Add time:08/29/2019         Source:sciencedirect.com

Beryllium is a critical material for many strategic industries. It is widely used despite its relatively high cost because it performs better in certain critical applications than its alternatives. The beryllium industry produces three primary forms of beryllium: copper-beryllium alloy is the largest, followed by pure beryllium metal and beryllium oxide ceramics.As a result of the increasing industrial use of beryllium, occupational exposure to the metal may be an important issue. Prior to 1950 when exposure levels of ≤ 2 μg/m3 were mandated by the Atomic Energy Commission, beryllium levels were very high. The estimated daily weighted average beryllium exposure levels for some workers in a plant that extracted and produced beryllium metal were 1000 μg/m3 in the 1940s and 1950s, > 50 μg/m3 during the mid-1960s, and > 30 μg/m3 during the mid-1970s. At present, the time-weighted average (TWA) concentrations are in the range of 0.01-1 μg/m3.Exposures to beryllium are much more hazardous by the inhalation route than by the ingestion route. Beryllium and its compounds are poorly absorbed from the gastrointestinal tract. In general, inhalation exposure to beryllium compounds results in the long-term storage of appreciable amounts of beryllium in lung tissue, particularly in pulmonary lymph nodes, and in the skeleton, which is the ultimate site of beryllium storage. Urinary beryllium concentrations are below the detection limits of 0.03-0.06 μg/L.Exposure to beryllium compounds has caused dermatitis, acute pneumoconiosis, and chronic beryllium disease (CBD, chronic pulmonary granulomatosis, berylliosis). Exposure to soluble beryllium salts may cause skin reactions such as edematous, erythematous, and papulovesicular dermatitis. These changes usually disappear after the cessation of exposure. Granulomatous necrotic changes and ulcerations due to skin penetration by insoluble beryllium salts were also observed. These pathological changes are based on delayed allergic hypersensitivity. Acute toxicity of beryllium at concentrations usually above 25 μg/m3 is manifested by skin, eye, nose, and throat irritation, followed by upper and lower airway inflammation, pulmonary edema, and (above 100 μg/m3) chemical pneumonitis.CBD is the best-known negative health effect caused by exposure to beryllium. CBD is a T cell-mediated disorder. Beryllium, acting as a hapten, interacts with antigen-presenting cells in the lungs. The beryllium blood lymphocyte proliferation test (BeLPT) is used as a medical surveillance tool for the assessment of persons at risk of developing clinical and subclinical CBD. It is generally accepted that sensitization occurs among a subset of workers. Several reports suggest that sensitization and CBD were associated with beryllium air TWA levels exceeding 0.2 μg/m3. A threshold limit value (TLV)-TWA of 0.05 μg/m3 recommended in 2008 by American Conference of Governmental Industrial Hygienists is expected to be protective for the beryllium-sensitive population.An excess incidence of lung cancer was found in populations occupationally exposed to beryllium, and was higher for individuals with acute beryllium disease than those with CBD. In their carcinogenicity rating, the International Agency for Research on Cancer (IARC, 1993, IARC, 2012) classified beryllium as a group 1 substance (i.e. sufficient evidence for carcinogenicity in humans). The U.S. Environmental Protection Agency (EPA) inhalation unit risk is 2.4 × 10×3 per μg/m3. In general, it seems that the lung cancer risk related to occupational exposure to beryllium is linked to the higher exposure levels that were associated with acute beryllium pneumonitis and predominated prior to the 1950s. The risk of additional lung cancer caused by 40 years of occupational exposure to beryllium or its compounds at the present TLV-TWA of 0.05 μg/m3 amounts to 1.5 × 10−5.

We also recommend Trading Suppliers and Manufacturers of BERYLLIUM NITRATE (cas 13597-99-4). Pls Click Website Link as below: cas 13597-99-4 suppliers