Diethyltoluamide or N,N-Diethyl-3-methylbenzamide, more commonly known as DEET, is used by millions of people around the world as a mosquito repellent. It's the active ingredient in some of the world's best known brands.

About 200 million people use it every year and over 8 billion doses have been applied over the past 50 years.

DEET was developed by the United States Army. It's been in use since 1946; originally tested as a pesticide on farm fields.

The way DEET works on mosquitoes was supposedly quite simple - they just simply hate the smell of the stuff.

However, researchers studying the toxicity of deet have found that it inhibits the activity of a key central nervous system enzyme, acetycholinesterase, not only in insects but in mammals too. In short, it appears to be a neurotoxin.

Deet uses the same mode of action used by highly toxic organophosphate and carbamate insecticides.

These insecticides are often used in combination with deet and the researchers also found that deet interacts with carbamate insecticides to increase their toxicity.

This isn't the first study to cast doubt on the human/environmental safety aspects of using DEET. According to the Extension Toxicology Network at Cornell University, Deet is absorbed promptly from the skin and distributed to all organs including the brain and the fetus. Deet is also known to be slightly toxic to coldwater fish.

Insect repellents play an incredibly important role in helping prevent mosquito-borne disease; so I'm by no means suggesting that we stop using them; just to consider how much we use, alternative earth friendly products and perhaps incorporating other strategies for dealing with mosquitoes.

Related:

Dealing with flies
Avoiding mosquito bites
Uses for eucalyptus oil
Pesticide persistence