Factors affecting the carcinogenicity of mineral fibres and their relationship to the synergistic effects of tobacco smoke.

In order to better understand the mechanisms underlying the synergistic effects of asbestos (1332214) fiber and cigarette smoke exposures in inducing pulmonary tumors the relationship of the combined effects of these agents to the fiber mass inhaled, fiber dimensions, and fiber durability in the lungs was explored. A synergistic effect between asbestos exposure and cigarette smoking for the development of bronchial carcinoma has been recognized for almost 20 years. The carcinogenicity of asbestos has been found to be related to fiber type, mass dose, fiber length, and durability in the lungs. The highest incidence of asbestos induced mesotheliomas has been reported in animals exposed to preparations containing the highest number of long, thin fibers. In addition, fiber length and fiber type have been found to be related to the deposition and retention of asbestos fibers in the lung. The adsorption of polycyclic aromatic hydrocarbons present in cigarette smoke onto the surface of asbestos fibers was discussed as a possible mechanism involved in mediating the synergistic effects seen between cigarette smoke and asbestos fiber exposure and the relationship between fiber length and such adsorption was explored.