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Anti-malaria pesticides causing congenital disabilities

23 February 2017

Research by the University of Pretoria Institute for Sustainable Malaria Control (UP ISMC) has discovered that conventional methods for controlling malaria (DDT and other common insecticides) leads to endocrine disruption, which means that it interferes with hormones in the human body.

Worldwide, the use of dichlorodiphenyltrichloroethane, of DDT is controversial. “DDT is known to potentially cause health problems, but the exact effects of indoor residual spraying (IRS) were previously unknown,” explains director of the UP ISMC, Prof Tiaan de Jager. IRS is a programme to spray homes in South African malaria hotspots with insecticides to limit the transmission of the disease. An important focus area for the UP ISMC was to understand the developmental effects of constant exposure to insecticides. Its most recent research focused on 750 mothers and babies in Vhembe, Limpopo. The purpose of this study is to understand the effects of DDT exposure on children including birth difficulties, thyroid levels, and neurodevelopment during the first two years of life.

“There have been reports of poor reproductive health in the Vhembe area, which is why we chose this region and its community for our research,” adds Prof de Jager. In other similar research on new mothers and their babies, researchers found that DDT exposure leads to endocrine disruption. “This means DDT chemicals interfere with human hormones. And as a result, individuals experience a decrease in retinol binding protein, limiting vitamin A uptake with an effect on nutritional status,” advises Prof de Jager.

In addition to these effects, research uncovered that high concentration of environmental DDT impacts semen quality in young men, reducing fertility and leading to congenital disabilities. “Our researchers found that boys whose mothers were exposed to DDT spraying, showed a high rate of defects of the reproductive system,” adds Prof de Jager.

Another significant finding from yet another study in the area is that DDT and dichlorodiphenyldichloroethylene (DDE, a DDT breakdown product) levels in dust are an accurate measure of insecticide exposure in people who live in IRS areas. This knowledge will make future studies of DDT exposure simpler.

“We acknowledge that we are still dependent on the use of DDT and other pesticides, but we need to communicate, educate and make people aware of the potential risk,” advises Prof de Jager. “The use of DDT and other insecticides has contributed immensely to controlling malaria in South Africa. And after an alarmingly sharp rise in 2000, the incidence of malaria has significantly decreased due to a more efficient use of DDT and better access to anti-malarial drugs.”

Advice

People living in malaria regions where an IRS programme is used should allow spray workers to do their job. However, we recommend people ensure all food is covered safely or removed, close open water containers, pack clothing away and wait outside while spraying occurs. Post-spraying, try and ventilate the home.

For more info on the research, visit: http://www.researchmatters.up.ac.za/researcher-projects/view/48