Use of the orthogonal design method to study the synergistic effects of asbestos fibres and 12-O-tetradecanoylphorbol-13-acetate (TPA) in the BALB/3T3 cell transformation system.

An orthogonal design method was used to study the transforming effects of chrysotile and crocidolite asbestos fibres in BALB/3T3 cells. Three experiments, designed by tables L9 (3(4)), L8 (2(7)) and L6 (3(1) x 2(2)) of the orthogonal method respectively, were performed separately. The results indicate exponential reductions in survival of treated cells concomitant with a linear increase in exposure concentrations from 0.1 to 10.0 micrograms/cm2, and that chrysotile was more toxic than crocidolite; the total transformation frequency was significantly increased with both chrysotile and TPA concentrations. There was synergism between chrysotile and TPA in sequential treatment, which suggests that chrysotile is an initiator and has a complete transforming effect at 10.0 micrograms/cm2. Crocidolite only has an initiating-like effect within the dose range of 0.1-10.0 micrograms/cm2, and no synergistic effect when associated with TPA.