A. J. Lanza to McConnell, Brown and Gardner on X-Rays of J-M's Lompoc Diatomaceous Earth Workers (1937)

A two-page memorandum of May 10, 1937, from Dr. A. J. Lanza, assistant medical director of the Metropolitan Life Insurance Company, to Dr. McConnell, Vandiver Brown and Dr. Gardner. It reports an April 12 visit by Gardner, Lanza and Dr. Shepard of Metropolitan Life's Pacific Coast office to Johns-Manville's diatomaceous earth operations at Lompoc, California. Reviewing X-ray films with the company physician, they found most men showed no dust reaction, but "a few of men who had worked for considerable periods of time" showed "an unusual type of shadow." There was no typical silicosis, but these atypical reactions "suggested that this dust might have harmful potentialities," a view strengthened by Gardner's animal experiments in which injected diatomaceous earth caused "a progressive fibrosis."

What it shows

Lanza concluded that "the discovery of a few cases with abnormal films after prolonged exposures makes one hesitate to state that there is no hazard." He recommended X-raying all employees when hired and again every two or three years, so that it might "finally" be possible "to evaluate a hazard about which little is known." The plant's manager reported dust controls installed since Metropolitan Life's December 1935 survey; no dust samples were taken on this visit.

In Johns-Manville's chronology

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

Memorandum from Dr. A.J. Lanza to Dr. McConnell, V. Brown and Dr. Gardner dated 5/10/37. Summarizes trip made by Drs. Gardner, Shepard and Lanza to J-M's Lompoc Plant. X-ray files of the J-M employees were examined and a few were noted to have "an unusual type of shadow". Opinion expressed that a typical reaction of long-term employees suggests this dust (diatomaceous earth) might be potentially harmful. Dr. Gardner's experiments show that intravenous and intra peritoneal injections of diatomaceous earth cause a progressive fibrosis. Lanza states "the discovery of a few cases with abnormal films after prolonged exposures makes one hesitate to state that there is no hazard."

Editor's note: J-M's description speaks of "a typical reaction" in long-term employees. Lanza's memo says the reactions were atypical, with no typical silicosis.