The mechanisms by which chemicals cause their toxic or carcinogenic effects frequently involve the formation of electrophiles or free radicals, including reactive oxygen species. They often covalently bind to cellular macromolecules or cause other forms of damage which may eventually lead to cell and organ toxicity or the initiation of cancer, The International Symposium on Biological Reactive Intermediates, which began in 1975 and has been presented at five year intervals since, will next assemble at the Universite Rene Descartes, in Paris on July 16-20,2000, under the local chairmanship of Prof. Patrick Dansette. The name of the symposium will be The Sixth International Symposium on Biological Reactive Intermediates and the name of the published proceedings will be: Biological Reactive Intermediates VI: Chemical and Biological Mechanisms in Susceptibility to, and Prevention of Environmental Diseases. The program has been generated by an international program committee chaired by Prof. Terrence Monks, Univ. of Texas, Austin, and will feature 72 invited presentations from the USA and Europe. Highlights of the program will include a keynote presentation by Prof. Sten Orrenius of the Karolinska Institute, Stockholm and a closing lecture by Prof. F. Peter Guengerich, Vanderbilt Univ., Nashville. US members of the international organizing committee include Prof. D.J. Jollow, Medical Univ. of South Carolina, Charleston, Prof. I.G, Sipes, Univ. of Arizona, Tucson, and R. Snyder, Rutgers Univ., Piscataway. The total cost of the meeting is estimated at $235,000, of which this proposal requests $10,000 to help support the participation of 10 US speakers at $1,000/speaker.