Pre- and Postnatal Exposure to Polychlorinated Biphenyls and Cognitive Development in Early Childhood Open Access

Abstract

Prior cohort studies suggest that exposure to polychlorinated biphenyls (PCBs) may hinder cognitive development. The aim of this study was to determine if perinatal exposure to PCBs affects behavior and intelligence in children at age 45 months. We sampled 438 mother-child pairs from a birth cohort conducted in a highly exposed district in the Slovak Republic. Mothers in our population had a median PCB 153 serum level of 1.73 ng/ml. Prenatal exposure was estimated as maternal PCB 153, the most abundant congener, and PCB 118, the most abundant mono-ortho dioxin-like congener. Children's body burdens of PCB 153 and 118 were measured at 16- and 45-months. At 45-months, mothers completed the Child Behavior Checklist ages 1 ½ - 5 (CBCL), which is used to identify behavioral problems. Children completed five subtests of the Wechsler Preschool and Primary Scale of Intelligence (WPPSI-III), which is an intelligence test. Negative binomial and multiple linear regression analyses were used to measure the associations between PCB exposure and CBCL syndrome score or WPPSI-III subtest score, respectively. After adjusting for potential confounders, increased anxious/depressed behavior problems were reported more frequently among children more highly exposed to PCB 153 and 118 (exponentiated beta coefficients representing a change in score for a 1-unit increase in PCB; PCB 153: 1.04, 95% confidence interval (CI): 1.0, 1.1; PCB 118: 1.4, 95% CI: 1.1, 1.9). Other associations between 16- or 45-month PCB exposure and cognitive outcomes were null. Maternal exposure to PCB 153 and 118 was not associated with any of the 14 outcomes. Perinatal exposure in a highly exposed population did not appear to substantially affect cognitive development at 45-months; however, internalizing behaviors, as found on the anxious/depressed syndrome scale, may be more affected by exposure than intelligence and other behaviors.

Table of Contents

Table of Contents

Chapter 1: Literature Review .................................................... 1

Introduction ........................................................................... 1 Cognitive Testing .................................................................... 4

Probable Risk and Protective Factors .......................................... 5

Cohort Studies of the Effects of PCB Exposure .............................. 7

Summary .............................................................................. 20

Present Study: Slovakia Cohort ................................................. 22

References ............................................................................ 26 Table 1.1 .............................................................................. 33

Chapter 2: A Cohort Study of Perinatal Exposure to Polychlorinated

Biphenyls and Cognitive Development at 45 Months ....................... 38

Introduction .......................................................................... 39 Methods ............................................................................... 41 Results ................................................................................. 46 Discussion ............................................................................. 50 References ............................................................................ 55 Table 2.1 .............................................................................. 60 Table 2.2 .............................................................................. 62 Table 2.3 .............................................................................. 64 Table 2.4 .............................................................................. 65 Table 2.5 .............................................................................. 66

Appendix A. IRB Letter of Exemption ......................................... 67

About this Master's Thesis

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School	Rollins School of Public Health
Department	Epidemiology
Degree	MPH
Submission	Master's Thesis
Language	English
Research Field	Health Sciences, General
Keyword	Child Behavior Checklist Wechsler Preschool and Primary Scale of Intelligence Cognitive development Polychlorinated biphenyls Perinatal exposure
Committee Chair / Thesis Advisor	Howards, Penelope, Emory University
Partnering Agencies	Does not apply (no collaborating organization)

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