Early Life Exposure To Multiple Metals, Nutrition, and Growth in Children – A Scoping Review

Background: In utero and childhood exposure to toxic metals is associated with poor child growth, a predictor of adverse health outcomes. Most existing research focuses on exposure to single metals; the effects of metal mixtures largely remain understudied. Further, few studies consider how diet/nutrients interact with metal mixtures. Objective: To synthesize research on the relationship between in utero and childhood metal mixture exposures, nutritional status-metal exposure interactions, and child anthropometric outcomes. Methods: PubMed and Embase were used to search literature published in 2010–2023. Included studies consisted of at least two in utero or childhood toxic metal exposures and examined anthropometric parameters as their main outcomes. Included articles underwent full-text screenings. Information on exposures, findings, nutritional variables, and statistical methods was extracted. Results: After deduplication and title and abstract screening, 95 publications were included; 70 on prenatal growth and 25 on postnatal growth. Nutritional status/diet was assessed as an effect modifier in 4.3% studies on prenatal and 12% studies on postnatal growth. Birthweight (91.4%), and height and body mass index (64%) were common indicators of prenatal and postnatal growth, respectively. Finally, 41.4% of studies on prenatal and 20% on postnatal growth included statistical models that tested for mixture effects. Conclusion: Although many studies included multiple metals, their mixture effects largely remain untested. Additionally, inclusion of nutritional status/dietary intakes in statistical models is rare, highlighting the need for further research.