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Hydrogen Cyanide


CAS No.74-90-8

Hydrogen cyanide (HCN) is a colorless or pale-blue liquid or gas with a bitter, almond-like odor. Hydrogen cyanide interferes with the body’s use of oxygen and may cause harm to the brain, heart, blood vessels, and lungs. Exposure can be fatal. Workers may be harmed from exposure to hydrogen cyanide. The level of exposure depends upon the dose, duration, and work being done.

Hydrogen cyanide may be used in the workplace for fumigation, electroplating, mining, chemical synthesis, and the production of synthetic fibers, plastics, dyes, and pesticides. Some examples of workers at risk of being exposed to hydrogen cyanide include the following:

  • Workers who fumigate ships and buildings
  • Agricultural workers who fumigate outdoor pests in areas such as fruit orchards
  • Factory workers in industries that manufacture acrylic fibers, synthetic rubber, and plastics
  • Steel and iron workers who work in plants that harden iron and steel

NIOSH recommends that employers use the Hierarchy of Controls to prevent injuries. If you work in an industry that uses hydrogen cyanide, please read chemical labels and the accompanying Safety Data Sheets for hazard information. Visit NIOSH’s page on Managing Chemical Safety in the Workplace to learn more about controlling chemical workplace exposures.

The following resources provide information about occupational exposure to hydrogen cyanide. Useful search terms for hydrogen cyanide include “formonitrile,” “hydrocyanic acid,” and “prussic acid.”

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