In 1974, the Societal Institute of the Mathematical Sciences (SIMS) initiated.a series of five-day Research Application Conferences (RAC's) at Alta, Utah, for the purpose of probing in depth societal fields in light of their receptivity to mathematical and statistical analysis. The first 10 conferences addressed ecosys tems, epidemiology, energy, environmental health, time series and ecological processes, energy and health, energy conversion and fluid mechanics, environ mental epidemiology: risk assessment, atomic bomb survivor data: utilization and analysis, and modem statistical methods in chronic disease epidemiology. These Proceedings are a result of the eleventh conference of Scientific Issues in Quantitative Cancer Risk Assessment, which was held in 1989 at Snowbird, Utah. For five days, 45 speakers and observers contributed their expertise in the relevant biology and statistics. The presentations were timely and the discussion was both enlightening and at times spirited. This volume hopefully presents a record that will be useful both now and in the future. Suresh H. Moolgavkar of the Fred Hutchinson Cancer Research Center (Seattle, WA) and the University of Washington (Seattle) chaired the Conference. The Conference was supported by the following organizations: The Dow Chemical Company Haskell Laboratory, E.1. duPont Health and Welfare Canada International Life Sciences Institute Monsanto Company National Cancer Institute Procter & Gamble Shell Oil Company U. S. Department of Energy U.S. Environmental Protection Agency U.S. Food and Drug Administration SIMS is grateful to the above organizations for their support of this Conference. D.L. Thomsen, Jr.