Sister chromatid exchanges in rodent tracheal epithelium exposed in vitro to environmental pollutants.

In our highly industrialized world, air pollution has become a major topic. The human respiratory tract is constantly exposed to air pollutants by inhalation. Besides gaseous pollutants airborne particulates are of great importance, containing a complex mixture of several hundred substances. The tracheobronchial epithelium is the major target site of airborne particulates as well as the origin of the most common cancer in man, the bronchogenic carcinoma. In our study we collected samples of airborne particulates in winter 1991 in the highly industrialized Rhine-Ruhr area (Germany) with a high-volume sampler on glass fiber filters. Airborne particulates were extracted with di-chloromethane and quantitatively transferred to dimethyl sulfoxide (DMSO) for tissue culture experiments. As target cells for genotoxicity testing we used cultures of rodent tracheal epithelial cells from the Syrian golden hamster and from the rat. Induction of "sister chromatid exchanges" (SCE) was utilized as a sensitive cytogenetic endpoint for evaluation of the genotoxic activity of extracts of airborne particulates. In presence of global extracts (GEX) we observed a dose-dependent, highly significant increase of SCE in tracheal epithelial cells of the Syrian golden hamster and of the rat. It is remarkable that even quantities of chemical substances equivalent to airborne particulates from less than 1 m3 of air were genotoxic. Results of this study and earlier reports demonstrate that rodent tracheal epithelial cells offer a reliable and sensitive in vitro model for genotoxicity testing of airborne particulates. Therefore, tracheal epithelial cells in vitro appear a meaningful alternative to other human and rodent cell culture systems which have been used for genotoxicity testing of air pollutants.