Margaret M. Mroz

Machining risk of beryllium disease and sensitization with median exposures below 2 μg/m3

We examined the prevalence of beryllium sensitization in relation to work process and beryllium exposure measurements in a beryllia ceramics plant that had operated since 1980. We interviewed 136 employees (97.8% of the workforce), ascertained beryllium sensitization with the beryllium lymphocyte proliferation blood test, and reviewed historical industrial hygiene measurements. Of eight beryllium-sensitized employees (5.9%), six (4.4% of participating employees) had granulomatous disease on transbronchial lung biopsy. Machinists had a sensitization rate of 14.3% compared to a rate of 1.2% among other employees. Machining had significantly higher general area and breathing zone measurements than did other processes in the time period in which most beryllium-sensitized cases had started machining work. Daily weighted average (DWA) estimates of exposure for machining processes also exceeded estimates for other work processes in that time period, with a median DWA of 0.9 μ/m3. Machining process DWAs accounted for the majority of DWAs exceeding the 2.0 μg/m3 OSHA standard, with 8.1% of machining DWAs above the standard. We conclude that lowering machining process-related exposures may be important to lowering risk of beryllium disease.

Reexamination of the blood lymphocyte transformation test in the diagnosis of chronic beryllium disease

The T cell response to beryllium, measured in bronchoalveolar lavage by the lymphocyte transformation test (LTT), is a critical diagnostic test for discriminating between chronic beryllium disease (CBD) and other granulomatous diseases. We examined the sensitivity, reproducibility, and methods of a less invasive, peripheral blood LTT in 17 patients with CBD and in 18 beryllium-exposed control subjects. Ninety-four percent of CBD cases (16/17) had abnormal blood LTT results, and all 18 beryllium-exposed control subjects had normal blood LTT results. Split samples for 10 beryllium disease cases and eight control subjects demonstrated that the blood LTT was reproducible between two separate laboratories. The LTT was equally sensitive with 10% and 20% serum in the culture medium. We conclude that an abnormal blood LTT can be used to diagnose CBD in patients with compatible lung pathology.

Screening blood test identifies subclinical beryllium disease.

We evaluated the beryllium-specific lymphocyte transformation test as a workplace screening tool for early beryllium disease. Fifty-one of 58 workers with current beryllium exposure completed questionnaires and gave blood specimens for the lymphocyte transformation test. Six workers (11.8%) had elevated test results ranging from 5.7-fold to 16.7-fold stimulation. Of five who underwent clinical evaluation, four had beryllium disease, demonstrated by granulomata on transbronchial lung biopsy and elevated lymphocyte transformation tests by bronchoalveolar lavage cells (ranging from 18.6-fold to 44.3-fold stimulation). Our data show that (1) minimally symptomatic cases of beryllium disease can be identified by this peripheral blood test, (2) not all individuals with a positive peripheral blood lymphocyte transformation test have beryllium disease at the time of their initial evaluation, and (3) lymphocyte transformation test reproducibility is good, justifying further evaluation of this test for screening. We conclude that the peripheral blood lymphocyte transformation test may prove useful in preventing clinical chronic beryllium disease by early diagnosis in a subclinical phase.

Risks of beryllium disease related to work processes at a metal, alloy, and oxide production plant

OBJECTIVES: To describe relative hazards in sectors of the beryllium industry, risk factors of beryllium disease and sensitisation related to work process were sought in a beryllium manufacturing plant producing pure metal, oxide, alloys, and ceramics. METHODS: All 646 active employees were interviewed; beryllium sensitisation was ascertained with the beryllium lymphocyte proliferation blood test on 627 employees; clinical evaluation and bronchoscopy were offered to people with abnormal test results; and industrial hygiene measurements related to work processes taken in 1984-93 were reviewed. RESULTS: 59 employees (9.4%) had abnormal blood tests, 47 of whom underwent bronchoscopy. 24 new cases of beryllium disease were identified, resulting in a beryllium disease prevalence of 4.6%, including five known cases (29/632). Employees who had worked in ceramics had the highest prevalence of beryllium disease (9.0%). Employees in the pebble plant (producing beryllium metal) who had been employed after 1983 also had increased risk, with a prevalence of beryllium disease of 6.4%, compared with 1.3% of other workers hired in the same period, and a prevalence of abnormal blood tests of 19.2%. Logistic regression modelling confirmed these two risk factors for beryllium disease related to work processes and the dependence on time of the risk at the pebble plant. The pebble plant was not associated with the highest gravimetric industrial hygiene measurements available since 1984. CONCLUSION: Further characterisation of exposures in beryllium metal production may be important to understanding how beryllium exposures confer high contemporary risk of beryllium disease.

Interaction of genetic and exposure factors in the prevalence of berylliosis

Prevalence of berylliosis, a lung disorder driven by the activation of beryllium-specific T cells, is associated with a major histocompatibility complex (MHC) class II marker (HLA-DPB1Glu69) and with the type of industrial exposure. We evaluated the interaction between marker and exposure in a beryllium-exposed population in which the prevalence of berylliosis was associated with machining beryllium. The presence of the marker was associated with higher prevalence (HLA-DPB1Glu69-positive machinists 25%; HLA-DPB1Glu69-negative machinists 3.2%, P = 0.05) and predicted berylliosis independent of machining history (odds ratios 11.8 and 10.1). The study shows that in berylliosis the carrier status of a genetic susceptibility factor adds to the effect of process-related risk factors.

Beryllium particulate exposure and disease relations in a beryllium machining plant.

We examined the relationship between exposure to beryllium and the presence of beryllium sensitization (BeS) and chronic beryllium disease (CBD) in a cohort of workers in a beryllium precision machining facility. Twenty workers with BeS or CBD (cases) were compared with 206 worker-controls in a case-control study. Exposure for each job title was measured using cascade impactors placed in the workers’ breathing zone to measure total beryllium exposure and exposure to particles <6 &mgr;m and <1 &mgr;m in aerodynamic diameter. Cumulative exposure was calculated as &Sgr; (job title exposure estimate × years in job title). Individual lifetime-weighted (LTW) exposure was calculated as &Sgr; [(job title exposure × years in job title) ÷ total years employment)]. Workers in the case group were more likely to have worked as machinists (odds ratio, 4.4; 95% confidence interval, 1.1 to 17.5) than those in the control group. The median cumulative exposure was consistently greater in the cases compared with the controls for all exposure estimates and particle size fractions, although this was not statistically significant. The median cumulative exposure was 2.9 &mgr;g/m3-years in the cases versus 1.2 &mgr;g/m3-years in the controls for total exposure, and 1.7 &mgr;g/m3-years in the cases versus 0.5 &mgr;g/m3-years in the controls for exposure to particles <6 &mgr;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 LTW exposure was 0.25 &mgr;g/m3 in both groups. The median LTW exposure to particles <6 &mgr;m was 0.20 &mgr;g/m3 in the cases compared with 0.14 &mgr;g/m3 in the controls. The differences in cumulative and LTW exposure were not statistically significant. None of the 22 workers with LTW exposure <0.02 &mgr;g/m3 had BeS or CBD. Twelve workers (60%) in the case group had LTW exposures >0.20. In conclusion, increased cumulative and LTW exposure to total and respirable beryllium was observed in workers with CBD or BeS compared with the controls. These results support efforts to control beryllium exposure in the workplace.

Efficacy of serial medical surveillance for chronic beryllium disease in a beryllium machining plant.

There is limited information on the use of the blood beryllium lymphocyte proliferation test (BeLPT) at regular intervals in medical surveillance. Employees of a beryllium machining plant were screened with the BeLPT biennially, and new employees were screened within 3 months of hire. Of 235 employees screened from 1995 to 1997, a total of 15 (6.4%) had confirmed abnormal BeLPT results indicating beryllium sensitization; nine of these employees were diagnosed with chronic beryllium disease. Four of the 15 cases were diagnosed within 3 months of first exposure. When 187 of the 235 employees participated in biennial screening in 1997 to 1999, seven more had developed beryllium sensitization or chronic beryllium disease, increasing the overall rate to 9.4% (22 of 235). The blood BeLPT should be used serially in beryllium disease surveillance to capture new or missed cases of sensitization and disease. Beryllium sensitization and chronic beryllium disease can occur within 50 days of first exposure in modern industry.

Aerosols generated during beryllium machining

Some beryllium processes, especially machining, are associated with an increased risk of beryllium sensitization and disease. Little is known about exposure characteristics contributing to risk, such as particle size. This study examined the characteristics of beryllium machining exposures under actual working conditions. Stationary samples, using eight-stage Lovelace Multijet Cascade Impactors, were taken at the process point of operation and at the closest point that the worker would routinely approach. Paired samples were collected at the operators breathing zone by using a Marple Personal Cascade Impactor and a 35-mm closed-faced cassette. More than 50% of the beryllium machining particles in the breathing zone were less than 10 microns in aerodynamic diameter. This small particle size may result in beryllium deposition into the deepest portion of the lung and may explain elevated rates of sensitization among beryllium machinists.

Risk of Chronic Beryllium Disease by HLA-DPB1 E69 Genotype and Beryllium Exposure in Nuclear Workers

RATIONALE Beryllium sensitization (BeS) and chronic beryllium disease (CBD) are determined by at least one genetic factor, a glutamic acid at position 69 (E69) of the HLA-DPB1 gene, and by exposure to beryllium. The relationship between exposure and the E69 genotype has not been well characterized. OBJECTIVES The study goal was to define the relationship between beryllium exposure and E69 for CBD and BeS. METHODS Workers (n = 386) from a U.S. nuclear weapons facility were enrolled into a case-control study (70 BeS, 61 CBD, and 255 control subjects). HLA-DPB1 genotypes were determined by sequence-specific primer-polymerase chain reaction. Beryllium exposures were reconstructed on the basis of worker interviews and historical exposure measurements. MEASUREMENTS AND MAIN RESULTS Any E69 carriage increased odds for CBD (odds ratio [OR], 7.61; 95% confidence interval [CI], 3.66-15.84) and each unit increase in lifetime weighted average exposure increased the odds for CBD (OR, 2.27; 95% CI, 1.26-4.09). Compared with E69-negative genotypes, a single E69-positive *02 allele increased the odds for BeS (OR, 12.01; 95% CI, 4.28-33.71) and CBD (OR, 3.46; 95% CI, 1.42-8.43). A single non-*02 E69 allele further increased the odds for BeS (OR, 29.54; 95% CI, 10.33-84.53) and CBD (OR, 11.97; 95% CI, 5.12-28.00) and two E69 allele copies conferred the highest odds for BeS (OR, 55.68; 95% CI, 14.80-209.40) and CBD (OR, 22.54; 95% CI, 7.00-72.62). CONCLUSIONS E69 and beryllium exposure both contribute to the odds of CBD. The increased odds for CBD and BeS due to E69 appear to be differentially distributed by genotype, with non-*02 E69 carriers and E69 homozygotes at higher odds than those with *02 genotypes.

Beryllium medical surveillance at a former nuclear weapons facility during cleanup operations.

Despite increasing need to remediate beryllium-contaminated buildings in industry, little is known about the magnitude of risk associated with beryllium abatement or the merits of beryllium medical surveillance for cleanup workers. We examined beryllium lymphocyte proliferation tests and reviewed medical evaluations on workers at a nuclear weapons facility during the process of decontamination and decommissioning. Of 2221 workers, 19 (0.8%) were beryllium sensitized based on two or more abnormal beryllium lymphocyte proliferation tests. Eight of 19 sensitized individuals underwent full clinical evaluation, of whom two were diagnosed with chronic beryllium disease (CBD). Notably, seven beryllium sensitized and CBD cases were hired after the start of cleanup operations. Beryllium medical surveillance detects sensitization and CBD in cleanup workers. Exposure controls and medical surveillance need to be ‘broad-based’ to include all cleanup workers involved in beryllium-contaminated building remediation.