Beryllium (Be) is a light alkaline metal that confers special properties on the alloys and ceramics in which it is incorporated. Beryllium-copper alloys find use as components of computers, in the encasement of the first stage of nuclear weapons, in devices that require hardening such as missile ceramic nose cones, and in heat shield tiles used in space vehicles. Because of the use of beryllium in dental appliances, dentists and dental appliance makers are often exposed to beryllium dust in toxic concentrations and may develop beryllium disease.
Beryllium is highly toxic by inhalation and is classified by the IARC as a class 1, known human carcinogen. Inhalation of beryllium particles produces both acute beryllium disease and chronic disease characterized by progressive pulmonary fibrosis. Skin disease also develops in workers exposed to beryllium. The pulmonary disease is called chronic beryllium disease (CBD) and is a chronic granulomatous pulmonary fibrosis. In the 5–15% of the population that is immunologically sensitive to beryllium, CBD is the result of activation of an autoimmune attack on the skin and lungs. The disease is progressive and may lead to severe disability,
Introduction to Toxicology: Occupational & Environmental 1017 cancer, and death. Although some treatment approaches to CBD show promise, the prognosis is poor in most cases. The current permissible exposure levels for beryllium of 0.01 mcg/m3 averaged over a 30-day period or 2 mcg/m3 over an 8-hour period are insufficiently protective to prevent CBD. Both NIOSH and the ACGIH have recommended that the 8-hour PEL and TLV be reduced to 0.05 mcg/m3. These recommendations have not yet been implemented. Current OSHA information on beryllium appears at https://www.osha.gov/SLTC/beryllium/index.html.
Environmental beryllium exposure is not generally thought to be a hazard to human health except in the vicinity of industrial sites where air, water, and soil pollution have occurred.
Cadmium (Cd) is a transition metal widely used in industry.
Workers are exposed to cadmium in the manufacture of nickel cadmium batteries, pigments, low-melting-point eutectic materi als; in solder; in television phosphors; and in plating operations. It is also used extensively in semiconductors and in plastics as a sta bilizer. Cadmium smelting is often done from residual dust from lead smelting operations, and cadmium smelter workers often face both lead and cadmium toxicity.
Cadmium is toxic by inhalation and by ingestion. When met als that have been plated with cadmium or welded with cadmium- containing materials are vaporized by the heat of torches or cutting implements, the fine dust and fumes released produce an acute respiratory disorder called cadmium fume fever. This disor der, common in welders, is usually characterized by shaking chills, cough, fever, and malaise. Although it may produce pneumonia, it is usually transient. However, chronic exposure to cadmium dust produces a far more serious progressive pulmonary fibrosis. Cad mium also causes severe kidney damage, including renal failure if exposure continues. Cadmium is a human carcinogen and is listed as a class 1, known human carcinogen by the IARC.
The current OSHA PEL for cadmium is 5 mcg/m3 but is insufficiently protective of worker health. The OSHA cadmium standard may be found at https://www.osha.gov/pls/oshaweb/ owadisp.show_document?p_table=STANDARDS&p_id=10036.