ROUND AND ROUND IT GOES - THE EPIDEMIOLOGY OF CHILDHOOD LEAD-POISONING, 1950-1990

Although lead toxicity has been recognized for 2,000 years, knowledge of its neurobehavioral effects, sources of exposure, and risk population has grown dramatically during the last 40 years. In 1950, the level of blood lead believed to be toxic to children was in the range of 60 to 80 micrograms per deciliter. The principal source of poisoning was considered to be lead paint and the risk population was perceived to be poor children living in dilapidated housing. By 1990, epidemiological research had established that lead was ubiquitous. The risk population had expanded to include 17 percent of American children under the age of six. Contributors to the advance of lead research have been the civil rights and environmental movements, improved laboratory techniques, and the availability of large data bases. This article reviews the scientific and political processes that have led to a redefinition of the lead problem.