Organophosphate ester flame retardant exposure and perinatal outcomes

Abstract

Background and Aims: Following a phase out of PBDE flame retardants in the mid-2000s due to concerns about toxicity, exposure to organophosphate ester (OPFRs) flame retardants increased, leading to increasing concerns regarding the toxicity of OPFRs. We hypothesize that prenatal exposure to OPFRs adversely affects outcomes at birth. Our overarching hypothesis is that prenatal exposure to OPFRs flame retardant chemicals adversely affects outcomes at birth. We propose to quantify prenatal exposure to a suite of flame retardants utilizing maternal urine collected during pregnancy to address our specific aims: 1) examine exposure trends over calendar time, and 2) investigate associations with perinatal outcomes, specifically low birth weight, preterm birth, and small for gestational age. Methods: We quantify prenatal exposure utilizing a single maternal urine collected during pregnancy, quantifying 9 OPFRs: Dipropyl phosphate (DPRP), Dibutyl phosphate + Di-isobutyl phosphate (DBUP_DIBP), bis(butoxyethyl) phosphate (BBOEP), bis(2-ethylhexyl) phosphate (BEHP), Bis(2-chlorethyl) phosphate (BCETP), Bis(1-chloro-2-propyl) phosphate (BCPP), Bis(1,3-dichloro-2-propyl) phosphate (BDCPP), Diphenyl phosphate (DPHP), and bis(2-methylphenyl) phosphate (BMPP). The study sample includes over 7000 pregnancies from 19 ECHO cohorts over 9 states. Outcomes include gestational age (continuous and categorized to consider preterm birth), birth weight (continuous and categorized to consider low birth weight), birthweight for gestational age (continuous and categorized to consider small for gestational age). Key confounders expected to be associated with both exposures and outcomes based on prior literature include cohort, maternal age, socioeconomic status (measured by education, marital status, income, or related variables), race/ethnicity, BMI, and year of birth. Results: The following compounds were detected in over 85% of the samples: BDCPP, DBUP_DIBP, and DPHP, while BBOEP, BCETP, and BCPP were detected in over 50% of samples. DPHP had the highest geometric mean concentration of 1.0 ng/mL, followed by BDCPP (0.86 ng/mL). Analysis of associations between exposures and outcomes is underway.