A. Stefaniak, G. Day, M. Duling, M. Stanton, R. Lawrence, NIOSH, Morgantown, WV; S. Chipera, R. Scripsick, Los Alamos National Laboratory, Los Alamos, NM.
Beryllium is a lightweight metal used in diverse manufacturing applications. Exposure to beryllium metal and oxide particles is associated with development of chronic beryllium disease; however, exposure to beryl or bertrandite ore dust is not yet associated with development of disease. The purposes of this study were to characterize aerosols generated during milling of bertrandite and beryl ores and to assess whether these dusts might serve as models for understanding beryllium hazard potential. Twelve work areas were sampled (six in a bertrandite mill, six in a beryl mill) using closed-face 37-mm cassette and micro-orifice uniform deposit impactor samplers positioned in fixed locations. Total dust was determined gravimetrically and beryllium content spectrometrically. In 5 of 12 work areas, aerosols were collected from ventilation ductwork using a five-stage aerosol cyclone and characterized using X-ray diffraction. Concentrations of beryllium in ore dusts tended to be higher during beryl processing (max = 2.1 µg/m3, crushing) compared to bertrandite (max = 1.2 µg/m3, wet grinding). Mass median aerodynamic diameters (MMADs) of beryllium particles generated during beryl processing were <1 µm in all work areas (except crushing). In contrast, MMADs of beryllium particles generated during bertrandite processing were >5 µm in all work areas. Mass percentages of beryllium in size-separated dusts were consistent with levels in feedstock materials: 0.06 to 6.4% in the beryl plant (4.2% in ore) and 0.003 to 1.7% in the bertrandite plant (0.23% in ore). Process-dependent changes in particle chemistry were observed in the beryl plant: ore crushing (crystalline beryl) → melting and heat treating (unidentifiable amorphous phase) → ball-milling (amorphous phase with trace of beryllium oxide) → product drumming (pure crystalline beryllium hydroxide). In summary, the unique physicochemical properties of beryl and bertrandite ore dusts and their apparent lack of association with disease may lend insights to the differential toxicity of beryllium aerosols.
A. Madl, ChemRisk Inc., San Francisco, CA; K. Unice, J. Brown, ChemRisk Inc., Pittsburgh, PA; M. Kolanz, Brush Wellman Inc., Cleveland, OH; M. Kent, Brush Wellman Inc., Elmore, OH.
The current occupational exposure limit (OEL) for beryllium has been in place for more than 50 years and was believed to be protective against chronic beryllium disease (CBD), until studies in the 1990s identified beryllium sensitization (BeS) and subclinical CBD in the absence of physical symptoms. Inconsistent sampling and exposure assessment methodologies have often prevented the characterization of a clear exposure-response relationship for BeS and CBD. Industrial hygiene (3831 personal lapel and 616 general area samples) and health surveillance data from a beryllium machining facility provided an opportunity to reconstruct worker exposures prior to the ascertainment of BeS or the diagnosis of CBD. Airborne beryllium concentrations for different job titles were evaluated; historical trends of beryllium levels were compared for pre- and post-engineering control measures; and mean and upper bound exposure estimates were developed for workers either identified as beryllium sensitized or diagnosed with subclinical or clinical CBD. Four methods were used to reconstruct historical exposures of each worker: Industrial hygiene data were pooled by year, job title, era of engineering controls, and the complete work history (lifetime weighted average) prior to diagnosis. Results showed that exposure metrics based on shorter averaging times (i.e., year vs. complete work history) better represented the upper-bound worker exposures that could have contributed to the development of BeS or CBD. It was observed that all beryllium sensitized and CBD workers were likely exposed to beryllium concentrations greater than 0.2 µg/m3 (95th percentile), and 90% were exposed to concentrations greater than 0.4 µg/m3 (95th percentile) within a given year of their work history. Based on this analysis, it would appear that BeS and CBD generally occurred as a result of exposures greater than 0.4 µg/m3 and that maintaining exposures below 0.2 µg/m3 95% of the time may prevent BeS and CBD in the workplace.
M. Corbett, Ultra-Fine Occupational Consulting, Toledo, OH; T. Knudson, Brush Wellman Inc., Cleveland, OH; J. Miller, Ngenuity, Los Alamos, NM.
Copper beryllium alloy strip products are commonly used for electronic connectors in computers, telecommunications, and automotive devices to improve performance, reliability, and miniaturization. Formed electronic connectors are often plated with additional metals to improve corrosion properties, solderability, hardness, wearability, friction, adhesion, and conductivity. Worker exposure to airborne beryllium during plating of copper beryllium alloys is not well documented in the scientific literature. An exposure assessment was conducted to characterize airborne beryllium concentrations during plating and associated support operations on copper beryllium alloy. A representative precision stamping and plating facility participated in the study. Seven chemical processing, similar exposure groups were identified as having a potential for airborne beryllium exposure including photoetching, deburring, bright cleaning, racking, plating, selective plating/con-tip, and wastewater treatment. The results from an initial survey indicated that 24 of 24 (100%) lapel samples were below the OSHA permissible exposure limit (PEL) of 2 μg/m3 and 22 of 24 (98%) were below the California OSHA (Cal/OSHA) PEL of 0.2 μg/m3. Improvements in chemical solution containment, facility housekeeping, work practices, and local exhaust ventilation (LEV) maintenance prompted a follow-up survey. The results from the follow-up survey indicated that 84 of 85 (99%) lapel samples were below the OSHA PEL and 76 of 85 (89%) were below the Cal/OSHA PEL. Statistical analysis demonstrates that racking and plating operator exposures are anticipated to be below the OSHA and Cal/OSHA PEL’s greater than 99% of the time. Statistical analysis of photoetching, deburring, bright cleaning, selective plating/con-tip, and wastewater treatment operators has the potential to exceed the Cal/OSHA PELs more than 5% of the time.
J. Miller, Ngenuity, Los Alamos, NM; T. Knudson, Brush Wellman Inc., Cleveland, OH; J. Dugger, M. Williams, Perot Systems, Knoxville, TN.
Precision stamping is a high-speed mechanical process used to cut and form strips of copper beryllium alloy into connectors that are incorporated into electrical components used in the computer, telecommunication, and automobile industries. Worker exposure to airborne beryllium during precision stamping of copper beryllium is not documented in the scientific literature. To help fill this data gap, an exposure assessment study was conducted to characterize airborne concentrations of beryllium during precision stamping of copper beryllium alloy. Four companies representative of the stamping industry participated in the study. Certified industrial hygienists performed an initial qualitative assessment to determine which manufacturing processes were believed to have some potential for generating beryllium aerosols. Three groups of manufacturing processes were investigated: mechanical (e.g., stamping), chemical (e.g., plating), and material handling (e.g., assembly). This presentation reports on the results of the mechanical and material handling processes. Workers were aggregated into similar exposure groups (SEGs) based on similarities of the jobs they performed. The mechanical process SEG included press operators and tool makers. The material handling SEG included assembly operators, inspectors,and shipping technicians. Results indicated that for the mechanical process SEG, 66 of 75 (88%) of personal breathing-zone, time-weighted average air samples had a total beryllium mass less than the analytical limit of detection (LOD=0.005 µg per filter). For the material handling SEG, 51 0f 53 (96%) of the results were below the LOD. Values for the 11 results above the analytical limit of quantification ranged from 0.006 to 0.12 µg of beryllium per cubic meter of air (μg/m3). All of the measured airborne beryllium exposures were below the OSHA permissible exposure limit (PEL) of 2 μg/m3 and the California OSHA PEL of 0.2 μg/m3.
E. Donovan, ChemRisk Inc., San Francisco, CA.
Data from surveys of the general work force and new employees at a beryllium manufacturer were used to evaluate the performance of the beryllium blood lymphocyte proliferation test (BeBLPT). Over 10,000 results from nearly 2400 participants collected over 12 years were analyzed using consistent criteria to describe the performance characteristics of the BeBLPT. Approximately 2% of new employees had at least one positive BeBLPT result at the time of hire, and approximately 1% of new employees with no known potential occupational or possible take-home exposures to beryllium were confirmed positive (two positive results) from the time of hire. Positive results were observed in some workers within weeks or months of initial exposure, and the median time to the first positive result in confirmed positive individuals was five months. The prevalence of positive BeBLPT results was greatest during the first year of employment, with an apparent peak in months 4-8. At least one negative or borderline-negative result was observed in 100% of new workers who underwent follow-up testing after they had been confirmed positive. There was no correlation between time of employment and an increasing prevalence of confirmed positive BeBLPT results in individual surveys; however, the cumulative incidence of confirmed positive results in subsets of workers that participated in multiple surveys increased over time. When interpreting results from studies using the BeBLPT (especially when considering worker-specific interventions), the detection of confirmed positive results in nonoccupationally exposed persons, the apparent reversions of previously confirmed positive results, the identification of a positive BeBLPT peak prevalence period, and the variation in intra- and inter-laboratory test methods and interpretation should be considered. Additional research to refine the BeBLPT or develop a new test is needed to properly characterize the relationship between sensitization and subclinical or clinical indicators of chronic beryllium disease.
A. Dufresne, McGill University, Montréal, QC, Canada; C. Dion, Y. Cloutier, S. Viau, IRSST, Montréal, QC, Canada; G. Perrault, Consultant, Montréal, QC, Canada.
A notice of intended change that has been posted by ACGIH will lower the current 8-hr occupational exposure limit for beryllium. The proposed guideline will be based in part on previously reported workplace exposures, which themselves may depend on the type of sampling method. To examine the influence of sampling method in beryllium exposure assessment, a study was conducted in foundries and smelters to contrast the performance of five different dust sampling devices. Five sampling survey were conducted in three different settings, and both personal and fixed station samples were collected using the following sampling heads: IOM samplers (inhalable dust), 35-mm plastic cassettes (total dust), aluminum SKC cyclones (respirable dust), 8-stage Sierra cascade impactors, and 12-stage micro-orifice uniform deposit (MOUDI) impactors. In total, beryllium concentrations were determined for 58/61 inhalable dust samples, 52/54 total dust samples, 49/49 respirable dust samples, 53/56 8-stage Sierra samples, and 16/21 12-stage MOUDI samples. Beryllium concentrations were highest for personal samples collected in foundries using IOM samplers (median = 0.84 µg/m3, 95% CI: 0.190, 2.11). Normalized in reference to IOM samplers, median ratios for beryllium exposures determined using 37-mm plastic cassettes, SKC aluminium cyclones, Sierra impactors, and MOUDI impactors were 0.836, 0.218, 0.545, and 0.615 respectively. For fixed-station samples, median ratios in reference to IOM samplers were 0.667, 0.129, 0.708, and 0.633 for exposures measured using 37-mm plastic cassettes, SKC cyclones, Sierra impactors, and MOUDI impactors, respectively. While these comparisons are based on a limited number of samples, our findings suggest that the sampling method may have a substantial effect on the numerical value determined for beryllium exposure. Therefore, differences in sampling efficiency should be discussed and considered in setting the new beryllium exposure limit in order to maximize worker protection.
K. Ashley, G. Applegate, T. Wise, J. Fernback, NIOSH, Cincinnati, OH; M. Goldcamp, Wilmington College, Wilmington, OH.
Experiments were carried out to investigate the collection efficiency of the vacuum sampling method described in ASTM International Standard D7144, Standard Practice for Collection of Surface Dust by Micro-Vacuum Sampling for Subsequent Metals Determination. Weighed masses (≈5, ≈10 and ≈25 mg) of three National Institute of Standards and Technology (NIST) Standard Reference Materials (SRMs) were spiked onto surfaces of various substrates. The SRMs used were (1) No. 1579, Powdered Lead-Based Paint; (2) No. 1648, Urban Particulate Matter; and (3) No. 2583, Trace Elements in Indoor Dust. Twelve different substrate materials, which were chosen to be representative of surfaces commonly encountered in occupational and/or indoor settings, were selected for investigation. Samples of SRMs originally spiked onto these surfaces were collected using the standardized microvacuum sampling procedure. Gravimetric analysis of material collected within preweighed inserts (housed within the samplers) was used to measure SRM recoveries. Recoveries ranged from 21.6% (±10.4%, 95% confidence limit [CL]) for SRM 1579 from industrial carpet to 59.2% (±11.0%, 95% CL) for SRM 1579 from glass. In general, SRM recoveries were higher from smooth and hard surfaces and lower from rough and porous surfaces. Material captured within collection nozzles attached to the sampler inlets was also weighed. A significant fraction of SRM originally spiked onto substrate surfaces was captured within collection nozzles. Percentages of SRMs captured within collection nozzles ranged from ≈13% (±4 - ±5%, 95% CLs) for SRMs 1579 and 2583 from industrial carpet to ≈45% (±7 - ±26%, 95% CLs) for SRM 1648 from glass, tile, and steel. For some substrates, loose material from the substrate itself (i.e., substrate particles and fibers) was sometimes collected along with the SRM, both within inserts as well as collection nozzles. Co-collection of substrate material can bias results and contribute to sampling variability.
A. Ekechukwu, W. Spencer, Savannah River National Laboratory, Aiken, SC.
The Department of Energy (DOE) desires a rapid and simple analysis for beryllium to support field surveys of workplaces. DOE laboratories analyze up to 50,000 survey smears a year. The current analysis method is labor intensive, provides only a moderate rate of analyses with slow data reporting, and requires expensive analytical instrumentation. An alternative field portable analysis has recently been developed and published as ASTM Method, D7202-05, Standard Test Method for Determination of Beryllium in the Workplace Using Field-Based Extraction and Fluorescence Detection. This method is based on a novel fluorescent reagent, 10-hydroxy benzoquinoline-7-sulphonic acid (HBQS), which, when used in caustic solutions, is selective and highly sensitive for beryllium. Savannah River National Laboratory developed a design for an automated beryllium analyzer based on this method that combines digestion and subsequent analysis by fluorescence using commercial components. The instrument as designed is capable of analyzing 200 samples per 8-hr shift; the liquid waste generated can be trapped in a solid adsorbent and disposed. The cost of fabrication of the design is estimated between $80,000 and $120,000. In addition, the detection limits of the fluorescence system are an order of magnitude lower than the current laboratory instrumentation, inductively coupled plasma-emission spectrometry, and does not suffer from the same concomitant metal interferences.