Tea consumption in pregnancy as a predictor of pesticide exposure and adverse birth outcomes: The MIREC Study

Abstract

IntroductionPesticide residues in tea may contribute to exposure during pregnancy; however, the impact on maternal and infant health is not well understood. The aim of this study was to determine whether tea intake in the first trimester was associated with elevated concentrations of various pesticides in maternal blood or urine. Further, we examined the relationship between tea consumption and adverse birth outcomes. MethodsData from the Maternal–Infant Research on Environmental Chemicals (MIREC) Study, a pan-Canada pregnancy cohort, were used. All singleton, live births (n=1898) with available biomarkers were included in the analyses. Descriptive statistics were used to characterize the population. The geometric means (GM) of organochlorine (OC) pesticide constituents or metabolites in maternal plasma (lipid adjusted) and organophosphate (OP) pesticide metabolites (adjusted for specific gravity) in maternal urine were calculated for participants who drank regular, green or herbal tea in the first trimester and for those who did not. Differences between groups were examined using chi-square or t-tests. Associations between frequency of drinking tea and adverse birth outcomes were examined using logistic regression (preterm birth and small-for-gestational-age) or generalized linear models (birthweight decile and head circumference). ResultsThe GM of the OC pesticide constituent trans-nonachlor was 2.74mg/g lipid, and for metabolites oxychlordane and p,p′-DDE this was 1.94ng/g lipid and 55.8ng/g lipid, respectively. OP pesticide metabolite concentrations adjusted for specific gravity, were dimethylphosphate (GM: 3.19µg/L), dimethylthiophosphate (GM: 3.29µg/L), dimethyldithiophosphate (GM: 0.48µg/L), diethlphosphate (GM: 2.46), and diethylthiophosphate (GM: 0.67µg/L). There was no significant difference in mean concentrations for these OC or OP pesticide constituents or metabolites between tea drinkers — of any type — and non-tea drinkers. Further, no association was found between tea intake and adverse birth outcomes. ConclusionsPesticide concentrations did not differ by tea intake. Further, tea intake in the first trimester was not associated with adverse birth outcomes. In this study population, there was no evidence for concern about tea intake being a source of the OP or OC pesticide metabolites measured or adversely affecting birth outcomes; however, tea intake was lower than national Canadian data for women of reproductive age.