Carcinogenic Effect of Egg White,Egg Yolk and Lipids in Mice. ∗

Summary

Mice of the T. M. strain were maintained from the age of 4 weeks on the Rockland rat diet (Group 1) supplemented with hard boiled egg white (Group 2), raw egg yolk (Group 3) or with cholesterol and lard (Group 4). In one series of experiments males and females were caged separately, while in the other one they were bred and their offspring maintained on the same diets. Each of the groups of the second series of experiments consisted of mice from 3 to 4 successive generations. The results were: The mice of Groups 2 and 3 developed a very high incidence of lymphosarcoma and lung adenocarcinoma. The mice of Group 3 developed, also, a relatively high incidence of mammary cancer (33% of the breeding females) which did not appear in the animals of Group 2 nor in the controls. Incidence of mammary cancer was particularly high in the mice of Group 4. From these results it appears that both egg white and egg yolk are carcinogenic, but that their carcinogenicity differs. A carcinogenic substance causing the development of lymphosarcomas and lung adenocarcinomas, would be present in both, while a mammary carcinogen, lipid in nature, is present in the yolk only.