[Co-carcinogenic effect of crocidolite plus benzo(a)pyrene on the lungs of rats]

Epidemiological reports have indicated that occupational exposure to asbestos and smoking may greatly increase the incidence of lung carcinoma. In this study rats were injected intratracheally with crocidolite or benzo(a)pyrene [B(a)P] only, and crocidolite plus B(a)P in combination. The incidence of lung carcinomas in crocidolite group was 6.4% (3/47), in B(a)P group 10.4% (5/48) and crocidolite plus B(a)P group 46.3% (25/54). Besides, the survival curve and the mean survival time of rats with carcinoma dropped distinctly. Significant difference was shown among the crocidolite plus B(a)P group, crocidolite and B(a)P groups (P < 0.005). The result indicated the synergetic effect of crocidolite and B(a)P on the development of lung carcinoma in rats and the importance of giving up smoking in the people exposed to asbestos. A model of lung carcinoma in rat was successfully prepared for further study in experiment on treatment, prevention and mechanism.