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The millions of kids
who will inevitably turn up with head
lice during the coming school year have gained Food and Drug
Administration protection against one dangerous prescription
treatment--lindane, an organochlorine insecticide that can be toxic to
brain cells. But another prescription lice shampoo--brand-named Ovide--is
being marketed with use instructions that increase the risk of harm.
The FDA recently recommended that lindane be used only with extreme
caution in anyone weighing less than 110 pounds, which includes most
school-aged children. Consumers Union, publisher of Consumer
Reports, has long advocated taking lindane off the market.
The makers of Ovide, which has been available in the U.S. since 1999,
have moved to take over lindane’s market share. Ovide’s active
ingredient is malathion, an insecticide whose use for mosquito control
has alarmed parents across the U.S.
Though it’s one of the safer organophosphate
insecticides--considerably safer than lindane--malathion works by
interfering with chemical reactions in the nervous system, whether of
an insect or a person. In its raw state, malathion readily soaks
through the skin. So far, the makers of Ovide have not done studies to
determine how much of the malathion gets into a child’s circulatory
system.
That said, years of use have established that when applied to the
scalp for lice control, Ovide is not absorbed excessively. But lice
experts say that the product’s use instructions pose an unnecessary
hazard.
A recent study by Terri Meinking, associate professor of dermatology
at the University of Miami School of Medicine, found that “Ovide
killed lice within 20 minutes of exposure, by far the fastest of any
product tested.” However, the product’s instructions say to soak the
child’s hair with Ovide and leave it on for 8 to 12 hours. The longer
it stays on the head, the more of it is absorbed--and the more likely
that lice will quickly become resistant to it. Moreover, it smells bad
and might catch fire if the child is near a flame.
If your child gets head lice, remember that though they are
unpleasant, lice neither transmit disease nor make children ill. “The
major hazard of head lice is enforced school absence” because of
draconian “no-nit” policies, says Ronald C. Hansen, M.D., chief of
pediatric dermatology at Phoenix Children’s Hospital in Arizona. If
your child’s school has such a policy, refer its administrators to the
American Academy of Pediatrics, whose guidelines explicitly discourage
it.
Many lice cases can be resolved by starting with over-the-counter
treatments, such as Nix or Rid, which contain relatively safe
pyrethroid insecticides. Carefully follow package instructions. Check
the child’s head daily, and remove remaining lice and nits with a
fine-tooth metal comb until you have gone several days without
spotting any. Wetting the child’s hair with a conditioner may make
combing less painful. Use Ovide as a last resort, leaving it on for
only 10 to 15 minutes, then washing the child’s hair to remove all
residue.
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