Review : Laboratory Studies in the Prediction of Lung Cancer Risk

Abstract

The value of studies involving the exposure of laboratory animals by the inha lation route in research aimed at identifying agents which might pose a risk of respiratory tract cancer in humans is reviewed. Among the problems encoun tered are: anatomical differences between species which affect aerodynamics; the higher efficiency of the rodent nose in removing particles before the air stream reaches the lungs; difficulties in imitating human exposure conditions while at the same time avoiding the absorption of test chemicals through the skin; the fact that prolonged irritation of respiratory tract epithelium by non genotoxic agents - if it causes necrosis followed by regenerative hyperplasia- can lead non-specifically to cancer development; and a tendency of mice of many strains to develop adenomatous tumours of the lung despite no deliber ate exposure to any known carcinogens. The value of laboratory rodents in relation to lung cancer risk from bis(chloromethyl) ether, cadmium, nickel, chromium, tobacco smoke, asbestos and other fibrous dusts, and general industrial air pollution is discussed in the light of the above considerations.