More than one hundred short-term bioassays are now available for detecting the toxicity, mutagenicity, and potential carcinogenicity of chemicals. These bioassays were developed and validated with individual compounds, and their principal application was perceived to be in evaluating the health hazard of such materials. However, man is rarely exposed to single chemicals; his exposure to hazardous chemicals is more commonly a multifactorial phenomenon. Although chemical analysis can be used to detect known hazardous compounds, it would be a staggering and expensive task to analyze large numbers of samples for all known or suspected hazardous constituents. Furthermore, the biological activity of a complex mixture cannot be reliably predicted from knowledge of its components. On the other hand, bioassays alone cannot tell us which components of complex mixtures are responsible for the biological activity detected. Thus, cost effectiveness and technical feasibility dictate stepwise and perhaps iterative application -of both chemical and biological methods in evaluating the health effects of complex environmental mixtures. Through the coupling of reliable biological detection systems with methods of chemical fractionation and analysis, it is frequently possible to isolate the individual chemical species that show biological activity. Initially, complex mixtures may be separated and bioassayed in carefully defined chemical fractions. The results of such short-term screening bioassays then may be used td guide the course of further fractionation and to determine the need for more stringent and comprehensive biological testing.

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Keynote Address.- Keynote Address.- Session 1: Ambient Air.- Bioassay of Particulate Organic Matter from Ambient Air.- Collection, Chemical Fractionation, and Mutagenicity Bioassay of Ambient Air Particulate.- Evaluation of Collection and Extraction Methods for Mutagenesis Studies on Ambient Air Pariculate.- Integration of the Ames Bioassay and Chemical Analyses in an Epidemiological Cancer Incidence Study.- Mutagenicity of Airborne Particulate Matter in Relationship to Traffic and Meteorological Conditions.- Dectection of Genetically Toxic Metals by a Microtiter Microbial DNA Repair Assay.- A Culture System for the Direct Exposure of Mammalian Cells to Airborne Pollutants.- Session 2: Drinking Water and Aqueous Effluents.- Is Drinking Water a Significant Source of Human Exposure to Chemical Carcinogens and Mutagens?.- Alternative Strategies and Methods for Concentrating Chemicals from Water.- Detection of Organic Mutagens in Water Residues.- Short-term Methods for Assessing In Vivo Carcinogenic Activity of Complex Mixtures.- The Initiating and Promoting Activity of Chemicals Isolated from Drinking Waters in the Sencar Mouse: A Five-city Survey.- Aqueous Effluent Concentration for Application to Biotest Systems.- Session 3: Terrestrial Systems.- Potential Utility of Plant Test Systems for Environmental Monitoring: An Overview.- Arabidopsis Assay of Environmental Mutagens.- Soybean System for Testing the Genetic Effects of Industrial Emissions and Liquid Effluents.- Mutagenicity of Nitrogen Compounds from Synthetic Crude Oils: Collection, Separation, and Biological Testing.- The Detection of Potential Genetic Hazards in Complex Environmental Mixtures Using Plant Cytogenetics and Microbial Mutagenesis Assays.- Session 4: Mobile Sources.- Short-term Carcinogenesis and Mutagenesis Bioassays of Mobile-source Emissions.- Tumorigenesis of Diesel Exhaust, Gasoline Exhaust, and Related Emission Extracts on Sencar Mouse Skin.- Bacterial Mutagenesis and the Evaluation of Mobile-source Emissions.- Comparison of the Mutagenic Activity in Carbon Particulate Matter and in Diesel and Gasoline Engine Exhaust.- Mutagenic Effects of Environmental Particulates in the CHO/HGPRT System.- A Preliminary Study of the Clastogenic Effects of Diesel Exhaust Fumes Using the Tradescantia Micronucleus Bioassay.- Ability of Liver Homogenates and Proteins to Reduce the Mutagenic Effect of Diesel Exhaust Particulates.- Session 5: Stationary Sources.- Bioassays of Effluents from Stationary Sources: An Overview.- Coal Fly Ash as a Model Complex Mixture for Short-term Bioassay.- Possible Effects of Collection Methods and Sample Preparation on Level 1 Health Effects Testing of Complex Mixtures.- Biological Monitoring of Fluidized Bed Coal Combustion Operations I. Increased Mutagenicity During Periods of Incomplete Combustion.- Biological Monitoring of Fluidized Bed Coal Combustion Operations II. Mammalian Responses Following Exposure to Gaseous Effluents.- In Vitro and In Vivo Evaluation of Potential Toxicity of Industrial Particles.- Mutagenicity and Carcinogenicity of a Recently Characterized Carbon Black Adsorbate: Cyclopenta(cd)pyrene.- Mutagenicity of Coal Gasification and Liquefaction Products.- Session 6: Hazard Assessment.- The Role of Short-term Tests in Assessing the Human Health Hazards of Environmental Chemicals: An Overview.- The International Program for the Evaluation of Short-term Tests for Carcinogenicity (IPESTTC).- Sperm Assays in Man and Other Mammals as Indicators of Chemically Induced Testicular Dysfunction.- Assessing Carcinogenic Risk Resulting from Complex Mixtures.