Association between perfluoroalkyl substances exposure and thyroid function in adults: A meta-analysis

A pathway level analysis of PFAS exposure and risk of gestational diabetes mellitus

Per- and polyfluoroalkyl substances (PFAS) have been found to be associated with gestational diabetes mellitus (GDM) development, a maternal health disorder in pregnancy with negative effects that can extend beyond pregnancy. Studies that report on this association are difficult to summarize due to weak associations and wide confidence intervals. One way to advance this field is to sharpen the biologic theory on a causal pathway behind this association, and to measure it directly by way of molecular biomarkers. The aim of this review is to summarize the literature that supports a novel pathway between PFAS exposure and GDM development. Epidemiological studies demonstrate a clear association of biomarkers of thyroid hormones and glucose metabolism with GDM development. We report biologic plausibility and epidemiologic evidence that PFAS dysregulation of maternal thyroid hormones and thyrotropin (TSH) may disrupt glucose homeostasis, increasing the risk of GDM. Overall, epidemiological studies demonstrate that PFAS were positively associated with TSH and negatively with triiodothyronine (T3) and thyroxine (T4). PFAS were generally positively associated with glucose and insulin levels in pregnancy. We propose dysregulation of thyroid function and glucose metabolism may be a critical and missing component in the accurate estimation of PFAS on the risk of GDM.

Impact of kidney hyperfiltration on concentrations of selected perfluoroalkyl acids among US adults for various disease groups

Data from the National Health and Nutrition Examination Survey (N = 6141) for the years 2003-2016 for US adults were analyzed to evaluate the impact of glomerular hyperfiltration on the observed concentrations of perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS), perfluorodecanoic acid, perfluorohexane sulfonic acid (PFHxS), and perfluorononanoic acid (PFNA) for several disease groups. Hyperfiltrators were defined as having an estimated glomerular filtration rate (eGFR) ≥ 110 mL/min/1.73 m², and normal filtrators were defined as those having an eGFR between 90 and 110 mL/min/1.73 m². The seven disease groups for which the data were analyzed were as follows: those (i) without any diseases; (ii) with hypertension only; (iii) with albuminuria only; (iv) with anemia only; (v) with diabetes only; (vi) with hypertension and one or more of diabetes, anemia, and albuminuria; and (vii) with two or more of diabetes, anemia, and albuminuria without hypertension. For almost every PFAA, for all seven disease groups except the albuminuria only group, hyperfiltrators had lower adjusted geometric means (AGM) than normal filtrators. For example, for the disease group with hypertension only, for PFOS, the AGMs for hyperfiltrators and normal filtrators were 8.3 and 10.6 ng/mL, respectively, for the total population. For the group with albuminuria only, normal filtrators were found to have higher AGMs than hyperfiltrators for the total population and males. For example, for PFHxS, the AGMs for normal and hyperfiltrators were 0.98 and 1.05 ng/mL, respectively, for the total population. For females, these AGMs for normal and hyperfiltrators were 0.96 and 0.86 ng/mL respectively. Males usually had higher AGMs than females, but the reverse was also true occasionally. Usually, male-female differences were substantially narrower for normal filtrators than hyperfiltrators. Irrespective of the filtration status, the disease group with hypertension only had the highest AGMs for every PFAA. AGMs for the anemia only group were the lowest for every PFAA as compared with other disease groups among hyperfiltrators.

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

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

On the swelling behavior of poly(N-Isopropylacrylamide) hydrogels exposed to perfluoroalkyl acids

Per- and polyfluoroalkyl substances (PFAS) have rapidly accumulated in the environment due to their widespread use prior to commercial discussion in the early 21st century, and their slow degradation has magnified concerns of their potential toxicity. Monitoring their distribution is, therefore, necessary to evaluate and control their impact on the health of exposed populations. This investigation evaluates the capability of a simple polymeric detection scheme for PFAS based on crosslinked, thermoresponsive poly(N-isopropylacrylamide) (PNIPAM) hydrogels. Surveying swelling perturbations induced by several hydrotropes and comparable hydrocarbon analogs, tetraethylammonium perfluorooctane sulfonate (TPFOS) showed a significantly higher swelling ratio on a mass basis (65.5 ± 8.8 at 15°C) than any of the other analytes tested. Combining swelling with the fluorimetric response of a solvachromatic dye, nile red, revealed the fluorosurfactant to initiate observable aggregation (i.e., its critical aggregation concentration) at 0.05 mM and reach saturation (i.e., its charge neutralization concentration) at 0.5 mM. The fluorosurfactant was found to homogeneously distribute throughout the polymer matrix with energy dispersive X-ray spectroscopy, marking the swelling response as a peculiar nexus of fluorinated interfacial positioning and delocalized electrostatic repulsion. Results from the current study hold promise for exploiting the physiochemical response of PNIPAM to assess TPFOS's concentration.

Legacy and Emerging Per- and Polyfluoroalkyl Substances: Analytical Techniques, Environmental Fate, and Health Effects

Due to their unique chemical properties, per- and polyfluoroalkyl substances (PFAS) have been used extensively as industrial surfactants and processing aids. While several types of PFAS have been voluntarily phased out by their manufacturers, these chemicals continue to be of ecological and public health concern due to their persistence in the environment and their presence in living organisms. Moreover, while the compounds referred to as “legacy” PFAS remain in the environment, alternative compounds have emerged as replacements for their legacy predecessors and are now detected in numerous matrices. In this review, we discuss the historical uses of PFAS, recent advances in analytical techniques for analysis of these compounds, and the fate of PFAS in the environment. In addition, we evaluate current biomonitoring studies of human exposure to legacy and emerging PFAS and examine the associations of PFAS exposure with human health impacts, including cancer- and non-cancer-related outcomes. Special focus is given to short-chain perfluoroalkyl acids (PFAAs) and ether-substituted, polyfluoroalkyl alternatives including hexafluoropropylene oxide dimer acid (HFPO-DA; tradename GenX), 4,8-dioxa-3H-perfluorononanoic acid (DONA), and 6:2 chlorinated polyfluoroethersulfonic acid (6:2 Cl-PFESA; tradename F-53B).

Per- and polyfluoroalkyl substance mixtures and gestational weight gain among mothers in the Health Outcomes and Measures of the Environment study

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) are environmentally persistent chemicals commonly used in the production of household and consumer goods. While exposure to PFAS has been associated with greater adiposity in children and adults, less is known about associations with gestational weight gain (GWG).

METHODS

We quantified using mass spectrometry perfluorooctanoate (PFOA), perfluorooctanesulfonate (PFOS), perfluorohexanesulfanoate (PFHxS) and perfluorononanoate (PFNA) in maternal serum from 18 ± 5 weeks' gestation (mean ± standard deviation (std)) in a prospective pregnancy and birth cohort (2003-2006, Cincinnati, Ohio) (n = 277). After abstracting weight data from medical records, we calculated GWG from 16 ± 2 weeks' gestation (mean ± std) to the measured weight at the last visit or at delivery, rate of weight gain in the 2nd and 3rd trimesters (GWR), and total weight gain z-scores standardized for gestational age at delivery and pre-pregnancy BMI. We investigated covariate-adjusted associations between individual PFAS using multivariable linear regression; we assessed potential effect measure modification (EMM) by overweight/obese status (pre-pregnancy BMI<25 kg/m2 v. ≥25 kg/m2). Using weighted quantile sum regression, we assessed the combined influence of these four PFAS on GWG and GWR.

RESULTS

Each doubling in serum concentrations of PFOA, PFOS, and PFNA was associated with a small increase in GWG (range 0.5-0.8 lbs) and GWR (range 0.03-0.05 lbs/week) among all women. The association of PFNA with GWG was stronger among women with BMI≥25 kg/m2 (β = 2.6 lbs; 95% CI:-0.8, 6.0) than those with BMI<25 kg/m2 (β = -1.0 lbs; 95% CI:-3.8, 1.8; p-EMM = 0.10). We observed associations close to the null between PFAS and z-scores and between the PFAS exposure index (a combined summary measure) and the outcomes.

CONCLUSION

Although there were consistent small increases in gestational weight gain with increasing PFOA, PFOS, and PFNA serum concentrations in this cohort, the associations were imprecise. Additional investigation of the association of PFAS with GWG in other cohorts would be informative and could consider pre-pregnancy BMI as a potential modifier.

Human exposure pathways to poly- and perfluoroalkyl substances (PFAS) from indoor media: A systematic review protocol

BACKGROUND

Human exposure to per- and polyfluoroalkyl substances (PFAS) has been primarily attributed to contaminated food and drinking water. However, additional PFAS exposure pathways have been raised by a limited number of studies reporting correlations between commercial and industrial products and PFAS levels in human media and biomonitoring. Systematic review (SR) methodologies have been widely used to evaluate similar questions using an unbiased approach in the fields of clinical medicine, epidemiology, and toxicology, but the deployment in exposure science is ongoing. Here we present a systematic review protocol that adapts existing systematic review methodologies and study evaluation tools to exposure science studies in order to investigate evidence for important PFAS exposure pathways from indoor media including consumer products, household articles, cleaning products, personal care products, plus indoor air and dust.

OBJECTIVES

We will systematically review exposure science studies that present both PFAS concentrations from indoor exposure media and PFAS concentrations in blood serum or plasma. Exposure estimates will be synthesized from the evidence to answer the question, "For the general population, what effect does exposure from PFAS chemicals via indoor media have on blood, serum or plasma concentrations of PFAS?" We adapt existing systematic review methodologies and study evaluation tools from the U.S. EPA's Systematic Review Protocol for the PFBA, PFHxA, PFHxS, PFNA, and PFDA IRIS Assessments and the Navigation Guide for exposure science studies, as well as present innovative developments of exposure pathway-specific search strings for use in artificial intelligence screening software.

DATA SOURCES

We will search electronic databases for potentially relevant literature, including Web of Science, PubMed, and ProQuest. Literature search results will be stored in EPA's Health and Environmental Research Online (HERO) database.

STUDY ELIGIBILITY AND CRITERIA

Included studies will present exposure measures from indoor media including consumer products, household articles, cleaning products, personal care products, plus indoor air and dust, paired with PFAS concentrations in blood, serum or plasma from adults and/or children in the general population. We focus on a subset of PFAS chemicals including perfluorooctanoic acid (PFOA), perfluorooctanesulfonate (PFOS), perfluorobutanoic acid (PFBA), perfluorobutane sulfonate (PFBS), perfluorodecanoic acid (PFDA), perfluorohexanoic acid (PFHxA), perfluorohexanesulfonate (PFHxS), and perfluorononanoic acid (PFNA).

STUDY APPRAISAL AND SYNTHESIS METHODS

Studies will be prefiltered at the title and abstract level using computationally intelligent search strings to expedite the screening process for reviewers. Two independent reviewers will screen the prefiltered studies against inclusion criteria at the title/abstract level and then full-text level, after which the reviewers will assess the studies' risk of bias using an approach modified from established systematic review tools for exposure studies. Exposure estimates will be calculated to investigate the proportion of blood, serum or plasma) PFAS concentrations that can be explained by exposure to PFAS in indoor media.

Blood levels of perfluoroalkyl substances (PFASs), elements and their associations with metabolic syndrome (MetS) in Chinese male adults mediated by metabolic-related risk factors

Our preliminary studies have suggested PFASs, heavy metals, and trace elements could bring significant risks to MetS. However, the role of epigenetic mechanisms (i.e., miRNAs) and risk factors of metabolic alternation (i.e., thyroid functions, glucose and lipids metabolism) are not fully understood. To test this hypothesis, a further cross-sectional study with 80 male MetS cases and 64 male references was undertaken. Negative association between the serum n-perfluorooctanoic acid (n-PFOA) with miR-140-5p was found [β = -0.772; 95% confidence interval (CI), -0.244 to -0.300; p < 0.01, q < 0.05)] after adjusted with age. Higher levels of leptin and total bile acid were observed in the MetS group. The significantly positive associations between leptin with Cd (β = 1.015, p < 0.01, q < 0.05), Cu (β = 6.796, p < 0.05, q = 0.077) and Se (β = 7.633, p < 0.05, q = 0.060) were found; whereas total bile acid was significantly associated with Se (β = 8.954, p < 0.05, q = 0.140). Significantly positive associations between leptin and systolic/diastolic blood pressure were showed. Moreover, increased total bile acid concentrations were associated with hypertriglyceridemia [odds ratio (OR): 2.24 (95%CI, 1.10-4.58) adjusted by age.

The Relationship Between Perfluoroalkyl Substances Concentrations and Thyroid Function in Early Childhood: A Prospective Cohort Study

Background: Exposure to perfluoroalkyl substances (PFAS) has been suggested to affect thyroid function; however, data on early-life exposure and thyroid function in early childhood are scarce. We investigated the cross-sectional and longitudinal relationships of early-life exposure to PFAS with thyroid function at 2, 4, and 6 years of age. Methods: This study used data on PFAS exposure and thyroid function from the Environment and Development of Children (EDC) cohort study. A total of 660 children who visited at least once at 2, 4, or 6 years of age (381 children aged 2 years, 569 children aged 4 years, and 511 children aged 6 years) were included in this study. Serum thyrotropin (TSH) levels were measured at 2, 4, and 6 years of age. The relationship of serum PFAS (sPFAS) concentrations with TSH levels at the three time points was assessed by repeated-measure analysis using linear mixed models. The serum levels of free thyroxine (fT4) and triiodothyronine (T3) were measured once (at 6 years of age). The relationship of sPFAS with fT4 and T3 levels at 6 years of age was investigated by linear regression analyses. Results: None complained of hyper- or hypothyroid symptoms with normal fT4 and T3 levels. Repeated-measure analysis showed that TSH levels at 2, 4, and 6 years of age were inversely associated with serum perfluorononanoic acid (sPFNA), after adjusting for age, sex, and/or dietary iodine intake (p < 0.05). When stratified by sex, TSH levels were inversely associated with serum perfluorooctanoic acid (sPFOA) in boys and sPFNA in girls (p < 0.05 for both). fT4 levels at 6 years of age were positively related to sPFNA and serum perfluorohexane sulfonic acid at 2 years of age and sPFOA at 6 years of age, and T3 levels at 6 years of age showed positive relationships with serum perfluorodecanoic acid and serum perfluorooctane sulfonic acid at 6 years of age (p < 0.05 for all). When stratified by sex, similar positive relationships for sPFAS with fT4 and T3 levels were significant among boys only. Conclusions: A significant relationship was found between early-life exposure to PFAS and thyroid function. Early-life exposure to PFAS was associated with decreased TSH and increased fT4 or T3 levels among preschool-age children.

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

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

Correlates of stigma for patients with cancer: a systematic review and meta-analysis

OBJECTIVE

The systematic review and meta-analysis was performed to summarize the available evidence and identify the correlates of cancer stigma.

METHODS

PubMed, EMBASE, Web of Science, the Cochrane Library, and PsycINFO were electronically searched to identify eligible studies about correlates of stigma for patients with cancer. Two reviewers independently screened the literature, extracted data, and assessed the risk of bias of included studies. A meta-analysis was performed using the statistical program R.

RESULTS

Thirty-one studies involving a total of 7114 patients were included in the systematic review and meta-analysis. The results of the meta-analysis showed that cancer stigma shared positive associations with male gender, symptoms, depression, anxiety, body image loss, self-blame, social constraint, intrusive thoughts, and ambivalence over emotional expression, and negative associations with income, NK cell subsets, QOL, self-esteem, self-efficacy, cancer screening attendance, doctor's empathy, and medical satisfaction. The results of the descriptive analysis indicated that cancer stigma was positively associated with self-perception of aging, anger, internal attributions, stressful life events, self-perceived burden, and sleep dysfunction, while negatively associated with patient-provider communication and sleep quality.

CONCLUSION

Healthcare staff should pay attention to the identified correlates of cancer stigma. The results of our research can inform the design of interventions to reduce stigma and to improve clinical outcomes in people with cancer.

Orally Administered 6:2 Chlorinated Polyfluorinated Ether Sulfonate (F-53B) Causes Thyroid Dysfunction in Rats

The compound 6:2 chlorinated polyfluorinated ether sulfonate (F-53B), a replacement for perfluorooctanesulfonate (PFOS) in the electroplating industry, has been widely detected in numerous environmental matrices, human sera, and organisms. Due to regulations that limit PFOS use, F-53B use is expected to increase. Therefore, in this study, we performed a subchronic oral toxicity study of F-53B in Sprague Dawley (SD) rats. F-53B was administered orally once daily to male and female rats for 28 days at doses of 5, 20, and 100 mg/kg/day. There were no toxicologically significant changes in F-53B-treated rats, except in the thyroid gland. However, F-53B slightly reduced the serum concentrations of thyroid hormones, including triiodothyronine and thyroxine, compared with their concentrations in the vehicle group. F-53B also induced follicular hyperplasia and was associated with increased thyroid hormone biosynthesis-associated protein expression. These results demonstrate that F-53B is a strong regulator of thyroid hormones in SD rats as it disrupts thyroid function. Thus, caution should be exercised in the industrial application of F-53B as an alternative for PFOS.

Pharmacokinetic bias analysis of an association between clinical thyroid disease and two perfluoroalkyl substances

Exposure to perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) has been associated with the occurrence of thyroid disease in some epidemiologic studies. We hypothesized that in a specific epidemiologic study based on the National Health and Nutrition Examination Survey, the association of clinical thyroid disease with serum concentration of PFOA and PFOS was due to reverse causality. Thyroid hormone affects glomerular filtration, which in turn affects excretion of PFOA and PFOS. We evaluated this by linking a model of thyroid disease status over the lifetime to a physiologically based pharmacokinetic model of PFOA and PFOS. Using Monte Carlo methods, we simulated the target study population and analyzed the data using multivariable logistic regression. The target and simulated populations were similar with respect to age, estimated glomerular filtration rate, serum concentrations of PFOA and PFOS, and prevalence of clinical thyroid disease. The analysis showed little or no evidence of bias from the hypothesized mechanism. The largest bias was for the fourth quartile of PFOA in females, with an odds ratio of 0.93 (95% CI, 0.90, 0.97). The reported odds ratio of clinical thyroid disease for this group was 1.63 (1.07, 2.47), and if it were corrected for the bias would have been 1.74 (1.14, 2.65). Our results suggest that little of the reported association in the target study was due to reverse causality.

Perfluoroalkyl substances exposure and hearing impairment in US adults

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) are widely applied in consumer and industrial products such as nonstick cookware, waterproof clothing, food packaging materials, and fire-fighting foams. These "forever chemicals" are hypothesized to impact neurobehavioral functions. Yet no previous study has explored the role of PFAS on audiometrically determined hearing impairment (HI).

OBJECTIVES

To investigate the associations of serum concentrations of perfluoroalkyl substances with low-frequency HI (LFHI) and high-frequency HI (HFHI) in US adults.

METHODS

We evaluated the cross-sectional associations in 2371 adults aged 20-69 years who participated in the National Health and Nutrition Examination Survey (NHANES) 2003-2004, 2011-2012 and 2015-2016; and 449 adults aged ≥70 years from NHANES 2005-2006 and 2009-2010. Serum concentrations of perfluorohexane sulfonic acid (PFHxS), perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA) and perfluorodecanoic acid (PFDA), were measured using solid-phase extraction coupled to High Performance Liquid Chromatography-Turbo Ion Spray ionization-tandem Mass Spectrometry. LFHI was defined as a pure-tone average (PTA) of thresholds across 0.5-1-2 kHz >25 dB; HFHI defined as a PTA across 3-4-6 kHz >25 dB in the worse ear. Survey-weighted logistic regression models were used to compute odds ratios (ORs) and 95% confidence intervals (CIs) with adjustment for age, age-squared, sex, race/ethnicity, education, poverty-to-income ratio, body mass index, smoking status, exposures to occupational, recreational and firearm noises, and NHANES cycles.

RESULTS

There were no significant associations when perfluoroalkyl variables were fitted as a linear (log-transformed) term. However, statistically significant associations of HFHI with PFNA (OR = 1.70, 95% CI: 1.13-2.56) and PFDA (OR = 1.75, 95% CI: 1.00-3.05) were observed when comparing participants with serum concentrations ≥90th vs. <90th percentiles of PFNA (90th percentile = 1.8 ng/mL) and PFDA (90th percentile = 0.5 ng/mL), respectively, in adults aged 20-69 years. No significant associations were observed for other compounds in adults aged 20-69 years and for all compounds in adults ≥70 years.

CONCLUSIONS

Our study does not provide strong evidence to support the ototoxicity of PFAS exposure. Non-linear threshold dose-response associations between serum concentrations of PFNA and PFDA and HFHI need further investigation.

Polybrominated diphenyl ether (PBDE) and poly- and perfluoroalkyl substance (PFAS) exposures during pregnancy and maternal depression

BACKGROUND

Experimental studies in rodents suggest that polybrominated diphenyl ethers (PBDEs) and poly- and perfluoroalkyl substances (PFAS) may contribute to depressive symptoms. Few studies have examined the impact of these chemicals on depression in adults.

OBJECTIVE

To examine the associations between serum PBDE and PFAS concentrations during pregnancy and repeated measures of depressive symptoms in women assessed from pregnancy to 8 years postpartum.

METHODS

This study was based on 377 women from the Health Outcomes and Measures of the Environment Study, a birth cohort in Cincinnati, OH (USA). PBDEs (BDE-28, -47, -99, -100, -153, and ∑PBDEs) and PFAS (perfluorooctanoate [PFOA], perfluorooctane sulfonate [PFOS], perfluorohexane sulfonate [PFHxS], perfluorononanoate [PFNA]) were quantified in maternal serum at 16 ± 3 weeks gestation. Depressive symptoms were measured using the Beck Depression Inventory-II (BDI-II) at ~20 weeks gestation and up to seven times during postpartum visits (4 weeks, 1, 2, 3, 4, 5, and 8 years). We used linear mixed models to estimate covariate-adjusted associations between chemical concentrations and repeated measures of BDI-II. Multinomial logistic regression models were used to estimate the relative risk ratios of having a medium or high depression trajectory.

RESULTS

We found that a 10-fold increase in BDE-28 at 16 ± 3 weeks gestation was associated with significantly increased BDI-II scores (β = 2.5 points, 95% confidence interval [CI] 0.8, 4.2) from pregnancy to 8 years postpartum. Significant positive associations were also observed with BDE-47, -100, -153, and ∑PBDEs. A 10-fold increase in ∑PBDEs was associated with a 4.6-fold increased risk (95% CI 1.8, 11.8) of a high trajectory for BDI-II compared to a low trajectory. We observed no significant associations between PFAS and BDI-II scores.

CONCLUSION

PBDEs during pregnancy were associated with more depressive symptoms among women in this cohort.

Per- and Polyfluoroalkyl Substances and Obesity, Type 2 Diabetes and Non-alcoholic Fatty Liver Disease: A Review of Epidemiologic Findings

Per- and polyfluoroalkyl substances, a group of fluoro-surfactants widely detected in the environment, wildlife and humans, have been linked to adverse health effects. A growing body of literature has addressed their effects on obesity, diabetes and non-alcoholic fatty liver disease/ non-alcoholic steatohepatitis. This review summarizes the brief historical use and chemistry of per- and polyfluoroalkyl substances, routes of human exposure, as well as the epidemiologic evidence for associations between exposure to per- and polyfluoroalkyl substances and the development of obesity, diabetes and non-alcoholic fatty liver disease/ non-alcoholic steatohepatitis. We identified 22 studies on obesity and 32 studies on diabetes, while only 1 study was found for non-alcoholic fatty liver disease/ non-alcoholic steatohepatitis by searching PubMed for human studies. Approximately 2/3 of studies reported positive associations between per- and polyfluoroalkyl substances exposure and the prevalence of obesity and/or type 2 diabetes. Causal links between per- and polyfluoroalkyl substances and obesity, diabetes and non-alcoholic fatty liver disease/ non-alcoholic steatohepatitis, however, require further large-scale prospective cohort studies combined with mechanistic laboratory studies to better assess these associations.

Per- and polyfluoroalkyl substances and blood pressure in pre-diabetic adults-cross-sectional and longitudinal analyses of the diabetes prevention program outcomes study

The relationship of plasma concentration of per- and polyfluoroalkyl substances (PFAS) with blood pressure (BP) is uncertain. This study examined cross-sectional and prospective associations of PFAS with BP and hypertension. We quantified plasma PFAS concentrations from 957 participants enrolled in the lifestyle and placebo arms of the Diabetes Prevention Program (DPP), a randomized controlled trial with approximately 15 years of follow-up. We used multivariable linear and logistic regressions to test cross-sectional associations of six PFAS, including perfluorooctanesulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorohexane sulfonic acid (PFHxS), N-ethyl-perfluorooctane sulfonamido acetic acid (EtFOSAA), N-methyl-perfluorooctane sulfonamido acetic acid (MeFOSAA), and perfluorononanoic acid (PFNA), with BP and hypertension prevalence, respectively, at baseline. We used generalized linear mixed models to estimate longitudinal associations between baseline PFAS and the rate of BP changes, and Cox-Proportional hazard models to estimate risk of developing hypertension relative to baseline PFAS. Models were adjusted for baseline age, sex, race/ethnicity, treatment arm, educational attainment, income, marital status, smoking habit, alcohol drinking, and diet. We tested for effect modification by the treatment arm and sex, and accounted for multiple comparisons using the False-Discovery Rate (FDR). PFAS concentrations and hypertension prevalence within the study population (65.3% female, 57.7% White, 65.3% aged 40-59 years) were comparable to the general U.S. population. Cross-sectionally, we found small but statistically significant associations of baseline plasma concentrations of PFOA with systolic BP (β per doubling: 1.49 mmHg, 95% CI: 0.29, 2.70); and MeFOSAA with hypertension (RR = 1.09 per doubling, 95% CI: 1.01, 1.19). Estimates were not statistically significant after FDR adjustment. Longitudinally, we observed null associations in the placebo arm, but some inverse associations of baseline PFOS and MeFOSAA with systolic BP in the lifestyle arm, perhaps due to regression toward the mean. Baseline PFAS concentrations also were not prospectively associated with hypertension risk. Overall, there were modest and mostly null associations of plasma PFAS concentrations with BP and hypertension.

Quantitative bias analysis of the association between subclinical thyroid disease and two perfluoroalkyl substances in a single study

Exposure to perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) has been associated with the occurrence of thyroid disease in some epidemiologic studies. We hypothesized that in a specific epidemiologic study based on the National Health and Nutrition Examination Survey, the association of subclinical thyroid disease with serum concentration of PFOA and PFOS was due to reverse causality. Thyroid hormone affects glomerular filtration, which in turn affects excretion of PFOA and PFOS. We evaluated this by linking a model of thyroid disease status over the lifetime to physiologically based pharmacokinetic models of PFOA and PFOS. Using Monte Carlo methods, we simulated the target study population and analyzed the data using multivariable logistic regression. The target and simulated populations were similar with respect to age, estimated glomerular filtration rate, serum concentrations of PFOA and PFOS, and prevalence of subclinical thyroid disease. Our findings suggest that in the target study the associations with subclinical hypothyroidism were overstated and the results for subclinical hyperthyroidism were, in general, understated. For example, for subclinical hypothyroidism in men, the reported odds ratio per ln(PFOS) increase was 1.98 (95% CI 1.19-3.28), whereas in the simulated data the bias due to reverse causality gave an odds ratio of 1.19 (1.16-1.23). Our results provide evidence of bias due to reverse causality in a specific cross-sectional study of subclinical thyroid disease with exposure to PFOA and PFOS among adults.

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

BACKGROUND

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Thyroid Disrupting Effects of Old and New Generation PFAS

Per- and polyfluoroalkyl substances (PFAS) represent a group of synthetic compounds widely used in industry plants due to their low grade of degradation, surfactant properties, thermic and flame resistance. These characteristics are useful for the industrial production, however they are also potentially dangerous for human health and for the environment. PFAS are persistent pollutants accumulating in waters and soil and recoverable in foods due to their release by food packaging. Humans are daily exposed to PFAS because these compounds are ubiquitous and, when assimilated, they are difficult to be eliminated, persisting for years both in humans and animals. Due to their persistence and potential danger to health, some old generation PFAS have been replaced by newly synthesized PFAS with the aim to use alternative compounds presumably safer for humans and the environment. Yet, the environmental pollution with PFAS remains a matter of concern worldwide and led to large-scale epidemiological studies both on plants' workers and on exposed people in the general population. In this context, strong concern emerged concerning the potential adverse effects of PFAS on the thyroid gland. Thyroid hormones play a critical role in the regulation of metabolism, and thyroid function is related to cardiovascular disease, fertility, and fetal neurodevelopment. In vitro, ex vivo data, and epidemiological studies suggested that PFASs may disrupt the thyroid hormone system in humans, with possible negative repercussions on the outcome of pregnancy and fetal-child development. However, data on the thyroid disrupting effect of PFAS remain controversial, as well as their impact on human health in different ages of life. Aim of the present paper is to review recent data on the effects of old and new generation PFAS on thyroid homeostasis. To this purpose we collected information from in vitro studies, animal models, and in vivo data on exposed workers, general population, and pregnant women.

Perfluoropolyether carboxylic acids (novel alternatives to PFOA) impair zebrafish posterior swim bladder development via thyroid hormone disruption

Perfluoropolyether carboxylic acids (PFECAs, CF₃(OCF₂)_nCOO^-, n = 2-5) are novel alternatives to perfluorooctanoic acid (PFOA) and are widely used in industrial production. However, although they have been detected in surface water and human blood, their toxicities on aquatic organisms remain unknown. We used zebrafish embryos to compare the developmental toxicities of various PFECAs (e.g., perfluoro (3,5,7-trioxaoctanoic) acid (PFO3OA), perfluoro (3,5,7,9-tetraoxadecanoic) acid (PFO4DA), and perfluoro (3,5,7,9,11-pentaoxadodecanoic) acid (PFO5DoDA)) with that of PFOA and to further reveal the key events related to toxicity caused by these chemicals. Results showed that, based on half maximal effective concentrations (EC₅₀), toxicity increased in the order: PFO5DoDA > PFO4DA > PFOA > PFO3OA, with uninflated posterior swim bladders the most frequently observed malformation. Similar to PFOA, PFECA exposure significantly lowered thyroid hormone (TH) levels (e.g., T3 (3,5,3'-L-triiodothyronine) and T4 (L-thyroxine)) in the whole body of larvae at 5 d post-fertilization following disrupted TH metabolism. In addition, the transcription of UDP glucuronosyltransferase 1 family a, b (ugt1ab), a gene related to TH metabolism, increased dose-dependently. Exogeneous T3 or T4 supplementation partly rescued PFECA-induced posterior swim bladder malformation. Our results further suggested that PFECAs primarily damaged the swim bladder mesothelium during early development. This study is the first to report on novel emerging PFECAs as thyroid disruptors causing swim bladder malformation. Furthermore, given that PFECA toxicity increased with backbone OCF₂ moieties, they may not be safer alternatives to PFOA.

Perfluoroalkyl acids and thyroid hormones across stages of kidney function

Data for US adults aged ≥20 years for 2007-2012 (N = 7020) were used to study concentrations of thyroid stimulating hormone (TSH), free (FT3) and total triiodothyronine (TT3), free (FT4) total thyroxine (TT4), and thyroglobulin (TGN) across stages of glomerular function (GF). Data for 2007-2008 and 2011-2012 (N = 2549) were used to study associations between thyroid hormone biomarkers and five serum perfluoroalkyl acids (PFAAs). We report how thyroid hormone biomarkers vary in human serum across stages of GF. Stages considered were: GF-1 (normal, eGFR >90 mL/min/1.73 m2), GF-2 (60 ≤ eGFR≤90 mL/min/1.73 m2), GF-3A (45 ≤eGFR<60 mL/min/1.73 m2), and GF-3B/4 (15 ≤ eGFR<45 mL/min/1.73 m2). Regression models stratified by GF stages were fitted to evaluate associations between the concentrations of selected PFAAs and thyroid hormones and to evaluate the variability in concentrations of thyroid hormones across the stages of GF. Adjusted geometric means (AGM) for TSH sharply increased from GF-1 (1.34 μIU/mL) to GF-2 (1.58 μIU/mL) and then remained relatively stable. AGMs of FT3 and TT3 decreased consistently from GF-1 to GF-3B/4; from 3.24 to 2.79 pg/mL for FT3 and from 115.7 to 96.4 ng/dL for TT3. AGMs for FT4 increased from GF-2 onward. TGN increased as glomerular filtration worsened from GF-1 through GF-3B/4. In contrast to strong relationships of thyroid hormone markers to stages of renal function, only scattered, inconsistent findings characterized relationship of PFAAs to thyroid markers across stages of kidney disease. For example, TSH was positively associated with PFOA at GF-2 (β = 0.08522, p < 0.01) but negatively associated at GF-3A (β = - 0.22926, p = 0.04). Thus, associations between kidney disease and thyroid hormone are clear, but the relationships between PFAAs and thyroid hormones vary inconsistently from stage to stage and reveal no trend. For thyroid hormone investigations, we conclude stratification by glomerular function stage is likely not needed.

Effect of long- and short-chain perfluorinated compounds on cultured thyroid cells viability and response to TSH

PURPOSE

Perfluorinated chemicals are widespread pollutants persistent in the environment with links to some major health issues. The two main compounds, perfluoro-octanoic acid (PFOA) and perfluoro-alkyl sulphonate (PFOS), were recently classified as carcinogenetic and thus their use has been restricted. Short-chain PFCs were recently developed as an alternative, but no data regarding the possible endocrine toxicities of these compounds are available. Aim of this study was to investigate whether short-chain PFCs could jeopardize thyroid cell viability and/or interfere with the functional effect TSH.

METHODS

Fisher rat thyroid line-5 (FRTL-5) was treated with increasing concentrations of PFOA, PFOS, perfluorobutanesulfonic acid (PFBS), perfluorobutanoic acid (PFBA), pentafluoropropionic anhydride (PFPA), perfluoropentanoic acid (PFPeA) to evaluate modifications in cell viability and TSH-stimulated cAMP production.

RESULTS

Neither long nor short-chain PFCs affected cell viability (apart from PFOS 100 µM), or interfered with cAMP production.

CONCLUSIONS

The results of the present study demonstrate for the first time that short-chain PFCs have no acute cytotoxic effect on thyroid cells in vitro and that cAMP production is not modulated by any of the tested PFCs.

Association of perfluoroalkyl substances exposure with cardiometabolic traits in an island population of the eastern Adriatic coast of Croatia

BACKGROUND

Exposure to perfluoroalkyl substances (PFAS), ubiquitous environmental contaminants, may be related to cardiometabolic diseases in adults. Studies in European populations to examine the association of PFAS exposure and comprehensive cardiometabolic traits and metabolic syndrome (MetS) are limited.

METHODS

In this pilot cross-sectional study of a well-characterized adult population of the island of Hvar, situated off the eastern Adriatic coast of Croatia, we measured PFAS concentrations in plasma samples collected during 2007-2008 and examined their cross-sectional associations with cardiometabolic traits and MetS after adjustment of covariates (n = 122). PFAS investigated in this study included perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorohexane sulfonic acid (PFHxS), and perfluorononanoic acid (PFNA).

RESULTS

The geometric mean (range) was 8.91 (2.36, 33.67) ng/mL for PFOS, 2.87 (1.03, 8.02) ng/mL for PFOA, 0.77 (0.25, 2.40) ng/mL for PFHxS, and 1.29 (0.48, 3.46) ng/mL for PFNA, with frequency of detection at 100%, 100%, 95.9%, and 100%, respectively. PFOS, PFOA, and PFNA concentrations were positively associated with the risk of MetS as defined by the Adult Treatment Panel III (ATP III) criteria, with estimated odds ratios and 95% confidence intervals at 1.89 (0.93, 3.86), 2.19 (0.88, 5.44), and 2.95 (1.12, 7.80), respectively, with only PFNA reaching statistical significance. PFNA concentrations were associated with increased risk of overweight or obesity.

CONCLUSIONS

Background exposure to PFOS, PFOA, and PFNA was marginally associated with increased risk of MetS in this small study, and these results should be confirmed with a larger sample size and longitudinal follow-up.

High exposure to perfluorinated compounds in drinking water and thyroid disease. A cohort study from Ronneby, Sweden

Per- and polyfluoroalkyl substances (PFAS) are extremely persistent manmade substances. Apart from exposure through food and indoor air and dust, humans can be exposed through drinking water if the surface or groundwater is contaminated. In 2013 very high levels of PFOS and PFHxS were found in the drinking water from one of the two waterworks supplying the municipality of Ronneby, Sweden. A cohort was formed, including all individuals who had lived at least one year in Ronneby during the period 1980-2013 (ñ63,000). Each year, addresses that got their drinking water from the contaminated water works were identified. Through the Swedish personal identity number, each individual was linked to registers providing diagnoses and prescriptions for hyper- and hypothyroidism. In total, 16,150 individuals had ever been exposed. The hazard ratios did not indicate any excess risk of hyperthyroidism among those with contaminated water. For hypothyroidism, the risk of being prescribed medication was significantly increased among women with exposure during the mid part of the study period (but not men). However, the association with period of exposure was non-monotonic, so the significance is considered to be a chance finding. Our research was limited by the relatively simple exposure assessment.

Perfluoroalkyl and polyfluoroalkyl substances and fetal thyroid hormone levels in umbilical cord blood among newborns by prelabor caesarean delivery

BACKGROUND

Perfluoroalkyl and polyfluoroalkyl substances (PFAS) have been reported to disrupt the thyroid function. But epidemiological evidence on the association between PFAS and thyroid hormone (TH) levels in cord blood is scarce and controversial. We aimed to examine the association between cord blood PFAS concentrations and TH levels in prelabor caesarean deliveries.

METHODS

We measured ten PFAS and three THs in cord blood in 568 prelabor caesarean deliveries. The associations between PFAS and TH levels were examined using multiple linear regression model and sparse partial least squares (SPLS) regression model.

RESULTS

In SPLS analyses, thyroid stimulating hormone (TSH) level decreased with increasing concentrations of perfluorooctane sulfonate (PFOS, β = -0.012, 95% confidence interval [CI]: -0.019, -0.005), perfluorononanoic acid (PFNA, β = -0.012, 95% CI: -0.019, -0.005), perfluorodecanoic acid (PFDA, β = -0.012, 95% CI: -0.02, -0.005), perfluoroundecanoic acid (PFUA, β = -0.013, 95% CI: -0.021, -0.006) and perfluorododecanoic acid (PFDoA, β = -0.013, 95% CI: -0.023, -0.006). Moreover, we found a positive association between PFDoA and free thyroxine (FT4) levels (β = 0.190, 95% CI: 0.063, 0.304) after adjusting for potential confounders. Free tri-iodothyronine (FT3) levels were positively associated with concentrations of PFOS (β = 0.059, 95% CI: 0.023, 0.100), but negatively associated with PFDoA (β = -0.153, 95% CI: -0.212, -0.106). We also observed gender disparity in the associations of PFAS exposure and FT3, FT4, TSH levels.

CONCLUSION

Our results suggest that prenatal exposure to certain PFAS may disrupt fetal thyroid function. The effect may be gender-specific.

Determinants of per- and polyfluoroalkyl substances (PFAS) in midlife women: Evidence of racial/ethnic and geographic differences in PFAS exposure

BACKGROUND

Per- and poly-fluoroalkyl substances (PFAS) are public health concerns because of widespread exposure through contaminated foods/drinking water. Although some determinants of PFAS exposure have been suggested, the role of geographic location and race/ethnicity in PFAS exposure has not been well characterized.

OBJECTIVES

We examined potential determinants of PFAS from the Study of Women's Health Across the Nation (SWAN).

METHODS

This study includes 1302 women aged 45-56 years from 5 SWAN sites where white women and women from one minority group were recruited (black from Southeast Michigan, Pittsburgh, Boston; Chinese from Oakland; Japanese from Los Angeles). We determined concentrations of 11 PFAS in serum samples collected in 1999-2000 and examined 7 PFAS detected in most women (>97%). Linear regression with backward elimination was used to identify important determinants of PFAS serum concentrations among a set of pre-specified variables (age, body mass index, site, race/ethnicity, education, financial hardship, occupation, born outside the United States (US), parity, menstrual bleeding within the past year, smoking status, alcohol consumption, and consumption of fish, dairy, pizza, salty snack, and French fries).

RESULTS

Site and race/ethnicity were two major determinants of PFAS. White women had higher concentrations of linear perfluorooctanoic acid (PFOA) compared with the Chinese in Oakland (p < 0.0001) and blacks in Pittsburgh (p = 0.048). Black women in Southeast Michigan and Boston (vs. white women) had higher concentrations of linear (p < 0.001 for Southeast Michigan; p < 0.0001 for Boston) and total perfluorooctane sulfonic acid (PFOS) (p < 0.001 for both Southeast Michigan and Boston) and 2-(N-methyl-perfluorooctane sulfonamido) acetic acid (p = 0.02 for Southeast Michigan; p < 0.001 for Boston). Chinese (Oakland) and Japanese (Los Angeles) women had higher concentrations of perfluorononanoic acid (PFNA) compared with white women in each site (p < 0.01 for both). Within white women, those in Pittsburgh had relatively higher concentrations of PFAS. Within Chinese and Japanese women, those who were born outside the US had significantly lower concentrations of most PFAS but significantly higher PFNA concentrations. Menstrual bleeding and parity were significantly associated with lower PFAS concentrations. Higher intake of salty snacks including popcorn was significantly associated with higher concentrations of linear PFOA, PFOS and 2-(N-ethyl-perfluorooctane sulfonamido) acetic acid.

DISCUSSION

Geographic locations and race/ethnicity play an important role in differential exposure to PFAS, with racial/ethnic burdens differing between PFOS, PFOA and PFNA. Menstruation and parity were also determinants of PFAS concentrations possibly as an elimination route.

Association between illness representation and psychological distress in stroke patients: A systematic review and meta-analysis

AIMS

This paper aims to systematically review the illness perceptions of stroke patients and to examine the association between illness representation and psychological distress in empirical research studies.

BACKGROUND

Patients' perceptions of health threats determine their coping behavior. Several recent studies have focused on illness belief and distress in stroke patients. This information is suitable for a meta-analysis to further understand stroke patients' illness perceptions.

DESIGN

Systematic review and meta-analysis.

METHOD

An electronic literature search was conducted using the CINAHL, MEDLINE, PubMed, Cochrane library, and Google Scholar databases. Search strategies were title (stroke or cerebrovascular accident or CVA or cerebral vascular event or transient ischemic attack or TIA) and keyword (disease or illness) and keyword (perceptions or attitudes or opinion or experience or view or reflection or beliefs). The literature search covers the period of January 1990 to October 2018. Seven articles were included in the meta-analysis and Fisher's z was calculated with correlation coefficient or regression coefficient values for eight illness representation dimensions and psychological distress. All statistical analyses were performed using Comprehensive Meta-Analysis (CMA) version 3.0 software.

RESULTS

A total of 49 studies were reviewed, and seven studies with a total of 507 participants were eligible for the meta-analysis. For patients' perceived anxiety and depression, six of seven studies, with 285 to 461 participants, were examined in terms of the average corrected correlation coefficient across the studies. It was found that stroke patients' perception of a strong illness identity, timeline-acute/chronic, timeline-cyclical, consequences, and emotional responses were significantly and positively related to anxiety and depression. The pooled z-value ranged from 0.189 to 0.460. Conversely, for protective-related factors, such as stroke patients' perceived personal control, treatment control, and illness coherence, only perceived illness coherence was significantly negatively associated with depression (z-value, -0.122; 95% CI: -0.241, -0.002). For patients' perceived overall distress, three of seven studies with 173 participants showed that there were significant and positive associations between identity, consequence, emotions, and distress (z-value ranges = 0.493-0.711) as well as a significant and negative association between illness coherence and overall distress (z-value, -0.226; 95% CI: -0.379, -0.073).

CONCLUSION

An association between illness representation and distress exists in stroke patients. Risk factors are the most significant in terms of this relationship, and protective factors do not have a protective health impact. Protection factors need to be promoted to reduce patient distress.

Perfluorooctanoic Acid (PFOA) Exposure in Early Life Increases Risk of Childhood Adiposity: A Meta-Analysis of Prospective Cohort Studies

Some articles have examined perfluorooctanoic acid (PFOA) exposure in early life in relation to risk of childhood adiposity. Nevertheless, the results from epidemiological studies exploring the associations remain inconsistent and contradictory. We thus conducted an analysis of data currently available to examine the association between PFOA exposure in early life and risk of childhood adiposity. The PubMed, EMBASE, and Web of Science databases were searched to identify studies that examined the impact of PFOA exposure in early life on childhood adiposity. A random-effects meta-analysis model was used to pool the statistical estimates. We identified ten prospective cohort studies comprising 6076 participants with PFOA exposure. The overall effect size (relative risk or odds ratio) for childhood overweight was 1.25 (95% confidence interval (CI): 1.04, 1.50; I² = 40.5%). In addition, exposure to PFOA in early life increased the z-score of childhood body mass index (β = 0.10, 95% CI: 0.03, 0.17; I² = 27.9%). Accordingly, exposure to PFOA in early life is associated with an increased risk for childhood adiposity. Further research is needed to verify these findings and to shed light on the molecular mechanism of PFOA in adiposity.

Monthly Variations in Perfluorinated Compound Concentrations in Groundwater

Large-scale manufacturing of poly- and perfluorinated compounds in the second half of the 20th century has led to their ubiquity in the environment, and their unique structure has made them persistent contaminants. A recent drinking water advisory level issued by the United States Environmental Protection Agency lowered the advisory level concentration of perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) from 200 nanograms per liter and 400 nanograms per liter, respectively, to 70 nanograms per liter separately or combined. Small temporal variations in PFOS and PFOA concentrations could be the difference between meeting or exceeding the recommended limit. In this study, newly sampled data from a contaminated military site in Alaska and historical data from former Pease Air Force Base were collected. Data were evaluated to determine if monthly variations within PFOS and PFOA existed. No statistically significant temporal trend was observed in the Alaska data, while the results from Pease, although statistically significant, showed the spread of observed contaminant concentrations around the fitted line is broad (as indicated by the low R² values), indicating that collection date has little value in predicting contaminant concentrations. Though not currently the subject of a US EPA health advisory, data on perfluorobutanesulfonic acid (PFBS), perfluorohexane sulfonic acid (PFHxS), perfluoroheptanoic acid (PFHpA), and perfluorononanoic acid (PFNA) were collected for each site and their average concentrations evaluated.