Leroy U. Gardner, Second Progress Report on Experimental Asbestosis (1938)

Saranac Laboratory's ten-page "Second Progress Report on Experimental Asbestosis," dated April 18, 1938, with a page of four photographs of guinea pig lungs. After a year of breathing very finely ground chrysotile asbestos dust, guinea pigs, rabbits, white rats and a cat showed no fibrosis and only "the very earliest stages of asbestosis"; much less reaction than an earlier experiment with coarser dust at a tenth or less of the concentration. Dr. Leroy U. Gardner concluded that "the chemical hypothesis of the action of asbestos will have to be abandoned" and that asbestos fibers seem to act as "mechanical irritants," harmful only above "an unknown minimum length." He added that "until the hygienic significance of fibre length has been established all asbestos dust must still be considered hazardous."

What it shows

This is the report the asbestos companies who funded Gardner's experiments received in April 1938, a year after the first progress report. Gardner used the length theory to explain why the Thetford mills in Quebec seemed to have little disease despite heavy dust, why "mattress beating" in English plants caused the most asbestosis, and why American cases clustered among workers at the "opening" machines. If the theory held, he wrote, mills handling the very fine asbestos powders used for insulation might need only enough exhaust for "good housekeeping." He planned two more years of the fine-dust experiment and a new one with longer fiber.

The report went from Vandiver Brown to Sumner Simpson of Raybestos-Manhattan, who was startled by it (April 27). Brown answered that a mechanical action would be "good news" against claims that the disease progresses (April 28); the report itself does not discuss whether asbestosis progresses. The December 1938 progress report carried the work forward.

In Johns-Manville's index

Johns-Manville's attorneys indexed the Sumner Simpson Papers. Their index describes this document as follows:

"Second Progress Report on Experimental Asbestosis by the Saranac Laboratory April 18, 1938." States inhalation experiments on test animals failed to produce evidence of asbestosis. Animals were exposed to very finely ground dust for one year. Results suggests injury from asbestos may be mechanical in nature and produced only by fibers exceeding an unknown minimum length. Further experiments will attempt to prove this hypothesis.

Related documents

• Leroy U. Gardner to Vandiver Brown Sending the Second Progress Report on Experimental Asbestosis (1938)
• Vandiver Brown to Sumner Simpson Enclosing Gardner's Second Progress Report (1938)
• Sumner Simpson to Vandiver Brown on His Surprise at Gardner's Second Progress Report (1938)
• Sumner Simpson to E. H. Jeffords Sending Gardner's Second Progress Report (1938)
• Vandiver Brown to Sumner Simpson on Gardner's Findings and Claims of Progressive Fibrosis (1938)
• Leroy Gardner, First Progress Report on Asbestosis Experiments at the Saranac Laboratory (1937)
• Dr. A. J. Lanza to Vandiver Brown on the Mechanical Action of Asbestos Dust (1938)
• Dr. Kenneth Lynch to Julian Mitchell on Gardner's Fine-Dust Findings (1938)

About this copy

This is document 03427-03436 of the Sumner Simpson Papers, as numbered in the collection's index.