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Smith and Cabral (1980) exposed female Agus and Wistar rats to diets containing 100 mg/kg HCB for
up to 90 or 75 weeks, respectively. An increased incidence of liver tumors (histological type not
specified) due to HCB exposure was observed in both Agus and Wistar rats; tumor incidence was
14/14 and 4/6, respectively, compared to 0/12 and 0/4, respectively, in the control animals.
Male and female Syrian golden hamsters were exposed to diet containing 0, 200 or 400 mg/kg diet
HCB for 90 days; 25-50 animals/group were sacrificed on the 91st day (Lambrecht et al., 1982). The
remaining 25 animals/group were placed on control diet and sacrificed at 6 week intervals up to 1 year.
Hepatoma incidence in the 200 and 400 mg/kg diet groups was 1/13 and 1/20, respectively, for males
and 1/15 and 1/7, respectively for females. No hepatomas were noted in 43-50 control animals for
each sex.
Male and female Sprague-Dawley rats (94/sex/group) were fed diets containing 0, 75 or 150 mg/kg
diet HCB for up to 2 years (Lambrecht et al., 1983a, b, 1986). Four animals/sex/group were killed at
0, 1,2,3,4,8,16,32 and 64 weeks. Treatment-related increases in the incidence of hepatic tumors
(hepatomas, hemangiomas, hepatocarcinomas and bile duct adenomas/carcinomas) and renal-cell
adenomas were noted in both male and female animals. Tumor incidence data is noted in Table 3.
Table 3.
Hexachlorobenzene-induced hepatic tumors in male and female Sprague-Dawley rats
(Lambrecht et al., 1983 a,b; 1986)
Dose group
(mg/kg diet)
Tumor type
Tumor incidence
males females
0 hepatoma/hemangioma 0/54 0/52
75 10/52 23/56
150 11/56 35/55
0 hepatocarcinoma 0/54 0/52
75 3/52 36/56
150 4/56 48/55
0 bile duct adenoma/carcinoma 0/54 1/52
75 2/52 19/56
150 2/56 29/55
0 renal-cell adenomas 7/54 1/52
75 41/52 7/56
150 42/56 15/55
Arnold et al. (1985) conducted two studies on the effects of chronic feeding of HCB in Sprague-
Dawley rats. In the first study, male and female Sprague-Dawley rats were fed diets containing 0, 0.32,
1.6, 8 or 40 mg/kg diet HCB for 3 months after weaning. Group sizes were 40/sex except for the
control and high-dose groups (64 and 66/sex, respectively). After 3 months, the F 0 rats were bred and
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