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p = 0.02) and mammary gland adenocarcinoma (23/81 exposed vs. 1/39 control; p = 10 -3 ) was also
increased. Among male and female C3Hf mice exposed for 15 days, the incidence of lung adenoma
(45/79 exposed vs. 3/30 control, males, p = 10 -5 ; 46/87 exposed vs. 12/62 control, females, p = 10 -4 )
and Harderian gland adenoma (32/79 exposed vs. 3/30 control, males, p = 0.001; 25/87 exposed vs.
2/62 control, females, p = 10 -4 ) was increased. Among female C3Hf mice alone, the incidence of
mammary adenocarcinoma (36/87 exposed vs. 6/62 control; p = 10 -5 ), thymic lymphosarcoma (2/87
exposed vs. 0/39 control; p = 0.02), and hepatoma (29/87 exposed vs. 15/62 control; p = 0.15) was
increased.
Innes et al. (1969) treated male and female B6C3F 1 and B6AKF 1 mice (24/sex) with 158 mg/kg
body weight urethane (on day 7) by oral gavage from day 7 to 28 of life. Thereafter, animals were
exposed to a concentration of 600 ppm urethane in their diet. Control groups (90/sex/strain) received
received vehicle alone, then normal diet. Surviving animals were sacrificed and autopsied between 78
and 88 weeks of age. Significant increases in the incidence of pulmonary adenomas or carcinomas and
hepatomas were observed in treated animals of both sexes and strains (see Table 2, p < 0.05, Fisher’s
exact test). The incidence of angiomas was increased in male and female B6AKF 1 mice (p < 0.01).
Harderian gland adenomas were increased in B6C3F 1 females and B6AKF 1 males and females (p <
0.01). Lymphomas were increased in B6AKF 1 male mice (p < 0.01).
Table 2.
Tumor incidence data on two strains of mice exposed to urethane by oral gavage and in
drinking water (Innes, 1969).
B6C3F 1 B6AKF 1
male female male female
tumor type treated control treated control treated control treated control
pulmonary 6/20 5/79 6/23 3/87 15/22 10/90 17/19 3/82
adenomas or
carcinomas
Hepatomas 8/20 8/79 12/23 0/87 14/22 5/90 5/19 1/82
Angiomas 4/22 0/90 11/19 0/82
Harderian gland
5/23 4/87 11/22 0/90 7/19 0/82
adenomas
lymphomas 6/22 1/90
Tomatis et al. (1972) report on a study in which urethane treatment was used as a positive control in a
study of DDT’s long-term health effects. Male and female CF-1 mice (60/sex) were exposed
continuously to drinking water containing 0.01% urethane for 6 generations. Control animals (60/sex)
were given plain drinking water. Parent generation animals were sacrificed at 140 weeks and
subsequent generations at 130 weeks. Survival among animals of both sexes was reduced by urethane
treatment. For statistical purposes, group size was determined by the number of animals surviving at the
time of the appearance of the first tumor of any type. Comparison of groups was made by combining
data from all generations. Lung tumor incidence was found to be significantly increased in urethane
treated male mice (261/314 exposed vs. 157/328 controls, p = 10 -21 , Fisher’s exact text) and female
mice (181/241 exposed vs. 124/340 controls, p = 10 -20 ). Among treated males, lymphoma incidence
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