Environment/Climate Change
Longitudinal patterns and predictors of urinary organophosphate ester metabolite concentrations from gestation through childhood in the MIREC Cohort Yohane Vincent Abero Phiri* Yohane Vincent Abero Phiri Phiri Phiri Phiri Phiri Phiri Phiri Phiri Phiri Phiri Phiri Phiri Phiri Phiri Phiri Phiri Phiri Phiri Department of Epidemiology and Biostatistics, School of Public Health, University of Nevada, Las Vegas, NV, USA.
Background: Organophosphate esters (OPEs) are ubiquitous flame-retardant replacements, yet longitudinal exposure patterns remain unclear; thus, we aimed to identify the determinants of early-life OPE exposure trajectories.
Methods: Urinary OPE metabolites were quantified in the Maternal-Infant Research on Environmental Chemicals (MIREC) cohort characterizing longitudinal exposure patterns. We measured concentrations of bis(2-chloroethyl) phosphate (BCEP), bis(1-chloro-2-propyl) phosphate (BCIPP), bis(1,3-dichloro-2-propyl) phosphate (BDCIPP), di-n-butyl phosphate (DNBP), and diphenyl phosphate (DPHP) at 6-13 and 16-21 weeks of gestation and at ages 2-5 and 7-9 years, adjusting for specific gravity. Temporal variability was assessed using random-intercept linear mixed-effects models with intraclass correlation coefficients (ICCs). We also used Spearman correlations to evaluate cross-time and cross-metabolite associations, latent class growth analysis (LCGA) to identify longitudinal exposure trajectories, and logistic regression to identify predictors of high-exposure trajectories.
Results: Urinary OPE levels were 1.8-14 times higher in childhood than during gestation, with prenatal reproducibility strongest for BCEP, BCIPP, and BDCIPP (ICCs: 0.63-0.70), moderate for DPHP (0.45-0.51), and low for DNBP (0.21-0.25), whereas childhood and prenatal-childhood ICCs were uniformly low (0.02-0.19). LCGA identified two distinct patterns per metabolite including a reference trajectory increasing from low concentrations and either a high-stable or early-peak prenatal trajectory. Predictors of the elevated trajectory included older maternal age, higher parity, smoking, female child sex, and lower household income.
Conclusion: Distinct trajectories and predictors revealed longitudinal variability and weak prenatal-childhood correlations in OPE exposures, highlighting the value of MIREC’s repeated childhood measurements for capturing dynamic exposure patterns.