beryllium (Be)

Toxic metal found in several alloys used in very specialized applications such as in aircraft, rockets and missiles, spacecrafts, and nuclear reactors. Acute beryllium poisoning can result from a less than 50 day exposure to its concentrations as low as 20 micrograms (millionth of a gram) per cubic meter of ambient air. It causes usually-fatal berylliosis by inhalation, and produces its subacute and chronic forms from skin contamination. Classified as a hazardous pollutant, beryllium's maximum concentration of discharge is set generally at 0.1 micrograms per cubic meter of ambient air.