Carcinogenicity study of 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane in B6C3F1 mice.

1,1-Bis(tert-butylperoxy)-3.3.5-trimethylcyclohexane (BBTC) is widely used in the manufacture of rubber. The present carcinogenicity study in B6C3F1 mice was carried out in order to assess its potential to induce tumours. BBTC was administered at dietary levels of 0 (control), 0.25 and 0.5% for 78 wk; these dose levels were selected on the basis of a subchronic toxicity study, in which body weights were depressed to less than 90% of the control group values and swelling of hepatocytes was histologically evident in animals fed 1% BBTC or more in the diet. Neoplasms were found in all groups, including the control group, but there were no significant differences between groups of either sex in mortality, tumour incidences or tumour distribution. All tumours were considered to be spontaneous because of the similarity to background data for B6C3F1 mice. This study thus provides no evidence of carcinogenicity of BBTC in B6C3F1 mice.