Metropolitan Life Insurance Company, A Study of Dust Conditions in Raybestos-Manhattan's Bridgeport and Stratford Plants (1930)

A 21-page report on the Bridgeport and Stratford, Connecticut, plants of the Raybestos Division of Raybestos-Manhattan, made in February and March 1930 by Metropolitan Life's Industrial Health Service, the fourth in its asbestos series. Dust counts in the brake-lining weave rooms were low. Ninety-one employees with three or more years in asbestos were examined, twelve were X-rayed, and of the nine readable films five showed asbestosis, including a foreman of 16 years and a weaver of 12. The report noted that "all doubtful cases were classed as negative, the diagnosis being given as positive for dust fibrosis only where the evidence was unmistakable."

What it shows

Even at plants the investigators called relatively clean, more than half of the men X-rayed had asbestosis. The summary concludes that asbestos dust causes "a mild fibrosis," but adds: "What the end results of this type of fibrosis are we are not yet in a position to state." The copy is marked "Return to S. Simpson," apparently for Sumner Simpson of Raybestos-Manhattan. See also the Manheim study.

In Johns-Manville's chronology

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

Metropolitan Life Survey of Raybestos-Manhattan's Bridgeport and Stratford Plants. This study, conducted during the months of February - March, 1930 by the Industrial Health Service of the Metropolitan Life Insurance Company, was part of a series of studies of the asbestos industry in the United States and Canada. The purpose of the study was to determine the extent and nature of atmospheric pollution to which asbestos workers were exposed and the existence of demonstrated harmful effects to such workers was achieved through air sampling and physical examinations of 91 workers. Twelve individuals from the group were given a physical exam and also x-rayed; of these, five were found to have unmistakable evidence of asbestosis. The number of cases of disease in the study was considered too small to draw any definite conclusions. In a summary section, the report states the actual dust levels were found to be relatively low. The number of years of exposure, together with the x-ray appearances "tend to confirm the impression" that the action of asbestos dust on the lungs causes a mild fibrosis. The Report states "we are not yet in a position" to determine the "final results of the fibrosis."

Editor's note: J-M's description says five of the twelve men X-rayed had asbestosis. The report says three of the twelve films were unsatisfactory, so the five cases were among nine men whose films could be read.

Related documents

• Metropolitan Life Insurance Company, Report on a Dust Survey of the Manville Plant (1929)
• Metropolitan Life Insurance Company, A Study of Dust Conditions in Raybestos-Manhattan's Manheim Plant (1930)