Scientists have uncovered the molecular underpinnings of DEET, the world's most widely used insect repellent. Researchers say the findings could lead to modern repellents that are safe enough even for children to use. VOA's Jessica Berman reports.

Fifty years ago, US Army and Department of Agriculture scientists developed DEET to protect soldiers in the trenches from disease-transmitting insects.

Today, DEET is widely used around the world by everyone, from campers to travelers, to ward off blood sucking insects, including malaria-infected mosquitoes.

"But no one has ever come up with a satisfying explanation for how it does this, by what's the mechanism by which DEET works," said Leslie Vosshall.

Leslie Vosshall is a professor of neurogenetics at Rockefeller University in New York and the lead author of a study published in the latest issue of the journal Science that describes how DEET works to protect the user.

Applied mostly to clothing and exposed arms and legs for the best protection, DEET is generally considered harmless.

But questions about DEET's safety arise periodically, and Vosshall says the compound is not recommended for use by very young children.

"Our goal with this work was to figure out how DEET works so that we could go beyond DEET and come up with insect repellents that were safe that you could use at lower doses and that you could use them on babies," she said.

In experiments involving both mosquitoes and fruit flies, Vosshall says researchers discovered proteins or receptors in the antennae of both insects that detect a variety of odors, including the smell of human sweat and breath.

She says DEET works by shutting down some of these odor receptors in the antennae, and the insects get confused and are no longer able to home in on their target.

"DEET acts on the proteins that sit inside the insect's antennae and prevents them from working," said Vosshall. "So, as the mosquito is flying toward you, as it encounters a cloud of DEET, it stops being able to smell you. And therefore it doesn't find you and doesn't bite you."

Now that researchers have discovered how DEET works, Vosshall hopes they will be able to invent an insect repellent for the 21st century.