Beryllium particulate exposure and disease relations in a beryllium machining plant

We examined the relationship between exposure to beryllium and the presence of betyllium sensitization (BeS) and chronic beryllium disease (CBD) in a cohort of workers in a beryllium precision machining facility. Twenty worke rs with BeS or CBD (cases) were compared with 206 worker-controls in a case -control study. Exposure for each job title was measured wing cascade impac ters placed in the workers' breathing zone to measure total beryllium expos ure and exposure to particles < 6 <mu>m and <1 <mu>m in aerodynamic diamete r Cumulative exposure was calculated as Sigma (job title exposure estimate x years in job title). Individual lifetime-weighted (LTW) exposure was calc ulated as Sigma [(job title exposure x years in job title) divided by total years employment)]. Workers in the case group were more likely to have wor ked as machinists (odds ratio, 4.4; 95% confidence interval 1.1 to 17.5) th an those in the controlgroup. The median cumulative exposure was consistent ly greater in the cases compared with the controls for all exposure estimat es and particle size fractions, although this was not statistically signifi cant The median cumulative exposure was 2.9 mug/m(3)-years in the cases ver sus 1.2 mug/m(3)-yeays in the controls for total exposure, and 1.7 mug/m(3) -years in the cases versus 0.5 mug/m(3)-years in the controls for exposure to particles <6 <mu>m in diameter With cumulative exposure categorized into low, intermediate and high-exposure groups, the odds ratios were 2.4 (95% confidence interval 0.7 to 8.2) for the intermediate-exposure group and 1.2 (95% confidence interval 0.4 to 4.2) for the high-exposure group compared with the low-exposure group. The median LWT exposure was 0.25 mug/m(3) in b oth groups. The median, LTW exposure to particles < 6 <mu>m was 0.20 in the cases compared with 0.14 mug/m(3) in the controls. The differences in cumu lative and LTW exposure were not statistically significant. None of the 22 workers with LTW exposure < 0.02 <mu>g/m(3) had BeS or CBD. Twelve workers (60%) in the case group had LTW exposures >0.20 In conclusion increased cum ulative and LTW exposure to total and respirable beryllium was observed in workers with CBD or BeS compared with the controls. These results support e fforts to control beryllium exposure in the workplace.