LIBBY WORKERS AND ASBESTOS
Treatment of missing employment history

Dilemma over missing employment history of Libby asbestos workers

Dates of termination were unknown for 58 of 640 Libby workers (9%) who left employment before September 1953. These workers were assumed to have worked for 384 days, based on the mean duration of employment among all workers with known termination date before September 1953.

U.S. Census Bureau data (2004) indicate that 95% of the local population identify themselves as white. Because workers at this facility were known to be primarily Caucasian, 935 workers with race unknown were assumed to be white (NIOSH 2001).

Similarly, because 96% of the workforce was male, seven workers with sex unknown were assumed to be male after review of names.

Courtesy of National Institute of Health