Dr. J. F. Knox of Turner Brothers Asbestos, Report to the Quebec Asbestos Mining Association on Pulmonary Cancer (1950)

A five-page report to the Quebec Asbestos Mining Association "re Pulmonary Cancer and Supplementary Memorandum re Cancer Research," with comments by Dr. J. F. Knox, factory medical officer for Turner Brothers Asbestos Co. Ltd. of Rochdale, England (part of Turner & Newall). Of 100 post-mortem examinations of Rochdale asbestos workers on his records from 1930 to 1950, Knox found 10 in which lung cancer was associated with asbestosis, a rate of 10%, at an average age at death of 56.4 after an average 22.4 years of exposure. He warned that such autopsy figures had to be viewed "with reserve," agreed that the Association's proposed approach was "an excellent one," and wrote that all concerned would benefit from "the widest publication of accurate statistics."

What it shows

Knox's own figures point the same way as the British Chief Inspector's (Annual Report for 1947). Looking at four of the cases, men suspended from work as disabled who died within a year, he wrote that "it is reasonable to assume" that the disability they were suffering from "was in fact the early symptoms of carcinoma of the lung." Coming from the medical officer of a major asbestos manufacturer, the report gave the Quebec producers a firsthand count of lung cancer among asbestos workers as they planned their own study at the Saranac Laboratory (November 1950 Saranac meeting).

In Johns-Manville's chronology

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

Dr. J.F. Knox (Turner Brothers) reports to QAMA regarding pulmonary cancer on 12/19/50. In an examination of autopsies from 1930 to 1950, he finds ten cases out of 100 cases in which carcinoma was associated with asbestosis. Knox points out the limitations of such small studies, and advocates clinical studies comparing cancer rates of those in the general population with those of asbestos workers as a group.