Bioassay of p-Quinone Dioxime for Possible Carcinogenicity (CAS No. 105-11-3)

p-Quinone dioxime, a rubber vulcanization accelerator, was selected for bioassay by the National Cancer Institute because of a lack of adequate carcinogenicity data. A bioassay for the possible carcinogenicity of p-quinone dioxime was conducted using Fischer 344 rats and B6C3F1 mice. p-Quinone dioxime was administered in the feed, at either of two concentrations, to groups of 50 male and 50 female animals of each species. Twenty animals of each sex and species were placed on test as controls, with the exception of 18 in the control male mouse group. The high and low concentrations of p-quinone dioxime were 750 and 375 ppm for rats and 1,500 and 750 ppm for mice. The compound was administered to rats and mice for 104 weeks. The period of compound administration was followed by an observation period of 1 week for both species. There were no significant positive associations between the concentrations of p-quinone dioxime administered and mortality in rats or mice of either sex. Adequate numbers of animals in all groups survived sufficiently long to be at risk from late-developing tumors. Distinct dose-related mean body weight depression was observed among rats and slight mean body weight depression, relative to controls, was observed among mice, indicating that the dosages of p-quinone dioxime administered to the animals in this bioassay may have approximated the maximum tolerated concentrations. Tumors of the urinary bladder were observed only in dosed rats. For female rats, there was a significant positive association between concentration administered and the incidences of a combination of urinary bladder neoplasms. The high dose to control Fisher exact comparison was also significant for these tumors in female rats. No compound-related neoplasms were observed in male rats or mice of either sex. Under the conditions of this bioassay, dietary administration of p-quinone dioxime was carcinogenic to female Fischer 344 rats, causing neoplasms of the urinary bladder. The compound was not carcinogenic to male Fischer 344 rats or B6C3F1 mice of either sex. Levels of Evidence of Carcinogenicity: Male Rats: Negative Female Rats: Positive Male Mice: Negative Female Mice: Negative Synonyms: 2,5-cyclohexadiene-1,4-dione; dioxime p-benzoquinone; p-quinonedioxime; dioxime 1,4-cyclohexadienedione