Historical cohort study of US man-made vitreous fiber production workers: VII. Overview of the exposure assessment

Data and procedures used to reconstruct the history of exposures at each of the 15 plants (19 distinct sites) are presented. The assessment consisted of five steps: (1) develop a Technical History of operations, stable periods, and time Points of changes relevant for exposures, and identify the presence of potentially confounding co-exposures; (2) develop a set Of unique department-job names with descriptions and a job Dictionary for all verbatim names in work histories; (3) collect all company and other exposure data (>1600 observed), and develop quantitative fiber, formaldehyde, and silica exposure estimates; (4) integrate estimates with the Technical History to make Exposure Extrapolation Tables; and (5) use the the Tables with job data to develop an Exposure Matrix for each plant. Nineteen Exposure Matrices were made, with 82 to 621 lines, covering up to 54 years of operations.