Industrial Hygiene Foundation, An Epidemiological Study of Lung Cancer in Asbestos Miners, Report to the Quebec Asbestos Mining Association (1957)

The full, restricted report of September 1957 by Dr. Daniel C. Braun and T. David Truan of the Industrial Hygiene Foundation of America to the Quebec Asbestos Mining Association, which paid for the study, on lung cancer deaths among miners at Thetford Mines and Asbestos, Quebec, from 1950 to 1955. It concluded that the miners did "not have a significantly higher death rate from lung cancer" than the general population. But it also found that "a miner who develops the disease asbestosis does have a greater likelihood of developing cancer of the lung," which the authors suspected came from under-reporting of asbestosis in the mine medical records, and it concluded that cigarette smoking was "a much more important consideration" in lung cancer than asbestos.

What it shows

The authors found the asbestosis recorded in the medical records "far below" what published figures would predict, and "strongly recommended that the chest x-rays of all workers be submitted to an independent reading for the diagnosis of asbestosis." Dr. Kenneth Smith of Johns-Manville and Hugh Jackson reviewed a shortened version from which all references to asbestosis and lung cancer, and to smoking, had been removed (Smith to Sabourin, December 1957). The version published in June 1958 keeps the main conclusion and drops the asbestosis and smoking conclusions (published article).

In Johns-Manville's chronology

Johns-Manville's own chronology of what the company knew describes this document as follows:

Report entitled "An Epidemiological Study of Lung Cancer in Asbestos Miners," prepared by the IHF, dated 9/57. The draft report discusses an epidemiological study conducted by the IHF at the request of the QAMA. Dr. Braun and Mr. Truan of the IHF studied miners from the Thetford and Asbestos mines in Quebec to discover whether the incidence of lung cancer is greater among asbestos miners than among the general population and whether there is a correlation between lung cancer and asbestosis. (It was Dr. Kenneth Smith and Dr. Paul Cartier who proposed this study to the QAMA.) The study found that "asbestos miners at Thetford Mines and Asbestos in the province of Quebec do not have a significantly higher death rate from lung cancer than do comparable segments of the general population."

However, the study found that a miner who develops asbestosis has a greater likelihood of developing lung cancer than a person without the disease, although the authors explained that this may have been found because there was an under-reporting of the number of cases of asbestosis, which led to an artificially high incidence for lung cancer. Braun and Truan discovered that the incidence of asbestosis indicated in the medical records was far below that which would be expected on the basis of all previously published figures.

Braun and Truan strongly recommended that the chest x-rays of all the miners surveyed be submitted to an independent radiologist for diagnosis of asbestosis, since there was an "inaccurately low incidence rate" for asbestosis. The study also indicated that "cigarette smoking is a very important factor in the incidence of cancer of the lung." In fact it is "a much more important consideration in the production of lung cancer than is exposure to asbestos."