His major research interests are occupational, environmental and molecular epidemiology. He has been interested in studying the impact of exposures to various pollutants on health and the interactions between host factors (genetic and acquired susceptibility), and environmental exposures in producing acute and chronic diseases. This research is part of a field known as molecular epidemiology. He has been active in developing new methods for assessing health effects after exposure to pollutants and has a very active interest in international occupational and environmental health studies.