Saranac Laboratory, Final Report on the Capacity of Inhaled Kaylo Dust to Injure the Lung (1952)

A confidential 31-page final report of January 30, 1952, "Investigation Concerning the Capacity of Inhaled Kaylo Dust to Injure the Lung," submitted by Dr. Arthur J. Vorwald of the Saranac Laboratory to the Owens-Illinois Glass Company. Begun in February 1945 and run for more than five years, the study exposed guinea pigs, rats and hamsters to dust of Kaylo, Owens-Illinois's calcium silicate insulation, which contained asbestos and some free silica. Its summary states that Kaylo dust inhaled over a long period "is capable of producing" in guinea pigs "the peribronchiolar fibrosis of asbestosis," and that it does not cause silicosis.

What it shows

In guinea pigs exposed for 30 months or less, the lesions showed no fibrosis but were "compatible with an early stage in the development of asbestosis." The nine guinea pigs exposed for 33 and 36 months showed "a true fibrosis of a type characteristic of the response of guinea pigs to inhaled asbestos fibers." Rats and hamsters, exposed for 18 months, developed no fibrosis apart from a barely recognizable trace in one hamster; the report said the typical fibrosis would not be expected in that time. The animals breathed an average of about 116 million particles per cubic foot. The report attributed the reaction to the asbestos fibers rather than the calcium silicate. Dust exposure had little effect on tuberculosis in infected animals, apart from a slightly unfavorable effect when exposure came first. The final report confirmed what Saranac had told Owens-Illinois in 1948. The company's plant survey is in Saranac's May 1951 industrial hygiene report.

In Johns-Manville's chronology

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

Vorwald final report dated 1/30/52 re Kaylo. Owens-Illinois to approve before publication. No silicosis; but did cause a mild asbestosis reaction.

Editor's note: J-M's description says Owens-Illinois was to approve the report before publication. Nothing in the report says so.

Related documents

• Arthur J. Vorwald to Owens-Illinois on Kaylo Causing Asbestosis in Animals (1948)
• Saranac Laboratory, Report of Industrial Hygiene Survey of the Owens-Illinois Kaylo Division Plant (1951)