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adenomas/mouse (20 animals/group, both sexes combined) was 0.19 ± 0.1, 0.60 ± 0.2, 0.50 ± 0.27
and 0.60 ± 0.15 in the control, low, medium and high-dose groups, respectively. The incidence of lung
adenomas in the high-dose group was significantly increased (p < 0.05 by Student’s T-test or chisquare
test).
IV.
DERIVATION OF CANCER POTENCY
Basis for Cancer Potency
The NCI (1978) carcinogenicity bioassay demonstrated a statistically significant increased incidence of
squamous cell papillomas and carcinomas of the forestomach in low-dose male mice (2/46, p < 0.029)
and low-dose (3/47; p < 0.003) and high-dose (3/45; p < 0.003) female mice when compared to
tumor incidences in male (1/180) and female (1/180) historical controls. The female mouse tumor
incidence data from this study was chosen as the basis of a cancer potency factor because it
demonstrated induction of a rare tumor type by allyl chloride in the most sensitive sex of a sensitive
species.
Methodology
Transformed doses were calculated as follows:
transformed dose = experimental dose × (5 days/7 days) × (78 weeks/92 weeks)
Animals were dosed 5 days/week, and the duration of exposure and of the experiment were 78 and 92
weeks, respectively. Experimental doses were 129 and 258 mg/kg/day; transformed doses were 78
and 156 mg/kg/day. A linearized multistage procedure (GLOBAL82) was then applied to the tumor
incidence data; the resulting unadjusted cancer potency factor (q 1 * ) was 1.01 E-3 (mg/kg/day) -1 . A q 1
*
for humans was calculated from the unadjusted q 1 * as follows:
human q 1
*
= unadjusted q 1 * × (70 kg/0.025 kg) 1/3 × (104 weeks/92 weeks) 3
= 2.1 E-2 (mg/kg/day) -1
The reference human body weight and the average female mouse weight were 70 kg and 0.025 kg,
respectively, and the experiment length and the mouse lifespan were 92 weeks and 104 weeks,
respectively. A unit risk factor of 6.0 E-6 (µg/m 3 ) -1 was derived from the human q 1 * by OEHHA/ATES
using an inspiration rate of 20 m 3 /day.
V. REFERENCES
Hazardous Substance Data Bank (HSDB) 1994. National Library of Medicine, Bethesda MD (CD-
ROM Version). Micromedix, Inc., Denver CO, Edition 22.
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