The beryllium occupational exposure limit: historical origin and current inadequacy.

This report considers the historical origin of the current beryllium occupational exposure limit (OEL) and the evidence that led most authorities to conclude that it was adequately protective against clinically evident chronic beryllium disease (CBD). Nearly 40 years later, during the late 1980s, it was shown that in addition to CBD, beryllium can cause asymptomatic sensitization and asymptomatic (“subclinical”) lung disease. It is now known that beryllium sensitization can progress to beryllium disease. Moreover, beryllium sensitization has been found in workers employed at facilities where exposures infrequently, if ever, exceeded the OEL. Historic beryllium exposure limits, which in their time seemed adequate to protect against clinically evident CBD, no longer seem sufficient. There is considerable concern that current occupational exposure limits (OEL) provide insufficient protection for beryllium-exposed workers. The beryllium OEL, first proposed and adopted by the U.S. Atomic Energy Commission (AEC) in 1949 and subsequently adopted by virtually all advisory and regulatory agencies, has persisted with only minor changes despite major advances in our understanding of berylliuminduced disease and important changes in the diagnostic approach used for beryllium-affected workers. Over the past decade, an increasing number of authorities have argued that the beryllium OEL should be lowered, but no changes have thus far been made. In 1996, Brush Wellman, the sole North American beryllium producer, expressed uncertainty that the Occupational Safety and Health Administration (OSHA) permissible exposure limit (PEL) was adequately protective. The following year, the U.S. Department of Energy (DOE) published interim guidelines, with final regulations published in 1999, for a Beryllium Disease Prevention Program for workers at DOE sites, but DOE did not modify its OEL. Also in 1999, the American Conference of Governmental Industrial Hygienists (ACGIH) published a notice of intent to lower its threshold limit value (TLV) for beryllium, but no changes have been made. OSHA, in 2002, published a Request for Information as a first step toward setting a new beryllium PEL, but new values have yet to be proposed. The origins of the beryllium OEL and its persistence for more than 55 years provide interesting perspectives on historic and current practices of occupational medicine and industrial hygiene. Both its origin and persistence can be understood in light of the evolving knowledge about chronic beryllium disease (CBD) and the development of increasingly advanced diagnostic methods.