G. W. H. Schepers, T. M. Durkan and A. B. Delahant, "Effect of Inhaled Commercial Hydrous Calcium Silicate Dust on Animal Tissues" (1955)

A 13-page article by Dr. G. W. H. Schepers, T. M. Durkan and A. B. Delahant of the Saranac Laboratory, published in the A.M.A. Archives of Industrial Health in 1955, reporting long-term inhalation experiments with a commercial hydrous calcium silicate insulation made with asbestos (Owens-Illinois's Kaylo, though the article does not name it). The work was begun in 1943 under Leroy Gardner and finished after his death. The dust caused chronic bronchiolitis, fibrosis and other lesions that "closely resembled those found in experimental asbestosis and included asbestos bodies," and it mildly to moderately worsened tuberculosis in infected animals. The authors conclude that the chrysotile in the product, "rather than the hydrous calcium silicate, was the cause of the deleterious effects."

What it shows

This is the published form of the Kaylo work that Schepers's predecessor Arthur Vorwald had reported privately to Owens-Illinois in 1948 (Vorwald's letter). The fact notes that J-M's own Thermobestos was of essentially the same composition. Owens-Illinois later sent a reprint to a consultant, describing the finding as a "mild asbestosis reaction" (Hazard to Brought).

In Johns-Manville's chronology

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

Schepers published article on 7/15/55 re Saranac investigation of Kaylo contains no conclusion concerning risk to users per se. The dust created asbestosis type lesions; affected course of tuberculosis. J-M's Thermobestos line is essentially the same composition.

Related documents

• W. G. Hazard of Owens-Illinois to Ira I. Brought on Kaylo and the Saranac Experiments (1956)