Lead is perhaps the oldest of industrial toxins, dating back to Roman times. Despite the historic knowledge of lead, this metal remains a public health concern today. This is due both to the pervasiveness of lead in the environment and to the awareness of toxic effects of lead occurring at exposure levels lower than previously thought harmful. At the 1991 Annual Meeting in Dallas, Texas, the Society of Toxicology hosted the symposium: "An Update on Exposure and Effects of Lead." The goal of the symposium was to present an overview on critical issues associated with lead toxicity--ranging from fundamental mechanisms, such as the role of lead binding proteins, to assessment of the potential effectiveness of lead abatement measures, such as the impact on blood lead of home deleading. These issues are summarized in Fig. 1 using the four-stage paradigm of risk assessment as described by the National Academy of Science (NRC, 1977). Clearly, understanding potential impacts of lead in humans is interdisciplinary, involving the efforts of toxicologists, pathologists, epidemiologists, environmental chemists, and others. The following is a summary of each of the individual presentations.