Prenatal Phthalate Exposure and Performance on the Neonatal Behavioral Assessment Scale in a Thai, Agricultural Birth Cohort Público

Valenzuela, Connor (Spring 2018)

Permanent URL: https://etd.library.emory.edu/concern/etds/8c97kq430?locale=es
Published

Abstract

Background: Phthalates are endocrine disrupting chemicals (EDC) derived from phthalic acid and found in human tissues either as phthalate diesters or their monoester metabolites. Studies have demonstrated that phthalate exposure is associated with a number of adverse health outcomes, particularly in highly susceptible populations including pregnant women and children. Of interest is the effect that high phthalate exposure can have on neurodevelopment during critical development periods (i.e. infancy or prenatal exposure). Our objective was to evaluate prenatal environmental exposure to phthalates by measuring their monoester and oxidative metabolites in longitudinally collected urine samples and characterize their relation to infant neurodevelopment in a Thai pregnant farmworker population.

Methods: We performed analysis of de-identified pilot cohort data using linear regression models to evaluate the effect of prenatal phthalate exposure on infant neurodevelopment using the Neonatal Behavioral Assessment Scale (NBAS) among 10 Thai agricultural workers.

Results: In our limited cohort, we found inconclusive effects of prenatal phthalate exposure on infant development. Using linear regression, we observed a single significant association between average high molecular weight (HMW) phthalate exposure and decreased range of state average score (p=0.0346, R2 = 0. 5683). The results do not agree with current research, as no associations were found with low molecular weight (LMW) or high molecular weight (HMW) phthalates and any other domain average scores.

Conclusions: No conclusive protective or harmful effect of either LMW or HMW phthalates on NBAS outcomes was found in our analyses. Additional research with larger samples is needed to further examine these relationships and investigate both mechanisms by which phthalates can cause deficits in neurobehavioral assessment and which trimester of exposure has the greatest effect on infant neurodevelopment.

Table of Contents

Table of Contents

1 Introduction    ……………………………………………………………………………………1

2 Materials and Method    …………………………………………………………………………3

            2.1 SAWASDEE Pilot Cohort…………………………………………………………….3

            2.2 Exposure Assessment: Phthalate – Maternal Urine Samples  .….……………………4

            2.3 NBAS Outcomes………………………………………………………………………4

            2.4 Statistical Analyses …………………………………………………………………...5

3 Results …………………………………………………………………………………………...6

            3.1 Demographic Characteristics …………………………………………………………6

            3.2 Exposure .......…………………………………………………………………………6

            3.3 Outcome ……………………………………………………………………………....7

            3.4 Linear Regression Models…………………………………………………………….7

4 Discussion ……………………………………………………………………………………….8

            4.1 Limitations ……………………………………………………………………………9

5 Conclusions and Future Directions ……………………………………………………………...9

References ………………………………………………………………………………………..11

Tables …………………………………………………………………………………………….13

            Table 1: Phthalate Study Cohort Characteristics (n=10) ………………………………..13

            Table 2: Summary Statistics for Phthalate Concentration in Urine, Urine ng/mL ……...14

Table 3: Summary Statistics for Low Molecular Weight (LMW) Phthalate Concentration in Urine, Urine ng/mL  …………………………………………………………………..15

Table 4: Summary Statistics for Log Low Molecular Weight (LMW) Phthalate Concentration in Urine (Natural Log Transformed), Urine ng/mL ……………………..15

 

Table 5: Summary Statistics for High Molecular Weight (HMW) Phthalate Concentration in Urine, Urine ng/mL …………………………………………………………………...15

            Table 6: Summary Statistics - NBAS Outcomes …..........................................................16

            Table 7: Correlation Coefficients for Exposures with Covariates, (n=10) ……………...16

            Table 8: Spearman Correlation Coefficients for Covariates, (n=10) ……………………16

            Table 9: Spearman Correlation for Exposures with NBAS Outcomes ………………….17

            Table 10: Habituation Models …………………………………………………………..18

            Table 11: Orientation Models …………………………………………………………...19

            Table 12: Motor Models ………………………………………………………………...20

            Table 13: Range of State Models ………………………………………………………..21

            Table 14: Regulation of State Models …………………………………………………..22

            Table 15: Autonomic Stability Models ………………………………………………….23

            Table 16: Abnormal Reflex Models …....……………………………………………….24

            Table 17: NBAS Clusters ……………………………………………………………….25

Figures …………………………………………………………………………………………...26

            Figure 1: Generic structure of phthalate diesters and their monoester metabolite ……...26

            Figure 2: General phthalate metabolism ………………………………………………...26

Figure 3: Potential mechanism for weight as a confounder for the relationship between phthalate exposure and NBAS scores …………………………………………………...26

Figure 4 Potential mechanism for birth weight as an intermediate between phthalate exposure and NBAS scores ……………………………………………………………...27

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