Association of Prenatal Chlorpyrifos Exposure with Sexually Dimorphic Differences in Anogenital Distance Among Thai Farmworker Children Open Access

Dang, Thomas (Spring 2022)

Permanent URL: https://etd.library.emory.edu/concern/etds/2b88qd40r?locale=en
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Abstract

Pesticides are used globally, yet prenatal exposure can unknowingly impact infants and their adulthood health. There needs to be a better understanding of adverse effects following prenatal exposure to endocrine-disrupting chemicals (EDCs). Research has focused on organophosphate insecticides and their effect on the reproductive health of newborns after maternal exposure. Anogenital Distance (AGD) measurements measured during infancy can provide a noninvasive measurement and accessible end-point marker for male and female reproductive health at birth and adulthood. AGD can be an early predictor to better treat for reproductive health complications early in life to allow these children a healthy adulthood.

We attempt to answer the overarching question of whether trimester-specific or mean prenatal exposure across pregnancy to chlorpyrifos in Thai farmworker children, as measured by its primary urinary metabolite (TCPy), is associated with sex-specific anogenital distance at 12 months of age. We hypothesized that chlorpyrifos exposure in the first trimester and averaged over pregnancy will be associated with shorter AGD in males and longer ADG in females. Identifying early markers of reproductive development through AGD could clarify the biological associations between maternal exposure and reproductive function without confounding by the many postnatal contributors to reproductive health.

Exposure was assessed by measuring its primary urinary metabolite (TCPy). Analysis included linear exposure-outcome models: trimester-specific and average exposure over pregnancy adding in covariates identified a priori. Differences in effect based upon sex were evaluated because literature demonstrates sexually dimorphic adverse effects. Focus was primarily on prenatal exposure as this critical time window of 12 months is hypothesized to drive environmental-related disease outcomes in children.

Findings were consistent with previous studies further supporting that prenatal exposure to pesticides is associated with AGD measurements. Models were produced unadjusted and then adjusted for creatinine levels to correct for urine dilution, consistent with the literature. We generally observed reductions in AGD in males and increases in females. Generally, this was observed in trimester-specific models and overall pregnancy, supported by previous studies. By understanding the effects of exposure to infants, better protective policies can protect mothers while giving their baby the best chance to a healthy and happy life. 

Table of Contents

INTRODUCTION

I.     Organophosphate Pesticides and Chlorpyrifos

II.   Thailand Agriculture

III.  Chlorpyrifos Exposure and Toxicity

IV.  Anogenital Distance

V.   Purpose

VI.  Hypothesis and Main Question

METHODS

I.     Study Population and Sample Collection

II.   TCPy, Creatinine and PON Phenotpying Analysis

TCPy and Creatinine Analysis

Measurements of paraoxonase (PONase) and arylesterase (AREase)

III.  Statistical Analyses

RESULTS

I.     Demographics and Study Population

II.   TCPy Metabolite

III.  PON1 Phenotyping

IV.  Associations between TCPy metabolite and AGD

DISCUSSION

I.     Important Findings & Comparison to Other Studies

II.   Strengths and Limitations

III.  Policy Implications

CONCLUSION

TABLES AND FIGURES

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