Head-lice shampoos can be dangerous.(health)

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 ...