There is a lack of consensus about whether the current exposure standard in 10 CFR 850 (i.e., 2 µg Be/m3) is adequate to protect workers. Although this issue was recognized during the rulemaking process for 10 CFR 850, it was also recognized that the scientific data needed to establish a different limit was lacking. The rule therefore establishes an action level (AL) that is one-tenth of this level, i.e., 0.2 µg Be/m3. Therefore, work place levels shall be maintained below the AL and as low as practical. Visitors to beryllium work areas should be discouraged unless essential to the mission in question.

2.1 Acute Beryllium Disease

Acute beryllium disease is caused by dust or fumes of soluble beryllium salts (such as BeF2 or BeSO4), which are intermediaries in the extraction of beryllium hydroxide and the production of beryllium metal and oxide. This disease occurred almost exclusively among workers in such processes and in the production of phosphors for fluorescent lights in the 1930s and 1940s. Unlike CBD, acute beryllium disease is a chemical pneumonitis whose severity is determined by the magnitude of exposure. Acute beryllium disease is generally reversible.

2.2 Beryllium Sensitization and Chronic Beryllium Disease

Health effects from beryllium are caused by the body's immune system response to inhaled dust or fumes containing beryllium metal, alloys, or compounds. This immune system response to beryllium is similar to an allergic reaction and may evolve over many years, even decades. Early evidence of this reaction may be detected by a blood test [i.e., the beryllium lymphocyte proliferation test (Be-LPT)] before there is evidence of damage to the lungs. The Be-LPT is used as a screening test for early evidence that an individual may be at higher risk for beryllium disease based on reaction of the immune system to the metal. Positive test results indicate beryllium sensitization. Sensitization is not a disease. There is no impairment from, or symptoms of, sensitization itself.

The body's reaction may continue to progress and cause damage to the lungs. CBD is said to exist when there is evidence of harmful effects to the lungs, i.e., when healthy lung tissue becomes damaged and changes from functioning lung tissue to fibrotic tissue. Damage to the lungs may be detected early by biopsy before there are symptoms (e.g. shortness of breath). Damage (i.e., fibrosis) may progress to the point that symptoms are severe enough to disable or cause death. In summary, the health effects from beryllium may be clinically silent (i.e., without symptoms) or may progress to substantial impairment or death.

Detection and diagnosis of beryllium health effects are usually a two-step process. First, the Be-LPT is performed to determine whether a worker is sensitized. If the initial test result is confirmed to be positive on a repeat test, the worker is offered further tests, which include bronchoscopy and other medical tests that the examining physician deems necessary to determine whether lung damage or CBD exists.

Not all exposed workers develop sensitization or disease. Research suggests that a small percentage of the population may have a genetic predisposition to CBD. Once a worker becomes sensitized or is diagnosed with CBD, the process is not reversible. There is no cure for CBD. Early diagnosis and treatment of CBD are expected to reduce adverse health effects and improve a person's prognosis.

2.3 Skin and Implantation

Beryllium and its compounds can cause a variety of skin problems depending on the chemical form of beryllium and the type of exposure, as follows:

* Irritant dermatitis--Caused by contact with a soluble compound. Symptoms are inflammation, local edema (i.e., accumulation of excessive amounts of fluids), and transudation of serum (i.e., passage of serum through the skin).

* Allergic contact dermatitis--May occur within 6-15 days of exposure to dust, fumes, or mist. Symptoms include erythema (i.e., inflammatory redness) and varying degrees of edema; lesions may be present.

* Chemical ulcer or ulcerating granuloma--A persistent lesion that results from implantation of a beryllium crystal or metal under the skin. The lesion will not heal until the foreign body (i.e., beryllium) is removed.

A very small number of CBD cases have resulted from skin implantation; the typical effects are those noted above.

2.4 Cancer