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Every year, approximately one-third of
the U.S. population uses insect repellents containing DEET
to ward off mosquitoes and other pests. At present, DEET is
used in more than 230 products with concentrations of up to
100 percent.
However, DEET should be used with caution
due to its possible damaging effects to brain cells. Studies
have shown that DEET causes brain cell death and behavioural
changes in rats after frequent and prolonged use. This
exposure causes neurons to die in regions of the brain that
control muscle movement, learning, memory, and
concentration. Rats treated with an average human dose of
DEET (40 mg/kg body weight) performed far worse when
challenged with physical tasks requiring muscle control,
strength and coordination. These findings are consistent
with reported human symptoms following DEET's use by the
military in the Persian Gulf War.
With heavy exposure to DEET and other
insecticides, humans may experience memory loss, headache,
weakness, fatigue, muscle and joint pain, tremors and
shortness of breath. These symptoms may not be evident until
months or even years after exposure. The most severe damage
occurs when DEET is used concurrently with other
insecticides, such as permethrin, for prolonged and frequent
periods of time. At this time, there is little information
about the short-term, singular and occasional use of DEET.
Further government testing of the chemical's safety is
necessary. However, frequent and long-term use of DEET,
especially in combination with other chemicals or
medications, could cause brain deficits in vulnerable
populations, particularly children.
Until further studies are done, it is
important to be cautious when using this insecticide:
Use insecticides
containing DEET sparingly and infrequently. If
you do use one on your skin, avoid wearing it for prolonged
periods of time.
Be wary of using
insect repellent containing DEET on children. Children
are more susceptible to subtle brain changes caused by
chemicals in their environment because their skin more
readily absorbs them. Also, their still-developing nervous
systems are more potently affected. For the same reasons,
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NEVER use insect
repellent containing DEET on infants.
Be aware that
DEET can be present in commonly used preparations like
insecticide-based lice-killing shampoos. Use
the same precautions with such preparations as you would
with insect repellent.
Do not combine
insecticides with each other or use them while using other
medications. Even an
over-the-counter antihistamine could interact with DEET to
cause toxic side effects.
Do not spray your
yard for insects and then take medications afterward. There
is a possibility that you've inhaled a small amount of the
insecticide that might interact negatively with the
medication. Also, be sure to wash your skin thoroughly after
spraying your yard. Lawn treatment chemicals are very strong
and were not formulated to be applied to human skin.
From the Duke
University Medical Center News Office
The Dangers of
DEET
From This week on MedMinute, a
service of Duke University News.
Use caution when
using insect repellents containing DEET.
Every year, approximately
one-third of Americans use insect repellents containing the
insecticide DEET. Duke University Medical Center
pharmacologist Mohamed Abou-Donia has spent 30 years
researching the effects of pesticides. He has found that
prolonged exposure to DEET can impair functioning in parts
of the brain.
"Damage to these areas could result in
problems with muscle coordination, muscle weakness, walking
or even memory and cognition."
Abou-Donia says rats given even small
doses of DEET for 60 days had a harder time accomplishing
even the easiest tasks. Abou-Donia says short-term exposure
to DEET does not appear to be harmful, but warns against
using any product with more than a 30 percent concentration.
Use as little of the product as you can, and DO NOT use a
product containing DEET if you're taking any medication.
"We found that the combined exposure to
DEET and other chemicals is more dangerous than just DEET
alone."
Abou-Donia also warns to never put a
product containing DEET on an infant's or child's skin. The
side-effects could be even more serious. I'm Cabell Smith
for MedMinute.
From the Duke
University Medical Center News Office
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