09/06/2011 10:52 am ET | Updated Nov 06, 2011

A Crawling Issue: Head Lice Treatments Worse Than The Pest Itself?

As children flock back to school, the annual plague of head lice lurks beyond the classroom doors.

The vile creatures don't spread disease but can be a severe nuisance for teachers and families. The vermin are estimated to afflict between 6 million and 12 million young children in the U.S. each year and parents generally turn to a variety of pesticide-based shampoos and treatments for relief.

Parents often aren't aware that some of the most prescribed and over-the-counter treatments can be harmful to children, an iWatch News investigation found. The Food and Drug Administration's adverse event reports - collected anonymously from doctors, hospitals and others - detail cases where the pesticides in lice treatments have been involved in conditions ranging from headaches to death. The reports were obtained under the Freedom of Information Act.

One of the biggest worries for some health experts is a prescription treatment for head lice and scabies called lindane. The pesticide has been targeted for worldwide phase-out since 2009 by the Stockholm Convention, a global treaty that targets some of the world's deadliest toxins. The U.S. has not ratified the treaty , and has no imminent plans to ban lindane for head lice.

Since 2006, lindane can no longer be used here on crops or cattle, or for any other purpose regulated by the Environmental Protection Agency. A so-called "second line" treatment - meaning it's only to be used if other methods fail - for head lice and scabies, lindane has been linked to cancer, seizures and deaths, according to the FDA.

"It's not permitted to put lindane on your dog in the U.S.," said Joe DiGangi, PhD, a senior science and technical advisor at the International POPs Elimination Network, an umbrella organization for groups that seek to eliminate some of the world's most toxic chemicals. "But they're still allowing it to be put on your child's head."

Lindane accounted for $10.5 million in U.S. sales in 2010 for head lice and scabies, according to IMS Health, a healthcare information company.

Pesticides called permethrin and malathion can also be problematic for lice treatment. Permethrin is found in popular over-the-counter products, such as Nix. Malathion and lindane generally require a prescription for drugs that go by the names Ovide or Kwell, respectively.

Nix, along with other products, has been approved for use on children as young as two months old.