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Table 1.
Potassium bromate-induced tumor incidences in male and female Fisher 344 rats
(Kurokawa et al., 1983)
Sex Dose group Average dose 1
(mg/kg-day)
Tumor type Tumor incidence 2
male control 0 kidney tumors 3 3/53
low dose 12.4 32/53
high dose 22.5 46/52
control 0 peritoneal mesotheliomas 6/53
low dose 12.4 17/52
high dose 22.5 28/46
female control 0 kidney tumors 3 0/47
low dose 14.2 28/50
high dose 28.3 39/49
control 0 thyroid tumors 3/52
low dose 14.2 10/52
high dose 28.3 12/52
1. Doses as reported by Gold et al. (1987).
2. Tumor incidences as reported by Gold et al. (1987).
3. Adenomas and adenocarcinomas
IV.
DERIVATION OF CANCER POTENCY
Basis for Cancer Potency
Gold et al. (1987) list the results from positive drinking water studies in male and female F344 rats
(Kurokawa et al., 1983) and from negative feeding studies in male and female Wistar rats (Fisher et
al., 1979) and "Theiller's Original" mice (Ginocchio et al., 1979). Male and female rats are of similar
sensitivity. Cancer potency is based on results from Kurokawa et al. (1983). The dose-response data
for renal adenomas and adenocarcinomas in male rats are listed in Table 1 and are the basis for the
cancer potency for potassium bromate (Cal/EPA, 1992).
Methodology
Expedited Proposition 65 methodology (with cross-route extrapolation) was used to derive a cancer
potency factor. A unit risk factor was then calculated by OEHHA/ATES from the cancer potency
factor using a reference human body weight of 70 kg and an inspiration rate of 20 m 3 /day.
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