Kenneth W. Smith, "Pulmonary Disability in Asbestos Workers" (1955)

A six-page article by Dr. Kenneth W. Smith, medical director of Johns-Manville, published in the American Medical Association's Archives of Industrial Health in August 1955. Smith writes that "relatively few of the people exposed to the fiber develop the disease," and reports an X-ray survey of 708 employees of an asbestos mill: 649, or 91 percent, had normal X-rays, 52 showed marked linear markings, and 7 had definite asbestosis, none with less than 20 years of exposure. He also reports that dusty work did not raise rates of ordinary respiratory illness, and that conflicting opinions made it "extremely difficult to confirm or deny conclusively" a link between asbestosis and lung cancer.

What it shows

The 708 men appear to be the Canadian Johns-Manville mill workers of Smith's confidential 1949 survey (Survey of Men in Dusty Areas). That report had found only 4 men with normal X-rays, 475 with early fibrosis, 52 with advanced fibrosis and 7 with early asbestosis, and said the seven had not been told. The published version keeps the 52 and the 7 but counts 649 men as normal, and says nothing about telling workers their results. It also states as a general finding that "no cases of asbestosis were found who had worked less than 20 years in the dust."

In Johns-Manville's chronology

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

Published version of 1949 K. Smith Report. Lower disease estimates than in 1949 version due change in x-ray classifications of many workers. No mention of disclosure issue.