Carcinogenesis Bioassay of Propyl Gallate in F344 Rats and B6C3FJ Mice

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Abstract
Chronic toxicity studies were conducted by maintaining groups of 50 F344 rats and 50 B6C3F1 mice of each sex on nutritionally complete diets containing 0%, 0.6%, or 1.2% propyl gallate for 103 weeks. Survival of rats and mice of both sexes was not significantly affected by the administration of this compound. Dosed rats and mice showed growth retardation and reduced feed utilization efficiency. Increased incidence of hepatic cytoplasmic vacuolization and suppurative inflammation of the prostate gland were observed in dosed male rats and were considered to be related to propyl gallate administration. Tumors of the preputial gland, islet ceil tumors of the pancreas, and pheochromocytoma of the adrenal gland were observed with significantly (p < 0.05) higher incidence in the low-dose male rats; however, there was little evidence of a dose response or of an effect in the high-dose group. Rare tumors (an astrocytoma and a glioma) were found in the brains of two low-dose female rats but none was found in the high-dose group. Malignant lymphoma occurred with a significant (p < 0.05) positive trend in male mice and the incidence in the high-dose group was significantly (p < 0.05) higher than that of the concurrent controls. However, the high-dose incidence was not significantly different from the historical control rate for the laboratory that conducted the bioassay. Under the conditions of the bioassay, propyl gallate was not considered to be clearly carcinogenic for F344 rats, although the increased incidence of preputial gland tumors, islet-cell tumors of the pancreas, and pheochromocytoma of the adrenal glands in low-dose male rats may have been related to compound administration. Thus, the evidence for carcinogenicity in male rats is regarded as being equivocal, while there was no indication of a carcinogenic response in female rats. Propyl gallate was not considered to be carcinogenic for B6C3F1 mice, although the increased incidence of malignant lymphoma in dosed male mice may have been related to administration of the test compound.