Development of retrospective quantitative and qualitative job-exposure matrices for exposures at a beryllium processing facility

Objectives To construct a job-exposure matrix (JEM) for an Ohio beryllium processing facility between 1953 and 2006 and to evaluate temporal changes in airborne beryllium exposures. Methods Quantitative area-and breathing-zone-based exposure measurements of airborne beryllium were made between 1953 and 2006 and used by plant personnel to estimate daily weighted average (DWA) exposure concentrations for sampled departments and operations. These DWA measurements were used to create a JEM with 18 exposure metrics, which was linked to the plant cohort consisting of 18 568 unique job, department and year combinations. The exposure metrics ranged from quantitative metrics (annual arithmetic/geometric average DWA exposures, maximum DWA and peak exposures) to descriptive qualitative metrics (chemical beryllium species and physical form) to qualitative assignment of exposure to other risk factors (yes/no). Twelve collapsed job titles with long-term consistent industrial hygiene samples were evaluated using regression analysis for time trends in DWA estimates. Results Annual arithmetic mean DWA estimates (overall plant-wide exposures including administration, non-production, and production estimates) for the data by decade ranged from a high of 1.39 mu g/m(3) in the 1950s to a low of 0.33 mu g/m(3) in the 2000s. Of the 12 jobs evaluated for temporal trend, the average arithmetic DWA mean was 2.46 mu g/m(3) and the average geometric mean DWA was 1.53 mu g/m(3). After the DWA calculations were log-transformed, 11 of the 12 had a statistically significant (p<0.05) decrease in reported exposure over time. Conclusions The constructed JEM successfully differentiated beryllium exposures across jobs and over time. This is the only quantitative JEM containing exposure estimates (average and peak) for the entire plant history.