Efficacy of a program to prevent beryllium sensitization among new employees at a copper-beryllium alloy processing facility

Abstract

Objectives: In 2000, 7% of workers at a copper-beryllium facility were beryllium sensitized. Risk was associated with work near a wire annealing/pickling process. The facility then implemented a preventive program including particle migration control, respiratory and dermal protection, and process enclosure. We assessed the program's efficacy in preventing beryllium sensitization.

Methods: In 2000, the facility began testing new hires (program workers) with beryllium lymphocyte proliferation tests (BeLPTs) at hire and at intervals during employment. We compared sensitization incidence rates (IRs) and prevalence rates for workers hired before the program (legacy workers) with rates for program workers, including program worker subgroups. We also examined trends in BeLPTs from a single laboratory.

Results: In all, five of 43 legacy workers (IR = 3.8/1,000 person-months) and three of 82 program workers (IR = 1.9/1,000 person-months) were beryllium sensitized, for an incidence rate ratio (IRR) of 2.0 (95% confidence interval [CI] 0.5, 10.1). Two of 37 pre-enclosure program workers (IR = 2.4/1,000 person-months) and one of 45 post-enclosure program workers (IR = 1.4/1,000 person-months) were beryllium sensitized, for IRRs of 1.6 (95% CI 0.3, 11.9) and 2.8 (95% CI 0.4, 66.2), respectively, compared with legacy workers. Test for trend in prevalence rates was significant. Among 2,159 first-draw BeLPTs during 95 months, we identified seven months when high numbers of redraws were required, with one possible misclassification in this facility.

Conclusions: Fewer workers became sensitized after implementation of the preventive program. However, low statistical power due to the facility's small workforce prevents a definitive conclusion about the program's efficacy. These findings have implications for other copper-beryllium facilities, where program components may merit application.

Figure 2

Control chart of the proportion of abnormal BeLPT results vs. total BeLPT results during a 95-month period, Lab 1 Straight black line = average number of abnormal tests during all 95 months Upper gray line = upper control limit: three sample standard errors above the expected number of abnormal results for each month, adjusting for total number of tests that month Straight gray line = lower control limit BeLPT = beryllium lymphocyte proliferation test

Figure 3

Control chart of the proportion of non-normal BeLPT results vs. total BeLPT results during a 95-month period, Lab 1 Straight black line = average number of tests requiring redraw during all 95 months Upper gray line = upper control limit: three sample standard errors above the expected number of abnormal results for each month, adjusting for total number of tests that month Straight gray line = lower control limit BeLPT = beryllium lymphocyte proliferation test