Book excerpt: Lead is a ubiquitous toxic agent that is especially damaging to the young child and the developing fetus. Unlike many environmental health risks, the risks associated with lead are no longer theoretical but have been observed for many years. Indeed, the first regulation of lead in paint was enacted in the 1920s. Currently, because of growing evidence of lead toxicity at lower concentrations, the U.S. Centers for Disease Control and Prevention recently lowered its lead-exposure guideline to 10 ug/dl lead in blood from 25 ug/dl. Measuring Lead Exposure in Infants, Children, and Other Sensitive Populations addresses the public health concern about the logistics and feasibility of lead screening in infants and children at such low concentrations. This book will serve as the basis for all U.S. Public Health Service activities and for all state and local programs in monitoring lead.