Dr. Kenneth W. Smith to Whirlpool Corporation on Mineral Fiber Insulation (1957)

A one-page letter of December 2, 1957, from Dr. Kenneth W. Smith, J-M's medical director, to John Woods, insulation engineer at Whirlpool Corporation in Evansville, Indiana, who had asked about silicosis from handling J-M's Mineral Fiber insulation. Smith writes that to J-M's knowledge the product "does not contain any free silica, nor does it produce any form of pulmonary fibrosis or pneumoconiosis." He cites two published studies and a survey by the Metropolitan Life Insurance Company's Industrial Health Section of about four hundred employees at a J-M mineral wool plant, which found no silicosis or lung fibrosis and led J-M to conclude that mineral wool was "innocuous from the point of lung fibrosis."

In Johns-Manville's chronology

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

K.W. Smith responds to Whirlpool Corp. in letter dated 12/2/57. Smith states that mineral wool is ". . . innocuous from the point of lung fibrosis."