Beryllium health effects, exposure limits and regulatory requirements

Beryllium is the lightest chemically stable metallic element. Research and development in the 1930s led to its use in industrial applications beginning in the 1940s. Subsequently, reports of lung and skin disease surfaced leading to epidemiologic and toxicology studies of beryllium's health effects. These studies have identified a range of health effects with solubility of the chemical form of beryllium as a key determinant whether the effects are acute (short term) or chronic (long term). The development of lymphocyte proliferation testing (BeLPT) for beryllium sensitization (BeS) in the 1980s and its use in medical screening has led to increasing awareness that occupational chronic beryllium disease (CBD) has not been controlled to the extent once thought. The enforceable long-standing occupational exposure limits intended to prevent CBD are now considered to be obsolete. However, proposed new limits have yet to be adopted. The basis for existing and proposed occupational and public exposure limits and regulatory requirements are discussed here. The current ACGIH and OSHA adopted occupational exposure limit for workers is 2.0 μg/m 3 , based as an 8-hour time weighted average (TWA). An occupational exposure limit of 0.2 μ/m 3 (8-Hr TWA) has been adopted by California as a regulatory limit and is being used by others as well. To protect the public from CBD, there is a long-standing EPA beryllium ambient air limit set of 0.01 μg/m 3 as a 30-day TWA. Unlike the acute health effects, CBD affects a few percent (0–4%) of those exposed to beryllium. The latency period between exposure and CBD can vary from months to decades. CBD is caused by the immune system's continuing reaction to the less soluble forms of beryllium retained in the body. An individual is considered to be sensitized to beryllium if BeLPT results show they are able to mount an immune response to beryllium. The morbidity and mortality associated with CBD are primarily due to lung damage caused by chronic inflammation. CBD is treatable but not curable. The existing ERPGs for Be are intended to prevent the acute health effects, primarily chemical pneumonitis caused by the more soluble forms of Be. Patients who survive acute beryllium disease will typically recover in less than 1 year. The need for an emergency response to prevent chronic effects is less obvious, and short-term exposure to the less soluble forms of Be could contribute to risk for CBD. Based on medical surveillance data from various DOE sites for current workers tested (13,270) and former workers (43,628), the number of sensitization and CBD cases at each site is a few percent (0–4%). Sensitization and CBD are due to an immune-system response, and they have not been found to be sensitive to the length of employment of a worker in a beryllium facility.