Effect of fuel properties on mutagenic activity in extracts of heavy-duty diesel exhaust particulate.

The effect of varying fuel properties on the emission of mutagenic materials was studied in diesel exhaust particles from a heavy duty engine run under transient speed and load conditions while using nine fuels varying in aromatics, sulfur and boiling point. Mutagenic activity of the soluble organic fraction (SOF) of the particulate was determined using the Ames Salmonella test system with strain TA98 with and without S9 activation. Increasing mutagenic activity relative to fuel consumed (mutants/lb fuel) or to engine work output (mutants/hp-h) was correlated with increasing fuel aromatics (p less than 0.05), but not with fuel sulfur. Increased fuel sulfur levels were correlated with increased amounts of SOF but with decreasing mutagenic activity of the SOF (mutants/microgram SOF) (p less than 0.05). As a result, mutants/hp-h were essentially the same for high- and low-sulfur fuels with high aromatics. No association was found between the fuels' boiling points and the mutagenic activity of the SOF. Mutagenic activity with S9 was generally lower than without, but the correlations were not changed.