Something in the ground

Research team looking for environmental agents that cause mental retardation

An interdisciplinary team from the School of Medicine and Arnold School of Public Health is searching for possible links between chemical exposure during pregnancy and mental retardation. The $1.4 million study was funded by the National Institutes of Health and focuses on 152,000 children born between 1996 and 2001 in South Carolina. USC researchers are looking for geographical clusters of children diagnosed with some level of mental retardation; they will test soil samples in those areas to look for unusual levels of chemicals.

“Currently, there are very few chemicals—other than lead and mercury which are well-documented neurotoxins— that are known causes of mental retardation,” said Suzanne McDermott, a professor in family and preventive medicine and co-principal investigator of the project.

“But science has identified only 60 to 65 percent of the causes of mental retardation. There are still a lot of unknown causes, and it's our job to find them. It could be that there are other chemicals that affect the fetus only during different stages of development.”

The scientists hope to correlate soil chemical findings with information about when expectant mothers were living nearby and at what stage in their pregnancies their children might have been exposed. “In the end, we hope to have some suspected causal agents that can be tested to see what effect they might have on human neural systems,” McDermott said. “This might lead to new guidelines or precautions for pregnant women.”