The overall objective is to develop a series of data bases on which assessment of potential health consequences, especially total burden of environmental carcinogens and mutagens, resulting from utilization of fossil fuels can be made more objectively and with greater precision than is currently possible. The program of research has the objective of determining the character and range of potential health effects associated with several technologies for fossil fuel combustion by relating evaluations of a variety of biological responses to critical operating parameters characteristic of existing and alternative combustion equipment. The ultimate aim is to define conditions of combustion for each of several fuel types which result in the emission of minimal amounts of substances with mutagenic and/or carcinogenic properties. This objective is being approached through the following lines of investigation: (1) Conducting parametric combustion studies using laboratory and larger-scale combustors to determine effects of temperature, equivalence ratio and fuel type on the formation of particulates and polycyclic compounds. (2) Subjecting selected samples from the combustion experiments to exhaustive chemical analysis. (3) Evaluating the biological and biochemical properties of selected samples produced under defined combustion conditions with respect to mutagenicity in bacteria and human cells and ability to form covalent adducts with nucleic acids when activated in vitro and in vivo.