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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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