Revisiting the role of mutagenesis in the induction of lung cancers in rats by diesel emissions.

Recent studies have reported the induction of lung tumors in rats chronically exposed to levels of diesel-engine emissions which interfered with lung clearance. The present analysis suggests that the mutagenic substances (e.g. dinitropyrenes, polycyclic aromatic hydrocarbons) present in diesel particulates are not major contributors to rat-lung carcinogenesis. The cancers presumably result from lung "overloading" and the ensuing inflammatory response. In the absence of additional data, this putative mechanism of diesel-caused cancer cannot be extrapolated to other species at risk from exposure to diesel emissions.