A survey of pathological changes associated with long-term high tar tobacco smoke exposure in a murine model.

Balb/c mice were exposed to the fresh smoke of a daily equivalent of thirty high tar filtered cigarettes for periods of up to 95 weeks. Detailed surveys of the gross and histopathological data are presented which indicates that there is the induction or production of significant numbers of malignant tumours of several types in the animals exposed to tobacco smoke. There are also significant histopathological changes which consist mainly of interstitial pneumonia and focal low grade emphysema. These features contribute significantly to the reduction in life span of the test animals in which the main causes of death are malignancies and inflammatory diseases of the lungs.