Should beware of mosquito repellants?
Marc Olivier
Mosquito repellent lotions contain DEET, an agent that would be dangerous. : Marc Ollivier
French laboratories, including that of Angers, have demonstrated the toxicity of these products on the nervous systems of insects ... but also mammals.
"We struggled to publish these results because it took a lot of brakes," says Professor Bruno Lapied, a researcher at the University of Angers. The study has just been published in the American journal BioMed Central Biology.
For three years, an international team, led by the French Vincent Corbel (Montpellier) and Bruno Lapied (Angers), works on the neurological toxicity of diethyltoluamide (DEET), present in most repellents used to protect against stings of mosquitoes. Some 200 million people make use of this product applied to human skin each year for fifty years.
Cosmetic or pesticide?
"By performing tests, we noticed that at medium doses, this compound causes the death of the mosquito when it is not supposed to play the role of an insecticide," reveals Bruno Lapied. Precisely, and what constitutes the surprise of this study, the DEET would have neurotoxic effects on a key enzyme of the central nervous system, acethylcholinesterase, also present in the mammals, and the man in particular.
We know very little about DEET. Does it prevent the location of humans in the eyes of a mosquito? Does he blur his sense of smell? What is certain now is "it can disrupt a subject's nerve impulse and the connection between nerves and muscles," observed Bruno Lapied in in vitro tests.
Is DEET dangerous for humans? "It is too early to say, notes his colleague, Vincent Corbel, researcher in Montpellier. But on insects or small mammals, this neurotoxicity can lead to the death of the subject since it prevents nerve transmission. Researchers do not want to cry out for disaster. "We do not say that mosquito bombs can kill men, warns Vincent Corbel, but we must be careful and continue our research. "
This research could lead to a reclassification of DEET, which currently falls under the regulation of cosmetics and not that of the stricter pesticides. "The toxicity of DEET is recognized and it is not recommended for pregnant women and children, says one at the pharmaceutical laboratory AIM, whose head office is located in Brittany Chatelaudren, 20 km from Saint-Brieuc. For our anti-mosquito sprays, we prefer to use another molecule, 35 / 35, which would not have the same neurotoxic effects ".
Further research will be conducted by the end of the year on small rodents to better understand the mode of action of DEET. "We still have to analyze this compound and its interaction with other drugs or pesticides," adds Bruno Lapied. Combined with other substances, DEET may cause a dangerous cocktail.
Researchers are referring to the Gulf War Syndrome. "We know that US soldiers used high-dose repellent in combination with other products. This mixture could perhaps explain the neurological pathologies, ranging from loss of balance to brain cancer, which some Gulf War veterans have been victims of.
Arnaud WAJDZIK.
west france news source