Feeding studies on sodium cyclamate, saccharin and sucrose for carcinogenic and tumour-promoting activity.

Groups of 50 female Swiss mice were fed for 18 months on a standard diet containing sucrose (10 %), sodium cyclamate (5 %) or saccharin (5 %), while 100 control mice were fed on the standard diet alone. The survival times were comparable in all groups and no acute toxic effects were encountered. No local tumours in the gastro-intestinal tract, nor excess incidence of distant tumours, were found in animals fed on the various sweeteners. The mice fed on the diet containing 10 % sucrose gained more weight than animals in the other groups, but did not show an increased incidence of neoplasms. Comparable groups of mice were given a single intragastric instillation of 50 pgbenzo[a]pyrene in 0.2 ml polyethylene glycol 400,7 days before the start of feeding of the different test diets. Some mice in all these groups developed, as expected, benign and malignant neoplasms of the forestomach epithelium, but treatment with the sweetening agents had no obvious effect on the incidence, number or histological type of these or of any other type of neoplasm. No neoplasms of the urinary bladder were seen on careful macroscopic examination of mice at necropsy ; the bladders were not examined microscopically. It is concluded that, under the experimental conditions described, the three sweeteners examined showed no carcinogenic or tumour-promoting activity.