Deet Finally Exposed as Neurotoxic
naturalnews.com
David Gutierrez
05 Jul 2010
New research shows that the insect-repelling chemical deet actually functions
in the same way as deadly nerve gases and dangerous pesticides, by attacking
the nervous systems of both insects and mammals.
"These findings question the safety of deet, particularly in combination
with other chemicals," said researcher Vincent Corbel of Institut de
Recherche pour le Developpement in Montpellier.
The chemical known as deet (for N,N-diethyl-meta-toluamide) is found in nearly
every commonly used mosquito repellent in the world, and eight billion doses
have been applied since its introduction to the consumer market in 1957.
The chemical was originally developed as an insect repellent by the U.S.
Army in 1946, following experience with jungle warfare in World War II.
Deet's popularity comes largely from its effectiveness in repelling a variety
of medically significant insects over longer periods of time than more natural
repellents (such as certain vegetable-based oils), and the fact that it can
be incorporated into sprays, liquids or lotions. Yet although researchers
have long insisted that the chemical is safe, they still recommend that consumers
use the minimum amount of repellent necessary to cover exposed skin or clothing,
and that deet repellents not be applied directly to any irritated or injured
skin. While the United States allows the sale of 100 percent deet repellents,
many other countries limit maximum concentrations of the chemical to 30 or
50 percent.
In spite of the chemical's long use, researchers are unsure exactly how deet
functions to repel mosquitoes. It has long been believed to affect mosquito
behavior without harming the insects, probably by interfering with their
sense of smell and their ability to find human prey.
Yet the new study, published in the journal BioMed Central Biology, suggests
that deet may function by interfering directly with insects' nervous systems.
"We've found that deet is not simply a behavior-modifying chemical but
also inhibits the activity of a key central nervous system enzyme, acetylcholinesterase,
in both insects and mammals," the researchers said.
In experiments performed in cockroaches and rats, the researchers found that
deet blocked the action of the neurological enzyme acetylcholinesterase.
This is the same mechanism that causes the toxic effects of popular carbamate
and organophosphate pesticides, as well as chemical weapons such as sarin
and VX nerve gas. This may mean that deet repellants are actually insecticides
and could damage the human nervous system.
Organophosphates are among the pesticides most commonly implicated in pesticide
poisoning worldwide, and are also a commonly used suicide method in agricultural
areas. Like nerve gases, organophosphates irreversibly inactivate acetylcholinesterase,
leading to excessive salivation and eye watering at low doses, and muscle
spasms or death at higher doses. Although carbamates are not as toxic as
organophosphates, their effects can be just as severe at high enough doses.
Strong evidence also links these pesticides to dangerous health effects caused
by long-term exposure even at low doses.
Previous studies have implicated deet in causing seizures in children, but
the current study is the first to uncover how the chemical acts directly
on the nervous system.
The researchers also found that the effects of deet were enhanced when it
was used in combination with organophosphates or carbamates, as in mixed
repellent-insecticide products.
Bahie Abou-Donia of the Duke University Medical Center said that the new
findings are consistent with previous research into the risks of deet.
"Deet is a good chemical for protection against insects," Abou-Donia
said. "But prolonged exposure results in neurological damage, and this
is enhanced by other chemicals and medications."
The researchers in the new study suggested that pregnant women and children
under the age of six avoid using deet-containing mosquito repellents. Abou-Donia
went farther, calling for such products to carry warning labels about deet's
potential to cause neurological harm.
The Environmental Protection Agency has a review of deet's safety planned
for 2012.
Sources for this story include: news.bbc.co.uk; www.sciencedaily.com; www.usnews.com; www.dailymail.co.uk.
