Grant: Banting Postdoctoral Fellowship Program

Background: Studies have shown that exposure to neurotoxicants mixtures (i.e., exposure to many neurotoxicants like lead and arsenic at once) during pregnancy and within the first postnatal year might lead to poorer development of the offspring brain. Studies have also shown that these effects can be different depending on offspring sex. However, we don't know when within pregnancy and the first postnatal year neurotoxicant mixtures have their greatest effects on the brain, and if the timing of exposure to neurotoxicants differs depending on offspring sex. When baby teeth develop, they trap traces of neurotoxicants. Furthermore, baby teeth form like rings on a tree, therefore by analyzing baby teeth, we can determine when and how much of certain neurotoxicants a person was exposed to during pregnancy and into the first year of life. Therefore this study will provide the clearest picture to date of when neurotoxicant mixtures have their greatest impact on the developing brain. Objective 1: Examine the link between timing of a mixture of neurotoxicant exposures (including lead, mercury, arsenic, cadmium and manganese) and child IQ Objective 2: Examine if the effects of mixture timing on IQ differ depending on offspring sex. Methods: This research will use data from the Maternal-Infant Research on Environmental Chemicals cohort (MIREC) that includes data from pregnant women and their offspring across infancy and childhood. Neurotoxicant mixture timing will be measured by studying baby teeth (that have fallen out of the child's mouth). We will assess IQ using a standardized IQ test delivered by trained researchers. Significance: The proposed study will provide important evidence on our ability to measure the amount and the timing of neurotoxicant exposures, and examine their associations with offspring brain development. This study will also provide new evidence on whether certain time periods when the brain is most at risk differs depending on child sex.