No one questions that head lice are creepy. And once they emerge at a school, they can spread rapidly from one child and one household to another.

Still, even if lice give people the willies, they aren’t known to spread disease. And no less an authority than the U.S. Centers for Disease Control and Prevention says that head lice should not be considered a medical or public health hazard, even though they can cause annoying itching.

All of which leads some medical experts to ask: Are some pesticide-laced shampoo treatments for head lice more dangerous than the vermin themselves?

In fact, an investigation by the Center for Public Integrity’s iWatch News found that some widely used prescription and over-the-counter treatments can be harmful to children. The investigation said that — in reviewing adverse event reports obtained from the Food and Drug Administration under the Freedom of Information Act — it found cases where the pesticides in lice treatments have been linked to everything from headaches to death.

One of the biggest worries is a medication for head lice and scabies called lindane. According to iWatch, the pesticide has been targeted for worldwide phase-out since 2009 by the Stockholm Convention, a global treaty that deals with some of the world’s deadliest toxins. But the U.S. has not ratified the treaty, and has no imminent plans to ban lindane for head lice.

Jerry Jabbour, vice president of Wockhardt USA, which makes lindane, conceded that the product is a powerful pesticide, but said most of the concerns are linked to agricultural uses and occur because lindane does not break down naturally in the environment.

Used as directed for scabies and lice, he said, “it’s a good alternative when first-line therapies don’t work. Anything that you use on your body or in your body, it has the potential for adverse events to happen. We see there’s physician demand for the product … and we feel like we’re providing an alternative.”

But as a U.S. National Library of Medicine website indicates, in rare cases lindane treatments have caused seizures and death. The worst cases usually are related to overuse of the medication, “but a few patients experienced these problems even though they used lindane according to the directions.”

Among U.S. children 3 to 11 years old, there are an estimated 6 million to 12 million cases a year of head lice.