Exposure-Response Analysis for Beryllium Sensitization and Chronic Beryllium Disease Among Workers in a Beryllium Metal Machining Plant

Abstract

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 postengineering control measures, and mean and upper bound exposure estimates were developed for workers identified as beryllium sensitized or diagnosed with subclinical or clinical CBD. Five approaches 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. Results showed that beryllium-sensitized and CBD workers were exposed to beryllium concentrations greater than 0.2 microg/m3 (95th percentile), and 90% were exposed to concentrations greater than 0.4 microg/m3 (95th percentile) within a given year of their work history. Based on this analysis, BeS and CBD generally occurred as a result of exposures greater than 0.4 microg/m3 and maintaining exposures below 0.2 microg/m3 95% of the time may prevent BeS and CBD in the workplace.

Risk of beryllium sensitization in a low‐exposed former nuclear weapons cohort from the cold war era

“…Sensitization may develop in workers after few months and up to four decades following initial exposure [Stange et al, 2001;Newman et al, 2005;Cummings et al, 2007;Madl et al, 2007]. Follow-up studies among beryllium industry workers have shown that 6-8% of sensitized workers progress to lung disease per year [Newman et al, 2005].…”

Beryllium in urine by ICP-MS: a comparison of low level exposed workers and unexposed persons

“…This level was first recommended in 1949 by the U.S. Atomic Energy Commission and was adopted in 1956 (Madl et al 2007). A number of studies have since established that an occupational exposure limit of 2 lg/m 3 is not adequately protective because controlling beryllium inhalation exposure to comply with regulatory levels (2 lg/m 3 ) does not appear to prevent cases of beryllium sensitisation and chronic beryllium disease (Madl et al 2007;Day et al 2007). In 2009, the American Conference of Governmental Industrial Hygienists (ACGIH) reduced the Threshold Limit Value (TLV) by a factor of 40-0.05 lg/m 3 for beryllium over an 8-h shift , (ACGIH website http://www.acgih.org/store/ProductDetail.cfm?id= 758).…”

“…However, a measurement of exposure could aid improvements in workplace controls and prevent sensitisation occurring. While airborne beryllium levels via personal mounted samplers can be determined as part of routine occupational hygiene methods (Madl et al 2007), routine biological monitoring to assess exposure has not been widely used. Air monitoring alone will not assess overall systemic beryllium exposures in workers as a result of other possible routes of exposure to be accounted for such as dermal and ingestion routes.…”

Beryllium health effects, exposure limits and regulatory requirements

“…These include reports on epidemiologic studies of exposed workers, studies of the cellular and molecular biology of CBD and of the aerosols associated with CBD. [27][28][29][30][31][32] The aerosols in these studies were produced by machining metal, precision grinding beryllium oxide ceramics, fume from casting and metal recovery of copper beryllium alloys and the heat from rolling and extruding copper beryllium alloys that result in a removable oxide layer.…”