DDT is a controversial insecticide which was banned by most countries including Seychelles because of its impacts on human health and the environment. In this country it was removed from sale in the 1970’s. It is toxic to birds, fish and mammals. It builds up in the food chain and does not degrade in the environment for many years. DDT exposure has been linked to a series of health problems from nerve damage to cancer.
But recently the World Health Organization has re-assessed the use of DDT and said it can safely be sprayed indoors to keep malaria, a mosquito borne disease, at bay. It says DDT should now be one of the main tools for controlling malaria. Spraying of DDT was a major factor in the eradication of malaria from southern Europe and North America in the 1960s.
African countries, such as Tanzania, are already using DDT. But this has become a controversial battle. Environmental, health, and social responsibility groups say the risks associated with the chemical outweigh the benefits. In addition, it is known that mosquitoes become immune to DDT.
The Stockholm Convention on POPS (Persistent Organic Pollutants), which Seychelles has signed, banned DDT globally in 2004, but recognized "urgent and immediate need of many of the malaria-endemic countries to maintain their reliance on the use of DDT for indoor residual spraying to control insect vectors, particularly malaria vectors, until viable, effective and affordable alternatives are found.”
Keeping this in mind, a major issue closer to home is whether governments and normal citizens will now resort to using DDT to control other mosquito borne diseases. In Seychelles, Mauritius and La Reunion, where Chigungunya ravaged the population and resulted in losses of millions of dollars, there may be a strong temptation to use DDT. At the moment health officials are worried that the epidemic of hemorrhagic Dengue in India could reach Seychelles and be propagated by the large population of Aedes mosquitoes emerging after the recent rains.
Will these concerns outweigh the worries that DDT may have on the long term health of human societies and the environment? How can the mosquito population be sensibly controlled? Are there other ways of stopping the spread of these diseases? These questions and others will now be debated even more seriously.
by Nirmal Shah, The People, 12 October, 2006