Joint Effects of Air Pollution Mixtures and Psychosocial Factors on Child Psychopathology in a South African Birth Cohort Restricted; Files Only

Christensen, Grace (Fall 2023)

Permanent URL: https://etd.library.emory.edu/concern/etds/2b88qd543?locale=zh
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Abstract

Risk of childhood psychopathology is complex and includes both environmental and social risk factors. A majority of the current literature on psychosocial stress and air pollution’s effect on child psychopathology focuses on outdoor air pollution exposure and stress in high-income countries with relatively low exposures. Very little is known about the effects of indoor air pollution (IAP), especially in low- and middle-income countries where many children and pregnant women are exposed to high levels of IAP as well as psychosocial stressors.

The overarching goal of this dissertation is to investigate the individual and joint effects of prenatal and early-life exposure to IAP mixtures and psychosocial factors (PF) on child psychopathology. We leverage data from a unique birth cohort from South Africa, the Drakenstein Child Health Study.

AIM 1: We investigated the effect of prenatal exposure to IAP and PFs on trajectories of childhood psychopathology symptoms at 24, 42, and 60 months. We found externalizing behavior trajectory was associated with particulate matter and smoking, while internalizing behavior trajectory was associated with volatile organic compounds.

AIM 2: We investigated the pre- and early postnatal periods as sensitive periods of exposure to IAP and PFs on childhood psychopathology at 6.5 years. Prenatal exposure to IAP and PFs, as well as the total prenatal mixture was associated with increased psychopathology. Analyses also indicated that the prenatal period is a sensitive period for IAP exposure, while PFs, including depression and alcohol, were associated with childhood psychopathology in both periods.

AIM 3: We investigated inflammation during infancy as a potential mediator of the association between prenatal exposure to IAP and PFs and childhood psychopathology. IAPs were associated with increased inflammation, while the association with PFs did not have a consistent pattern. We did not find evidence of mediation by inflammatory markers, possibly due to the small sample size and evidence of effect modification by HIV status and ancestry.

Overall, our findings add evidence that prenatal exposure to IAPs and PFs are associated with psychopathology during childhood. These findings can be used to target interventions to reduce exposure to IAPs and PFs and prevent childhood psychopathology.

Table of Contents

Chapter 1 : Introduction and Background. 1

Overarching Goal and Specific Aims. 1

Background. 3

Childhood Psychopathology. 3

Indoor Air Pollution. 4

Maternal Psychosocial Factors. 8

Joint Effects of Air Pollution and stress. 11

Biological Pathways and Inflammation. 12

Critical Periods of Exposure. 13

Data Source. 14

Chapter 2 : Joint Effects of Indoor Air Pollution and Maternal Psychosocial Factors During Pregnancy on Trajectories of Early Childhood Psychopathology. 15

Abstract 16

Introduction. 17

Methods. 19

Data Source. 19

Indoor Air Pollution Assessment 20

Assessment of Psychosocial Factors. 21

Outcome Assessment 21

Statistical Analysis. 22

Results. 29

Study Population. 29

Trajectories. 32

Single-exposure models. 33

Joint effects models. 34

Sensitivity analyses. 45

Discussion. 49

Chapter 3 : Sensitive periods for exposure to indoor air pollutants and psychosocial factors in association with symptoms of psychopathology at school-age in a South African birth cohort 54

Abstract 55

Introduction. 57

Methods. 60

Study Population. 60

Exposure Assessment 60

Outcome Assessment 62

Statistical Analysis. 63

Sensitive Periods of Exposure. 70

Results. 71

Study Population Characteristics. 71

Prenatal Exposure Analyses. 73

Postnatal Exposure Analyses. 89

Sensitive Period Analyses. 90

Discussion. 108

Chapter 4 : Joint Effects of Prenatal Exposure to Indoor Air Pollution and Psychosocial Factors on Early Life Inflammation. 115

Abstract 116

Introduction. 118

Methods. 120

Study Population. 120

Indoor Air Pollution Assessment 121

Assessment of Psychosocial Factors. 122

Assessment of Inflammatory Markers. 122

Statistical Analysis. 124

Results. 129

Single-Exposure Analyses. 131

Joint Effects Analyses. 140

Discussion. 145

Chapter 5 : Mediation of the prenatal indoor air pollution and psychosocial factor association with CBCL at 6.5 years by inflammation at 6 weeks old. 149

Introduction. 150

Methods. 151

Study Population. 151

Outcome Assessment 155

Statistical Analysis. 155

Results. 159

Exposure-Outcome Analyses. 159

Mediator-Outcome Analyses. 168

Mediation Analyses. 170

Discussion. 174

Chapter 6 : Summary of Findings, Future Directions. 177

Summary of Findings. 177

Overall Findings. 177

Findings from AIM 1. 178

Findings from AIM 2a. 179

Findings from AIM 2b. 180

Findings from AIM 3a. 181

Findings from AIM 3b. 181

Strengths and Limitations. 182

Strengths. 182

Limitations. 183

Future research. 184

References 186

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