For at least 40 years there has been a great interest in the problems created by infectious airborne agents and other toxic sub stances transported through the air. During the Second World War, this problem grew out of the very high incidence of upper respira tory infections appearing in new military recruits who were brought together in very large, open quarters. As a result, very interest ing methods were developed to measure these airborne agents, espe cially bacteria, and some important methods were refined for their control. These methods primarily concentrated on ultraviolet radia tion, propylene glycol and other means to reduce the dust in an en vironment. Because of the specialized circumstances at that time the whole consideration of airborne particles became prominent. Now, with the new strides in the recognition of mutagenic and carcinogenic effects attributed to exposure to airborne chemicals from today's technology, the problem has again become quite promi nent. The development of experimental chambers has made it possible to conduct studies under carefully controlled conditions.

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Section A: Assay and Exposure Technology.- Session I: Assay and Exposure Technology of In Vitro Microbial Assay Systems Applied to Airborne Agents.- An Exposure System for Quantitative Measurements of the Microbial Mutagenicity of Volatile Liquids.- Review of Fractionation and Bioassay Characterization Techniques for the Evaluation of Organics Associated with Ambient Air Particles.- Airborne Particle Collection and Extraction Methods Applicable to Genetic Bioassays.- Session II: Assay and Exposure Technology of In Vitro Mammalian Cell Systems Applied to Airborne Agents.- In Vitro Analysis of Mammalian Cells Exposed In Vitro and In Vivo to Airborne Agents.- Methods for Detecting Gaseous and Volatile Carcinogens Using Cell Transformation Assays.- CHO/HGPRT Mutation Assay: Evaluation of Gases and Volatile Liquids.- Lung Cells Grown on Cellulose Membrane Filters as an In Vitro Model of the Respiratory Epithelium.- Session III: Plant Bioassays for the Detection of Airborne Genotoxic Agents.- Monitoring Ambient Air for Mutagenicity Using the Higher Plant Tradescantia.- Environmental Clastogens Detected By Meiotic Pollen Mother Cells.- Plant Genetic Systems with Potential for the Detection of Atmospheric Mutagens.- Session IV: Animal Exposure Technology for the Detection of Genotoxic Agents.- Systems for Exposure of Animals to Airborne Agents.- Techniques for the Generation and Monitoring of Vapors.- Problems Associated with Assessing the Mutagenicity of Inhalable Particulate Matter.- Section B: Airborne Agents.- Session V: Benzene.- An Overview of the Problem of Benzene Toxicity and Some Recent Data on the relationship of Benzene Metabolism to Benzene Toxicity.- Benzene Metabolites: Evidence for an Epigenetic Mechanism of Toxicity.- Cytogenetic Effects of Inhaled Benzene in Murine Bone Marrow.- Benzene Leukemogenesis.- Session VI: Organic Halides C. Maltoni Moderator.- Genetic Effects of Ethylene Dibromide in Drosophila Melanogaster.- Mutagenic and Oncogenic Effects of Chloromethanes, Chloroethanes and Halogenated Analogues of Vinyl Chloride.- Vinyl Chloride: A Model Carcinogen for Risk Assessment.- Session VII: Miscellaneous Agents.- Inhalation Anesthetics.- Mutagenic and Carcinogenic Effects of Formaldehyde.- The Microbial Mutagenicity of Nitroarenes.- Mutagenic Effects in Human and Mouse Cells by a Nitropyrene.- Genotoxic Properties of Radon and Its Daughters.- Multiple Tissue Comparisons of Sister Chromatid Exchanges Induced by Inhaled Styrene.- An Overview of Ethyl Carbamate (Urethane) and Its Genotoxic Activity.- Section C: Monitoring and Risk Assessment.- Session VIII: Monitoring of Human Populations At Risk.- Cytogenetic Monitoring of Human Populations.- Thioguanine Resistent Lymphocytes As Indicators of Somatic Cell Mutation in Man.- Detection of Point Mutations in Mammalian Sperm.- Session IX: Extrapolation of Genotoxic Data To Human Health Effects.- Extrapolation of Laboratory Data to Human Health Effects.- Molecular Dosimetry as a Bridge Between Mammalian and Non-Mammalian Test Systems.- Is Radiation an Appropriate Model for Chemical Mutagenesis and Carcinogenesis?.- Session X: Regulatory Risk Assessment.- Impact of Energy and Pollution on Public Health.- Policy and Procedures for Using Mutagenicity Data in Assessing Genetic Risk.- The Sensitivity of Method Procedure as a Regulatory Mechanism for Approval of Carcinogens.- Contributed Papers.- The Human Genetic Risk of Airborne Genotoxics: An Approach Based on Electrophoretic Techniques Applied to Mice.- Photon-Emitting Microorganisms as Test Objects for Detecting Genotoxic Agents.- Detection of Genotoxic Airborne Chemicals in Rat Liver Culture Systems.- The Induction of Sister Chromatid Exchange in Human Lymphocytes and Bacterial Mutagenesis by Organic Extracts of Urban Airborne Particles.- An epidemiological Study of Cancer Deaths in Pathfor, Kentucky.- List of Participants.- Agent Index.