Asbestos and benzo(a)pyrene synergism in the transformation of Syrian hamster embryo cells.

Four varieties of asbestos fibers, crocidolite, anthophyllite, amosite, and chrysotile, induced a low rate of morphologic transformation in Syrian hamster cells. Of the four tested, chrysotile was the most lethal as reflected by colony survival. When cells were exposed to 1 microgram of benzo(a)pyrene (BP)/1 ml medium or 3 J/m2 ultraviolet irradiation and to different concentrations of the asbestos fibers, an enhancement of transformation occurred only with BP. The enhancement was dose responsive with all fiber species except for amosite which was dose independent. The synergistic activity of BP and asbestos suggests that asbestos facilitates the transport of BP to the cell site(s) critical for transformation. These results provide a basis for investigating the carcinogenic and cocarcinogenic potential of asbestos fibers in mammalian cells.