A. I. Cummins, Examination of the Dust and Fine Fractions of Some Asbestos Samples (1934)

A ten-page confidential report of April 4, 1934, from the J-M Research Laboratories by A. I. Cummins, giving "the results of a preliminary study" of the dusts and fine fractions of six asbestos fibers: short and long fiber Quebec chrysotile, African blue (crocidolite), amosite, and two other South African and Rhodesian grades. Cummins collected the dusts, photographed them under the microscope and tested how abrasive the fine fractions were. He made "no attempt" to give an opinion on the relative harmfulness of the dusts, but wrote that it "would appear reasonable" that the exceedingly long African blue fibers and the large amosite particles "could be more harmful" than the smaller chrysotile fibers and particles.

What it shows

The report found that single fibers several hundred microns long "float readily in air," and that long fibers seemed capable of fairly stable suspension in the air. Yet its summary concluded that it was "doubtful if fibres as found in asbestos dusts can readily find their way into the lungs," reasoning from the way fibers matted together on filters and respirator pads. The report is J-M's own laboratory work on asbestos dust in 1934; it describes no study of workers or of disease.

About this copy

The author's initials are hard to read on the cover. They may be A. B., which would make him the A. B. Cummins of J-M's research staff who tested company products for free silica in 1958 (Dr. Smith and the J-M Research Center), but that is a guess.

In Johns-Manville's chronology

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

A.I. Cummins Research Report "Examination of the Dust and Fine Fractions of Some Asbestos Samples," 4/4/34. Cummins states that no attempt has been made to express an opinion on the harmfulness of various dusts, but it appears reasonable that the long blue and amosite fibers are more harmful than smaller chrysotile.