Rubbed the wrong way: Some pet flea collars contain chemical linked to brain tumors in children.

RODALE NEWS, EMMAUS, PA—A new study links chemicals used in some lice treatment products and pet collars, as well as some commonly used on food crop fields and golf course greens, to childhood brain tumors. The risk is higher among children whose genes prevent them from neutralizing harmful pesticides.

THE DETAILS: Researchers looked at current and stored blood samples, and interviewed parents to investigate a possible connection between a child's womb or early-life exposure to certain pesticides and brain tumor development. Particularly, they looked for exposure to organophosphorus- and carbamate-type insecticides, and also took into account a child's gene variations that might alter the way the child breaks down pesticides in the body. While general insecticide exposure increased the risk of tumors, if a child was not able to neutralize AChE inhibitors (nerve-damaging organophosphorus insecticides are AChE inhibitors) due to a genetic trait, they were even more likely to develop brain tumors. Researchers found that a child's genetic variations did not seem to increase the risk of childhood brain tumors independently, but when coupled with exposure to organophosphorus insecticides, and possibly carbamate insecticides, the risks increased significantly.

WHAT IT MEANS: While organophosphorus pesticides have largely been banned for use in the home and garden, people are still being exposed to them via golf course chemical drift, mosquito-control sprayings, and food crops. Some organophosphorus pesticides, such as chlorpyrifos, are even registered for direct use on turkeys and sheep.

This is not the first study to link pesticide exposure to childhood cancer. Last year, researchers found a relationship between pesticide exposure and the most common form of childhood cancer, acute lymphoblastic leukemia (ALL). And other age groups aren't immune to the effects of chemical pest-killers, either. Researchers have tied pesticide exposure to an increased risk of lymphoma and Parkinson's disease in all ages, and a study published late last year found a connection between insecticides and the autoimmune diseases lupus and rheumatoid arthritis.