Further studies with the somatic white-ivory system of Drosophila melanogaster: genotoxicity testing of ten carcinogens.

To provide further background data for the white-ivory somatic mutation Drosophila assay, ten selected carcinogens (acetamide, acrylamide, benzo(alpha)pyrene, cyclophosphamide, diethylstilbestrol, 4-nitroquinoline N-oxide, propyleneimine, safrole, thiourea, and o-toluidine) have been tested in this system. Seventy-two hours after egg laying, larvae were fed with different concentrations of each carcinogen during the rest of their development until pupation, and the genotoxic effects were measured as significant increases in the appearance of visible mutant clones of ommatidia in the eyes of the emerging adult flies. Our results indicate that three of the ten carcinogens tested (cyclophosphamide, 4-nitroquinoline N-oxide, and propyleneimine) were strong genotoxic agents, two (diethylstilbestrol and acrylamide) induced significant positive results but without a dose-response relationship, and safrole was weakly positive. On the other hand, acetamide, benzo(alpha)pyrene, thiourea, and o-toluidine were unable to increase the frequency of mutant clones.