Mearl F. Stanton

Experimental Pulmonary Carcinogenesis with Asbestos

Abstract Three methods have been used to test the carcinogenic response of the lung and pleura of the rat to asbestos. No carcinogenic response of pulmonary epithelium or pleura was noted to either healing infarcts or implanted war pellets that contained asbestos. Sarcomas of the pleura and pericardium developed in 74% of rats in which the pleura was covered with an asbestos-impregnated fibrous glass coat. The fibrous glass alone caused only slight reaction, with complete healing. The last method may serve as an accurate and convenient means of quantitating the neoplastic response of the pleura to asbestos.

Squamous Carcinoma of the Lung from Cigarette Smoke Condensate in Implanted Beeswax Pellets

A simple method of inducing carcinomas of the lung in rats has been employed to examine the mechanism of pulmonary carcinogenesis by cigarette smoke condensate (CSC). The method consists of injecting directly into the surgically exposed lung a heated mixture of beeswax and tricaprylin to which CSC or its components has been added. During the subsequent 2 years, a progressive series of metaplastic and neoplastic epithelial changes occur at the surface of the solidified pellet which, because of their focal nature, can be examined in detail and compared quantitatively. Final crude incidence rates for squamous cell carcinoma of the lung ranged from 14% to 34% when doses of a refined heptane soluble fraction were employed at levels of 12 mg to 72 mg. Preliminary response to the neutral fraction of CSC and a primary subfraction indicate that the highest carcinogenic potential resides with the neutral polynuclear aromatic hydrocarbons. Both the highly polar subfraction of the neutrals and the weak acid fraction are also active at proportions compatible with response on mouse skin painting experiments.