H. M. Jackson, "X-Ray Study, Dr. L. J. Bristol, Trudeau Institute" (1970)

A two-page summary of December 11, 1970, by H. M. Jackson, manager of J-M's industrial health program, with a one-page chart of results. In mid-1968 J-M engaged Dr. L. J. Bristol of the Trudeau Institute to read the chest X-rays of every employee with three years' service or more at all locations with possible dust disease exposure; he read 8,860 sets by August 1970. Jackson writes that the study "confirms" that "the health problems are severe in seven plants": Billerica, Manville, Pittsburg, Marrero, Long Beach, Nashua and Waukegan, with Zelienople and Toronto also to be "regarded as critical operations."

What it shows

At Billerica, where amosite had been the main fiber since 1939, 30% of the X-rays were classed as pneumoconiosis, which Jackson links to the difficulty of controlling exposure at the fiber-feeding stage; "only recently" had controls reached acceptable fiber levels. Long Beach, using mostly chrysotile with a little crocidolite, had 8.4%. Newer plants with good dust control from the start (Stockton, Denison, Tilton) showed little or none. Jackson adds that many work stations at the problem plants "have not yet been controlled to acceptable levels." The chart lists the plant-by-plant figures, including 264 pneumoconiosis readings among 3,165 sets at Manville and 112 among 1,376 at Waukegan. It follows Jackson's 1969 report to J-M's president on Bristol's early readings at six plants, and is the company-wide result of that program.

In Johns-Manville's chronology

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

Jackson in a memorandum entitled "X-ray Study Dr. L.J. Bristol - Trudeau Institute," dated 12/11/70, discusses the purpose, methods, and results of Dr. Bristol's study. Jackson states that a number of interesting observations can be made from the study. Billerica has been in operation since 1939 and amosite has been the primary type of asbestos used there.

This fact and the difficulty in controlling exposure may account for the high incidence of pneumoconiosis there 30%. In comparison, Long Beach has been in operation since 1938; the principal, fiber has been chrysotile, and the incidence of pneumoconiosis is 8.4%. Jackson notes that the plants with severe lung problems are Billerica, Manville, Pittsburg, Marrero, Long Beach, Nashua and Waukegan.

Related documents

• Draft Summary and Chart of Dr. L. J. Bristol's X-Ray Study of J-M Plants (1970)