MedicalResearch.com Interview with: Edson R. Severnini PhD Assistant Professor Of Economics And Public Policy Carnegie Mellon University MedicalResearch.com: What is the background for this study? What are the main findings?  Response: Although lead has been banned from gasoline, paint, and other substances in the United States and many other countries around the world, the legacy of lead use is a critical environmental and public health issue. Surface soil contamination, in particular, has been long recognized as an important pathway of human lead exposure, and is now a worldwide health concern. This study estimates the causal effects of exposure to lead in topsoil on cognitive ability among 5-year-old children. We draw on individual level data from the 2000 U.S. Census, and USGS data on lead in topsoil covering a broad set of counties across the United States. We find that higher lead in topsoil increases considerably the probability of 5-year-old boys experiencing cognitive difficulties such as learning, remembering, concentrating, or making decisions. Living in counties with topsoil lead concentration above the national median roughly doubles the probability of 5-year-old boys having cognitive difficulties. This harmful effect does not seem to extend to 5-year-old girls, potentially due to the natural protection of estrogen.  (more…)