Exposomal research in the context of birth cohorts What have they taught us?

Objective: To review birth cohorts with an exposomal approach and their key outcomes and challenges. Exposome encompasses all human environmental exposures from conception onward. The impact of environmental exposures is greatest in critical stages of life, including fetal and early childhood. Birth co-horts provide a good study setting to assess exposome in the sensitive periods of life. Here, we review birth cohorts with an exposomal approach and their key outcomes and challenges. Data Sources: MEDLINE was searched for birth cohorts that have used an exposomal approach. Study Selections: Relevant studies in English language were selected and reviewed. Results: The outcomes of birth cohorts with an exposomal approach improve our understanding of the association between environmental exposures and childhood diseases. For example, results from The Canadian Healthy Infant Longitudinal Development Study suggest an association between first trimester exposure to traffic-related air pollution and increased risk of allergic sensitization at 12 months of age (P =.6). In a smaller Canadian birth cohort study, it was found that regular use of air fresheners (adjusted P =.04) and presence of mold in the residence (adjusted P <.001) were associated with early childhood wheezing and cough. The application of emerging molecular omics technologies and new analytical tools has facilitated the comprehensive assessment of exposome in birth cohorts. Conclusion: Birth cohort studies with an exposomal approach improve our understanding of the origin of childhood diseases by examining a complex network of environmental exposures during pregnancy and years beyond birth. International collaboration is required to develop large birth cohorts for better and more extensive assessment of exposome with standardized protocols and new statistical frameworks. (C) 2020 American College of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.