[The phototoxic activity of carcinogenic polycyclic hydrocarbons and their degradation products in the biological test (author's transl)].

The phototoxic activity of carcinogenic polycyclic hydrocarbons was evaluated using ciliates of the species Tetrahymena pyriformis maintained in sterile, semisynthetic media. This ciliate-light-test was developed into and standardized for a rapid microbiological assay of carcinogenic activity of polycyclic aromatic hydrocarbons. --In this fashion, six polycyclic aromatic compounds with differing carcinogenic activities were tested:benzo(a)-pyrene, benzo(b)fluoranthene, indeno(1,2,3-c,d)pyrene, benzo(a)anthracene, fluoranthene, and cyclopenteno (c,d)pyrene. An essential parallelism between phototoxic and carcinogenic activities, resp., was clearly obvious. --The combined effects of benzo(a)pyrene and fluoride ions was also investigated using the ciliate-light-test. Fluoride ions in the concentration of 1 ppm did not affect the phototoxicity of benzo(a)pyrene, suggesting that fluorides possess no cocarcinogenic activities. --Degradation products of benzo(a)pyrene obtained by UV-irradiation (mixtures of quinones) were also tested for phototoxic activity. It could be shown that such degradation products entirely free from benzo(a)pyrene still possessed 50% of the activity of the original, non-irradiated solution. This is taken to indicate that the degradation products products resulting of UV-irradiation may still retain a measure of carcinogenic activity, --a finding of considerable importance from the viewpoint of environmental hygiene.