Induction of Transplantable Tumors by Repeated Subcutaneous Injections of Natural and Synthetic Vitamin E in Mice and Rats

Natural vitamin E and synthetic vitamin E (dl/‐α‐tocopheryl acetate) were tested for their tnmorigenicity in rodents. Transplantable tumors, at the site of injection, were induced by repeated injections of these compounds in two strains of mice, NFS/N and C57BL/6N × C3H/He Fl, and in a strain of rats, Fischer 344. Natural vitamin E was tumorigenic in both strains of female mice only when injected with soya oil. In contrast, dl‐α‐tocopheryl acetate alone was capable of inducing tumors in Fischer 344 rats. Only one out of 5 male NFS/N mice given dl‐α‐tocopheryl acetate developed a tumor. Therefore, Fischer 344 rats were more susceptible to tumor formation by dl‐α‐tocopheryl acetate than NFS/N mice. dl‐α‐Tocopheryl acetate with soya oil or with palm oil also resulted in the formation of transplantable tumors in NFS/N mice and Fischer 344 rats. There was no difference in the tumor incidence between mice treated with dl‐α‐a‐tocopheryl acetate alone and dl‐α‐tocopheryl acetate plus soya oil or palm oil. However, in rats, the incidence was lower for a group treated with dl‐α‐tocopheryl acetate plus palm oil than for those with dl‐αa‐tocopheryl acetate alone and with dl‐α‐tocopheryl acetate plus soya oil.