Effects of gestational exposures to chemical mixtures on birth weight using Bayesian factor analysis in the Health Outcome and Measures of Environment (HOME) Study

Association between prenatal exposure to per- and polyfluoroalkyl substances and infant anthropometry: A prospective cohort study

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) are a group of synthetic organic chemicals with potential endocrine-disrupting effects, and have been found to impair the physical growth of offspring in both experimental and epidemiological studies. We aimed to investigate the effects of prenatal PFAS exposure on repeated measurements of multiple anthropometric indicators in infants.

METHOD

PFAS were measured in serum samples collected from pregnant women at 12-16 gestational weeks. We calculated z-scores for the weight-for-age (WAZ), weight-for-length (WLZ), head circumference-for-age (HCZ), arm circumference-for-age (ACZ), triceps skinfold-for-age (TSZ), and subscapular skinfold-for-age (SSZ) at birth, 6 months, and 12 months of age according to the child growth standards of the World Health Organization (WHO) for anthropometric indicators. A total of 964 mother-infant pairs were included. A multivariate linear regression was performed to examine the associations between prenatal PFAS concentrations and anthropometric indicators at each time point. A generalized estimating equation (GEE) model was used to examine the longitudinal effects of PFAS exposure on repeated measurements of anthropometric indicators. Ultimately, a Bayesian kernel machine regression (BKMR) model was used to assess the joint effects of the PFAS mixture on anthropometric indicators.

RESULTS

In GEE models, perfluorododecanoic acid (PFDoA) in the high tertile group was associated with increased WAZ/WLZ, with β values (95% confidence intervals (CI)) of 0.12 (0.00, 0.23) and 0.18 (0.03, 0.32), respectively. Perfluorononanoic acid (PFNA) was associated with increased ACZ in the middle and high tertile groups. The BKMR models also presented the associations of the PFAS mixture with increased WAZ/WLZ throughout infancy, with more profound effects in females. Meanwhile, a pattern of inverse associations was observed between the perfluorooctanoic acid (PFOA) concentrations in the high tertile group and decreased WAZ, WLZ, and HCZ in males. In addition, the associations between PFAS and increased TSZ/SSZ at birth were identified by both linear regression and BKMR models.

CONCLUSION

Prenatal PFAS exposure (PFNA and PFDoA) was associated with increased infant anthropometry, especially in female infants, while prenatal PFOA exposure was associated with decreased weight, and head and arm circumference in male infants. The findings indicate that prenatal PFAS exposure may impair the growth trajectory of offspring.

Polybrominated diphenyl ether (PBDE) exposure and adverse maternal and infant health outcomes: Systematic review

Polybrominated diphenyl ethers (PBDEs) are flame retardants found in ambient environment and are measured in humans. There are reports on general PBDE toxicity, including endocrine disrupting properties. Studies on adverse maternal and infant outcomes and underlying toxicity mechanisms needs to be understood. The objective of this study was to conduct a systematic review to examine the state of science on the relationship between PBDE and adverse maternal/infant health outcomes and related maternal biomarker changes. This literature review was conducted using PubMed, Scopus, Embase and Web of Science for published articles from January 2005-February 2022. Article quality was assessed using Newcastle-Ottawa Scale. Of the 1518 articles, only 54 human observational studies were screened in for this review. A second reviewer examined the validity of these articles. Reports on associations between PBDE and maternal health outcomes included gestational hypertension/preeclampsia (N = 2) and gestational diabetes mellitus/glycemic index (N = 6). Meanwhile, reports on PBDE and infant outcomes (N=32) included effects on infant birth weight, birth length and cephalic perimeter, preterm birth, fetal growth restriction and APGAR scores. Although findings on PBDE exposure and adverse infant outcomes showed inconsistencies across studies, in general, negative correlations between maternal PBDEs and infant birth weight, birth length and cephalic perimeter were seen, in few cases, after stratification by sex. Association between maternal PBDE and maternal biomarkers (N=18) suggested negative impact of PBDE exposure on markers relevant to neuro-endocrine system and inflammatory processes. The review findings identified potential associations between maternal PBDE and adverse maternal/infant health outcomes. Furthermore, PBDE-related biomarker changes suggest disturbances in maternal mechanisms relevant to endocrine disrupting properties of PBDEs. The observed study heterogeneity can be attributed to factors namely, sample size, study design and statistical analysis. Overall review findings imply the necessity for further research to validate PBDE exposure-related adverse maternal/infant health effects and to validate underlying toxicity mechanisms.

The regulation of endocrine-disrupting chemicals to minimize their impact on health

Endocrine-disrupting chemicals (EDCs) are substances generated by human industrial activities that are detrimental to human health through their effects on the endocrine system. The global societal and economic burden posed by EDCs is substantial. Poorly defined or unenforced policies can increase human exposure to EDCs, thereby contributing to human disease, disability and economic damage. Researchers have shown that policies and interventions implemented at both individual and government levels have the potential to reduce exposure to EDCs. This Review describes a set of evidence-based policy actions to manage, minimize or even eliminate the widespread use of these chemicals and better protect human health and society. A number of specific challenges exist: defining, identifying and prioritizing EDCs; considering the non-linear or non-monotonic properties of EDCs; accounting for EDC exposure effects that are latent and do not appear until later in life; and updating testing paradigms to reflect 'real-world' mixtures of chemicals and cumulative exposure. A sound strategy also requires partnering with health-care providers to integrate strategies to prevent EDC exposure in clinical care. Critical next steps include addressing EDCs within global policy frameworks by integrating EDC exposure prevention into emerging climate policy.

Per- and polyfluoroalkyl substances, gestational weight gain, postpartum weight retention and body composition in the UPSIDE cohort

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) are synthetic chemicals found in drinking water and consumer products, resulting in ubiquitous human exposure. PFAS have been linked to endocrine disruption and altered weight gain across the lifespan. A limited and inconsistent body of research suggests PFAS may impact gestational weight gain (GWG) and postpartum body mass index (BMI), which are important predictors of overall infant and maternal health, respectively.

METHODS

In the Understanding Pregnancy Signals and Infant Development (UPSIDE/UPSIDE-MOMs) study (n = 243; Rochester, NY), we examined second trimester serum PFAS (PFOS: perfluorooctanesulfonic acid, PFOA: perfluorooctanoic acid, PFNA: perfluorononanoic acid, PFHxS: perfluorohexanesulfonic acid, PFDA: perfluorodecanoic acid) in relation to GWG (kg, and weekly rate of gain) and in the postpartum, weight retention (PPWR (kg) and total body fat percentage (measured by bioelectrical impedance)). We fit multivariable linear regression models examining these outcomes in relation to log-transformed PFAS in the whole cohort as well as stratified by maternal pre-pregnancy BMI (< 25 vs. =  > 25 kg/m2), adjusting for demographics and lifestyle factors. We used weighted quantile sum regression to find the combined influence of the 5 PFAS on GWG, PPWR, and body fat percentage.

RESULTS

PFOA and PFHxS were inversely associated with total GWG (PFOA: ß = -1.54 kg, 95%CI: -2.79, -0.30; rate ß = -0.05 kg/week, 95%CI: -0.09, -0.01; PFHxS: ß = -1.59 kg, 95%CI: -3.39, 0.21; rate ß = -0.05 kg/week, 95%CI: -0.11, 0.01) and PPWR at 6 and 12 months (PFOA 6 months: ß = -2.39 kg, 95%CI: -4.17, -0.61; 12 months: ß = -4.02 kg, 95%CI: -6.58, -1.46; PFHxS 6 months: ß = -2.94 kg, 95%CI: -5.52, -0.35; 12 months: ß = -5.13 kg, 95%CI: -8.34, -1.93). PFOA was additionally associated with lower body fat percentage at 6 and 12 months (ß = -1.75, 95%CI: -3.17, -0.32; ß = -1.64, 95%CI: -3.43, 0.16, respectively) with stronger associations observed in participants with higher pre-pregnancy BMI. The PFAS mixture was inversely associated with weight retention at 12 months (ß = -2.030, 95%CI: -3.486, -0.573) amongst all participants.

CONCLUSION

PFAS, in particular PFOA and PFHxS, in pregnancy are associated with altered patterns of GWG and postpartum adiposity with potential implications for fetal development and long-term maternal cardiometabolic health.

Metals and per- and polyfluoroalkyl substances mixtures and birth outcomes in the New Hampshire Birth Cohort Study: Beyond single-class mixture approaches

We aimed to investigate the joint, class-specific, and individual impacts of (i) PFAS, (ii) toxic metals and metalloids (referred to collectively as "metals"), and (iii) essential elements on birth outcomes in a prospective pregnancy cohort using both established and recent mixture modeling approaches. Participants included 537 mother-child pairs from the New Hampshire Birth Cohort Study. Concentrations of 6 metals and 5 PFAS were measured in maternal toenail clippings and plasma, respectively. Birth weight, birth length, and head circumference at birth were abstracted from medical records. Joint, index-wise, and individual associations of the metals and PFAS concentrations with birth outcomes were evaluated using Bayesian Kernel Machine Regression (BKMR) and Bayesian Multiple Index Models (BMIM). After controlling for potential confounders, the metals-PFAS mixture was associated with a larger head circumference at birth, which was driven by manganese. When using BKMR, the difference in the head circumference z-score when changing manganese from its 25th to 75th percentiles while holding all other mixture components at their medians was 0.22 standard deviations (95% posterior credible interval [CI]: -0.02, 0.46). When using BMIM, the posterior mean of index weight estimates assigned to manganese for head circumference z-score was 0.72 (95% CI: 0, 0.99). Prenatal exposure to the metals-PFAS mixture was not associated with birth weight or birth length by either BKMR or BMIM. Using both traditional and new mixture modeling approaches, prenatal exposure to manganese was associated with a larger head circumference at birth after accounting for exposure to PFAS and multiple toxic and essential metals.

Systematic review and meta-analysis of birth weight and PFNA exposures

We used a systematic review that included risk of bias and study sensitivity analysis to identify 34 studies examining changes in birth weight (BWT) in relation to PFNA biomarker measures (e.g., maternal serum/plasma or umbilical cord samples). We fit a random effects model of the overall pooled estimate and stratified estimates based on sample timing and overall study confidence. We conducted a meta-regression to further examine the impact of gestational age at biomarker sample timing. We detected a -32.9 g (95%CI: -47.0, -18.7) mean BWT deficit per each ln PFNA increase from 27 included studies. We did not detect evidence of publication bias (p_E = 0.30) or between-study heterogeneity in the summary estimate (p_Q = 0.05; I² = 36%). The twelve high confidence studies yielded a smaller pooled effect estimate (β = -28.0 g; 95%CI: -49.0, -6.9) than the ten medium (β = -39.0 g; 95%CI: -61.8, -16.3) or four low (β = -36.9 g; 95%CI: -82.9, 9.1) confidence studies. The stratum-specific results based on earlier pregnancy sampling periods in 11 studies showed smaller deficits (β = -22.0 g; 95%CI: -40.1, -4.0) compared to 10 mid- and late-pregnancy (β = -44.2 g; 95%CI: -64.8, -23.5) studies and six post-partum studies (β = -42.9 g; 95%CI: -88.0, 2.2). Using estimates of the specific gestational week of sampling, the meta-regression showed results consistent with the categorical sample analysis, in that as gestational age at sampling time increases across these studies, the summary effect estimate of a mean BWT deficit got larger. Overall, we detected mean BWT deficits for PFNA that were larger and more consistent across studies than previous PFAS meta-analyses. Compared to studies with later sampling, BWT deficits were smaller but remained sizeable for even the earliest sampling periods. Contrary to earlier meta-analyses for PFOA and PFOS, BWT deficits that were detected across all strata did not appear to be fully explained by potential bias due to pregnancy hemodynamics from sampling timing differences.

Mixtures of environmental contaminants and diabetes

BACKGROUND

Many studies have been published on the relationships between different environmental contaminants and diabetes. In these studies, the environmental contaminants have most often been evaluated one by one, but in real life we are exposed to a mixture of contaminants that interact with each other.

OBJECTIVE

The major aim of this study was to see if a mixture of contaminants could improve the prediction of incident diabetes, using machine learning.

METHODS

In the Prospective Investigation of the Vasculature in Uppsala (PIVUS) study (988 men and women aged 70 years), circulating levels of 42 contaminants from several chemical classes were measured at baseline. Incident diabetes was followed for 15 years. Six different machine-learning models were used to predict prevalent diabetes (n = 115). The variables with top importance were thereafter used to predict incident diabetes (n = 83).

RESULTS

Boosted regression trees performed best regarding prediction of prevalent diabetes (area under the ROC-curve = 0.70). Following removal of correlated contaminants, the addition of nine selected contaminants (Cd, Pb, Trans-nonachlor the phthalate MiBP, Hg, Ni, PCB126, PCB169 and PFOS) resulted in a significant improvement of 6.0 % of the ROC curve (from 0.66 to 0.72, p = 0.018) regarding incident diabetes (n = 51) compared with a baseline model including sex and BMI when the first 5 years of the follow-up was used. No such improvement in prediction was seen over 15 years follow-up. The single contaminant being most closely related to incident diabetes over 5 years was Nickel (odds ratio 1.44 for a SD change, 95 % CI 1.05-1.95, p = 0.022).

CONCLUSION

This study supports the view that machine learning was useful in finding a mixture of important contaminants that improved prediction of incident diabetes. This improvement in prediction was seen only during the first 5 years of follow-up.

Per- and polyfluoroalkyl substances and psychosocial stressors have a joint effect on adverse pregnancy outcomes in the Atlanta African American Maternal-Child cohort

BACKGROUND

African Americans (AAs) experience high rates of adverse pregnancy outcomes relative to Whites. Differential in utero exposure to environmental chemicals and psychosocial stressors may explain some of the observed health disparities, as exposures to per- and polyfluoroalkyl substances (PFAS) and experiences of discrimination have been linked to adverse birth outcomes. Few studies have examined chemicals and non-chemical stressors together as an exposure mixture, which may better reflect real-life exposure patterns. Here, we adapted methods designed for the analysis of exposure mixtures to examine joint effects of PFAS and psychosocial stress on birth outcomes among AAs.

METHODS

348 participants from the Atlanta African American Maternal-Child cohort were included in this study. Four PFAS were measured in first trimester serum samples. Self-report questionnaires were administered during the first trimester and were used to assess psychosocial stress (perceived stress, depression, anxiety, gendered racial stress). Quantile g-computation and Bayesian kernel machine regression (BKMR) were used to estimate the joint effects between PFAS and psychosocial stressors on gestational age at delivery and birthweight for gestational age z-scores. All models were adjusted for maternal education, maternal age, parity, and any alcohol, tobacco and marijuana use.

RESULTS

Our analytic sample included a socioeconomically diverse group of pregnant women, with 79 % receiving public health insurance. In quantile g-computation models, a simultaneous one-quartile increase in all PFAS, perceived stress, depression, anxiety, and gendered racial stress was associated with a reduction in birthweight z-scores (mean %change per quartile increase = -0.24, 95 % confidence interval = -0.43, -0.06). BKMR similarly showed that increasing all exposures in the mixture was associated with a modest decrease in birthweight z-scores, but not a reduced length of gestation.

DISCUSSION

Using methods designed for analyzing exposure mixtures, we found that a simultaneous increase in in utero PFAS and psychosocial stressors was associated with reduced birthweight for gestational age z-scores.

Principal Component Pursuit for Pattern Identification in Environmental Mixtures

BACKGROUND

Environmental health researchers often aim to identify sources or behaviors that give rise to potentially harmful environmental exposures.

OBJECTIVE

We adapted principal component pursuit (PCP)-a robust and well-established technique for dimensionality reduction in computer vision and signal processing-to identify patterns in environmental mixtures. PCP decomposes the exposure mixture into a low-rank matrix containing consistent patterns of exposure across pollutants and a sparse matrix isolating unique or extreme exposure events.

METHODS

We adapted PCP to accommodate nonnegative data, missing data, and values below a given limit of detection (LOD). We simulated data to represent environmental mixtures of two sizes with increasing proportions <LOD and three noise structures. We applied PCP-LOD to evaluate its performance in comparison with principal component analysis (PCA). We next applied principal component pursuit with limit of detection (PCP-LOD) to an exposure mixture of 21 persistent organic pollutants (POPs) measured in 1,000 U.S. adults from the 2001-2002 National Health and Nutrition Examination Survey (NHANES). We applied singular value decomposition to the estimated low-rank matrix to characterize the patterns.

RESULTS

PCP-LOD recovered the true number of patterns through cross-validation for all simulations; based on an a priori specified criterion, PCA recovered the true number of patterns in 32% of simulations. PCP-LOD achieved lower relative predictive error than PCA for all simulated data sets with up to 50% of the data <LOD. When 75% of values were <LOD, PCP-LOD outperformed PCA only when noise was low. In the POP mixture, PCP-LOD identified a rank-three underlying structure and separated 6% of values as extreme events. One pattern represented comprehensive exposure to all POPs. The other patterns grouped chemicals based on known structure and toxicity.

DISCUSSION

PCP-LOD serves as a useful tool to express multidimensional exposures as consistent patterns that, if found to be related to adverse health, are amenable to targeted public health messaging. https://doi.org/10.1289/EHP10479.

Healthy eating index and diet diversity score as determinants of serum perfluoroalkyl acid (PFAA) concentrations in a national survey of Swedish adolescents

Food is an important source of perfluoroalkyl acid (PFAA) exposure for the general adult population, but few data exist for adolescents. Healthy food habits established during adolescence may positively influence health later in life. Associations between serum PFAA concentrations and a healthy eating index (SHEIA15), as well as a diet diversity score (RADDS), were determined in a nationally representative adolescent population from Sweden (Riksmaten Adolescents 2016-2017, RMA). Using consumption data from food registrations and frequency questionnaires, we additionally analyzed associations with commonly consumed food groups. Associations were analyzed by fitting a cumulative probability model using ordinal regression. Among the seven PFAAs detected in ≥70% of the 1098 participants (age 10-21 years), median concentrations ranged from <1 ng/g serum of perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), perflurorundecanoic acid (PFUnDA), linear (lin-) perfluorohexanesulfonic acid (PFHxS) and branched (br-) perfluorooctanesulfonic acid (PFOS) to 1-2 ng/g serum of lin-perfluorooctanoic acid (PFOA) and lin-PFOS. PFNA, PFDA, PFUnDA and lin-PFOS concentrations were positively associated with both SHEIA15 and RADDS, a finding most likely driven by higher consumption of seafood. PFDA, PFUnDA and lin-PFOS concentrations were positively related to commonly consumed fish/shellfish groups, such as lean marine fish and shellfish. Inverse associations between PFAA concentrations and dairy consumption suggest an underlying factor behind dairy consumption that similarly affects adolescent exposure to the different PFAAs. Isomeric differences in dietary exposure between lin-PFOS and br-PFOS were suggested, as br-PFOS concentrations, in contrast to lin-PFOS, were not associated with SHEIA15, RADDS and consumption of different food groups. We conclude that Swedish adolescents, adhering to a diverse and healthy diet, appears to be more highly exposed to legacy PFAAs than those eating less healthy. Additional research is necessary for a better understanding of the health implications of healthy eating from a PFAA exposure perspective.

Exposure to phthalates in early pregnancy and the risk of fetal growth restriction: a nested case-control study in a Zhuang Chinese population

Phthalates (PAEs) are common endocrine disrupting chemicals (EDCs) that disrupt fetal development. The present study aimed to evaluate the effects of single and coexposure to phthalates in early pregnancy on fetal growth restriction (FGR) by a nested case-control study based on the Guangxi Zhuang Birth Cohort (GZBC). Maternal serum concentrations of seven phthalates in 97 neonates with FGR and 291 matched controls were detected through gas chromatography-mass spectrometry (GC-MS). The associations between phthalates and FGR were analyzed using multiple logistic regression, weight quantile sum (WQS) regression, and Bayesian kernel machine regression (BKMR) models. We found that exposures to butyl-benzyl phthalate (BBP, OR_adj = 1.849, 95% CI: 1.080-3.177, P_adj = 0.025, P_trend = 0.046), di (2-ethyl-hexyl) phthalate (DEHP, OR_adj = 3.893, 95% CI: 1.305-11.910, P_adj = 0.015, P_trend = 0.098) and dimethyl phthalate (DMP, OR_adj = 1.722, 95% CI: 1.089-2.725, P_adj = 0.020, P_trend = 0.002) were significantly positively associated with the risk of FGR, while mono-butyl phthalate (MBP) showed a significant negative association with FGR (OR_high = 0.192, 95% CI: 0.036-0.795, P_adj = 0.033, P_trend = 0.035) only among girls. The WQS model identified that BBP, di(2-ethyl)phthalate (DEP), DMP, DEHP, di-n-butyl phthalate (DBP), and MBP were highly weighted in the association with FGR. The BKMR model supported the positive association between joint exposure to phthalates and the risk of FGR and identified no significant interaction between the seven phthalates. Overall, maternal exposure to BBP, DEHP, and DMP may cause adverse effects on FGR, especially with combined effects.

Per-and polyfluoroalkyl substances (PFAS) and persistent chemical mixtures in dust from U.S. colleges

Indoor spaces contain several classes of persistent organic chemicals, including per- and polyfluoroalkyl substances (PFAS), polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs), and organochlorine pesticides (OCPs). However, concentrations of PFAS and persistent chemical mixtures and their associations with building characteristics on college campuses are understudied. We collected dust from 43 nonresidential spaces on four U.S. college campuses in 2016 and evaluated associations of room characteristics (carpeting, upholstered furniture, and years since last furnished) with dust concentrations of PFAS, PBDEs, PCBs, and OCPs. Nine PFAS, twelve PBDEs, two PCBs, and four OCPs were each detected in at least 75% of the spaces, including several chemicals (e.g., DDT) that have been banned for decades. Concentrations were correlated within and, in some cases, between chemical classes. Wall-to-wall carpeting (compared to rooms without wall-to-wall carpeting) was associated with higher concentrations of six individual PFAS and a mixture of PFAS, and the number of pieces of upholstered furniture was associated with increased concentrations of a mixture of PBDEs. These findings indicate that carpeting and furniture are current sources of PFAS and PBDEs, respectively. Building and finish materials should be carefully selected to avoid exposure to persistent chemicals.