SISTER-CHROMATID EXCHANGES IN RODENT TRACHEAL EPITHELIUM EXPOSED IN-VITRO TO ENVIRONMENTAL-POLLUTANTS

In our highly industrialized world, air pollution has become a major t opic. The human respiratory tract is constantly exposed to air polluta nts by inhalation. Besides gaseous pollutants airborne particulates ar e 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 canc er in man, the bronchogenic carcinoma. In our study we collected sampl es of airborne particulates in winter 1991 in the highly industrialize d Rhine- Ruhr area (Germany) with a high-volume sampler on glass fiber filters. Airborne particulates were extracted with di-chloromethane a nd 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 ha mster and from the rat. Induction of ''sister chromatid exchanges'' (S CE) was utilized as a sensitive cytogenetic endpoint for evaluation of the genotoxic activity of extracts of airborne particulates. In prese nce of global extracts (GEX) we observed a dose-dependent, highly sign ificant increase of SCE in tracheal epithelial cells of the Syrian gol den hamster and of the rat. It is remarkable that even quantities of c hemical substances equivalent to airborne particulates from less than 1 m(3) of air were genotoxic. Results of this study and earlier report s demonstrate that rodent tracheal epithelial cells offer a reliable a nd sensitive in vitro model for genotoxicity testing of airborne parti culates. Therefore, tracheal epithelial cells in vitro appear a meanin gful alternative to other human and rodent cell culture systems which have been used for genotoxicity testing of air pollutants.