US EPA

3101207 

Journal Article 

Epidemiological Studies Of Diseases Due To Asbestos In Canada 

Mcdonald, AD; Mcdonald, JC 

1976 

1 

Revue Francaise des Maladies Respiratoires
ISSN: 0301-0279 

NIOSH/00134174 

4 

25-38 

Surveys of the incidence of asbestos (1332214) related diseases in Quebec, Canada, were conducted. Chest X-ray films of 13,000 exposed workers were reviewed to determine if a correlation existed between radiological changes and dust exposure. Medical questionnaires and pulmonary function tests were administered to 1,015 male workers. Mortality rates were determined for 11,500 subjects selected from a government supplied list of asbestos workers. A weak correlation, 0.3, was found between observed radiological changes and dust exposure. There was no difference in performance on pulmonary function tests between smokers and nonsmokers. The incidence of exertional dyspnea increased with increased dust exposure but could not be correlated with smoking. There were 4,500 deaths among 11,500 exposed workers. Of these, 224 were due to lung cancer and 7 to mesothelioma. The risk factor for lung cancer was calculated to be 3.6. The authors conclude that X-ray changes are not reliable indicators of asbestos exposure as they are easily masked by other factors, especially individual predisposition. They note an apparent causal relationship between asbestos exposure and lung cancer. (French)