Estimating historical exposures of workers in a beryllium manufacturing plant

Background Beryllium is known to be toxic to the lungs, causing beryllium l ung disease and associated with increased lung cancer risk. Airborne beryll ium exposures have been monitored since the 1940s. This study describes met hods used to measure airborne beryllium concentrations and how historical m easurements from a beryllium manufacturing plant were used to estimate work ers' exposures in a lung cancer case-control study. Methods Airborne beryllium concentrations had been measured using all-glass impingers, high-volume air filters, and personal respirable and total dust samplers. To provide consistency in exposure estimates over time, measurem ents collected by the other monitoring methods were converted to approximat e the most frequently used high-volume, time-weighted average measurements. Because industrial hygiene measurements were not collected in every year f or all jobs throughout the duration of the case-control study, exposure est imates had to be extrapolated from the existing measurements over time and across jobs. Results Over 7,000 historical measurements were available to estimate beryl lium exposures of workers over time. Average exposures between jobs varied considerably and exposures for all jobs decreased dramatically between the 1940s and 1970s due to major plant production changes. Conclusions Although error in the exposure metrics for the cases and contro ls likely occurred due to limitations of the exposure assessment data, the exposure estimates for each job over time provided a reasonable, objective mechanism for categorizing workers by the relative exposures they were like ly to have encountered during their tenure. Am. J. Ind. Med. 39:145-157, 20 01. Published 2001 Wiley-Liss, Inc.