An efficient approach to study the toxicological effects of complex mixtures.

In vitro studies in the field of inhalation toxicology suffer a number of problems due to the difficulties in exposing cells of the respiratory tract directly to inhalable substances in a way that is comparable to the in vivo situation. The most promising approach is based on a biphasic cell culture technique, where cells are grown on microporous membranes at an air-liquid interface. In this way, the cells can be nutrified from the basal side of the membrane whereas the apical part with the cultivated cells is in direct contact with the test atmosphere, meaning gaseous and/or particulate compounds. This type of exposure requires (1) a special exposure device and conditions, (2) a close contact between the cultivated cells and the inhalable substances without the interference of medium as well as (3) precise control of the pollutant levels. Exposure of cells under these conditions results in dose-dependent reactions with regard to cyto- and genotoxicity or cell activation associated, for example, with the release of bioactive mediators. Such an experimental approach is not only suitable for cultivated cells, but it can also be used in a modified Ames assay for the detection of mutagenicity by exposing bacteria to gaseous compounds or complex mixtures. This is not only true under laboratory conditions but can also be achieved under real indoor situations.