Environment/Climate Change
Prenatal exposure to Organophosphate Ester Flame Retardant and Child Cognition at Age 4-6 years: The Environmental influences on Child Health Outcomes (ECHO) Cohort Akhgar Ghassabian* Akhgar Ghassabian Taylor Etzel Jennifer L. Ames Thomas G. O’Connor Jessie P Buckley Sarvenaz Shahin Julie B. Herbstman Emily S Barrett Donghai Liang Lisa A. Croen Rebecca J. Schmidt Lesliam Quiros-Alcala Susan L Schantz Kristen Lyall Giehae Choi Courtney Carignan Tracey J. Woodruff Rachel Morello-Frosch Claudia Buss Kurunthachalam Kannan Deborah H. Bennet
Despite experimental evidence showing developmental neurotoxicity of organophosphate esters (OPEs) flame retardants and plasticizers, epidemiological data are sparse. We examined associations between prenatal exposure to OPEs and child cognition and tested if associations differed by child sex.
We used data from 831 mother-child pairs from 3 sites in the Environmental influences on Child Health Outcomes Cohort with data on gestational urinary OPE metabolites and child cognition (pregnancies 2009-2019). We used 9 dilution-standardized OPE biomarkers modeled as log2-transformed for detection>75%, categorical (high, low, or non-detect) for detection 50-75%, or detect/non-detect binary variables for detection<50%. Children’s cognition was measured using the Wechsler Preschool and Primary Scale of Intelligence or Wechsler Intelligence Scale for Children at mean age 5.7 years (SD=0.7). We examined associations of OPE biomarkers with age- and sex-standardized cognition scores using linear regression with generalized estimating equations to account for clustering within cohorts. We tested for effect measure modification by sex.
The OPE biomarkers with the highest detection rates were: diphenyl phosphate (DPHP) (96.4%), the composite of dibutyl phosphate and di-isobutyl phosphate (85.7%), and bis(1,3-dichloro-2-propyl) phosphate (81.8%). A unit increase in log2(DPHP) was associated with a 0.46 point lower cognition score (95%CI: -0.90, -0.02). Detectable concentrations for bis(1-chloro-2-propyl) phosphate (BCPP) and bis(2-methylphenyl) phosphate (BMPP) (vs. non-detectable levels) were associated with higher cognition scores in males only (β=4.02, 95%CI: 1.25, 6.79 and 3.26, 95%CI: 0.34, 6.17, respectively). No other associations with other OPEs were observed.
Prenatal exposures to DPHP, a widely detected OPE, may be associated with slightly lower child cognitive functioning. Findings with less detected OPEs, i.e., BMPP and BCPP, in males need further investigation.