Mississippi State University has recently launched a five-year study to examine the effects of pesticides on children’s health, thanks to a new grant from the National Institutes of Health. Janice E. Chambers, Giles Distinguished Professor at MSU, has received a $1.26 million grant to conduct research on the ways agricultural chemicals act on the human nervous system. Chambers heads the university’s center for environmental health services, housed in the College of Veterinary Medicine. She also holds a $712,000 grant from the Environmental Protection Agency to study the risks chemicals in flea collars may pose, especially to children.
“Our nation has an excellent quality of food, thanks in part to the development of effective pesticides,” Chambers said. “Our study seeks to understand how these chemicals might affect children so that we can make appropriate decisions about pesticide use.”
Research toxicologist Russell L. Carr, assistant professor of veterinary medicine, is a co-investigator in the study.
Specifically, their work will examine the effects of a certain class of chemicals, organophosphorous (OP) insecticides, which are used both for agricultural and residential purposes. OP insecticides are a subcategory of acetylcholinesterase inhibitors. Acetylcholinesterase is a normal enzyme in the body used in nerve transmitting, and when inhibitors are present, the transmitters are broken down, disrupting the passage of impulses between nerves.
When muscles and glands are overstimulated, neurotransmitters in the body continue to activate. Smooth muscle tissue is most affected. High, toxic levels of OP insecticides in humans can cause salivation, tearing, urination and defecation.
In proper amounts, OP insecticides are used to kill insects and can be applied to animals to control pests. There are insecticides used in crop spraying, home gardening, fruit spraying and other areas in the environment.
“They are very effective if used properly, but we are looking at what happens with repeated exposure to them,” John Tyler, associate professor of small animal internal medicine, said.
Tyler said the study would look at low-level repeated exposure of humans to OP insecticides, taking note of cumulative effects from all sources of exposure.
“No one has looked at the potential of problems from dog flea control products, and that’s something we are looking at,” Tyler said.
The study will use data from many sources to come to a conclusion.
Children may be exposed to pesticides through agricultural drift-chemicals carried from the spray site by air, as well as by an adult bringing the chemicals home on clothes or by contamination of food, Chambers said.
“There have also been cases in which some organophosphorous chemicals such as methyl parathion have been illegally used to spray homes,” Chambers said.
That chemical is typically used to control cotton pests. Carr became interested in this experiment for serious reasons.
“People have been worried since the early ’90s, as amounts of insecticide were found on apples, and children ate those apples, and concern was raised about how it would affect them,” Carr said.
A particular concern is whether exposure to OP insecticides can alter the brain’s biochemistry, leading to long-term changes in behavior and cognition.
To evaluate the risk, the MSU researchers will use rats as a model to test the biochemical effects on actual behavior.
“We will expose the animals to levels comparable to those humans would actually receive,” Chambers said.
Carr said that young rats would be used in order to determine if abilities to function are decreased as they monitor early development and cognition in the rats. Earlier studies have been based on in vitro laboratory research. Carr emphasizes the importance of the study. “This is very important, especially if we find negative effects. Just because people are exposed doesn’t mean they will have negative effects, but young children have lower defense mechanisms and it’s vital to see what happens,” Carr said.
Although the task will be difficult and require many hours of behavioral testing with tests never before conducted by the school, Carr looks forward to see what happens.
“I’m excited about the tests, but that’s my job.”
Carr holds a doctorate in animal physiology from MSU, with an emphasis in environmental toxicology.He has been a co-investigator on a number of NIH and EPA grants dealing with the effects of insecticides. Chambers is a diplomate of the American Board of Toxicology and a fellow of the Academy of Toxicology Sciences.
She has served on the scientific advisory panel of grants from NIH, EPA, and the United States Department of Agriculture, among others.