home edit2 whole TSD November 2002 PDF format - OEHHA

Table 1. Liver hepatoma incidence in dd mice treated with hexachlorocyclohexane (HCH)
(Hanada et al. (1973).
HCH Isomer
α-HCH
β-HCH
γ-HCH
Technical HCH
Sex
males
females
males
females
males
females
males
females
Hepatoma incidence
mg/kg diet HCH
100 300 600
1/8 7/7 7/7
0/8 2/3 6/8
0/9 0/8 0/8
0/9 0/8 0/4
0/10 0/9 3/4
0/8 0/7 1/3
0/10 4/4 4/4
0/8 3/5 5/5
In the study by Kashyap et al. (1979), Swiss mice (30/sex/group) were exposed to 0 or 100 mg/kg
diet for 80 weeks. Mice were also exposed to technical HCH by gavage (10 mg/kg/day) or skin
painting (0.25 mg in 0.1 mg olive oil). A significant increase in liver hepatocarcinomas and
lymphoreticular tumors of type B was observed in mice exposed to technical HCH in the diet or by
gavage (Table 2).
Table 2. Tumor incidence in mice treated with technical hexachlorocyclohexane (HCH) (Kashyap et
al., 1979).
HCH Treatment Group Sex Animals/g
roup
Control
m 25
f 26
100 mg/kg/day (diet) m 23
f 25
10 mg/kg/day (gavage) m 26
f 28
0.25 mg/0.1 mg (olive oil) m 25
(gavage)
f 18
m = male, f = female
Liver
tumors
4
1
16
9
12
7
5
3
Total tumors
9
5
22
21
17
16
11
7
Wolff et al. (1987) reported on the carcinogenic effects of γ-HCH in several strains of mice. Female
yellow, black, and pseudoagouti mice (36-96 per group) were exposed to 0 or 160 ppm γ-HCH in the
diet for up to 24 months. Different response rates were observed between strains, indicating significant
genetic variability in response to γ-HCH. In yellow mice, a significant increase in the incidence of Clara
cell hyperplasia, papillary lung tumors and hepatocarcinomas and adenomas was observed (Table 3).
The higher incidence of tumors in the obese yellow mice indicate that bioaccumulation of γ-HCH in
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