Ceramic particle traps are being developed for use as diesel exhaust emission controls for over-the-road as well as heavy-duty diesel engines used in mining. These devices collect entrained diesel aerosols, and on reaching the regeneration temperature, catalyze combustion of trapped materials. Although they reduce the ouput of diesel soot, little is known about the physical and chemical properties and biological activity of the particulates they transmit. While these control devices reduce the opacity of tailpipe emissions, and thus are desirable from an aesthetic point of view, the possible impact of this new technology on human health needs evaluation. This is particularly true for occupational settings such as underground mines where workers may be exposed to diesel fumes at twenty-five times the levels found in congested urban canyons with proportionately greater risk. The long-term project objective is to assess the relative hazard to human health of particulate emissions from diesel engines with and without ceramic particle traps. The study will focus on cancer risk as opposed to non-malignant respiratory effects. The comparative risk assessment will be accomplished through the following specific aims: 1) collection of particulate samples from a commercial mining diesel under simulated mining conditions; 2) determination of the mutagenic potency of the diesel particulate soluble organic fraction (SOF) with the Ames Salmonella/mammalian microsome test; 3) measurement of known carcinogens and/or bacterial mutagens in the SOF; 4) definition of the operating modes which contribute most to the production of chemical carcinogens under steady-state sampling conditions; 5) further examination of the chemical composition and biological activity of particulate emissions under conditions of transient diesel engine operation.
