Prenatal exposure to mixtures of persistent endocrine disrupting chemicals and postnatal body size in British girls

Abstract

Background: Endocrine disrupting chemical (EDC) exposure is ubiquitous. EDC exposure during critical windows of development may interfere with the body's endocrine system, affecting growth. Previous human studies have examined one EDC at a time in relation to infant growth. By studying mixtures, the human experience can be better approximated.

Aims: We investigated the association of prenatal exposure to persistent EDCs (per- and polyfluoroalkyl substances (PFAS), polychlorinated biphenyls (PCBs), and organochlorine pesticides (OCPs)) as mixtures with postnatal body size among female offspring.

Subjects: We used a sub-sample of the Avon Longitudinal Study of Parents and Children (N = 425), based in the United Kingdom.

Study design: We quantified 52 EDCs in maternal serum collected during pregnancy. We used Bayesian kernel machine regression with a random intercept to examine the association of prenatal concentrations of EDC mixtures with longitudinal postnatal body size measures for each EDC class separately (PFAS, PCBs, and OCPs) and for all three classes combined.

Outcome measures: Weight and height measures at 0, 2, 9, and 19 months were obtained by health professionals as part of routine child health surveillance.

Results: The mixture representing all three classes combined (31 chemicals) (n = 301) was inversely associated with postnatal body size. Holding all EDCs in the 31-chemical mixture at the 75th percentile compared to the 50th percentile was associated with 0.15 lower weight-for-age z-score (95% credible interval -0.26, -0.03). Weak inverse associations were also seen for height-for-age and body mass index-for-age scores.

Conclusions: These results suggest that prenatal exposure to mixtures of persistent EDCs may affect postnatal body size.

Keywords: ALSPAC; Early childhood growth; Organochlorine pesticide; Per- and polyfluoroalkyl substance; Polychlorinated biphenyl; Postnatal body size.

Figure 1.

Correlation heatmap of serum concentrations of persistent endocrine disrupting chemicals across women during pregnancy in the Avon Longitudinal Study of Parents and Children (N=425). Spearman correlation coefficients presented for untransformed distributions, sectioned according to per- and polyfluoroalkyl substances (PFAS), polychlorinated biphenyl (PCB), and organochlorine pesticide (OCP) group membership. PCB and OCP concentrations were lipid-adjusted.

Figure 2.

Chemical-specific effect estimates of mixture members on weight-for-age z-scores in ALSPAC mother-daughter dyads estimated by BKMR (n=301). Single chemical associations and 95% credible bands are presented with other chemicals fixed at their median. The model adjusted for maternal education, parity, pre-pregnancy body mass index, maternal age at delivery, prenatal smoking, age at measurement, and gestational week at sample collection. All chemical concentrations were natural log-transformed and standardized; PCB and OCP concentrations were lipid-adjusted.

Figure 3.

A Overall effect of the mixture on weight-for-age z-scores (estimates and 95% credible intervals), comparing the outcome when all exposures are at a particular quantile to the median (n=301). B Overall effect of the mixture on height-for-age z-scores (estimates and 95% credible intervals), comparing the outcome when all exposures are at a particular quantile to the median (n=300). C Overall effect of the mixture on body mass index (BMI)-for-age z-scores (estimates and 95% credible intervals), comparing the outcome when all concentrations are at a particular quantile to the median (n=300). Bayesian kernel machine regression models adjusted for maternal education, parity, pre-pregnancy body mass index, maternal age at delivery, prenatal smoking, age at measurement, and gestational age at sample collection, and used a random intercept to account for repeated measures at 0, 2, 9, and 19 months. All chemical concentrations were natural log-transformed and standardized; PCB and OCP concentrations were lipid-adjusted.