The production of malignant tumors of the lung and pleura in dogs from intratracheal asbestos instillation and cigarette smoking

Nine dogs were given yearly intratracheal instillations of crocidolite asbestos for periods up to three years. The maximum dose totalled 66 mg/kg. In addition, seven of these dogs smoked nine cigarettes per day, five days per week for six years. A malignant pleural and/or peritoneal mesothelioma developed in six of these dogs, and adenocarcinoma of the lung developed in four, one of which had areas of squamous differentiation. The first animal died of a malignant tumor six years after the onset of exposure, and the last animal died eight years after the onset.