The association of pre-natal exposure to polychlorinated biphenyls (PCBs) and thyroid function among children at 72 months in Slovakia Público

Abstract

Polychlorinated biphenyls (PCBs) are purported to be endocrine disruptors with notable molecular similarities in structure to thyroid hormones. In prior research, prenatal exposure to PCBs has been reported to affect markers of postnatal thyroid function in infants, especially levels of thyroxine (T4) and thyroid-stimulating hormone (TSH), but no study has investigated the long-term effect of prenatal PCB exposure on thyroid function in children. The aim of this study was to assess whether prenatal exposure to PCBs affects the levels of triiodothyronine (T3), T4, and TSH in children aged 72 months using a cohort of mother-child pairs from Slovakia (n=256). Prenatal PCB exposure was assessed using the concentration of PCB congener 153 in maternal blood serum collected shortly after giving birth. Total T3, total T4, free T3, free T4, and TSH concentrations were measured in the serum of the children at a follow-up visit conducted 72 months after delivery. Multiple linear regression analyses were fit to evaluate the associations between log maternal PCB levels (ng/ml) and log child thyroid hormone levels. After adjusting for potential confounders, no association was found between prenatal PCB exposure and any of the thyroid hormones in 72-month old children (beta and 95% confidence interval: T4 (nmol/L)=0.008, -0.019-0035; TSH (mIU/L)=-0.017, -0.110-0.075). Although prior studies have reported an association between prenatal PCB exposure and neonatal thyroid function, the null findings of the present study suggest that prenatal PCB exposure might not have a long-term effect on child thyroid hormone function.

Table of Contents

Chapter 1:

Literature Review....................................................................................1

Introduction ...........................................................................................1

Thyroid Function.....................................................................................2

Prenatal PCB Exposure and Endocrine Outcomes in Neonates...............4

Cohort Studies of Prenatal PCB Exposure and Infant Thyroid Hormones......5

Present Study: Slovakia Cohort ..............................................................8

Summary................................................................................................10

Works Cited............................................................................................11

Chapter 2:

A Cohort Study of Prenatal Exposure to Polychlorinated Biphenyls and Thyroid

Function at 72 Months ..........................................................................16

Introduction ..........................................................................................16

Methods.................................................................................................18

Results ...................................................................................................21

Discussion .............................................................................................22

Works Cited............................................................................................25

Table 1....................................................................................................30

Table 2....................................................................................................31

Table 3....................................................................................................32

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, Public Health Health Sciences, Epidemiology
Palavra-chave	thyroid organochlorines thyroxine Slovak cohort PCB triiodothryonine thyroid stimulating hormone endocrine system Polychlorinated biphenyls
Committee Chair / Thesis Advisor	Howards, Penelope, Emory University

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