His scientific expertise is in radiation biology, cancer epidemiology, and public health. He is board certified in public health by the National Board of Public Health Examiners (NBPHE). He is on the National Council on Radiation Protection (NCRP), he chairs the Georgetown University Radiation Safety Committee, and he is an adjunct associate professor at the Bloomberg School of Public Health at the Johns Hopkins University in Baltimore. His research interests include the genetic determinants of cellular radiation resistance, and the genes that modify the risk of cancer. He lives with his family in Rockville, Maryland.