EVALUATION OF THE GENETIC TOXICITY OF MIDDLE DISTILLATE FUELS

Petroleum middle distillate (PMD) fuels are mixtures of hydrocarbons t hat distill between similar to 170-370 degrees C. Commercial products that fall into this category include kerosine, diesel fuel, jet fuel, and home heating oil. These products contain both saturated (paraffins and cycloparaffins) and aromatic species, but because of the boiling range normally contain very small amounts of the 3-6 ring polycyclic a romatic hydrocarbon (PAH) constituents, which are considered to be car cinogenic. Nevertheless, there is evidence of weak tumorigenic activit y when these materials are repeatedly applied to mouse skin. In the cu rrent studies representative products were tested in two commonly used , short-term assays for genetic toxicity, the Salmonella/mammalian mic rosome mutagenicity assay and the mouse bone marrow micronucleus test. All samples were inactive in the micronucleus assay, and three were c learly inactive in the Salmonella test. Of the remaining two, one was marginally active in the Salmonella assay, and one was equivocal. The marginally active sample contained detectable levels of PAH due to the use of catalytically cracked materials as blending stocks. The result s indicated that PMDs that do not contain cracked material were not mu tagenic. Thus they may produce tumors via nongenotoxic processes. Thos e products that do contain cracked stocks may have sufficient PAH to b e mutagenic in the Solmonella assay, and in those cases the PAH might also contribute to tumor formation. (C) 1994 Wiley-Liss, Inc.