessment decisions, and social factors.

Communities across the U.S. are discovering drinking water contaminated by perfluoroalkyl and polyfluoroalkyl substances (PFAS) and determining appropriate actions. There are currently no federal PFAS drinking water standards despite widespread drinking water contamination, ubiquitous population-level exposure, and toxicological and epidemiological evidence of adverse health effects. Absent federal PFAS standards, multiple U.S. states have developed their own health-based water guideline levels to guide decisions about contaminated site cleanup and drinking water surveillance and treatment. We examined perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) water guideline levels developed by the U.S. Environmental Protection Agency (EPA) and state agencies to protect people drinking the water, and summarized how and why these levels differ. We referenced documents and tables released in June 2018 by the Interstate Technology and Regulatory Council (ITRC) to identify states that have drinking water and groundwater guideline levels for PFOA and/or PFOS that differ from EPA's health advisories (HAs). We also gathered assessment documents from state websites and contacted state environmental and health agencies to identify and confirm current guidelines. Seven states have developed their own water guideline levels for PFOA and/or PFOS ranging from 13 to 1000 ng/L, compared to EPA's HA of 70 ng/L for both compounds individually or combined. We find that the development of PFAS guideline levels via exposure and hazard assessment decisions is influenced by multiple scientific, technical, and social factors, including managing scientific uncertainty, technical decisions and capacity, and social, political, and economic influences from involved stakeholders. Assessments by multiple states and academic scientists suggest that EPA's HA is not sufficiently protective. The ability of states to develop their own guideline levels and standards provides diverse risk assessment approaches as models for other state and federal regulators, while a sufficiently protective, scientifically sound, and enforceable federal standard would provide more consistent protection.

Induction of hepatic miR-34a by perfluorooctanoic acid regulates metabolism-related genes in mice.

Perfluorooctanoic acid (PFOA) is a widespread organic pollutant with various toxicological impacts on the liver. Members of the miR-34 family are P53-targeted growth suppressors. We found that PFOA exposure (5 mg/kg/d PFOA for 28 d) resulted in a significant increase of miR-34a in the livers of mice but had no effect on either miR-34b or miR-34c. We knocked out miR-34a in mice to explore the role of elevated miR-34a in PFOA-induced liver toxicity. Compared with the corresponding untreated control, significant increases in liver weight as well as serum alanine transaminase, aspartate aminotransferase, and cholinesterase levels were observed in miR-34a-/- and wild-type mice after PFOA exposure. Hepatic cells showed similar swelling in both miR-34a-/- and wild-type mice after PFOA treatment. Hepatic RNA-sequencing (RNA-seq) showed that PFOA led to significant alteration in lipid metabolism genes, especially those involved in the peroxisome proliferator-activated receptor pathway, in both wild-type and miR-34a null mice. With or without PFOA treatment, relatively fewer genes were altered in miR-34a-/- livers compared to wild-type livers. Among the changed genes by miR-34a, the most dominant were metabolism-related genes, such as Fabp3, Cyp7a1, and Apoa4. Our in vivo study indicated that miR-34a mainly exerts a metabolic regulation role, rather than the pro-apoptosis and cell cycle arrest role reported previously by many in vitro studies. In addition, although hepatic P53 was unchanged, the active type of P53 (acetylated P53 (acetyl-p53, Lys379)) was markedly altered under PFOA treatment. Therefore, the increase in acetylated P53 may have activated the transcription of miR-34a in mouse livers after PFOA treatment.

Prenatal exposure to perfluoroalkyl substances and adipocytokines: the HOME Study.

OBJECTIVE: Gestational perfluoroalkyl substances exposure has been associated with decreased birthweight. We determined if gestational perfluoroalkyl substances exposure was associated with fetal metabolic markers using data from the HOME Study, a prospective birth cohort of pregnant women and their children in Cincinnati, Ohio. METHODS: Maternal serum concentrations of perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS), perfluorononanoic acid, and perfluorohexane sulfonic acid were quantified. We measured neonatal adipocytokine (leptin and adiponectin) concentrations in umbilical cord serum, and estimated percent differences with a 2-fold increase in maternal perfluoroalkyl substances concentrations among 230 mother-infant pairs. RESULTS: Median maternal serum PFOA and PFOS concentrations were 5.6 ng/mL and 14 ng/mL, respectively. Leptin was positively correlated with infant birthweight (p < 0.001). There were no statistically significant associations between maternal perfluoroalkyl substances and neonatal adipocytokine concentrations; each 2-fold increase in PFOA was associated with a non-significant increase in leptin (5%; 95% CI: -10, 22) and adiponectin (7%; 95% CI: -4, 19). CONCLUSION: Despite known associations with reduced birthweight, gestational serum perfluoroalkyl substances concentrations were not associated with neonatal adipocytokine concentrations. Further exploration of pathways of perfluoroalkyl substances associated changes in birthweight may help identify biomarkers that could be used to identify at-risk populations and develop interventions.

Rubella immunity and serum perfluoroalkyl substances: Sex and analytic strategy.

BACKGROUND: Perfluoroalkyl substances (PFASs) have been associated with decreased immunity to childhood tetanus and diphtheria immunizations. If these vaccinations are vulnerable to influence from PFASs, questions arise about associations with other common inoculations. OBJECTIVE: To examine whether serum PFASs were associated with reduced immunity to rubella immunization, and whether interactions with sex or ethnicity warranted analytic stratification. Usually, toxicology analyses are calculated controlling for race and sex. However, sex differences in immune function have been reported and a reduction of immunity to rubella in women could pose risks such miscarriage. METHODS: We analyzed a nationally representative sample of individuals ≥ 12 years from the National Health and Nutrition Examination Survey (NHANES) for years 1999-2000 and 2003-2004 for whom PFAS measures were available. Our analytic strategy was to start with separate analyses for youth and adults controlling for several covariates including ethnicity and sex, as well as the interaction of these terms with PFASs. If there was a main effect of PFASs and an interaction term, we would stratify analyses of effect size. The outcome variable was Rubella IgG titers by quartile of perfluoroalkyl substances. RESULTS: After exclusion for missing data, the analyzed sample contained 581 adult women, 621 adult men, and 1012 youth. There was no significant effect of PFASs on immunity in youths but a significant effect of both PFOA and PFOS in adults, as well as a significant interaction of PFOA x sex and a borderline significant interaction of PFOS x sex. When effect size analyses were stratified by sex, a significant association between rubella titres and PFOA was found in men but not women and PFOS was not significant in either sex. CONCLUSIONS: These results support our earlier studies showing sex specific responses to PFASs and indicate the importance of thinking carefully about analytic strategies in population based toxicology research.

Serum Perfluorooctanoic Acid and Birthweight: An Updated Meta-analysis With Bias Analysis.

BACKGROUND: A recent meta-analysis of 15 studies found a change in birthweight of -12.8 g (95% CI = -23.1, -2.38) per ng/ml PFOA in maternal or cord blood and -27.1 g (-50.6, -3.6) per log ng/ml PFOA. Almost all studies were done in low-exposed populations. There are nine new studies, adding 6,019 births to the previous 6,937 births. METHODS: We conducted a meta-analysis of 24 studies. To combine all results, we approximated results for untransformed PFOA from nine studies using log-transformed PFOA. We also included another large study, excluded from previous analyses, in a sensitivity analysis. RESULTS: We found a change of birthweight of -10.5 g (-16.7, -4.4) for every ng/ml PFOA in maternal or cord blood. After adding one previously excluded large study, we found little evidence of an association (-1.0 g; 95% CI = -2.4, 0.4). Restricting to studies where blood was sampled from mothers early in the pregnancy or shortly before conception (5,393 births), we found little association of PFOA with birthweight (-3.3 g [-9.6, 3.0]). In studies where blood was sampled late in the pregnancy (7563 pregnancies), lower birthweight was associated with higher PFOA (-17.8 [-25.0, -10.6]). CONCLUSION: Present human evidence provides only modest support for decreased birthweight with increasing PFOA. Studies with a wide range of exposure, and studies with blood sampled early in pregnancy, showed little or no association of PFOA with birthweight. These are studies in which confounding and reverse causality would be of less concern.