Prenatal Organophosphate Pesticide Exposure and Neurodevelopmental Outcomes in a Thai Agricultural Birth Cohort Público

Matthews, Emilia Kristen (2014)

Permanent URL: https://etd.library.emory.edu/concern/etds/zk51vh626?locale=es
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Abstract

Recent research indicates low-level exposure to organophosphate (OP) pesticides during critical periods of development, particularly in utero, can have lasting neurotoxic effects. This study aimed to assess the relation between in utero OP pesticide exposure and neurologic integrity at birth, as measured by seven clusters on the Brazelton Neonatal Behavioral Assessment Scale (BNBAS). Trimester-resolved concentrations of urinary dialkylphosphate (DAP) metabolites (including diethylphosphates [DEPs] and dimethyl phosphates [DMPs]) of OP pesticides were measured to assess exposure to fetuses of tangerine farmworkers in Northern Thailand participating in a pilot birth cohort, the Study of Asian Women And their offSpring's Development and Environmental Exposures (SAWASDEE). Results from the SAWASDEE cohort indicate these infants are more highly exposed in utero to OP pesticides and perform less optimally on the BNBAS than two comparable U.S. birth cohorts, the Center for the Health Assessment of Mothers And Children of Salinas (CHAMACOS) cohort of California and the Mount Sinai Children's Environmental Health Cohort of New York. We observed inverse associations between total pregnancy ΣDAP and ΣDEP with Orientation (β = -5.10, 95% CI: -9.53, -0.68; β=-3.93, 95%CI: -7.86, 0.01, respectively) and Motor clusters (β = -2.92, 95% CI: -5.65, -0.19; β=-2.46, 95%CI: -4.87, -0.047, respectively), indicating poorer performance with increasing DAP metabolite concentrations. Second trimester metabolite concentrations showed stronger associations than total pregnancy metabolite concentrations (Orientation: ΣDAP β = -5.69, 95% CI: -9.69, -1.69; ΣDEP β = -4.66, 95% CI: -8.31, -1.01; Motor: ΣDAP β = -3.49, 95% CI: -5.78, -1.20; ΣDEP β = -3.06, 95% CI: -5.13, -0.99). A positive association between first trimester ΣDAP and ΣDMP with the Abnormal Reflex cluster was also observed (β = 0.91, 95% CI: 0.29, 1.61; β=0.99, 95%CI: 0.26, 1.71, respectively) indicating poorer performance with increasing DAP metabolite concentrations.These results are suggestive of a detrimental association between prenatal OP pesticide exposure and neurobehavioral functioning at birth, particularly on measures of attention, motor function, and abnormal reflexes. This study is the first to examine the impact of trimester-specific exposure to OP pesticides on neurodevelopment at birth using several measures of an exposure biomarker in a highly exposed agricultural population.

Table of Contents

I. BACKGROUND & SIGNIFICANCE…………………………………………1
A. Organophosphate Pesticides…………………………………….1
B. Prenatal Exposure…………………………………………………..2
C. Neurodevelopmental Effects………………………………….…2
D. Dialkyl phosphate Metabolites………………………………….3
E. SAWASDEE Birth Cohort…………………………………………5
F. Brazelton Neonatal Behavioral Assessment Scale……….6
II. METHODS……………………………………………………………...............8
A. Participants & Recruitment………………………………………8
B. Exposure Assessment………………………………………………9
C. Outcome Assessment……..………………………………………11
D. Aims and Hypotheses…………………………………………….12
E. Data Analysis……..…………………………………………………12
III. RESULTS…………………………………………………………...…………….14
A. Demographic Data…………………………………………………14
B. Exposure Distributions…………………………………………..15
C. Outcome Distributions…………………………………………..15
D. Logistic Regression………………………………………………..17
E. Linear Regression………………………………………………….17
F. Poisson Regression………………………………………………..18
G. Sensitivity Analysis………………………………………………..19

IV. DISCUSSION…………………………………………………………………….19
A. Interpretation of Results…………………………………………19
B. Limitations……………………………………………………………22
V. CONCLUSIONS & RECOMMENDATIONS……………………………25
A. Summary…………………………………………………………………………….25
B. Recommendations for Future Research………………………………….26
C. Policy Recommendations……………………………………………………..26
VI. REFERENCES…………………………………………………………………..28
VII. TABLES & FIGURES………………………………………………………….31
VIII. APPENDICES……………………………………………………………………45

A. Methods for Scoring the BNBAS……………………………..45
1. BNBAS Items……………………………………….45
2. BNBAS Scoring Form……………………………46
3. Seven Cluster Scoring Method……………….49
B. Logistic Regression Results…………………………………….50
C. IRB Approval…………………………………………………………54

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