Grant: Operating Grant

Half of the world is at risk for malaria. A total of 88 countries currently conduct Indoor Residual Spraying (IRS), the annual use of insecticides on the interior walls of residences to control malaria. Although recognized effective in curbing malaria, IRS exposes 120 million people to high levels of insecticides with poorly understood health consequences. Evidence from animal studies strongly suggests that exposure to insecticides commonly used for IRS, such as DDT (dichlorodiphenyl trichloroethane) and pyrethroids, may adversely impact the immune system. However, no studies have examined the potential effect of these insecticides on immune function in populations in which IRS is conducted. These populations are likely to be particularly susceptible to the toxic effects of insecticides due to poverty, malnutrition and poor health. Due to their limited detoxifying capabilities, children are believed to be most at risk. We propose to extend an existing U.S. National Institute of Environmental Health Sciences (NIEHS)-funded birth cohort study of 752 mother-child pairs taking place in South Africa to assess associations between prenatal exposure to IRS insecticides and 1) immune function and 2) allergic airway disease in children aged 3.5 and 5 years. This study will provide data to help define least-toxic strategies to malaria control. It will generate unique data on a question with global implications at limited costs due to a substantial investment ($US 3.6M) by NIEHS to initiate this study. Results also have national relevance since Canada indirectly funds IRS, and pyrethroid use in agriculture and consumer products in Canada is at its highest in history.