Association between Pesticide Biomarkers and Reproductive and Thyroid Hormones in Pregnant Women

Abstract

Introduction: Prenatal exposure to pesticides may be associated with health effects, including changes in maternal hormone levels that could potentially lead to adverse birth outcomes. The association of pesticides with reproductive and thyroid hormones were examined in the first 44 pregnant women (86 observations) recruited for a large prospective cohort study in Puerto Rico. Methods: Serum hormone levels (estrogen, progesterone, sex hormone-binding globulin (SHBG), free triiodothyronine (FT3), free thyroxine (FT4) and thyroid stimulating hormone (TSH)) and urinary pesticide biomarkers (parathion, a pyrethyroid metabolite, three DEET metabolites, and five organophospohate (OP) metabolites) were measured at two visits during pregnancy (16-20 and 24-28 weeks). We used linear mixed models with a random intercept to examine associations between the exposure biomarkers and hormones, adjusting for specific gravity, visit, maternal age, BMI and education. All pesticide biomarkers, progesterone and TSH were log-transformed. Results: The only significant association among reproductive hormones was a 9.13% increase (95% CI 2.90, 15.36) in SHBG with an IQR increase in diethylthiophosphate (OP metabolite). An IQR increase across all DEET metabolites (3-(diethylcarbamoyl)benzoic acid (DCBA), N-ethyl-3-methyl-benzamide and N,N-diethyl-3-(hydroxymethyl)benzamide) was associated with a 5.45% (95% CI -10.61, -0.29), 3.32% (95% CI -6.36, -0.28) and 1.66% (95% CI -3.67, 0.35) decrease in FT3, respectively. The results also suggested a 15.90% (95% CI -1.48, 36.33) and a 19.64% (95% CI -2.60, 46.97) increase in TSH with an IQR increase in DCBA and the pyrethroid metabolite, respectively. Conversely, a 9.16% decrease (95% CI -18.19, 0.86) in TSH was observed with an IQR increase in dimethyldithiophosphate (OP metabolite). Conclusions: In this exploratory study, pyrethroid, DEET and OP were associated with SHBG, TSH and FT3 which may potentially lead to adverse health effects.