Dietary exposure to metal mixtures throughout infants' first year of life in the New Hampshire Birth Cohort Study

Abstract

BACKGROUND AND AIM: Recent reports have raised concerns about infants’ exposure to metals and metalloids (here, “metals”) via their first solid foods. Although early exposure to metals may cause lifelong health effects, epidemiologic studies on infants' dietary exposure to metal mixtures are still scarce. We aimed to assess the impact of diet on urinary metal concentrations over the first year of life among 348 children from the New Hampshire Birth Cohort Study. METHODS: We used inductively coupled plasma mass spectroscopy (ICP-MS) to measure infant urinary arsenic speciation, cadmium, cobalt, chromium, copper, iron, mercury, manganese, molybdenum, lead, antimony, selenium, uranium, vanadium and zinc concentrations. Caregivers completed a 3-day food diary before infant urine collection at 6 weeks and 4, 6, and 12 months of age. RESULTS:We determined the weights of each metal and the impact of the mixture at 6 weeks and 12 months of age. Using quantile g-computation we found that urinary concentration of arsenic, molybdenum and cobalt increased from ~6 weeks to 12 months of age, and that urinary selenium and copper decreased. We observed similar findings in a subset of infants (n = 19) during weaning from 4 to 6 months of age. We are now focusing on identifying specific groups of foods responsible for these changes. CONCLUSIONS:Determining dietary contributors to infants’ exposure to potential harmful metals is a critical step in preventing their long-term consequences. KEYWORDS: mixture, heavy metals, food, biomarkers of exposure