The controversial insecticide DDT — which most nations have banned — is back on the menu for malaria control after the World Health Organization reversed a 30-year old policy on Friday (15 September).
The move puts annual indoor spraying of DDT alongside drugs and bednets as one of the three main tools for controlling the disease.
"The scientific and programmatic evidence clearly supports this reassessment," said Anarfi Asamoa-Baah, assistant director-general for HIV/AIDS, TB and malaria at the World Health Organization (WHO).
"[Indoor spraying] has proven to be just as cost-effective as other malaria prevention methods, and DDT presents no health risk when used properly."
The chemical kills the mosquitoes that spread malaria. It helped eradicate the disease from southern Europe and North America in the 1960s.
But DDT is also toxic to birds, fish and mammals. It accumulates in the food chain and remains in the environment for many years. In the 1970s, growing awareness of these threats led many countries to ban its use in agriculture.
In 2004 the Stockholm Convention — a global treaty to protect human health and the environment from pollutants — banned DDT. Although the convention includes an opt-out clause for nations that want to permit the use of DDT indoors to protect public health, few countries chose to use it.
Since then, there have been growing calls for countries to make DDT a central component of strategies for tackling malaria.
Some African countries, such as Tanzania and Uganda, have already relaxed their bans on DDT, but nongovernmental organisations say the risks associated with the chemical outweigh the benefits.
"It's about time the international community focused on combating malaria, but this approach takes us in exactly the wrong direction," said Paul Saoke, director of Physicians for Social Responsibility in Kenya, in a press release.
"DDT is a short-sighted response with long term consequences, and WHO should be helping countries fight malaria with safer and more effective alternatives."
The WHO reviewed research on using DDT and concluded that it can safely be sprayed indoors.
The decision could lead to an increase in aid-agency funding for efforts to control malaria by spraying DDT indoors.
Last year, the US President's Malaria Initiative said it would use some of its US$1.2 billion to fund such activities.
Timothy Ziemer, the initiative's coordinator, says he expects all 15 participating African countries to use the fund for indoor insecticide spraying, including DDT.