The promise and challenges of exposomics in child health research.

Childhood health is shaped by environmental exposures during sensitive windows of development. Longitudinal pregnancy and child cohorts have been designed to establish links between environmental exposures and child outcomes. The majority of studies focus on single exposures or groups of exposures and a specific health domain. The emerging field of exposomics aims to capture the totality of environmental exposures and through a multi-omics approach identify the biological response that mediates environmental triggers of health outcomes. Neighbourhood-level and individual-level environmental variables are measured by multidisciplinary methods to capture the exposome. Exposomics is in its infancy, but thus far a few multi-cohort projects have put this concept into practice and implemented a comprehensive measurement of the exposome during prenatal and early postnatal periods to determine associations with child health outcomes. Early findings have highlighted that children are exposed to a distinct collection of exposures in the womb and after birth and these development-specific exposures are associated with distinct molecular signatures. Exposomics has also proven useful in identifying the most important environmental drivers of child health and potential sources. Thus, this emerging field has the potential to inform public health interventions that promote healthy environments and identify the most vulnerable children. IMPACT: Discusses the emerging field of exposomics as a comprehensive approach to investigating environmental drivers of child health. Highlights current efforts to study the early life exposome and key findings. Identifies the value, challenges and limitations in exposomic research in child health.