Dietary guidelines adherence and pregnancy exposure to 10 classes of priority chemicals: an observational study in the Environmental influences on Child Health Outcomes Cohort

Background: Diet is a source of environmental toxicants; however, chemical exposures are not considered in the United States Dietary Guidelines for Americans (DGA). Objectives: We tested whether higher DGA adherence was associated with gestational chemical exposures. Methods: Pregnant participants in the Environmental influences on Child Health Outcomes Cohort completed a food frequency questionnaire or 24-h recall at a median of 21 wk of gestation, which we used to calculate the Healthy Eating Index (HEI)-2015 total and individual component scores to assess DGA adherence. In spot urine samples collected at a median of 22 wk of gestation, we measured 113 analytes representing 10 chemical classes, including insecticides, fungicides/herbicides, organophosphate esters (OPEs), halogenated phenols, benzophenones, bisphenols, parabens, antimicrobials, phthalates/alternatives, and polycyclic aromatic hydrocarbons (PAHs). Using Bayesian generalized linear mixed-effects regression, we estimated covariate-adjusted percentage differences (β; biomarkers with ≥70% detection) or detection risk ratios (biomarkers with 30%–69% detection) and 95% credible intervals (CrIs) in urinary chemical biomarker concentrations for each 10-point increase in HEI-2015 total score. We used quantile-based g-computation to identify the top HEI-2015 component contributors to associations. Results: Most participants (n = 1492) self-identified as non-Hispanic White (40%) or Black (36%), and 50% had incomes ≥$50,000. The median (25th, 75th percentile) HEI-2015 score was 61.9 points (53.6, 70.2; of 100). We detected 53 analytes, representing biomarkers of 45 chemical parent compounds, in >30% of participants. Higher HEI-2015 scores were associated with lower OPE, halogenated phenol, bisphenol, phthalate, and PAH biomarker concentrations, most notably monobenzyl phthalate (β: –13.5%; 95% CrI: –21.0%, –5.8%). However, higher HEI-2015 scores were also associated with higher insecticide, paraben, and benzophenone biomarker concentrations, most notably benzophenone-3 (β: 16.2%; 95% CrI: 5.9%, 26.8%). Lower added sugar and higher protein, vegetable, fruit, and whole-grain intake were consistent predictors of lower or higher chemical biomarker concentrations. Conclusions: Greater DGA adherence may minimize exposure to some, but not all, toxicants.