| Contents Notes |
The chemical and geochemical properties of beryllium resemble those of aluminum, zinc, and magnesium. This resemblance is primarily due to similar ionic potentials that facilitate covalent bonding. The three most common forms of beryllium in industrial emissions are the metal, the oxide, and the hydroxide. The main routes of beryllium intake for man and animals are inhalation and ingestion. While the absorption of ingested beryllium is probably quite small, the chemical properties of beryllium are such that inhaled beryllium has a long retention time in the lungs and, thus, a greater potential for absorption and/or physical irritation. The tissue distribution of absorbed beryllium is characterized by depositions primarily in the skeleton where the biological half-time is fairly long. The lung is the critical organ of both acute and chronic noncarcinogenic effects. However, unlike most other metals, the lung effects caused by chronic exposure to beryllium may be combined with systemic effects, of which one common factor may be hypersensitization. Certain beryllium compounds have shown carcinogenic activity in various experimental animals by various routes of exposure, but not by ingestion per se. Epidemiologic studies are inadequate to demonstrate or refute a human carcinogenicity potential. In terms of the weight of evidence for carcinogenicity. beryllium is judged to be in Group B2 signifying that the animal evidence for carcinogenicity is sufficient and that beryllium and its compounds are regarded as probably carcinogenic for humans. |
