H. M. Jackson to Dr. John P. McCann of General Dynamics on Insulation Work at Groton (1969)

A one-page letter of February 25, 1969, from H. M. Jackson, J-M's director of industrial relations, to Dr. John P. McCann, medical director of General Dynamics Corporation, after a visit to Groton, Connecticut, by Jackson and Dr. George Wright, J-M's medical consultant. "As Doctor Wright and I indicated, it would not appear that the manner in which you are fabricating the insulation materials creates any substantial asbestosis hazard," Jackson writes. He adds that it "would certainly be in order" to have the work area measured for fiber levels with the membrane filter technique, as General Dynamics was planning.

What it shows

J-M's health staff advised a large customer on the safety of its insulation work after a single visit, before any fiber measurements had been taken there, and spoke only of asbestosis. The same month J-M was adopting the membrane filter method in its own plants (Fenner's memo on the membrane filter technique, February 1969), and its first results soon showed most stations in its Manville textile plant above the company's own limit (Environmental Control Subcommittee, May 1969).

In Johns-Manville's chronology

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

Letter from Jackson to McCann of General Dynamics Corporation following a trip made by Jackson and Dr. Wright, 2/25/69. Jackson states: "It would not appear that the manner in which you are fabricating the insulation materials creates any substantial asbestosis hazard . . . It would certainly be in order, as you are planning, to have the work environs measured for fiber levels utilizing the membrane filter technique."