- Challenge: 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. Cardno ChemRisk was asked to evaluate industrial hygiene and health surveillance data from a beryllium machining facility to determine the best dose metric for beryllium (Be) sensitivity (BeS) or the diagnosis of chronic beryllium disease (CBD).
- Approach: Cardno ChemRisk evaluated airborne beryllium concentrations for different job titles, compared historical trends of beryllium levels, and developed mean and upper bound exposure estimates for workers identified as beryllium sensitized or diagnosed with subclinical or clinical CBD. Several approaches were used to reconstruct historical exposures of each worker: industrial hygiene data were pooled by year, by job title, by era of engineering controls and by the complete work history (lifetime weighted average) prior to diagnosis.
- Findings: 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. Based on this analysis, BeS and CBD generally occurred as a result of exposures greater than 0.4 ?g/m3; maintaining exposures below 0.2 ?g/m3 95% of the time may prevent BeS and CBD in the workplace.
- Value: This analysis identified an exposure concentration below which BeS and CBD may be prevented in the workplace.