Early Life Exposure to Chemical Mixtures: Implications for Neonatal Outcomes and Cognitive Ability

Kalloo, Geetika

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Year:: 2019
Contributor:: Kalloo, Geetika (creator); Braun, Joseph (Advisor); McCandless, Lawrence (Reader); Wellenius, Gregory (Reader); Brown University. Department of Epidemiology (sponsor)
Genre:: theses
Subject:: Epidemiology
Extent:: XI, 106 p.

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Abstract:: Given that exposure to mixtures of environmental chemicals among pregnant women are ubiquitous, potentially modifiable, and may increase the risk of adverse health outcomes during infancy and childhood, it is imperative to characterize the impact of chemical mixtures on health. To date, there have been relatively few investigations into the profiles and determinants of chemical mixtures found in pregnant women. In the first paper, we used two dimension reduction techniques and found that pregnant women in the United States are exposed to mixtures of environmental chemicals that can be characterized by distinct clusters and principal components. These clusters and principal components were associated with several sociodemographic, behavioral, lifestyle, and perinatal factors. This was one of the first studies conducted that investigated the patterns and profiles of chemical mixture exposure among pregnant women in the United States. Using the metrics of environmental chemical mixture exposure developed in the first paper, the second paper investigated the associations of chemical mixtures or individual chemicals with fetal growth, birth length, head circumference, and gestational duration. All methods of characterizing chemical mixture exposures in this cohort identified inverse associations of select organochlorine compounds, phenols, and cadmium with birth length, but not other neonatal outcomes. Additionally, chemicals included in these metrics of environmental chemical mixtures were associated with decreased birth length when examining associations one chemical at a time. The consistency between the two metrics of mixture exposure and individual chemical analysis suggests that these results are not method dependent and that prenatal exposure to specific chemical mixtures may be associated with neonatal development. In the third paper we examined differences in measures of children’s cognitive abilities associated with chemical mixtures using two metrics of aggregate exposure and individual biomarker concentrations. In this study, cluster membership reflecting combined exposure to As, Cd, Hg, certain phthalates, phenols, organochlorine compounds, organophosphate pesticides, and perfluoroalkyl substances was inversely associated with children’s cognitive abilities. However, individual chemical biomarker concentrations were generally not associated with measures of IQ, suggesting that the aggregate impact of these chemicals on cognitive abilities may be different from their individual effects.
Notes:: Thesis (Ph. D.)--Brown University, 2019

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Kalloo, Geetika, "Early Life Exposure to Chemical Mixtures: Implications for Neonatal Outcomes and Cognitive Ability" (2019). Epidemiology Theses and Dissertations. Brown Digital Repository. Brown University Library. https://repository.library.brown.edu/studio/item/bdr:1129505/

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Epidemiology Theses and Dissertations

Theses and Dissertations for the Epidemiology department.
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