Kerosene soot genotoxicity: enhanced effect upon co-exposure with chrysotile asbestos in Syrian hamster embryo fibroblasts

Epidemiological and experimental studies have suggested an enhancement of asbestos-induced bronchogenic carcinoma by cigarette smoke. Further, our recent experimental and epidemiological studies have indicated that besides smoking, several other compounds including kerosene soot may accelerate disease processes in asbestos-exposed animals as well as in the humans. Incomplete combustion of kerosene oil generates large volumes of soot, which contains various polycyclic aromatic hydrocarbons and aliphatic compounds. As reported earlier, exposure to kerosene soot is known to cause biochemical and pathological changes in the pulmonary tissue, which may cause cardiopulmonary disorders. In this study we investigated genotoxic effects caused by kerosene soot and chrysotile asbestos as well as co-exposure of kerosene soot and chrysotile using Syrian hamster embryo fibroblasts (SHE). The micronucleus assay revealed a significant increase of induced micronuclei (MN), (P less than or equal to 0.05) in SHE cells after treatment with kerosene soot (0.5-1.0 mu g/cm(2)) for 66 h (36 MN/1000 cells). Combined treatment with chrysotile and soot induced up to 110 MN/1000 cells (chrysotile alone: 80 MN/1000 cells; concentrations: 1 mu g/cm(2), exposure times: 66 h). Kinetochore staining revealed mainly clastogenic effects in all cases (soot: 21.3% CRMN+; chrysotile: 27%; soot + chrysotile: 27.6%; control: 20.8%). This is the first study showing that kerosene soot is not only genotoxic but it can also elevate the genotoxic potential of chrysotile asbestos. This information may be of importance for workers occupationally exposed to asbestos and domestically exposed to kerosene soot. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.