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Table 2.
Mortality and tumor incidences associated with dietary exposure of Fischer 344 rats
and B6C3F 1 mice to p-cresidine (NCI, 1979)
Sex/species
Treatment
group
Average Dose 1
(mg/kg-day)
Survival after
75 weeks (%)
Tumor type Tumor incidence 2
male mice controls 0 98 urinary bladder tumors 0/50
low-dose 260 50 40/50
high-dose 552 10 31/50
female mice controls 0 90 urinary bladder tumors 0/50
low-dose 281 78 42/50
high-dose 563 28 45/50
controls liver tumors 0/50
low-dose 14/50
high-dose 6/50
male rats controls 0 94 urinary bladder tumors 0/50
low-dose 198 96 30/50
high-dose 396 62 44/50
controls liver tumors 0/50
low-dose 13/50
high-dose 2/50
controls nasal cavity tumors 0/50
low-dose 2/50
high-dose 23/50
female rats controls 0 96 urinary bladder tumors 0/50
low-dose 245 98 31/50
high-dose 491 76 43/50
controls nasal cavity tumors 0/50
low-dose 0/50
high-dose 11/50
1. Doses as reported by Gold et al. (1984).
2. Tumor incidences as reported by Gold et al. (1984)
IV.
DERIVATION OF CANCER POTENCY
Basis for Cancer Potency
Results of the NCI (1979) feeding study in male and female B6C3F 1 mice and Fischer 344 rats are
listed in Gold et al. (1984). Urinary bladder tumors as well as tumors at other sites were observed in
both sexes of mice and rats. The most sensitive site appears to be the urinary bladder. Both sexes of
both species show similar sensitivities at this site. The potency derived from dose-response data on
female mice (benign and malignant urinary bladder tumors) is slightly greater than those for the other
groups and is taken as the best estimate here (see Table 2).
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