Predictors of phthalate metabolites exposure among healthy pregnant women in the United States

Abstract

BACKGROUND AND AIM: Phthalate exposure varies by geographic region, race, sex, product use, and other factors. Exposure is associated with detrimental reproductive and developmental outcomes. Few studies consider sociodemographic differences in exposure through the course of pregnancy. We examined determinants of phthalate metabolites during pregnancy in a cohort of diverse nulliparous pregnant women. METHODS: We report on urinary metabolites of 4 parent phthalates: Butyl benzyl phthalate (BBzP - MBzP), Di-isobutyl phthalate (DiBP - MiBP), Diethyl phthalate (DEP - MEP), Di-(2-ethylhexyl) phthalate (∑DEHP) from urine collected up to three times (e.g. once in each trimester) from 960 women enrolled in the Nulliparous Mothers To Be Study. Phthalate metabolites were adjusted for specific gravity; concentrations below the limit of detection (LOD) were replaced with LOD/√2. We calculated the geometric mean of concentrations in each trimester for each metabolite. Generalized linear models examined characteristics that predicted average levels of phthalate metabolites. RESULTS:In the prediction model, maternal race and clinical site were significant predictors (p-value .0.05) for MiBP and MEP. Compared to non-Hispanic White women, higher concentrations of MiBP were found in Hispanic and Asian women, and higher concentrations of MEP was found in Asian women respectively. Metabolite concentration varied throughout the US. Women who received care at in sites in Illinois, California and Pennsylvania had lower MBzP concentration in comparison to women who received care in sites in Ohio. Women who received care in Illinois had higher MEP levels on average when compared to women who received care in Ohio. Lastly, women who received care in New York and Pennsylvania had higher DEHP concentration in comparison to women receiving care in Ohio. CONCLUSIONS:These findings suggest differences in exposure among heterogenous groups of women and indicate independent exposure patterns that may imply the need for interventions targeted toward specific groups to reduce exposure. KEYWORDS: Phthalates, predictors, environmental epidemiology