[Studies on the mutagenic effect of extracts derived from airborne particulates within one year in differently burdened areas using the Ames test (author's transl)].

Suspended matter was collected at three sampling sites with different air pollution levels (DU = Duisburg, mining, iron and steel industry; D = Düsseldorf, residential city; K = Krahm, rural district) in 1978. The seasonal variations of the mutagenicity of extracts from samples collected monthly were assayed by the Ames-test. Th results are presented as the number of revertants related to air volume, weight of the suspended matter, weight of the dried extract and to the amount of benzo(a)pyrene in the extract. The mutagenicity varies according to the benzo(a)pyrene concentration in the atmosphere: the highest values are found during the winter, the lowest during the summer. When the mutagenicity is based on the benzo(a)pyrene content, it remains nearly constant throughout the year (sampling site DU) or rises in the summer (sampling sites D and K). These results indicate that at least in heavily polluted areas the larger part of the mutagens may originate from the same sources as benzo(a)pyrene (e.g. incomplete combustion). The direct (assayed without activating system) mutagenicity of the extracts is somewhat higher in winter than in summer. However, these differences are low or missing, when the mutagenicity is expressed as number of revertants per weight of suspended matter or dried extract. The mutagenicity reaches a maximum in summer, provided, the number of revertants is related to the benzo(a)pyrene concentration. These results indicate that the direct acting mutagens present in the air originate from other sources than that of benzo(a)pyrene (e.g. automobile exhaust). The mean values of the mutagenicity related to the number of revertants per dry-weight and weight of suspended matter do not differ among the three sampling sites. It can be assumed that the composition of the particulate matter may be similar with respect to mutagens regardless the level of pollution.