A carcinogenesis bioassay of tara gum, a potential stabilizer for cosmetics and foods, was conducted by feeding diets containing 25,000 or 50,000 ppm of the test substance to 50 F344 rats and 50 B6C3F1 mice of either sex for 103 weeks. Groups of 50 untreated rats and mice of either sex served as controls.
In the chronic bioassay, mean body weights of dosed and control rats of either sex were comparable over the course of the study. Feed consumption by low-and high-dose male rats was 92% and 95% that of the controls, and feed consumption by low-and high-dose female rats was 87% and 79% that of the controls. Mean body weights of high-dose mice of either sex were lower than those of controls; feed consumption by dosed mice was comparable with that of controls. Although the rats and mice might have been able to tolerate higher doses, 50,000 ppm (5%) is the recommended maximum concentration of a test substance mixed in feed, according to the guidelines of the Bioassay Program.
No tumors were observed in increased incidences that were considered to be related to administration of tara gum to either species. Interstitial cell tumors of the testis in male rats were observed in a statistically significant (P < 0.003 for trend and group comparisons) positive relationship (40/48 controls; 46/46 low dose; 48/48 high dose); because these tumors are present in almost all aged F344 male rats and because of the marginal statistical significance when time-adjusted analyses are applied, these increases are not regarded as being related to tara gum administration.
A significant (P<0.05) negative trend was observed in the proportion of male rats with pancreatic islet cell adenoma (5/45 controls, 1/44 low dose, 0/45 high dose), of female mice with alveolar/bronchiolar adenomas (7/50, 2/49, 2/50), and of female mice with hepatocellular adenomas (9/49, 4/49, 1/50).
Under the conditions of this bioassay, tara gum was not carcinogenic for F344 rats or B6C3F1 mice of either sex.