Perfluoroalkyl Substances, Sex Hormones, and Insulin-like Growth Factor-1 at 6-9 Years of Age: A Cross-Sectional Analysis within the C8 Health Project

Identification and quantification of novel per- and polyfluoroalkyl substances (PFAS) contamination in a Great Lakes urban-dominated watershed

Per- and polyfluoroalkyl substances (PFAS) are a large group of synthetic organic fluoro-compounds that are oil-, water-, and flame-resistant, making them useful in a wide range of commercial and consumer products, as well as resistant to environmental degradation. To assess the impact of urbanization and wastewater treatment processes, surface water and sediment samples were collected at 27 sites within the Great Lakes in the Lake Huron to Lake Erie corridor (HEC), an international waterway including the highly urbanized Detroit and Rouge Rivers. Samples were analyzed for 92 PFAS via UHPLC-MS/MS. Our previous data in the HEC found the highest amount of PFAS contamination at the Rouge River mouth. In addition to evaluating the input of the Rouge River into the HEC, we evaluated the transport of PFAS into the HEC from other major tributaries. PFAS were detected in both surface water and sediment at all sites in this study, with a total of 10 congeners quantified in all surface water samples and 16 congeners quantified in all sediment samples, indicating ubiquitous contamination. Perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) were pervasive in the HEC as these two compounds were detected in all sites and matrices, often at concentrations above the US EPA's recommended lifetime interim updated health advisories. Surface water samples contained more perfluorohexanoic acid (PFHxA) than any other congener, with average aqueous PFHxA across all surface water samples exceeding the average concentration previously reported in the Great Lakes. Sediment samples were dominated by PFOS, but novel congeners, notably 3-Perfluoropentyl propanoic acid (FPePA), were also quantified in sediment. The Rouge River and other tributaries contribute significantly to the PFAS burden in the HEC including Lake Erie. Overall, our results indicate the need for expanding toxicological research and risk assessment focused on congeners such as PFHxA and PFAS mixtures, as well as regulation that is tighter at the onset of production and encompasses PFAS as a group at a national level.

Positive Associations of Perfluoroalkyl and Polyfluoroalkyl Substances With Hypertension May Be Attenuated by Endogenous Sex Hormones: A Nationally Representative Cross-Sectional Study

BACKGROUND

Perfluoroalkyl and polyfluoroalkyl substance (PFAS) has endocrine-disrupting properties and may affect blood pressure. Endogenous hormones also play a crucial role in the progression of hypertension. However, their interaction with hypertension remains to be explored.

METHODS

This study included 10 794 adults aged ≥18 years from the China National Human Biomonitoring program. Weighted multiple logistic regression and linear regression were used to examine the associations of serum PFAS with hypertension, diastolic blood pressure, and systolic blood pressure. Joint effects of PFAS mixtures on hypertension, diastolic blood pressure, and systolic blood pressure were evaluated using quantile-based g-computation. Additive and multiplicative interactions were used to assess the role of PFAS with testosterone and estradiol on hypertension.

RESULTS

The prevalence of hypertension in Chinese adults was 35.50%. Comparing the fourth quartile with the first quartile, odds ratio (95% CI) of hypertension were 1.53 (1.13-2.09) for perfluorononanoic acid, 1.40 (1.03-1.91) for perfluorodecanoic acid, 1.34 (1.02-1.78) for perfluoroheptane sulfonic acid, and 1.46 (1.07-1.99) for perfluorooctane sulfonic acid. Moreover, PFAS mixtures, with perfluorononanoic acid contributing the most, were positively associated with hypertension, diastolic blood pressure, and systolic blood pressure. PFAS and endogenous hormones had an antagonistic interaction in hypertension. For example, the relative excess risk ratio, attributable proportion, and synergy index for perfluorononanoic acid and estradiol were -3.61 (-4.68 to -2.53), -1.65 (-2.59 to -0.71), and 0.25 (0.13-0.47), respectively.

CONCLUSIONS

Perfluorononanoic acid, perfluorodecanoic acid, perfluoroheptane sulfonic acid, perfluorooctane sulfonic acid, and PFAS mixtures showed positive associations with hypertension, systolic blood pressure, and diastolic blood pressure. Positive associations of PFAS with hypertension might be attenuated by increased levels of endogenous sex hormones.

Developmental 6:2 FTCA exposure impairs renal development in chicken embryos via IGF signaling

6:2 fluorotelomer carboxylic acid (6:2 FTCA) is a perfluorooctanoic acid (PFOA) substitute, which is supposedly less accumulative and toxic than PFOA. However, 6:2 FTCA is structurally similar to PFOA, and there had already been reports about its toxicities comparable to PFOA. The aim of the current study is to assess potential effects of developmental exposure to 6:2 FTCA on the development of kidney in chicken embryo and to investigate underlying mechanism. Fertile chicken eggs were exposed to 1.25 mg/kg, 2.5 mg/kg or 5 mg/kg doses of 6:2 FTCA, or 2 mg/kg PFOA, then incubated to hatch. Serum and kidney of hatchling chickens were collected. Blood urea nitrogen (BUN) and creatinine (Cre) levels were measured with commercially available kits. Morphology of kidney was assessed with histopathology. To further reveal molecular mechanism of observed endpoints, IGF signaling molecules were assessed in the kidney samples with qRT-PCR, results indicated that IGFBP3 is a potentially crucial molecule. Lentiviruses overexpressing or silencing IGFBP3 were designed and applied to enhance/suppress the expression of IGFBP3 in developing chicken embryo for further verification of its role in the observed effects. Disrupted nephron formation, in the manifestation of decreased glomeruli number/area and increased serum BUN/Cre levels, was observed in the animals developmentally exposed to 6:2 FTCA. Correspondingly, IGF signaling molecules (IGF1, IGF1R and IGFBP3) were affected by 6:2 FTCA exposure. Meanwhile, overexpression of IGFBP3 effectively alleviated such changes, while silencing of IGFBP3 mimicked observed effects. In conclusion, developmental exposure to 6:2 FTCA is associated with disrupted chicken embryo renal development, in which IGFBP3 seems to be a remarkable contributor, suggesting potential health risks for human and other species. Further risk assessments and mechanistic works are necessary.

Effects of Per- and Polyfluoroalkylated Substances on Female Reproduction

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

Estimating effects of longitudinal and cumulative exposure to PFAS mixtures on early adolescent body composition

Few methods have been used to characterize repeatedly measured biomarkers of chemical mixtures. We applied latent profile analysis (LPA) to serum concentrations of 4 perfluoroalkyl and polyfluoroalkyl substances (PFAS) measured at 4 time points from gestation to age 12 years. We evaluated the relationships between profiles and z scores of height, body mass index, fat mass index, and lean body mass index at age 12 years (n = 218). We compared LPA findings with an alternative approach for cumulative PFAS mixtures using g-computation to estimate the effect of simultaneously increasing the area under the receiver operating characteristic curve (AUC) for all PFAS. We identified 2 profiles: a higher PFAS profile (35% of sample) and a lower PFAS profile (relative to each other), based on their average PFAS concentrations at all time points. The higher PFAS profile had generally lower z scores for all outcomes, with somewhat larger effects for males, though all 95% CIs crossed the null. For example, the higher PFAS profile was associated with a 0.50-unit lower (β = -0.50; 95% CI, -1.07 to 0.08) BMI z score among males but not among females (β = 0.04; 95% CI, -0.45 to 0.54). We observed similar patterns with AUCs. We found that a higher childhood PFAS profile and higher cumulative PFAS mixtures may be associated with altered growth in early adolescence. This article is part of a Special Collection on Environmental Epidemiology.

Individual and joint associations of per- and polyfluoroalkyl substances (PFAS) with gallstone disease in adults: A cross-sectional study

Disturbances in the enterohepatic circulation are important biological mechanisms for causing gallstones and also have important effects on the metabolism of Per- and polyfluoroalkyl substances (PFAS). Moreover, PFAS is associated with sex hormone disorder which is another important cause of gallstones. However, it remains unclear whether PFAS is associated with gallstones. In this study, we used logistic regression, restricted cubic spline (RCS), quantile g-computation (qg-comp), Bayesian kernel machine regression (BKMR), and subgroup analysis to assess the individual and joint associations of PFAS with gallstones and effect modifiers. We observed that the individual associations of perfluorodecanoic acid (PFDeA) (OR: 0.600, 95% CI: 0.444 to 0.811), perfluoroundecanoic acid (PFUA) (OR: 0.630, 95% CI: 0.453 to 0.877), n-perfluorooctane sulfonic acid (n-PFOS) (OR: 0.719, 95% CI: 0.571 to 0.906), and perfluoromethylheptane sulfonic acid isomers (Sm-PFOS) (OR: 0.768, 95% CI: 0.602 to 0.981) with gallstones were linearly negative. Qg-comp showed that the PFAS mixture (OR: 0.777, 95% CI: 0.514 to 1.175) was negatively associated with gallstones, but the difference was not statistically significant, and PFDeA had the highest negative association. Moreover, smoking modified the association of perfluorononanoic acid (PFNA) with gallstones. BKMR showed that PFDeA, PFNA, and PFUA had the highest groupPIP (groupPIP = 0.93); PFDeA (condPIP = 0.82), n-perfluorooctanoic acid (n-PFOA) (condPIP = 0.68), and n-PFOS (condPIP = 0.56) also had high condPIPs. Compared with the median level, the joint association of the PFAS mixture with gallstones showed a negative trend; when the PFAS mixture level was at the 70th percentile or higher, they were negatively associated with gallstones. Meanwhile, when other PFAS were fixed at the 25th, 50th, and 75th percentiles, PFDeA had negative associations with gallstones. Our evidence emphasizes that PFAS is negatively associated with gallstones, and more studies are needed in the future to definite the associations of PFAS with gallstones and explore the underlying biological mechanisms.

Comparative steroidogenic effects of hexafluoropropylene oxide trimer acid (HFPO-TA) and perfluorooctanoic acid (PFOA): Regulation of histone modifications

As a widely used alternative to perfluorooctanoic acid (PFOA), hexafluoropropylene oxide trimer acid (HFPO-TA) has been detected in the environment and humans; however, little is known regarding its male reproductive toxicity. To compare the effects of HFPO-TA on steroid hormone synthesis with PFOA, we exposed Leydig cells (MLTC-1) to non-lethal doses (0.1, 1, and 10 μM) of PFOA and HFPO-TA for 48 h. It was found that the levels of steroid hormones, 17α-hydroxyprogesterone (OHP), androstenedione (ASD), and testosterone (T) were significantly increased in 1 and 10 μM of PFOA and HFPO-TA groups, with greater elevation being observed in the HFPO-TA groups than in the PFOA groups at 10 μM. We further showed that the two rate-limiting steroidogenic genes (Star and Cyp11a1) were up-regulated, while Hsd3b, Cyp17a1, and Hsd17b were down-regulated or unchanged after PFOA/HFPO-TA exposure. Moreover, PFOA exposure significantly up-regulated histone H3K4me1/3 and H3K9me1, while down-regulated H3K4me2 and H3K9me2/3 levels. By contrast, H3K4me2/3 and H3K9me2/3 were enhanced, while H3K4me1 and H3K9me1 were repressed after HFPO-TA treatment. It was further confirmed that H3K4me1/3 were increased and H3K9me2 was decreased in Star and Cyp11a1 promoters by PFOA, while HFPO-TA increased H3K4me2/3 and decreased H3K9me1 in the two gene promoters. Therefore, we propose that low levels of PFOA/HFPO-TA enhance the expression of Star and Cyp11a1 by regulating H3K4 and H3K9 methylation, thus stimulating the production of steroid hormones in MLTC-1 cells. Collectively, HFPO-TA exhibits stronger effects on steroidogenesis compared to PFOA, which may be ascribed to the distinct regulation of histone modifications. These data suggest that HFPO-TA does not appear to be a safer alternative to PFOA on the aspect of male reproductive toxicity.

Association between per- and polyfluoroalkyl substances and sex hormone levels in males based on human studies

BACKGROUND

Per- and poly-fluoroalkyl substances (PFAS) are ubiquitous chemicals in the environment and our daily lives. Several epidemiological studies have revealed that PFAS exposure is linked to male sex hormone levels; however, the conclusions are inconsistent across studies. Consequently, we performed a meta-analysis to systematically evaluate the association between PFAS exposure and male sex hormones.

METHODS

The Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) standards were followed during the meta-analysis. PubMed, Wed of Science, Embase, Cochrane Library, and Ovid databases were used to identify suitable articles before June 2023. The 95% CI and β values were calculated to assess the association between male sex hormone levels and PFAS exposure. Heterogeneity among the included studies was tested using inconsistency statistics (I2).

RESULTS

The literature search identified 12 published articles that met our search criteria, involving 7506 participants. Our results revealed that perfluorononanoic acid (PFNA) and perfluorooctanoic acid (PFOA) exposures were negatively correlated with testosterone (β = -0.05; 95% CI: -0.09, -0.02, P = 0.003) and (β = -0.04; 95% CI: -0.08, 0.00, P = 0.049), respectively.

CONCLUSION

Exposure to PFNA and PFOA is negatively correlated with changes in male testosterone levels. This correlation suggests that we need to pay attention in the future to whether they are potential risk factors for male reproductive health.

Evaluating the association between longitudinal exposure to a PFAS mixture and adolescent cardiometabolic risk in the HOME Study

Background

Exposure to per- and polyfluoroalkyl substances (PFAS) throughout gestation and childhood may impact cardiometabolic risk.

Methods

In 179 HOME Study participants (Cincinnati, OH; recruited 2003-2006), we used latent profile analysis to identify two distinct patterns of PFAS exposure from serum concentrations of four PFAS measured at birth and ages 3, 8, and 12 years. We assessed the homeostatic model of insulin resistance, triglycerides-to-high-density lipoprotein cholesterol ratio, leptin-to-adiponectin ratio, systolic blood pressure, visceral fat, and hemoglobin A1c levels at age 12 years. We used multivariable linear regression to assess the association of membership in the longitudinal PFAS mixture exposure group with a summary measure of overall cardiometabolic risk and individual components.

Results

One PFAS exposure profile (n = 66, 39%) had higher geometric means of all PFAS across all visits than the other. Although adjusted associations were null in the full sample, child sex modified the association of longitudinal PFAS mixture exposure group with overall cardiometabolic risk, leptin-to-adiponectin ratio, systolic blood pressure, and visceral fat (interaction term P values: 0.02-0.08). Females in the higher exposure group had higher cardiometabolic risk scores (ß = 0.43; 95% CI = -0.08, 0.94), systolic blood pressures (ß = 0.6; 95% CI = 0.1, 1.1), and visceral fat (ß = 0.44; 95% CI = -0.13, 1.01); males had lower cardiometabolic risk scores (ß = -0.52; 95% CI = -1.06, -0.06), leptin-to-adiponectin ratios (ß = -0.7; 95% CI = -1.29, -0.1), systolic blood pressures (ß = -0.14; 95% CI = -0.7, 0.41), and visceral fat (ß = -0.52; 95% CI = -0.84, -0.19).

Conclusions

Exposure to this PFAS mixture throughout childhood may have sex-specific effects on adolescent cardiometabolic risk.

Early menarche and other endocrine disrupting effects of per- and polyfluoroalkyl substances (PFAS) in adolescents from Northern Norway. The Fit Futures study

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) comprise a large group of chemicals that are ubiquitous in the environment and include recognized persistent organic pollutants. The aim of this cross-sectional study was to investigate possible endocrine disrupting effects of different PFAS in adolescents.

METHODS

Serum concentrations of PFAS, thyroid, parathyroid and steroid hormones were measured in 921 adolescents aged 15-19 years in the Fit Futures study, Northern Norway. The questionnaire included data on self-reported age at menarche and puberty development score (PDS). Multiple linear and logistic regression analyses and principle component analyses (PCA) were used to assess associations of PFAS with hormones concentrations and puberty indices.

RESULTS

In girls, total PFAS (∑PFAS), perfluorooctanoate (PFOA), perfluorooctane sulfonate (PFOS), perfluorononanoate (PFNA), perfluorodecanoate (PFDA) were positively associated with dehydroepiandrosterone sulfate (DHEAS) and negatively associated with 11-deoxycorticosterone (11-DOC)/DHEAS ratio. In boys, the associations with 11-DOC/DHEAS ratio were positive for ∑PFAS, perfluoroheptanoate (PFHpA), perfluoroheptane sulfonate (PFHpS), PFOA, and PFOS. Perfluoroundecanoate (PFUnDA) was negatively associated with free thyroxine (fT4) and free triiodothyronine (fT3) in boys. PFNA and PFDA were also negatively associated with fT3 in boys. Serum parathyroid hormone concentration (PTH) was negatively associated with ∑PFAS and perfluorohexane sulfonate (PFHxS) in girls, and with PFOS in boys. PFDA and PFUnDA were positively associated with early menarche, while ∑PFAS and PFOA were positively associated with PDS in boys. No associations of PFAS with serum testosterone, follicle-stimulating hormone, or luteinizing hormone were found in either sex. In girls, PFOA was positively associated with free testosterone index (FTI). In boys, PFOA was positively associated with androstendione and 17-OH-progesterone, while PFHpA was positively associated with estradiol.

CONCLUSIONS

Serum concentrations of several PFAS were associated with parathyroid and steroid hormones in both sexes, and with thyroid hormones in boys, as well as with early menarche in girls and higher PDS in boys.

Association of prenatal exposure to perfluorinated and polyfluoroalkyl substances with childhood neurodevelopment: A systematic review and meta-analysis

BACKGROUND

Although previous studies have shown an association between prenatal exposure to perfluorinated and polyfluoroalkyl substances (PFAS) and neurodevelopmental disorders in children, the results have been inconsistent. We summarize studies on the association between prenatal PFAS exposure and neurodevelopment in children in order to better understand the relationship.

OBJECTIVE

We conducted a meta-analysis of prenatal PFAS exposure and developmental outcomes associated with intellectual, executive function and behavioral difficulty in children to explore the relationship between prenatal exposure to perfluorinated and polyfluoroalkyl substances (PFAS) and neurodevelopmental disorders in children.

METHODS

We searched for articles published up to August 3, 2023, included and quantified original studies on PFAS and child Intelligence Quotient (IQ), executive function and behavioral difficulty during pregnancy, and systematically summarized articles that could not be quantified.

CONCLUSION

There is evidence of sex-specific relationship between PFAS exposure and children's PIQ. We found that PFOS [β = -1.56, 95% CI = -2.96, - 0.07; exposure = per 1 ln (ng/ml) increase], PFOA [β = -1.87, 95% CI = -3.29, - 0.46; exposure = per 1 ln (ng/ml) increase], PFHxS [β = -2.02, 95% CI = -3.23, - 0.81; exposure = per 1 ln (ng/ml) increase] decreased performance IQ in boys, but PFOS [β = 1.56, 95% CI = 0.06, 3.06; exposure = per 1 ln (ng/ml) increase] increased performance IQ in girls. PFAS are associated with executive function impairments in children, but not related to behavioral difficulty in children.

Association between exposure to per- and perfluoroalkyl substances (PFAS) and reproductive hormones in human: A systematic review and meta-analysis

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) is persistent endocrine disrupting chemicals. Previous evidence suggests that exposure to PFAS is associated with reproductive hormone levels, but the results of relevant studies are inconsistent. The objective of our study is to determine the association between exposure to PFAS and reproductive hormone levels in gender-specific general population.

METHOD

Based on scientific search strategies, we systematically searched PubMed, Web of Science, Embase, Medline, and Scopus to obtain the eligible studies published before January 21, 2023. The quality of the included articles was assessed using the Office of Health Assessment and Translation (OHAT) Risk of Bias tool. We combined the β coefficient and 95% confidence intervals (CI) using Stata.17 with random-effect model or fixed-effect model. We also performed subgroup analysis, sensitivity analysis, and Begger's and Egger's tests.

RESULTS

Eleven studies involving 7714 participants were included. Meta-analysis showed that PFHxS exposure was positively associated with estradiol (E2) levels in female [β = 0.030, 95% CI: (0.013, 0.046), P = 0.000]. A negative association was found between PFOA [β = -0.012, 95% CI: (-0.023, -0.002), P = 0.017] and PFOS [β = -0.011; 95% CI: (-0.021, -0.000), P = 0.042] exposure with male testosterone (TT) levels. In the subgroup analysis, there were stronger associations in children than in adults. And the high heterogeneity was mainly due to the cross-sectional studies. Publication bias was not found in most of the analyses.

CONCLUSION

Our study showed that PFAS exposure was significantly associated with reproductive hormone levels. Further related studies are needed to identify the association and potential mechanism in the future.

Associations of Prenatal Per- and Polyfluoroalkyl Substance (PFAS) Exposures with Offspring Adiposity and Body Composition at 16-20 Years of Age: Project Viva

BACKGROUND

Findings on the associations between prenatal PFAS exposures and offspring adiposity are inconsistent. Whether such associations may extend to adolescence is especially understudied.

OBJECTIVES

We investigated associations of prenatal PFAS exposures with offspring adiposity and body composition at 16-20 years of age.

METHODS

We studied 545 mother-child pairs in the prospective prebirth cohort Project Viva (Boston, Massachusetts). We measured six PFAS (PFOA, PFOS, PFNA, PFHxS, EtFOSAA, and MeFOSAA) in maternal early pregnancy (median age = 9.6 wk , range: 5.7-19.6 wk) plasma samples. At the late adolescence visit (median age = 17.4 y, range: 15.9-20.0 y), we obtained anthropometric measures and assessed body composition using bioelectrical impedance analysis and dual-energy X-ray absorptiometry. We examined associations of individual PFAS with obesity [i.e., age- and sex-specific body mass index (BMI) ≥ 95 th percentile] and adiposity and body composition using multivariable Poisson and linear regression models, respectively. We assessed PFAS mixture effects using Bayesian kernel machine regression (BKMR) and quantile g-computation. We used fractional-polynomial models to assess BMI trajectories (at 3-20 years of age) by prenatal PFAS levels.

RESULTS

Thirteen percent (n = 73 ) of the children had obesity in late adolescence. After multivariable adjustment, higher prenatal PFAS concentrations were associated with higher obesity risk [e.g., 1.59 (95% CI: 1.19, 2.12), 1.24 (95% CI: 0.98, 1.57), and 1.49 (95% CI: 1.11, 1.99) times the obesity risk per doubling of PFOS, PFOA, and PFNA, respectively]. BKMR showed an interaction between PFOA and PFOS, where the positive association between PFOS and obesity was stronger when PFOA levels were lower. Each quartile increment of the PFAS mixture was associated with 1.52 (95% CI: 1.03, 2.25) times the obesity risk and 0.52 (95% CI: - 0.02 , 1.06) kg / m 2 higher BMI. Children with higher prenatal PFOS, EtFOSAA, and MeFOSAA concentrations had higher rates of BMI increase starting from 9-11 years of age.

DISCUSSION

Prenatal PFAS exposures may have obesogenic effects into late adolescence. https://doi.org/10.1289/EHP12597.

Association of exposure to perfluoroalkyl substances (PFAS) and phthalates with thyroid hormones in adolescents from HBM4EU aligned studies

BACKGROUND

Perfluoroalkyl substances (PFAS) and phthalates are synthetic chemicals widely used in various types of consumer products. There is epidemiological and experimental evidence that PFAS and phthalates may alter thyroid hormone levels; however, studies in children and adolescents are limited.

AIM

To investigate the association of exposure to PFAS and phthalate with serum levels of thyroid hormones in European adolescents.

METHODS

A cross-sectional study was conducted in 406 female and 327 male adolescents (14-17 years) from Belgium, Slovakia, and Spain participating in the Aligned Studies of the HBM4EU Project (FLEHS IV, PCB cohort, and BEA, respectively). Concentrations of perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS), perfluorononanoic acid (PFNA), free thyroxine (FT4), free triiodothyronine (FT3), and thyroid-stimulating hormone (TSH) were measured in sera from study participants, and urinary metabolites of six phthalates (DEP, DiBP, DnBP, BBzP, DEHP, and DiNP) and the non-phthalate plasticizer DINCH® were quantified in spot urine samples. Associations were assessed with linear regression and g-computational models for mixtures. Effect modification by sex was examined.

RESULTS

In females, serum PFOA and the PFAS mixture concentrations were associated with lower FT4 and higher FT3 levels; MEP and the sums of DEHP, DiNP, and DINCH® metabolites (∑DEHP, ∑DiNP, and ∑DINCH) were associated with higher FT4; ∑DEHP with lower FT3; and the phthalate/DINCH® metabolite mixture with higher FT4 and lower FT3. In males, PFOA was associated with lower FT4 and the PFAS mixture with higher TSH levels and lower FT4/TSH ratio; MEP and ∑DiNP were associated with higher FT4; and MBzP, ∑DEHP, and the phthalate/DINCH® metabolite mixture with lower TSH and higher FT4/TSH. PFOA, mono-(2-ethyl-5-hydroxyhexyl) phthalate (OH-MEHP), mono-(2-ethyl-5-oxohexyl) phthalate (oxo-MEHP), and monocarboxyoctyl phthalate (MCOP) made the greatest contribution to the mixture effect.

CONCLUSIONS

Results suggest that exposure to PFAS and phthalates is associated with sex-specific differences in thyroid hormone levels in adolescents.

Plasma levels of per- and polyfluoroalkyl substances (PFAS) and cardiovascular disease - Results from two independent population-based cohorts and a meta-analysis

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) are persistent chemicals that have been linked to increased cholesterol levels and thus may have a role in the development of cardiovascular disease (CVD).

OBJECTIVES

To investigate associations between PFAS exposure and incident CVD (a combined CVD end-point consisting of myocardial infarction, ischemic stroke, or heart failure) in two independent population-based cohorts in Sweden. In addition, we performed a meta-analysis also including results from previous studies.

METHODS

In 2,278 subjects aged 45-75 years from the EpiHealth study, the risk of incident CVD in relation to relative plasma levels of perfluorohexanesulfonic acid (PFHxS), perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) was investigated. Associations between plasma levels of six PFAS and incident CVD were also examined in the PIVUS-study (n = 1,016, all aged 70 years). In addition, a meta-analysis was performed including three previous prospective studies, together with the results from the present study.

RESULTS

There were no overall statistically significant associations between levels of the different PFAS and incident CVD, neither in EpiHealth nor in PIVUS. However, there was a significant sex interaction for PFOS in EpiHealth (p = 0.008), and an inverse association could be seen only in men (Men, HR: 0.68, 95 % CI: 0.52, 0.89) (Women, HR: 1.13, 95 % CI: 0.82, 1.55). A meta-analysis of five independent studies regarding PFOA and incident CVD showed a risk ratio (RR) of 0.80 (CI: 0.66, 0.94) when high levels were compared to low levels.

CONCLUSIONS

This longitudinal study using data from two population-based cohort studies in Sweden did not indicate any increased risk of incident CVD for moderately elevated PFAS levels. A meta-analysis of five independent cohort studies rather indicated a modest inverse association between PFOA levels and incident CVD, further supporting that increasing PFAS levels are not linked to an increased risk of CVD.

Perfluoroalkyl substances in umbilical cord blood and blood pressure in offspring: a prospective cohort study

BACKGROUND

Humans are widely exposed to perfluoroalkyl substances (PFAS), which have been found to be associated with various adverse birth outcomes. As blood pressure (BP) is an important parameter reflecting cardiovascular health in early life, it is necessary to investigate the association of PFAS exposure during early lifetime and BP in childhood. Therefore, we investigated the potential association between PFAS levels in umbilical cord blood and BP of the offspring at 4 years of age in a prospective cohort study.

METHODS

PFAS in umbilical cord blood samples after birth were measured with high-performance liquid chromatography/tandem mass spectrometry in the Shanghai Birth Cohort. BP was measured at 4 years of age in the offspring. Multiple linear regression model was used to investigate the association between individual PFAS level and BP of the offspring. Bayesian kernel machine regression (BKMR) was used to analyze the relationship between the PFAS mixture and BP of the offspring, while weighted quantile sum (WQS) regression was utilized for sensitivity analysis.

RESULTS

A total of 129 mother-child pairs were included in our analysis. In multiple linear regressions, we observed that long-chain PFAS, mainly including perfluorooctane sulfonate (PFOS), perfluorodecanoic acid (PFDA) and perfluoroundecanoic acid (PFUA), was negatively associated with systolic blood pressure (SBP), diastolic blood pressure (DBP) and mean arterial blood pressure (MAP). BKMR showed that an increase in umbilical cord blood PFAS mixture levels was significantly associated with a decrease in SBP, DBP and MAP [Estimated differences (SD): -0.433 (0.161); -0.437 (0.176); -0.382 (0.179), respectively]. The most important component in the association with SBP, DBP, and MAP was PFUA. PFDoA was found to be positively associated with SBP, DBP and MAP in both models. Sensitivity analysis with WQS regression showed consistent results.

CONCLUSION

Our findings suggested that umbilical blood PFAS exposure was negatively associated with BP in offspring at 4 years of age, including SBP, DBP, and MAP.

Associations of prenatal and postnatal exposure to perfluoroalkyl substances with pubertal development and reproductive hormones in females and males: The HOME study

BACKGROUND

Prenatal and childhood exposure to per- and polyfluoroalkyl substances (PFAS) may be associated with lower reproductive hormones and later puberty, but epidemiological studies evaluating these associations are scarce.

OBJECTIVES

We examined associations of PFAS concentrations assessed from pregnancy to adolescence with pubertal development and reproductive hormones at age 12 years.

METHODS

We studied 200 mother-child pairs from the HOME Study in Cincinnati, OH (enrolled: 2003-2006). We quantified serum concentrations of perfluorooctanoate (PFOA), perfluorooctane sulfonate (PFOS), perfluorononanoate (PFNA), and perfluorohexane sulfonate (PFHxS) in pregnant women and their children at age 3, 8 and 12 years. At age 12 years, children self-assessed pubertal development using Tanner staging of pubic hair growth (males and females) and breast growth (females), and age at menarche. We quantified serum concentrations of dehydroepiandrosterone sulfate, luteinizing hormone, and follicle-stimulating hormone in both sexes; estradiol in females; testosterone in males. We estimated associations of PFAS with pubertal outcomes and reproductive hormones using a combination of ordinal regression, Cox proportional-hazard regression, and linear regression. Quantile-based g-computation was used for PFAS mixture.

RESULTS

In females, adolescent PFAS concentrations and their mixture were associated with later pubic hair growth, breast maturation, and age at menarche, but there was no pattern for prenatal or other postnatal concentrations. For instance, in females, each doubling in adolescent PFAS concentrations was associated with 79 % (PFOA), 63 % (PFOS), 56 % (PFNA), and 47 % (PFHxS) lower odds of attaining a higher stage for breast growth. In addition, adolescent PFAS concentrations were consistently associated with lower estradiol concentrations in females. No pattern was observed for associations of PFAS concentrations with pubic hair growth or reproductive hormones in males.

CONCLUSIONS

We observed associations between PFAS concentrations in adolescence and later pubertal development in females, but this could be due to reverse causation induced by excretion of PFAS through menstrual fluid.

Associations between per- and polyfluoroalkyl substances (PFAS) and diabetes in two population-based cohort studies from Sweden

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) have been suggested to contribute to the development of metabolic diseases such as obesity, diabetes and non-alcoholic fatty liver disease (NAFLD). However, evidence from epidemiological studies remain divergent. The aim of the present study was to evaluate associations between PFAS exposure and prevalent diabetes in a cross-sectional analysis and fasting glucose in a longitudinal analysis.

METHODS

In 2373 subjects aged 45-75 years from the EpiHealth study, three PFAS; perfluorohexanesulfonic acid (PFHxS), perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) were analyzed in plasma together with information on prevalent diabetes. Participants in the PIVUS study (n = 1016 at baseline, all aged 70 years) were followed over 10 years regarding changes in plasma levels of six PFAS; PFHxS, PFOA, PFOS, perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), and perfluoroundecanoic acid (PFUnDA), and changes in plasma levels of fasting glucose.

RESULTS

In the EpiHealth study, no overall associations could be observed between the levels of PFOA, PFOS or PFHxS and prevalent diabetes. However, there was a significant sex-interaction for PFOA (p = 0.02), and an inverse association could be seen between PFOA (on a SD-scale) and prevalent diabetes in women only (OR: 0.71, 95% CI: 0.52, 0.96, p-value: 0.02). This association showed a non-monotonic dose-response curve. In the PIVUS study, inverse relationships could be observed between the changes in levels (ln-transformed) of PFOA and PFUnDA vs the change in fasting glucose levels (ln-transformed) over 10 years (p = 0.04 and p = 0.02, respectively). As in EpiHealth, these inverse associations were significant only in women (PFOA: β: -0.03, p = 0.02, PFUnDA: β: -0.03, p = 0.03).

IMPACT

Exposure to per- and polyfluoroalkyl substances (PFAS) has been linked to unfavorable human health, including metabolic disorders such as obesity, diabetes and non-alcoholic fatty liver disease. However, results from in vivo, in vitro and epidemiological studies are incoherent. The aim of the present study was therefore to investigate associations between PFAS and diabetes in a cross-sectional study and glucose levels in a longitudinal study. Results show inverse associations in women only. Results also display non-monotonic dose response curves (i.e., that only low levels of PFOA are related to higher probability of prevalent diabetes). This suggests that sex differences and complex molecular mechanisms may underlie the observed findings. A better understanding of the factors and molecular mechanisms contributing to such differences is recognized as an important direction for future research.

CONCLUSIONS

PFOA was found to be inversely related to both prevalent diabetes and changes in plasma glucose levels among women only. Thus, our findings suggest there are sex differences in the inverse relationship of PFOA and type 2 diabetes and glucose levels.

Exposure to Perfluoroalkyl Substances and Associations with Pubertal Onset and Serum Reproductive Hormones in a Longitudinal Study of Young Girls in Greater Cincinnati and the San Francisco Bay Area

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS), endocrine disrupting chemicals with worldwide exposure, cause changes in mammary gland development in rodents. A few human studies report delay in pubertal events with increasing perfluorooctanoic acid (PFOA) exposure, but to our knowledge none have examined reproductive hormone levels at thelarche.

METHODS

In a cohort of Greater Cincinnati (GC) and San Francisco Bay Area (SFBA) girls recruited at 6-8 years of age, clinical examinations were conducted annually or semiannually with sequential Tanner staging. PFAS concentrations were measured in the first serum sample of 704 girls. In 304 GC girls, estradiol (E 2 ), estrone (E 1 ), testosterone (T), and dihydroepiandrosterone sulfate (DHEAS) were measured in serum at four time points around puberty. Relationships between PFAS and age at thelarche, pubarche, and menarche were analyzed using survival and structural equation models. The association between PFAS and reproductive hormones was assessed using linear regression models.

RESULTS

Median PFOA serum concentrations in GC (N = 353 , 7.3  ng / mL ) and the SFBA (N = 351 , 5.8  ng / mL ) were higher than in the U.S.

POPULATION

In multivariable Cox proportional hazard models [adjusted for race, body mass index (BMI)], increasing serum log-transformed PFOA was associated with a delay in pubarche [hazard ratio  ( HR ) = 0.83 ; 95% CI: 0.70, 0.99] and menarche (HR = 0.04 ; 95% CI: 0.01, 0.25). Structural equation models indicated a triangular relationship between PFOA, BMI percentile, and the age at the pubertal milestone. Increased PFOA had a statistically significant direct effect of delay on all three milestones, as did BMI. Perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDeA), and 2-(N -methyl-perfluorooctane sulfonamido) acetic acid (Me-PFOSA-AcOH) also were associated with later thelarche, and Me-PFOSA-AcOH also with later pubarche. PFOA was inversely associated with DHEAS (p < 0.01 ), E 1 (p = 0.04 ), and T (p = 0.03 ) concentrations at 6 months prior to puberty.

CONCLUSIONS

PFAS may delay pubertal onset through the intervening effects on BMI and reproductive hormones. The decreases in DHEAS and E 1 associated with PFOA represent biological biomarkers of effect consistent with the delay in onset of puberty. https://doi.org/10.1289/EHP11811.

Association of perfluoroalkyl and polyfluoroalkyl substances with sex hormones in children and adolescents 6-19 Years of age

Perfluoroalkyl and polyfluoroalkyl substances (PFAS) have raised concerns regarding sex hormones homeostasis disruption in critical windows including childhood and adolescence, but epidemiological evidence is limited. We aimed to explore the associations of total testosterone (TT), estradiol (E₂), and sex hormone binding globulin (SHBG) in children and adolescents with PFAS in 921 participants 6-19 years of age from NHANES 2013 to 2016. Multiple linear regression models and Bayesian Kernel Machine Regression (BKMR) models stratified by sex-age and sex-puberty-status groups were performed to explore the associations of the associations of individual or mixture of PFAS with sex hormone levels, respectively. Inverse associations were observed between n-PFOA and SHBG in female adolescents when the exposure was modeled as continuous (β = -0.20, 95% CI -0.33, -0.07) or categorized variable (P for trend = 0.005). In children, inverse associations were observed by BKMR in 6-11-year-old girls of high concentration, and in boys of low concentration of the PFAS mixture with TT. A positive association of PFAS mixture with SHBG was observed in boys. PFOS and PFNA were identified as major contributors to the associations in girls and boys, respectively. Although the 95% credible intervals included the null in adolescents, suggestive negative associations of PFAS mixture with TT and SHBG levels in adolescents aged 12-19 years were found by BKMR. Results by sex-puberty status presented a similar pattern, where significantly inverse associations between PFAS mixture and E₂ were observed in the pubertal. Our findings suggested the associations of either individual or mixture PFAS with decreased TT levels, and increased SHBG levels in U.S. children and adolescents, and with decreased E₂ levels in pubertal individuals. The associations were evident in children.

Association between early-childhood exposure to perfluoroalkyl substances and ADHD symptoms: A prospective cohort study

There is evidence that exposure to perfluoroalkyl substances (PFAS) is associated with attention-deficit/hyperactivity disorder (ADHD) symptoms. Previous studies have focused on prenatal exposure to PFAS, and only few studies have examined the associations of early-childhood exposure, especially at low exposure levels. This study explored the association between early-childhood exposure to PFAS and ADHD symptoms later in childhood. In 521 children, we measured the serum levels of six PFAS in peripheral blood at the ages of 2 and 4 years, including perfluorooctanoate (PFOA), perfluornonanoicacid (PFNA), perfluorodecanoic acid (PFDA), perfluoroundecanoic acid (PFUnDA), perfluorohexane sulfonic acid (PFHxS), and perfluorooctane sulfonate (PFOS). The ADHD Rating Scale IV (ARS) was utilized to measure ADHD traits at 8 years of age. We explored the relationship between PFAS and ARS scores using Poisson regression models after adjusting for potential confounders. Levels of exposure to individual PFAS and the summed value were divided into quartiles to examine possible nonlinear relationships. All six PFAS exhibited inverted U-shaped curves. Children in the 2nd and 3rd quartile levels of each PFAS showed higher ARS scores than those in the1^st quartile level. Below the 3rd quartile of the summed levels of six PFAS (ΣPFAS), a doubling of the ΣPFAS was associated with an 20.0 % (95 % CI: 9.5 %, 31.5 %) increase in ADHD scores. However, at the age of 4 years, none of the evaluated PFAS exhibited linear or nonlinear associations with the ARS scores. Thus, school-aged children may be vulnerable to the neurotoxic effects of exposure to PFAS at age 2 that contribute to ADHD, particularly at low to mid-levels.

Association between Serum Per- and Polyfluoroalkyl Substance Levels and Risk of Central and Peripheral Precocious Puberty in Girls

Concerns about the endocrine-disrupting effects of per- and polyfluoroalkyl substances (PFASs) have raised questions about their potential influence on precocious puberty in girls, which is an emerging concern in some populations. However, epidemiological evidence is lacking. In this study, 882 serum samples were collected from girls with central precocious puberty (CPP, n = 226), peripheral precocious puberty (PPP, n = 316), and healthy controls (n = 340) in 2021 in Shanghai, China. The serum levels of 25 legacy and emerging PFASs and 17 steroids were measured. Results showed that PFAS exposure was positively associated with estradiol levels. Eleven PFASs were significantly or marginally associated with the higher odds of the overall precocious puberty. Across subtypes, PFASs were more clearly associated with PPP, while the associations with CPP were consistent in direction but did not reach statistical significance. These findings were consistent with the assessment of PFAS mixtures using quantile-based g-computation (qgcomp) and Bayesian kernel machine regression, with perfluorobutane sulfonate and 6:2 polyfluorinated ether sulfonate showing the highest contribution to joint effects. Although changes in serum estradiol could arise from various factors, our results suggest that the PFAS exposure may contribute to the increase in estradiol secretion, thereby increasing the risk of precocious puberty, especially PPP. The potential effects of PFASs on precocious puberty warrant further investigation, given the associated complications of public health concern, including psychological distress and increased risk of multiple diseases.

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

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

Associations between exposure to a mixture of perfluoroalkyl and polyfluoroalkyl substances and age at menarche in adolescent girls utilizing three statistical models

Exposure to perfluoroalkyl and polyfluoroalkyl substances (PFAS) is suggested to interfere with endocrine function and may affect female pubertal development. However, the epidemiological evidence on age at menarche associated with PFAS exposure is still inconsistent. Our objective was to investigate association of serum PFAS concentrations with age at menarche among 12-19 years old girls. We used data on 432 girls from National Health and Nutrition Examination Survey (NHANES) 2007-2012 cycles. NHANES reported serum concentrations of perfluorooctanoic acid (PFOA), perfluorooctanesulfonic acid (PFOS), perfluorohexane sulfonate (PFHxS), perfluorononanoic acid (PFNA) and perfluorodecanoic acid (PFDA) as quantified by liquid chromatography tandem mass spectrometry (LC-MS/MS). Age at menarche was self-reported by girls or their guardians. Multivariable linear regression models were applied to estimate the association of individual PFAS exposure with age at menarche. The combined effects of PFAS mixture exposures on age at menarche were assessed using three statistical methods, including Bayesian kernel machine regression (BKMR), weighted quantile sum regression (WQS), and elastic net regression (ENR). In the single-chemical model, girls in the middle tertile of serum PFOA concentration had a lower age at menarche [regression coefficient (β) = -0.73 years, 95% confidence interval (CI): 1.44, -0.01; P = 0.047], compared with those in the lower tertile. Girls in the higher tertile of PFNA exposure were associated with older age at menarche (β = 0.36 years, 95% CI: 0.03, 0.80; P = 0.027), compared with those in the lower tertile. In the multiple-chemical models using BKMR and ENR approaches, higher PFNA exposure was significantly associated with older age at menarche among girls, after adjusting for other PFAS. We found suggestive evidence that higher PFAS mixture exposures may be related to an increase in age at menarche using the BKMR model. In conclusion, exposure to PFNA was associated with the later timing of menarche among girls.

PFASs: What can we learn from the European Human Biomonitoring Initiative HBM4EU

Per- and polyfluoroalkyl substances (PFASs) were one of the priority substance groups selected which have been investigated under the ambitious European Joint programme HBM4EU (2017-2022). In order to answer policy relevant questions concerning exposure and health effects of PFASs in Europe several activities were developed under HBM4EU namely i) synthesis of HBM data generated in Europe prior to HBM4EU by developing new platforms, ii) development of a Quality Assurance/Quality Control Program covering 12 biomarkers of PFASs, iii) aligned and harmonized human biomonitoring studies of PFASs. In addition, some cohort studies (on mother-child exposure, occupational exposure to hexavalent chromium) were initiated, and literature researches on risk assessment of mixtures of PFAS, health effects and effect biomarkers were performed. The HBM4EU Aligned Studies have generated internal exposure reference levels for 12 PFASs in 1957 European teenagers aged 12-18 years. The results showed that serum levels of 14.3% of the teenagers exceeded 6.9 μg/L PFASs, which corresponds to the EFSA guideline value for a tolerable weekly intake (TWI) of 4.4 ng/kg for some of the investigated PFASs (PFOA, PFOS, PFNA and PFHxS). In Northern and Western Europe, 24% of teenagers exceeded this level. The most relevant sources of exposure identified were drinking water and some foods (fish, eggs, offal and locally produced foods). HBM4EU occupational studies also revealed very high levels of PFASs exposure in workers (P95: 192 μg/L in chrome plating facilities), highlighting the importance of monitoring PFASs exposure in specific workplaces. In addition, environmental contaminated hotspots causing high exposure to the population were identified. In conclusion, the frequent and high PFASs exposure evidenced by HBM4EU strongly suggests the need to take all possible measures to prevent further contamination of the European population, in addition to adopting remediation measures in hotspot areas, to protect human health and the environment. HBM4EU findings also support the restriction of the whole group of PFASs. Further, research and definition for additional toxicological dose-effect relationship values for more PFASs compounds is needed.

Associations between per and polyfluoroalkyl ether sulfonic acids and vitamin D biomarker levels in Chinese newborns

Skeleton develops extremely fast during fetal and neonatal stages; thus, fetuses and newborns exhibit unique vulnerabilities to vitamin D metabolism dysregulation, giving vitamin D's principal role in calcium homeostasis. Previous studies linked legacy per and polyfluoroalkyl ether sulfonic acids (PFAS) with vitamin D biomarker status in adults and children; however, how PFAS, especially emerging CI-PFESAs, influence vitamin D among newborns is unknown. This study focused on the epidemiological linkages between PFAS and vitamin D biomarkers. Eleven PFAS, including legacy PFAS and emerging CI-PFESAs, as well as two vitamin D metabolites [25-hydroxyvitamin D2 (25(OH)D2) and 25-hydroxyvitamin D3 (25(OH)D3)], were determined in cord sera of 992 newborns from a birth cohort in Wuhan, China. The cord serum levels of 25(OH)D2 and 25(OH)D3 were summed as total 25(OH)D, which is a reliable biomarker of vitamin D status. The associations of separated PFAS with vitamin D biomarker levels were analyzed via multiple linear models, whereas the mixture effect was estimated by utilizing the weighted quantile sum (WQS) regression. We observed that per doubling changes in perfluorotridecanoate (PFTrDA), perfluorohexane sulfonate (PFHxS), and perfluorooctane sulfonate (PFOS) were associated with a 6.04 to 9.05 % change in total 25(OH)D levels. PFHxS contributed over half of the PFAS mixture effect on total 25(OH)D. Stratified analysis indicated that the associations of certain PFAS with vitamin D biomarkers were more pronounced among boys. The emerging CI-PFESAs were not robustly related to vitamin D biomarker levels. The results suggested that exposure to legacy PFAS might disturb vitamin D status in newborns. Future epidemiological studies are required to confirm the association and to determine healthy implications at a later age.

Association between polyfluoroalkyl substances exposure and sex steroids in adolescents: The mediating role of serum albumin

BACKGROUND

Polyfluoroalkyl substances (PFASs) are an emerging class of contaminants with endocrine disrupting hazards. The impact of PFASs exposure on sex steroids remain inconclusive.

METHODS

This study used data from the 2013-2016 National Health and Nutrition Examination Survey (NHANES), including 525 adolescents aged 12-19. We explored the association between serum PFASs and sex steroids using multiple linear regression, weighted quantified sum (WQS) regression, and Bayesian kernel machine regression (BKMR). Mediation analyses were performed to assess whether serum albumin mediates the effects of PFASs on sex steroids.

RESULTS

Single exposure to perfluorohexane sulfonic acid (PFHxS) or n-perfluorooctanoic acid (n-PFOA) was found to be inversely associated with sex hormone binding protein (SHBG) after adjustment for confounders. Results from both the WQS and BKMR models showed that mixed exposure to the five PFASs was negatively associated with SHBG and testosterone (TT) in all adolescents, while only in the WQS model, the mixed exposure to PFASs was negatively correlated with E₂ and FAI in boys and negatively correlated with TT and SHBG in girls. Serum albumin was found to possibly mediate 9.7 % of the association between mixed PFAS exposure and TT, and 9.7 % of the association between mixed PFAS exposure and SHBG.

CONCLUSION

Our study demonstrates a negative association between mixed exposure to PFASs and adolescent TT and SHBG levels, and suggests that albumin may merit further study as a potential target for PFAS harm reduction.

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

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

Serum PFAS and Urinary Phthalate Biomarker Concentrations and Bone Mineral Density in 12-19 Year Olds: 2011-2016 NHANES

CONTEXT

Per- and polyfluoroalkyl substances (PFAS) and phthalates are 2 families of environmental endocrine disruptors that may be associated with areal lower bone mineral density (aBMD).

OBJECTIVE

To examine associations between serum PFAS and urinary phthalate biomarker concentrations and their mixtures with aBMD Z-scores in adolescents.

DESIGN, PATIENTS, AND MEASURES

We examined serial cross-sectional data from male (n = 453) and female (n = 395) 12- to 19-year-old participants in the 2011 through 2016 National Health and Nutrition Examination Survey with measures of serum PFAS, urinary phthalate metabolites, and dual-energy X-ray absorptiometry aBMD Z-scores (total body less head). In sex-specific models, we used linear regression to examine associations of individual PFAS and phthalate biomarkers with aBMD Z-scores, and Bayesian kernel machine regression to examine the association of the overall PFAS/phthalate biomarker mixture with aBMD Z-scores. We replicated the analysis, stratifying by race/ethnicity.

RESULTS

Participants were (mean ± SD) 15 ± 2.1 years of age. In males, each doubling of serum perfluorooctanoate (PFOA), perfluorooctane sulfonate, urinary mono-isobutyl phthalate (MiBP), mono-n-butyl phthalate, and the overall PFAS/phthalate mixture was associated with a lower aBMD Z-score (eg, for PFOA: -0.24; 95% CI, -0.41 to -0.06). Serum PFOA and urinary MiBP were associated with higher aBMD Z-scores in females (eg, for PFOA: 0.09; 95% CI, -0.07 to 0.25). Findings did not differ by race/ethnicity.

CONCLUSIONS

Certain PFAS and phthalates may be associated with reduced bone mineral density in adolescent males. Bone mineral density tracks across the life course, so if replicated in longitudinal cohorts, this finding may have implications for lifelong skeletal health.

Toward a Mechanistic Understanding of Poly- and Perfluoroalkylated Substances and Cancer

Simple Summary

Poly- and perfluoroalkylated substances (PFAS) are industrial chemicals found in many household products that persist in the environment. While several excellent review articles exist on the potential harmful effects of PFAS, there are few focused on cancer. This concise and streamlined mini-review focuses on summarizing molecular mechanisms related to the potential cancer-promoting properties of PFAS. This review organizes and interprets the vast primary PFAS cancer biology literature and provides a coherent, unified, and digestible model of the molecular mechanisms that potentially explains PFAS cancer promotion.

Abstract

Poly- and perfluoroalkylated substances (PFAS) are chemicals that persist and bioaccumulate in the environment and are found in nearly all human populations through several routes of exposure. Human occupational and community exposure to PFAS has been associated with several cancers, including cancers of the kidney, testis, prostate, and liver. While evidence suggests that PFAS are not directly mutagenic, many diverse mechanisms of carcinogenicity have been proposed. In this mini-review, we organize these mechanisms into three major proposed pathways of PFAS action—metabolism, endocrine disruption, and epigenetic perturbation—and discuss how these distinct but interdependent pathways may explain many of the proposed pro-carcinogenic effects of the PFAS class of environmental contaminants. Notably, each of the pathways is predicted to be highly sensitive to the dose and window of exposure which may, in part, explain the variable epidemiologic and experimental evidence linking PFAS and cancer. We highlight testicular and prostate cancer as models to validate this concept.

Effects of perfluorooctanoic acid in oxidative stress generation, DNA damage in cumulus cells, and its impact on in vitro maturation of porcine oocytes

Perfluorooctanoic acid is a synthetic compound mostly used in a wide range of consumer products with several adverse effects on somatic cells and gametes. It has been linked to hepatotoxic and carcinogenic effects, alterations in the immune system, endocrine, and reproductive alterations. In vivo studies show an increase in reactive oxygen species and DNA damage. However, the mechanisms by which this compound affects fertility, remain contradictory. Therefore, the aim of the present study was to evaluate the effect of perfluorooctanoic acid on oocyte viability and maturation, as well as the viability, generation of oxidative stress, and genotoxic damage in the cumulus cells exposed during in vitro maturation. This compound had a negative effect on oocyte viability (lethal concentration, LC₅₀  = 269 μM) and maturation (inhibition maturation concentration IM₅₀  = 75 μM), while in cumulus cells the LC₅₀ was 158 μM. The generation of reactive oxygen species evaluated in cumulus cells, protein carbonylation, and DNA damage, was significantly increased at 40 μM perfluorooctanoic acid. This study provides evidence that perfluorooctanoic acid causes reactive oxygen species generation, protein oxidation, and DNA damage in cumulus cells, compromising the maturation and viability of porcine oocyte, which may affect fertility.

Efficient workflow for suspect screening analysis to characterize novel and legacy per- and polyfluoroalkyl substances (PFAS) in biosolids

Land application of treated sewage sludge (also known as biosolids) is considered a sustainable route of disposal because it reduces waste loading into landfills while improving soil health. However, this waste management practice can introduce contaminants from biosolids, such as per- and polyfluoroalkyl substances (PFAS), into the environment. PFAS have been observed to be taken up by plants, accumulate in humans and animals, and have been linked to various negative health effects. There is limited information on the nature and amounts of PFAS introduced from biosolids that have undergone different treatment processes. Therefore, this study developed analytical techniques to improve the characterization of PFAS in complex biosolid samples. Different clean-up techniques were evaluated and applied to waste-activated sludge (WAS) and lime-stabilized primary solids (PS) prior to targeted analysis and suspect screening of biosolid samples. Using liquid chromatography with high-resolution mass spectrometry, a workflow was developed to achieve parallel quantitative targeted analysis and qualitative suspect screening. This study found that concentrations of individual PFAS (27 targeted analytes) can range from 0.6 to 84.6 ng/g in WAS (average total PFAS = 241.4 ng/g) and from 1.6 to 33.8 ng/g in PS (average total PFAS = 72.1 ng/g). The suspect screening workflow identified seven additional PFAS in the biosolid samples, five of which have not been previously reported in environmental samples. Some of the newly identified compounds are a short-chain polyfluorinated carboxylate (a PFOS replacement), a diphosphate ester (a PFOA precursor), a possible transformation product of carboxylate PFAS, and an imidohydrazide which contains a sulfonate and benzene ring.

Molecular Gatekeeper Discovery: Workflow for Linking Multiple Exposure Biomarkers to Metabolomics

The exposome reflects multiple exposures across the life-course that can affect health. Metabolomics can reveal the underlying molecular basis linking exposures to health conditions. Here, we explore the concept and general data analysis framework of "molecular gatekeepers"─key metabolites that link single or multiple exposure biomarkers with correlated clusters of endogenous metabolites─to inform health-relevant biological targets. We performed untargeted metabolomics on plasma from 152 adolescent girls participating in the Growing Up Healthy Study in New York City. We then performed network analysis to link metabolites to exposure biomarkers including five trace elements (Cd, Mn, Pb, Se, and Hg) and five perfluorinated chemicals (PFCs; n-PFOS, Sm-PFOS, n-PFOA, PFHxS, and PFNA). We found 144 molecular gatekeepers and annotated 22 of them. Lysophosphatidylcholine (16:0) and taurodeoxycholate were correlated with both n-PFOA and n-PFOS, suggesting a shared dysregulation from multiple xenobiotic exposures. Sphingomyelin (d18:2/14:0) was significantly associated with age at menarche; yet, no direct association was detected between any exposure biomarkers and age at menarche. Thus, molecular gatekeepers can also discover molecular linkages between exposure biomarkers and health outcomes that may otherwise be obscured by complex interactions in direct measurements.

Association Between Exposure to Per- and Polyfluoroalkyl Substances and Birth Outcomes: A Systematic Review and Meta-Analysis

Background

A large body of emerging evidence suggests that per- and polyfluoroalkyl substances (PFAS) affect birth outcomes in various pathways, but the evidence is inconsistent. Therefore, this study aimed to systematically review the epidemiological evidence on PFAS exposure and birth outcomes.

Methods

Three electronic databases were searched for epidemiological studies through February 13, 2021. We used random-effects meta-analysis for eight birth outcome indicators to calculate summary effect estimates for various exposure types. The risk of bias and the overall quality and level of evidence for each exposure-outcome pair were assessed.

Results

The initial search identified 58 potentially eligible studies, of which 46 were ultimately included. Many PFAS were found to have previously unrecognized statistically significant associations with birth outcomes. Specifically, birth weight (BW) was associated with PFAS, with effect sizes ranging from −181.209 g (95% confidence interval (CI) = −360.620 to −1.798) per 1 ng/ml increase in perfluoroheptanesulfonate (PFHpS) to −24.252 g (95% CI = −38.574 to −9.930) per 1 ln (ng/ml) increase in perfluorodecaoic acid (PFDA). Similar patterns were observed between other PFAS and birth outcomes: perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) with birth length (BL) and ponderal index (PI), PFOS and perfluorododecanoic acid (PFDoDA) with head circumference (HC), PFHpS with gestational age (GA), and perfluorononanoic acid (PFNA) and PFHpS with preterm birth (PTB). Additionally, PFDA showed a statistically significant association with small for gestational age (SGA). The level of the combined evidence for each exposure-outcome pair was considered to be “moderate”.

Conclusion

This study showed that PFAS exposure was significantly associated with increased risks of various adverse birth outcomes and that different birth outcome indicators had different degrees of sensitivity to PFAS. Further studies are needed to confirm our results by expanding the sample size, clarifying the effects of different types or doses of PFAS and the time of blood collection on birth outcomes, and fully considering the possible confounders.

Exposure to perfluoroalkyl substances was associated with estrogen homeostasis in pregnant women

Previous studies have suggested that perfluoroalkyl substances (PFASs) can act as endocrine disruptors, but few studies have investigated the effects of serum PFASs on estrogen homeostasis during pregnancy. The present study included 557 pregnant women in Tangshan City, North China, and determined 11 serum PFASs in the early term of pregnancy and three typical estrogens (estrone (E₁), estradiol (E₂) and estriol (E₃)) in the early (n = 557), middle (n = 339), and late (n = 286) terms of pregnancy. Sociodemographic factors and diet information were obtained by structured questionnaires. After adjusting for potential confounders, multiple linear regression model demonstrated negative associations of natural logarithmic transformed serum perfluoroundecanoic acid (Ln PFUdA) with Ln E₁and Ln E3 in the early term of pregnancy with β coefficients of -0.060 (95% confidence interval (CI): -0.101 to -0.019) and -0.041 (95% CI: -0.070 to -0.011), respectively. Ln perfluorodecanoic acid (PFDA) was negatively associated with averaged E1 in the early and middle (EM) terms of pregnancy with a β coefficient of -0.205 (95% CI: -0.357 to -0.053). Ln perfluorononanoic acid (PFNA) tended to be negatively associated with E₂ in the late term of pregnancy with a β coefficient of -0.134 (95% CI: -0.253 to -0.016) although p-value was slightly greater than 0.05 after false discovery rate (FDR) correction. Mixed effect model found that serum PFDA was negatively associated with E₁ (β = -0.123, 95% CI: -0.235 to -0.012) during the entire pregnancy. These findings suggested that exposure to PFASs disturbed estrogen homeostasis in pregnant women and the effects varied with the terms of pregnancy.

PFAS Molecules: A Major Concern for the Human Health and the Environment

Per- and polyfluoroalkyl substances (PFAS) are a group of over 4700 heterogeneous compounds with amphipathic properties and exceptional stability to chemical and thermal degradation. The unique properties of PFAS compounds has been exploited for almost 60 years and has largely contributed to their wide applicability over a vast range of industrial, professional and non-professional uses. However, increasing evidence indicate that these compounds represent also a serious concern for both wildlife and human health as a result of their ubiquitous distribution, their extreme persistence and their bioaccumulative potential. In light of the adverse effects that have been already documented in biota and human populations or that might occur in absence of prompt interventions, the competent authorities in matter of health and environment protection, the industries as well as scientists are cooperating to identify the most appropriate regulatory measures, substitution plans and remediation technologies to mitigate PFAS impacts. In this review, starting from PFAS chemistry, uses and environmental fate, we summarize the current knowledge on PFAS occurrence in different environmental media and their effects on living organisms, with a particular emphasis on humans. Also, we describe present and provisional legislative measures in the European Union framework strategy to regulate PFAS manufacture, import and use as well as some of the most promising treatment technologies designed to remediate PFAS contamination in different environmental compartments.

Per- and polyfluoroalkyl substance (PFAS) exposure, maternal metabolomic perturbation, and fetal growth in African American women: A meet-in-the-middle approach

BACKGROUND

Prenatal exposures to per- and polyfluoroalkyl substances (PFAS) have been linked to reduced fetal growth. However, the detailed molecular mechanisms remain largely unknown. This study aims to investigate biological pathways and intermediate biomarkers underlying the association between serum PFAS and fetal growth using high-resolution metabolomics in a cohort of pregnant African American women in the Atlanta area, Georgia.

METHODS

Serum perfluorohexane sulfonic acid (PFHxS), perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), and perfluorononanoic acid (PFNA) measurements and untargeted serum metabolomics profiling were conducted in 313 pregnant African American women at 8-14 weeks gestation. Multiple linear regression models were applied to assess the associations of PFAS with birth weight and small-for-gestational age (SGA) birth. A high-resolution metabolomics workflow including metabolome-wide association study, pathway enrichment analysis, and chemical annotation and confirmation with a meet-in-the-middle approach was performed to characterize the biological pathways and intermediate biomarkers of the PFAS-fetal growth relationship.

RESULTS

Each log2-unit increase in serum PFNA concentration was significantly associated with higher odds of SGA birth (OR = 1.32, 95% CI 1.07, 1.63); similar but borderline significant associations were found in PFOA (OR = 1.20, 95% CI 0.94, 1.49) with SGA. Among 25,516 metabolic features extracted from the serum samples, we successfully annotated and confirmed 10 overlapping metabolites associated with both PFAS and fetal growth endpoints, including glycine, taurine, uric acid, ferulic acid, 2-hexyl-3-phenyl-2-propenal, unsaturated fatty acid C18:1, androgenic hormone conjugate, parent bile acid, and bile acid-glycine conjugate. Also, we identified 21 overlapping metabolic pathways from pathway enrichment analyses. These overlapping metabolites and pathways were closely related to amino acid, lipid and fatty acid, bile acid, and androgenic hormone metabolism perturbations.

CONCLUSION

In this cohort of pregnant African American women, higher serum concentrations of PFOA and PFNA were associated with reduced fetal growth. Perturbations of biological pathways involved in amino acid, lipid and fatty acid, bile acid, and androgenic hormone metabolism were associated with PFAS exposures and reduced fetal growth, and uric acid was shown to be a potential intermediate biomarker. Our results provide opportunities for future studies to develop early detection and intervention for PFAS-induced fetal growth restriction.

Prospective associations of mid-childhood plasma per- and polyfluoroalkyl substances and pubertal timing

BACKGROUND

Exposure to per- and polyfluoroalkyl substances (PFAS) may disrupt pubertal timing. Higher PFAS plasma concentrations have been associated with later pubertal timing in girls, but cross-sectional findings may be explained by reverse causation.

OBJECTIVES

To assess prospective associations between PFAS plasma concentrations in mid-childhood and markers of pubertal timing in male and female adolescents.

METHODS

We studied 640 children in Project Viva, a Boston-area prospective cohort. We examined associations of plasma concentrations of 6 PFAS measured at mean 7.9 (SD 0.8) years (2007-2010) with markers of pubertal timing. Parents reported a 5-item pubertal development score at early adolescence (mean 13.1 (SD 0.8) years) and reported age at menarche annually. We calculated age at peak height velocity using research and clinical measures of height. We used sex-specific linear and Cox proportional hazards regression to estimate associations of single PFAS with outcomes, and we used Bayesian Kernel Machine Regression (BKMR) to estimate associations of the PFAS mixture with outcomes.

RESULTS

Plasma concentrations were highest for perfluorooctane sulfonate (PFOS) [median (IQR) 6.4(5.6) ng/mL], followed by perfluorooctanoate (PFOA) [4.4(3.0) ng/mL]. In early adolescence, girls were further along in puberty than boys [pubertal development score mean (SD) 2.9 (0.7) for girls and 2.2(0.7) for boys; age at peak height velocity mean (SD) 11.2y (1.0) for girls and 13.1y (1.0) for boys]. PFAS was associated with later markers of pubertal timing in girls only. For example, each doubling of PFOA was associated with lower pubertal development score (-0.18 units; 95% CI: -0.30, -0.06) and older age at peak height velocity (0.23 years; 95% CI: 0.06, 0.40)]. We observed similar associations for PFOS, perfluorodecanoate (PFDA), and the PFAS mixture. PFAS plasma concentrations were not associated with age at menarche or markers of pubertal timing in boys.

DISCUSSION

Higher PFAS plasma concentrations in mid-childhood were associated with later onset of puberty in girls.

Prenatal exposure to per- and polyfluoroalkyl substances (PFAS) and associations with attention-deficit/hyperactivity disorder and autism spectrum disorder in children

BACKGROUND

Prenatal exposure to per- and polyfluoroalkyl substances (PFAS) may be a risk factor for neurodevelopmental deficits and disorders, but evidence is inconsistent.

OBJECTIVES

We investigated whether prenatal exposure to PFAS were associated with childhood diagnosis of attention-deficit/hyperactivity disorder (ADHD) or autism spectrum disorder (ASD).

METHODS

This study was based on the Norwegian Mother, Father and Child Cohort Study and included n = 821 ADHD cases, n = 400 ASD cases and n = 980 controls. Diagnostic cases were identified by linkage with the Norwegian Patient Registry. In addition, we used data from the Medical Birth Registry of Norway. The study included the following PFAS measured in maternal plasma sampled mid-pregnancy: Perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), perfluoroundecanoic acid (PFUnDA), perfluorohexane sulfonate (PFHxS), perfluoroheptanesulfonic acid (PFHpS), and perfluorooctane sulfonate (PFOS). Relationships between individual PFAS and ADHD or ASD diagnoses were examined using multivariable adjusted logistic regression models. We also tested for possible non-linear exposure-outcome associations. Further, we investigated the PFAS mixture associations with ASD and ADHD diagnoses using a quantile-based g-computation approach.

RESULTS

Odds of ASD was significantly elevated in PFOA quartile 2 [OR = 1.71 (95% CI: 1.20, 2.45)] compared to quartile 1, and PFOA appeared to have a non-linear, inverted U-shaped dose-response relationship with ASD. PFOA was also associated with increased odds of ADHD, mainly in quartile 2 [OR = 1.54 (95% CI: 1.16, 2.04)] compared to quartile 1, and displayed a non-linear relationship in the restricted cubic spline model. Several PFAS (PFUnDA, PFDA, and PFOS) were inversely associated with odds of ADHD and/or ASD. Some of the associations were modified by child sex and maternal education. The overall PFAS mixture was inversely associated with ASD [OR = 0.76 (95% CI: 0.64, 0.90)] as well as the carboxylate mixture [OR = 0.79 (95% CI: 0.68, 0.93)] and the sulfonate mixture [OR = 0.84 (95% CI: 0.73, 0.96)].

CONCLUSION

Prenatal exposure to PFOA was associated with increased risk of ASD and ADHD in children. For some PFAS, as well as their mixtures, there were inverse associations with ASD and/or ADHD. However, the inverse associations reported herein should not be interpreted as protective effects, but rather that there could be some unresolved confounding for these relationships. The epidemiologic literature linking PFAS exposures with neurodevelopmental outcomes is still inconclusive, suggesting the need for more research to elucidate the neurotoxicological potential of PFAS during early development.

Associations of Prenatal Exposure to Per- and Polyfluoroalkyl Substances with the Neonatal Birth Size and Hormones in the Growth Hormone/Insulin-Like Growth Factor Axis

Toxicological data suggest a significant developmental toxicity of per- and polyfluoroalkyl substances (PFASs); however, evidence in humans remains inconclusive. Furthermore, the effects of prenatal exposure to PFASs on hormones in the growth hormone (GH)/insulin-like growth factor (IGF) axis of newborns remain largely unclear. We aimed to investigate the associations of prenatal exposure to PFASs with the neonatal birth size, GH, IGF-1, and IGF-binding protein 3 (IGFBP-3). The concentrations of 22 PFASs were measured in the plasma of 224 pregnant women collected within 3 days before delivery (39.3 weeks) in Guangzhou, China, and the anthropometric data were gathered from medical records. Paired cord blood was collected at delivery to determine GH, IGF-1, and IGFBP-3 levels. Multivariable linear regression models revealed the inverse associations of several long-chain PFASs with birth weight and ponderal index as well as the significant associations of perfluorobutanoic acid and perfluorooctanoic acid (PFOA) with IGFBP-3 levels. The Bayesian kernel machine regression confirmed the association of perfluorooctane sulfonate with birth weight and ponderal index and of PFOA with IGFBP-3 and identified an inverse joint effect of exposure to a mixture of multiple PFASs on birth weight. The findings provide the first comprehensive evidence on the individual and joint effects of multiple PFASs on the neonatal birth size and hormones in the GH/IGF axis, which requires further confirmation.

Associations between polyfluoroalkyl substance and organophosphate flame retardant exposures and telomere length in a cohort of women firefighters and office workers in San Francisco

BACKGROUND

Environmental chemical exposures can affect telomere length, which in turn has been associated with adverse health outcomes including cancer. Firefighters are occupationally exposed to many hazardous chemicals and have higher rates of certain cancers. As a potential biomarker of effect, we assessed associations between chemical exposures and telomere length in women firefighters and office workers from San Francisco, CA.

METHODS

We measured serum concentrations of polyfluoroalkyl substances (PFAS), urinary metabolites of flame retardants, including organophosphate flame retardants (OPFRs), and telomere length in peripheral blood leukocytes in women firefighters (N = 84) and office workers (N = 79) who participated in the 2014-15 Women Workers Biomonitoring Collaborative. Multiple linear regression models were used to assess associations between chemical exposures and telomere length.

RESULTS

Regression results revealed significant positive associations between perfluorooctanoic acid (PFOA) and telomere length and perfluorooctanesulfonic acid (PFOS) and telomere length among the whole cohort. Models stratified by occupation showed stronger and more significant associations among firefighters as compared to office workers. Among firefighters in models adjusted for age, we found positive associations between telomere length and log-transformed PFOA (β (95%CI) = 0.57(0.12, 1.02)), PFOS (0.44 (0.05, 0.83)), and perfluorodecanoic acid (PFDA) (0.43 (0.02, 0.84)). Modeling PFAS as categories of exposure showed significant associations between perfluorononanoic acid (PFNA) and telomere length among firefighters. Significant associations between OPFR metabolites and telomere length were seen for bis (1,3-dichloro-2-propyl) phosphate (BDCPP) and telomere length among office workers (0.21(0.03, 0.40)) and bis (2-chloroethyl) phosphate (BCEP) and telomere length among firefighters (- 0.14(- 0.28, - 0.01)). For OPFRs, the difference in the direction of effect by occupational group may be due to the disparate detection frequencies and concentrations of exposure between the two groups and/or potential unmeasured confounding.

CONCLUSION

Our findings suggest positive associations between PFAS and telomere length in women workers, with larger effects seen among firefighters as compared to office workers. The OPFR metabolites BDCPP and BCEP are also associated with telomere length in firefighters and office workers. Associations between chemical exposures and telomere length reported here and by others suggest mechanisms by which these chemicals may affect carcinogenesis and other adverse health outcomes.

Plasma Concentrations of Per- and Polyfluoroalkyl Substances and Body Composition From Mid-Childhood to Early Adolescence

CONTEXT

Per- and polyfluoroalkyl substances (PFAS) may alter body composition by lowering anabolic hormones and increasing inflammation, but data are limited, particularly in adolescence when body composition is rapidly changing.

OBJECTIVE

To evaluate associations of PFAS plasma concentrations in childhood with change in body composition through early adolescence.

METHODS

A total of 537 children in the Boston-area Project Viva cohort participated in this study. We used multivariable linear regression and Bayesian kernel machine regression (BKMR) to examine associations of plasma concentrations of 6 PFAS, quantified by mass spectrometry, in mid-childhood (mean age, 7.9 years; 2007-2010) with change in body composition measured by dual-energy x-ray absorptiometry from mid-childhood to early adolescence (mean age, 13.1 years).

RESULTS

In single-PFAS linear regression models, children with higher concentrations of perfluorooctanoate (PFOA), perfluorooctane sulfonate (PFOS), perfluorodecanoate (PFDA), and perfluorohexane sulfonate (PFHxS) had less accrual of lean mass (eg, -0.33 [95% CI: -0.52, -0.13] kg/m2 per doubling of PFOA). Children with higher PFOS and PFHxS had less accrual of total and truncal fat mass (eg, -0.32 [95% CI: -0.54, -0.11] kg/m2 total fat mass per doubling of PFOS), particularly subcutaneous fat mass (eg, -17.26 [95% CI -32.25, -2.27] g/m2 per doubling of PFOS). Children with higher PFDA and perfluorononanoate (PFNA) had greater accrual of visceral fat mass (eg, 0.44 [95% CI: 0.13, 0.75] g/m2 per doubling of PFDA). Results from BKMR mixture models were consistent with linear regression analyses.

CONCLUSION

Early life exposure to some but not all PFAS may be associated with adverse changes in body composition.

Plasma Concentrations of Per- and Polyfluoroalkyl Substances and Body Composition From Mid-Childhood to Early Adolescence

CONTEXT

Per- and polyfluoroalkyl substances (PFAS) may alter body composition by lowering anabolic hormones and increasing inflammation, but data are limited, particularly in adolescence when body composition is rapidly changing.

OBJECTIVE

To evaluate associations of PFAS plasma concentrations in childhood with change in body composition through early adolescence.

METHODS

A total of 537 children in the Boston-area Project Viva cohort participated in this study. We used multivariable linear regression and Bayesian kernel machine regression (BKMR) to examine associations of plasma concentrations of 6 PFAS, quantified by mass spectrometry, in mid-childhood (mean age, 7.9 years; 2007-2010) with change in body composition measured by dual-energy x-ray absorptiometry from mid-childhood to early adolescence (mean age, 13.1 years).

RESULTS

In single-PFAS linear regression models, children with higher concentrations of perfluorooctanoate (PFOA), perfluorooctane sulfonate (PFOS), perfluorodecanoate (PFDA), and perfluorohexane sulfonate (PFHxS) had less accrual of lean mass (eg, -0.33 [95% CI: -0.52, -0.13] kg/m2 per doubling of PFOA). Children with higher PFOS and PFHxS had less accrual of total and truncal fat mass (eg, -0.32 [95% CI: -0.54, -0.11] kg/m2 total fat mass per doubling of PFOS), particularly subcutaneous fat mass (eg, -17.26 [95% CI -32.25, -2.27] g/m2 per doubling of PFOS). Children with higher PFDA and perfluorononanoate (PFNA) had greater accrual of visceral fat mass (eg, 0.44 [95% CI: 0.13, 0.75] g/m2 per doubling of PFDA). Results from BKMR mixture models were consistent with linear regression analyses.

CONCLUSION

Early life exposure to some but not all PFAS may be associated with adverse changes in body composition.

Prenatal perfluoroalkyl substance exposure and neuropsychological development throughout childhood: The INMA Project

BACKGROUND

Perfluoroalkyl substances (PFASs) have been related to neurodevelopmental toxicity in animals. However, human studies are inconclusive.

OBJECTIVES

To evaluate the association between prenatal PFAS exposure and neuropsychological development during childhood.

METHODS

1240 mother-child pairs from the Spanish INMA Project were analyzed. Perfluorohexanesulfonic acid (PFHxS), perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS), and perfluorononanoic acid (PFNA) were measured in first-trimester maternal plasma. Neuropsychological development was assessed at 14 months, 4-5 and 7 years covering four domains: general cognitive, general motor, attention, and working memory. Associations were studied by means of multivariable regression analyses.

RESULTS

PFHxS, PFOA, PFOS, and PFNA medians were: 0.6, 2.4, 6.1, and 0.7 ng/mL. Higher PFAS prenatal exposure was associated with worse motor development at 14 months, especially in the case of PFHxS (β[95%CI]: -1.49[-2.73, -0.24]) and to a lesser extent PFOS (-1.25[-2.62, 0.12]). There was also a marginal positive association between general cognitive development at 4-5 years and PFOS (1.17[-0.10, 2.43]) and PFNA (0.99[-0.13, 2.12]). No clear associations for other neuropsychological outcomes or any sex differences were found.

DISCUSSION

This study shows no clear-cut evidence of an association between prenatal PFAS exposure and adverse neuropsychological development in children up to the age of 7 years.

Environmental exposure to per- and polyfluoroalkyl substances mixture and male reproductive hormones

BACKGROUND

Previous epidemiological studies on the relationship between per- and polyfluoroalkyl substances (PFAS) exposure and male reproductive hormones were mainly limited to a few legacy PFAS and ignored the possible mixture effects.

OBJECTIVES

To assess the associations of PFAS mixture, branched isomers and emerging alternatives of PFAS with male reproductive hormones.

METHODS

A total of 902 men (mean age: 31.3 years) were recruited in this cross-sectional study. We quantified 24 targeted PFAS, including 7 branched PFOS isomers, 2 branched PFOA isomers and 2 components of F-53B, in blood plasma. Five reproductive hormones, including total testosterone (TT), estradiol (E₂), follicular stimulating hormone (FSH), luteinizing hormone (LH) and insulin like factor 3 (INSL3), and sex hormone binding globulin (SHBG) were measured in serum. Associations were first assessed by confounder-adjusted multiple linear regression while correcting for multiple comparisons. Bayesian kernel machine regression (BKMR) and adaptive elastic net (AENET) were further used to assess mixture effects and the adjusted exposure response (ER) relationship of individual PFAS.

RESULTS

After adjusting for confounders, we found that PFAS mixture was significantly and inversely associated with E₂ and E₂/TT, with perfluoro-n-undecanoic acid (PFuDA) being the major contributor. Although the associations between PFAS mixture and other hormones were non-significant, certain individual PFAS presented significant associations. Notably, perfluoro-n-tridecanoic acid (PFTrDA) and perfluoro-n-dodecanoic acid (PFDoA) were found to be significantly and inversely associated with INSL3, a unique indicator of Leydig cells function. Meanwhile, significant positive associations were found between perfluorobutane sulfonic acid (PFBS) and FSH and between PFuDA and LH. But the associations with branched isomers or F-53B were sporadic and inconsistent.

CONCLUSIONS

Our findings provided the evidence that PFAS mixture may reduce E₂ level, and certain PFAS (i.e., PFTrDA and PFDoA) may have negative effects on Leydig cells function among young men. Additional studies are much needed to confirm our results and elucidate potential mechanisms.

Effects of the prenatal environment on cryptorchidism: A narrative review

Cryptorchidism, the absence of testes from the scrotum, is the most common genital disorder in boys and a risk factor for reduced fertility and testicular cancer. The mechanism responsible for cryptorchidism involves two discrete stages: a transabdominal and an inguinoscrotal phase. These phases of testicular descent are regulated by the prenatal sex hormone environment, including levels of testosterone, insulin-like factor 3, and calcitonin gene-related peptide. Environmental endocrine disruptors, which are unfavorable environmental factors, may also affect testicular descent through prenatal sex hormones. This review examined the effects of environmental factors, particularly environmental endocrine disruptors, such as phthalates, organochlorine pesticides, diethylstilbestrol, bisphenol A, dioxins/dioxin-like compounds, and perfluoroalkyl substances, and parental lifestyles on the risk of cryptorchidism. Although some studies have shown that environmental endocrine disruptors can affect testicular descent by changing the hormonal environment during the prenatal period, no significant association has been established between exposure to environmental endocrine disruptors and the incidence of cryptorchidism. Therefore, the role played by environmental endocrine disruptor exposure (if any) in the pathogenesis of cryptorchidism remains unknown. Further studies are needed to examine these issues.

Per- and polyfluoroalkyl substances (PFAS) as contaminants of emerging concern in Asia's freshwater resources

The occurrence of per- and polyfluoroalkyl substances (PFAS) in water resources is an emerging concern because of their environmental persistence and bioaccumulation in humans. In Western countries, health advisories regarding PFAS exposure have been released to warn the public of its potential adverse effects. However, awareness regarding PFAS exposure in Asia is still at its infancy as reflected by the minimal safeguards imposed to protect the population from exposure. Here, we reviewed studies on PFAS contamination in Asia with a focus on freshwater resources to determine whether PFAS is also a concern in this part of the globe. Peer reviewed articles which included information on PFAS levels from 2000 to 2020 were compiled. The highest PFAS contamination was detected in surface water relative to ground, tap, and drinking water. PFAS levels in water resources in several countries in Asia, such as China, Japan, and South Korea, were above the recommended level, similar to that in the United States. PFAS in South and Southeast Asia were just below the recommended level, but the rise of PFAS in China in the recent decade, alongside its remarkable economic and industrial growth, suggests that increased PFAS contamination in South and Southeast Asia may soon follow, as these countries compete with the global economy. Hence, there is a need for these countries to also implement measures that will reduce the exposure of their population to PFAS.

Perfluoroalkyl Chemicals and Male Reproductive Health: Do PFOA and PFOS Increase Risk for Male Infertility?

Poly- and perfluoroalkyl substances (PFAS) are manmade synthetic chemicals which have been in existence for over 70 years. Though they are currently being phased out, their persistence in the environment is widespread. There is increasing evidence linking PFAS exposure to health effects, an issue of concern since PFAS such as perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) bioaccumulate in humans, with a half-life of years. Many epidemiological studies suggest that, worldwide, semen quality has decreased over the past several decades. One of the most worrying effects of PFOS and PFOA is their associations with lower testosterone levels, similar to clinical observations in infertile men. This review thus focuses on PFOS/PFOA-associated effects on male reproductive health. The sources of PFAS in drinking water are listed. The current epidemiological studies linking increased exposure to PFAS with lowered testosterone and semen quality, and evidence from rodent studies supporting their function as endocrine disruptors on the reproductive system, exhibiting non-monotonic dose responses, are noted. Finally, their mechanisms of action and possible toxic effects on the Leydig, Sertoli, and germ cells are discussed. Future research efforts must consider utilizing better human model systems for exposure, using more accurate PFAS exposure susceptibility windows, and improvements in statistical modeling of data to account for the endocrine disruptor properties of PFAS.

Perfluoroalkyl substances and sex hormones in postmenopausal women: NHANES 2013-2016

BACKGROUND

Although an alteration in sex hormones has been linked to perfluoroalkyl substances (PFAS) in premenopausal women and girls, whether such associations exist in postmenopausal women remains uncertain.

OBJECTS

To examine the associations between serum PFAS concentrations and sex hormone levels in postmenopausal women.

METHODS

Data from the National Health and Nutrition Examination Survey (NHANES) 2013-2016 waves were used. A total of 706 postmenopausal women with information on serum PFAS [perfluorohexane sulfonic acid (PFHxS), pefluorodecanoic acid (PFDA); perfluorononanoic acid (PFNA); linear perfluorooctanoate (n-PFOA); linear perfluorooctane sulfonate (n-PFOS); monomethyl branched isomers of PFOS (Sm-PFOS)], sex hormones indicators [e.g., total testosterone (TT), estradiol (E₂) and sex hormone binding globulin (SHBG)] as well as selected covariates were included. An indicator of circulating free testosterone (FT), and ratio of TT to E₂ (TT/E₂) were generated. Multiple linear regression accounting for the primary sampling unit, strata, and environmental sampling weights of PFAS was used for association analyses. Effect modification by obesity and type of menopause was explored via stratified analyses as well as the testing of interaction terms. Principal component analysis (PCA) and Bayesian kernel machine regression (BKMR) were conducted to assess these relationships in a multiple PFAS exposure setting.

RESULTS

After adjusting for potential confounders, total perfluorooctanoate (TPFOA: n-PFOA + Sb-PFOA) and total perfluorooctane sulfonate (TPFOS: n-PFOS + Sm-PFOS), and their linear and branched isomers were positively associated with two androgen indicators (i.e., TT and FT). PCA results revealed that the principal component (PC) composed of n-PFOA was positively associated with ln (TT) [β = 0.09, 95% confidential interval (CI): 0.02, 0.16; per ln-ng/mL increase in exposure], and ln (FT) (β = 0.12, 95% CI: 0.05, 0.2) in overweight/obese [body mass index (BMI) ≥ 25 kg/m²] women, but not in those with BMI < 25 kg/m². Additionally, among overweight/obese women, PFHxS was positively associated with androgens and negatively with ln (SHBG) (β = -0.06, 95% CI: -0.12, -0.01). The PC composed of Sm-PFOS, n-PFOS, and PFHxS was positively associated with ln (TT) levels among overweight/obese women. Results from BKMR also confirmed the findings on n-PFOA and PFHxS.

CONCLUSIONS

Our study indicates that n-PFOA and PFHxS were positively associated with levels of several androgen indicators in postmenopausal women, particularly among overweight/obese ones. Given the higher risk of cardiometabolic diseases associated with elevated levels of androgens in postmenopausal women, future studies are needed to explore the potential underlying mechanisms.