Deet insect repellant found to be toxic to central nervous system

Discovered in 1953, deet is still the most common ingredient in insect repellent preparations. It is effective against a broad spectrum of medically important pests, including mosquitoes. Despite its widespread use, controversies remain concerning both the identification of its target sites at the molecular level and its mechanism of action in insects.

Researchers from the Institut de Recherche pour le Développement in Montpellier, and the University of Angers, investigated the mode of action and toxicity of deet (N,N-Diethyl-3-methylbenzamide) and found that it did not simply modify behaviour but inhibited the activity of a key central nervous system enzyme, acetycholinesterase, in both insects and mammals.

The researchers found that deet inhibits the acetylcholinesterase enzyme – the same mode of action used by organophosphate and carbamate insecticides. These insecticides are often used in combination with deet, and it appears that deet interacts with carbamate insecticides to increase their toxicity. Vincent Corbel, leading the study, seriously questioned the safety of deet, particularly in combination with other chemicals, and called for a multidisciplinary approach to the development of safer insect repellents for use in public health.

Journal reference:
Vincent Corbel, Maria Stankiewicz, Cedric Pennetier, Didier Fournier, Jure Stojan, Emmanuelle Girard, Mitko Dimitrov, Jordi Molgo, Jean Marc Hougard and Bruno Lapied. Evidence for inhibition of cholinesterases in insect and mammalian nervous systems by the insect repellent deet. BMC Biology

First published in August 2009


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