by Maridith Walker Geuder
photo by Russ Houston

Their life span is only a matter of weeks, but fleas can cause major problems for animals and animal lovers. An arsenal of sprays, powders, pills, and collars promises to rid our dogs, cats, and homes of the pest-but can the products harm humans?

That's a question Dr. Janice Chambers hopes to answer. Director of Mississippi State's Center for Environmental Health Sciences, the Giles Distinguished Professor wants to learn whether residues from flea control products can be transferred to adults and to children. A primary research focus of the center is pesticides and their potential effects on people, particularly children.

Janice Chambers, center, director of the Center for Environmental Health Sciences, is studying whether flea collar residues can be transferred to humans. Research toxicologist Scott Boone, left, and internal medicine veterinarian John Tyler assist.

The center's flea-control study, which is assessing the possible exposure levels of organophosphorus insecticides used by some flea-control products, is supported by a $600,000 grant from the Environmental Protection Agency.

Chambers is a toxicologist whose laboratories are housed at the College of Veterinary Medicine, where her project is being conducted. She and her collaborators are recruiting two dozen dogs to participate in a test of whether the chemicals on flea collars can be dislodged and transferred to humans.

Earlier, she conducted similar tests on animals that had been dipped, or immersed in baths that contain insecticides.

"The Food Quality Protection Act of 1996 establishes pesticide regulations to protect children's health," she noted. "That resulted in a need for new data to assess human exposure."

No other studies have been conducted to quantify the dislodgable flea control insecticide residues from pets, she added.

To determine if there is a risk to children and to adults, Chambers and her team are treating dogs according to the label directions for flea collars and dips. Before and after the treatment, researchers rub the animals' fur with white cotton gloves using a standardized research protocol.

Using standard methods, they extract and analyze residues from the gloves. Blood samples taken from the dogs help determine any internal levels of insecticides in the animals, while urine samples taken from participating adults and children in the household of the dog will determine any level of exposure in humans.

Through detailed data collection over the next year of the project, Chambers will provide valuable information about whether flea control strategies pose any risks to humans.

The study also has application to other insecticide exposures, Chambers explained. "Some of these same chemicals are used on crops," she noted. "EPA also is concerned about multiple exposures to one chemical or to multiple chemicals that act in the same way."

In addition to the flea control study, the Center for Environmental Health Sciences is conducting a project that seeks to explain the reasons for the greater vulnerability of children to pesticide effects, compared to adults. The goal is to help prevent danger to children, Chambers said. Another center study focuses on the impact of environmental estrogens on human reproductive system development.

Chambers is an editor of the Dictionary of Toxicology, published by Grove's Dictionaries, and is a previous recipient of the Burroughs Wellcome Toxicology Scholar Award.