STUDY ON THE CARCINOGENICITY OF TANNIC-ACID IN F344 RATS

The carcinogenicity of tannic acid, a compound that is used as a food additive, a clarifying agent and a refining agent, was examined in F34 4 rats of both sexes. Tannic acid was dissolved in distilled water at concentrations of 0.25 and 0.5%. The doses were selected on the basis of results from a 13-wk subchronic study. Groups of 50 male and 50 fem ale rats were given one of these solutions ad lib. as their drinking w ater for up to 2 yr. The mean body weights of the treated males were e ssentially comparable with those of the controls, whereas treated fema les had lower mean body weights than the control group. A variety of t umours developed in all groups, including the control group, but all t he neoplasms were histologically similar to those known to occur spont aneously in this strain of rats, and no statistically significant incr ease in the incidence of any tumour was found in the treated groups of either sex. Thus, it is concluded that, under the conditions of the e xperiment, tannic acid has neither carcinogenic potential in F344 rats nor modifying effects on spontaneous tumour development.