Page 75 - University of Pretoria RESEARCH REVIEW 2018
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Linking children’s health outcomes
to insecticide exposure – a cohort study
Riana Bornman, UP Institute for Sustainable Malaria Control (UP ISMC)
It is estimated that more than 120 million people globally are exposed to insecticides that are used to control malaria mosquitoes. While indoor residual spraying may be effective in controlling mosquitoes, little is known of the potential side effects in humans.
The Venda Health Examination
of Mothers, Babies and their Environment (VHEMBE) is a birth cohort of 752 mother-child pairs in the Limpopo province, South Africa, that has tracked the health outcomes of babies as they develop, and related these health outcomes to in utero insecticide exposure. Professor Riana Bornman in the Faculty of Health Sciences and the UP ISMC, is the local principal investigator, and works with Dr Jonathan Chevier (McGill University, Canada), and Brenda Eskanazi (University of California, Berkeley, US).
The study is undertaken in an area close to the Mozambique and Zimbabwe borders, which has the highest malaria burden in South Africa, and where homesteads are routinely sprayed to control mosquitoes. The study measures associations between insecticide exposure and a number
of perinatal outcomes, aspects of child growth and maternal health. This intensive research project relies on the efforts of a local team from surrounding communities. The field office is based at the Tshilidzini Hospital in Thohoyandou, Limpopo.
In 2018, the group described
the environmental predictors of pyrethroid metabolites in maternal urine, published in Environmental Health Perspectives. Pyrethroid
metabolites are associated with the use of insecticides in and around the home, especially the spraying of yards and food stocks. Pyrethroid metabolite levels are also associated with a high fat diet. Interestingly, pyrethroid levels seemed to influence children’s growth. After 3,5 years, mothers who had higher levels of pyrethroid metabolites when their babies were delivered
had thinner children who were more prone to infection. These associations were stronger for children who lived
in poorer households, and whose mothers had inadequate calorie intake during pregnancy.
Cohort studies are incredibly rare in Africa and require long-term investment, with respect to finance, human resources and sustained
effort. The VHEMBE cohort study has produced valuable insights into the effects of insecticides on human health, and highlights the healthcare challenges experienced by mothers and children living in rural communities with significant environmental pressure.
Supported by the Canadian Institute of Health Research, the VHEMBE cohort study will continue to investigate
the impact of postnatal exposure to insecticides used to control malaria, and of air pollution on immune function and allergic airway disease. The excellent news is that child follow- up in the VHEMBE cohort has been extended from age 5 to 8 years.
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