(now the U.S. Department of Energy [DOE]) recommended the first occupational exposure limit (OEL) for beryllium, 2.0 µg/m3. That limit was adopted by the American Conference of Governmental Industrial Hygienists (ACGIH), the National Institute for Occupational Safety and Health, the Occupational Safety and Health Administration (OSHA), the American Industrial Hygiene Association, and the American National Standards Institute (see Table 1-1). The OEL of 2.0 µg/m3 still stands although it has been challenged on several occasions.
The basis of the original standard was an estimate of the toxicity of beryllium in relation to other metals. It was assumed that beryllium toxicity was comparable with that of heavy metals on an atom-for- atom basis. Mercury and lead had occupational exposure limits of around 100 µg/m3, and that value was divided by 20 because the atomic weight of beryllium is about one-twentieth that of mercury and lead. The resulting value was divided by 2.5 to provide a margin of safety because understanding of CBD was lacking. The adequacy of the OEL of 2.0 µg/m3 was evaluated periodically in the 1960s; each time, it was deemed adequate because acute beryllium disease had become a rare occurrence and the incidence of CBD had become much lower.
Current scientific questions about exposure to beryllium in the workplace are related to CBD and cancer. Over the last 40 years, much has been learned about how beryllium causes CBD, and the diagnostic criteria for the disease have changed. Advances in medical and diagnostic technology allow physicians to identify beryllium-exposed workers with evidence of sensitization or milder forms of CBD (see Chapter 3). Research into dose-response relationships indicates that particle size, chemical form, concentration, and genetic factors may all play roles in determining whether a person develops CBD.
In addition, there has been debate over beryllium’s carcinogenic potential. In 1975, OSHA proposed to lower its permissible exposure limit to 1 µg/m3 on the presumption that beryllium was a carcinogen. However, that revision was never promulgated. OSHA was petitioned in 1999 and 2001 to issue an emergency temporary standard. The petitions were denied, but the agency indicated that it would begin data-gathering to revisit the adequacy of the standard for protecting worker health. The agency issued a formal request for information in 2002 (67 Fed. Reg. 70700 ). Peer review of OSHA’s health-effects and risk-assessment report is expected to be completed by November 2008 (73 Fed. Reg. 24723 ).
Other agencies have taken action in re-evaluating their occupational exposure guidelines for beryllium. In 1999, DOE established an action level of 0.2 µg/m3 intended to trigger workplace precautions and control measures to protect workers at DOE facilities (64 Fed. Reg. 68854 ). That action level is applicable only to DOE and DOE-contractor facilities and was established because DOE considered the OEL of 2 µg/m3 to be inadequate to protect worker health. DOE also established two surface-contamination guidelines for beryllium to reduce its accumulation on surfaces and its spread outside specific work areas (10 CFR 850.29-30 ). A beryllium surface guideline was set at 3 µg/100