vi Williamsburg, Virginia, February 21-23, 1978. This symposium was sponsored by the U. S. Environmental Protection Agency, Office of Energy Minerals and Industry, Washington, DC, and Office of Health and Ecological Effects, Health Effects Re­ search Laboratory, Biochemistry Branch, Research Triangle Park, NC. The symposium consisted of 24 formal presentations that amplify the three major topics discussed during the symposium: an overview of short-term bioassay systems; current methodology involving the collection and chemical analysis of environmental samples; and current research in­ volving the use of short-term bioassays in the fractionation and analysis of complex environmental mixtures. The purpose of this symposium was to present the state-of-the-art tech­ niques in bioassay and chemical analysis as applied to com­ plex mixtures and to foster continued advancement of this important area. Complex mixtures discussed include ambient air and water, waste water, drinking water, shale oil, syn­ thetic fuels, automobile exhaust, diesel particulate, coal fly ash, cigarette smoke condensates, and food products. It is our hope that this volume will serve as a refer­ ence to catalyze and encourage further research in this field. Michael D. Waters, Ph. D. Stephen Nesnow, Ph. D. vii Acknowledgment We would like to thank Gerald Rausa, Office of Energy Minerals and Industry, for his advice, encouragement, and support of this program. We would also like to express our appreciation to Wendy A. Martin, Peter A. Murphy, and David F. Wright of Kappa Systems, Inc.