Mnzava of WHO said “it is a wrong approach to talk about phasing out DDT without making provision for its alternatives. Until cost-effective and sustainable formulations are available, DDT will continue to be one of the insecticides for malaria control broadly and for the management of insecticide resistance in particular.”
Searching for safe, cheap pesticides
The pesticide industry is now searching for replacements that cost only a couple of dollars per application, yet are lethal to insects, slow to degrade and safe for humans, especially children.
“It’s a matter of great urgency,” said Jed Stone, head of access and advocacy for the Innovative Vector Control Consortium, a non-profit collaboration between public health institutions and agrochemical companies working to create new insecticides.
For decades, there was little research into insecticides designed to protect public health. “The whole field just went dead,” said Feachem. Instead, efforts focused exclusively on agriculture.
These women are carrying bed nets treated with pyrethroids. Mosquitoes are becoming resistant to the insecticide, sparking fears of a malaria resurgence.
Image: Flickr/Gates Foundation
“From the ‘70s onwards, there’ve been eight new classes of chemistries for agriculture and none for public health,” said John Lucas, business development manager for global vector control at Sumitomo Chemical, one of the companies now working with the consortium. “To be honest, the market is huge in ag and relatively tiny in public health,” Lucas said.
What’s more, the two markets have greatly different needs. For crops, pesticides must be short-lived to avoid contaminating food, while for public health uses such as mosquito nets, they need to last as long as possible. “So that’s why there’s no real supply of molecules in that [latter] area,” Lucas said.
The industry consortium aims to produce at least three new insecticides, as well as repurposing agricultural pesticides for indoor use.
Stone is optimistic about the “healthy and robust pipeline of new active ingredients and formulations,” now in progress.
The challenge, Lucas said, is that “many times, you find that the ones that work really well against insects happen to kill mammals as well. And it’s the skill of the chemist to find a compound that has low mammalian toxicity and high insecticidal activity.”
Now, with a rapid screen called the “one mouse test,” they can rule out anything that shows signs of toxicity right off the bat. Advances in entomology have also revealed many more insect target sites, opening the door for new active ingredients with totally different modes of action.