Lanza, McConnell and Fehnel, "Effects of the Inhalation of Asbestos Dust on the Lungs of Asbestos Workers" (1935)

The preliminary study of asbestos workers by Dr. A. J. Lanza, Dr. William J. McConnell and chemist J. William Fehnel of the Metropolitan Life Insurance Company, published in the U.S. Public Health Service's Public Health Reports on January 4, 1935. The authors say the asbestos industry had asked Metropolitan Life in 1929 whether asbestos dust was a hazard. They took dust counts in five U.S. fabricating plants and X-rayed 126 workers: 67 were found to have asbestosis (4 in the second stage) and 39 more were "doubtful," with the share rising with years of exposure. They concluded that asbestos dust caused a lung scarring "different from silicosis" and, it appeared, "milder," and that it was "not practicable as yet" to set a dust standard.

What it shows

This is the report that Johns-Manville and Raybestos-Manhattan reviewed in draft late in 1934, with J-M's attorney Vandiver Brown sending Metropolitan Life the companies' comments (J-M's comments on the Lanza report; Judd's reply to Brown). Even in published form it recommended that the industry "seriously face the problem of dust control," that new workers be X-rayed and those with tuberculosis or pneumoconiosis rejected, and that workers be examined with a chest X-ray "preferably every year, but at least every 2 years." It also reported frequent heart enlargement in workers with asbestosis (cor pulmonale) and warned that no one should assume asbestos dust was safe at higher levels than the silica standard just because the disease seemed milder.

In Johns-Manville's chronology

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

Lanza report regarding asbestosis risk among U.S. textile workers and Canadian mines/mills. Concludes asbestosis different from and milder than silicosis, heart enlargement associated with asbestosis [cor pulmonale] does not predispose to tuberculosis, little disability but possibly fatal, nexus to pneumonia and other infections unknown, too early to set a TLV, asbestos may cause disease more readily than Silica, industrial exposures can be substantially reduced. Recommended frequent X-rays (1 to 2 year maximum) [not adopted], further research.

Editor's note: J-M's description says the report covers Canadian mines and mills and concludes that asbestos may cause disease more readily than silica. The report says the Canadian work was done but includes only five U.S. fabricating plants, and says only that a higher permissible dust count for asbestos than for silica cannot be assumed.