Beryllium sensitization and disease among long-term and short-term workersin a beryllium ceramics plant

Workers at a beryllium ceramics plant were tested for beryllium sensitizati on and disease in 1998 to determine whether the plant-wide prevalence of se nsitization and disease had declined since the last screening in 1992; an e levated prevalence was associated with specific processes or with high expo sures, exposure-response relationships differed for long-term workers hired before the last plant-wide screening and short-term workers hired since th en. Methods: Current workers were asked to complete a questionnaire and to provide blood for the beryllium lymphocyte proliferation test (BeLPT). Thos e with an abnormal BeLPT were classified as sensitized, and were offered cl inical evaluation for beryllium disease. Task- and time-specific measuremen ts of airborne beryllium were combined with individual work histories to co mpute mean, cumulative, and peak beryllium exposures for each worker. Resul ts: The 151 participants represented 90% of 167 eligible workers. Fifteen ( 9.9% of 151)had an abnormal BeLPT and were split between long-term workers (8/77 = 10.4%) and short-term workers (7/74 = 9.5%). Beryllium disease was detected in 9.1% (7/77) of long-term workers but in only 1.4% (1/74) of sho rt-term workers (P = 0.06), for an overall prevalence of 5.3% (8/151). Thes e prevalences were similar to those observed in the earlier survey. The pre valence of sensitization was elevated in 1992 among machinists, and was sti ll elevated in 1998 among long term workers (7/40 = 18%) but not among shor t-term workers (2/36 = 6%) with machining experience. The prevalence of sen sitization was also elevated in both groups of workers for the processes of lapping, forming, firing, and packaging. The data suggested a positive rel ationship between peak beryllium exposure and sensitization for long-term w orkers and between mean, cumulative, and peak exposure and sensitization fo r short-term workers, although these findings were not statistically signif icant. Long-term workers with either a high peak exposure or work experienc e in forming were more likely to have an abnormal BeLPT (8/51 = 16%) than t he other long-term workers (0/26, P = 0.05). All seven sensitized short-ter m workers either had high mean beryllium exposure or had worked longest in forming or machining (7/55 = 13% versus 0/19, P = 0.18). Conclusions: A pla nt-wide decline in beryllium exposures between the 1992 and 1998 surveys wa s not matched by a decline in the prevalence of sensitization and disease. Similar to findings from other studies, beryllium sensitization/disease was associated with specific processes and elevated exposures. The contrast in disease prevalence between long-term and short-term workers suggests that beryllium sensitization can occur after a short period of exposure, but ber yllium disease usually requires a longer latency and;or period of exposure. The findings from this study motivated interventions to more aggressively protect and test workers, and new research into skin exposure as a route of sensitization and the contribution of individual susceptibility.