The "Symposium on Aneuploidy: Etiology and Mechanisms" was held at the Carnegie Institution of Washington Auditorium from March 25-29. 1985. This Symposium developed as a consequence of the concern of the Environmen tal Protection Agency with the support of the National Institute of Envi ronmental Health Sciences about human exposure to environmental agents that cause aneuploidy. The program was chosen to explore what is currently known about the underlying causes, the origins, and the extent of the prob lem of human aneuploidy, and whether exposure to environmental agents is assodated with...