Dr. van Wijngaarden's primary research efforts have focused on the influence of environmental exposures on cognitive outcomes in children and adults. He leads the Seychelles Child Development Study (SCDS) which for over 30 years has investigated the impact of pre- and postnatal methylmercury exposure on child development, Current SCDS research investigates how prenatal nutritional factors and genetics influence associations between prenatal methylmercury exposure and developmental outcomes, and examines longitudinal associations of cumulative postnatal methylmercury exposure with neurodevelopment over 24 years of follow up.