Tobacco Active and Passive Smoking

3. Does tobacco cause cancer in test animals?

Effects of tobacco smoke on test animals are not fully representative of those in humans, because exposure and tumour development are different. Nevertheless, results of animal studies help to understand the carcinogenic potential of tobacco smoke.

Different animal species exposed to tobacco smoke in different ways may develop tumours. Hamsters consistently developed tumours of the larynx, while some of the studies on rats and mice showed small increases in lung tumours. The evidence for malignant lung tumours in dogs is more uncertain.

Cigarette smoke condensate both initiates and promotes tumour development in animals. It has caused skin tumours in mice and rabbits when applied to skin, tumours of the lung and lymph system in mice when applied to the mouth, and lung tumours in rats when injected into the lungs. Condensate from bidi smoke also induced tumours in several organs in mice.

Collectively, these results provide evidence of the carcinogenic effect of tobacco smoke in test animals. More...