Bioassay of 2,4-dinitrotoluene for possible carcinogenicity

A bioassay of practical-grade 2,4-dinitrotoluene for possible carcinogenicity was conducted using Fischer 344 rats and B6C3F1 mice. 2,4-Dinitrotoluene was administered in the feed, at either of two concentrations, to groups of 50 male and 50 female animals of each species. For male and female rats, the high and low time-weighted average dietary concentrations of 2,4-dinitrotoluene were 0.02 and 0.008 percent, respectively. For male and female mice, the high and low time-weighted average concentrations were 0.04 and 0.008 percent, respectively. After a 78-week period of compound administration, observation of the rats continued for an additional 26 weeks and observation of the mice continued for 13 additional weeks. For the chronic rat bioassay, 25 rats of each sex were placed on test as high dose controls, and 50 rats of each sex served as the low dose controls. For the mice, 50 males and 50 females were placed on test as controls for each of the high dose and low dose groups. In both species the survival in all groups was adequate for statistical analysis of late-appearing tumors. In the male rats, a significantly increased incidence of fibroma of the skin and subcutaneous tissue occurred in both the high and the low dose groups when compared to their respective controls. A statistically significant incidence of fibroadenoma of the mammary gland occurred in the high dose female rats. Among the mice a variety of tumors was observed but none were considered to be associated with the dietary administration of 2,4-dinitrotoluene. Under the conditions of this bioassay dietary administration of 2,4-dinitrotoluene to Fischer 344 rats induced benign tumors (i.e., fibroma of the skin and subcutaneous tissue in males and fibroadenoma of the mammary gland in females). No evidence was provided for the carcinogenicity of the compound in B6C3F1 mice of either sex.