In Vitro Simulation of Concurrent Exposures to Asbestos Fibers and Nitrosamines

Human populations are constantly exposed to a multiplicity of environmental agents, the interactions of which can have a profound effect on cancer risk. One of the most well documented of such interactions involves combinations of asbestos and other environmental carcinogens. Epidemiological studies have shown that asbestos miners who smoke are at a greatly enhanced risk for lung cancer as compared with their non smoking contemporaries (Selikoff et al. 1980). In addition, laboratory studies have shown asbestos fibers to produce synergistic effects on lung tumor induction when experimental animals are exposed to combinations of intratrachelly instilled asbestos and polycyclic hydro-carbons, either radon 222 or whole body neutron exposure, and N-nitrosodiethylamine (Kung-Vosamae and Vinkmann 1980; Lafuma et al. 1980; Stenback et al. 1973; Miller et al. 1965; Saffiotti et al. 1972). The mechanism by which these synergistic effects are produced is poorly understood.