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.”
The NIOSH Pocket Guide to Chemical Hazards (NPG) helps workers, employers, and occupational health professionals recognize and control workplace chemical hazards.
The NIOSH Manual of Analytical Methods (NMAM) is a collection of methods for sampling and analysis of contaminants in workplace air, and in the blood and urine of workers who are occupationally exposed.
- NIOSHTIC-2 search results for hydrogen cyanide—NIOSHTIC-2 is a searchable database of worker safety and health publications, documents, grant reports, and journal articles supported in whole or in part by NIOSH.
- Immediately Dangerous to Life or Health (IDLH) Value Profile: Hydrogen Cyanide —NIOSH reviews relevant scientific data and researches methods for developing IDLH values.
- Hydrogen Cyanide (No. 6010)pdf icon—NMAM sampling and analysis of contaminants in workplace air, and in the blood and urine of workers who are occupationally exposed.
- Hydrogen Cyanide (No. 6017)pdf icon—NMAM sampling and analysis of contaminants in workplace air, and in the blood and urine of workers who are occupationally exposed.
- Cyanides (aersols and gases) (No. 7904)pdf icon—NMAM sampling and analysis of contaminants in workplace air, and in the blood and urine of workers who are occupationally exposed.
- NIOSH Worker Health Study Summaries—NIOSH conducts research to prevent illnesses and injuries in the workplace. The NIOSH Worker Notification Program notifies workers and other stakeholders about the findings of these research studies.
- Preventing hearing loss caused by chemical (Ototoxicity) and noise exposurepdf icon—DHHS (NIOSH) No. 2018-124.
- A Summary of Health Hazard Evaluations: issues related to occupational exposure to fight fighters, 1990-2001pdf icon—DHHS (NIOSH) No. 2014-115.
- The Emergency Response Safety and Health Database: Hydrogen Cyanide—The ERSH-DB contains accurate and concise information on high-priority chemical, biological and radiological agents that could be encountered by personnel responding to a terrorist event.
- NIOSH Criteria Documents: Criteria for a Recommended Standard: Occupational Exposure to Hydrogen Cyanide and Cyanide Salts—DHHS (NIOSH) No. 77-108 Presents a standard to prevent the adverse effects of exposure to Hydrogen Cyanide and Cyanide Salts over a working lifetime.
- ATSDR Medical Management Guidelines (MMGs): Hydrogen Cyanide
- ATSDR ToxFAQs: Cyanide
- ATSDR Toxicological Profile for Cyanide
- EPA Chemistry Dashboardexternal icon
- EPA Acute Exposure Guideline Levels (AEGLs): Hydrogen Cyanideexternal icon
- EPA Air Toxics: Cyanide Compoundsexternal icon
- EPA Integrated Risk Information System (IRIS): Hydrogen Cyanideexternal icon
- Homeland Security: National Terror Alert: Hydrogen Cyanideexternal icon
- NLM Hazardous Substance Data Bank: Hydrogen Cyanideexternal icon
- NLM, Haz-Map: Hydrogen Cyanideexternal icon
- OSHA Chemical Sampling Information: Hydrogen Cyanideexternal icon
- OSHA Hazard Communicationexternal icon
- Canadian Centre for Occupational Health and Safety (CCOHS): Hydrogen cyanide search resultsexternal icon
- European Chemicals Agency (ECHA): Hydrogen Cyanideexternal icon
- Gestis Substance Databaseexternal icon
- ILO International Safety Chemical Safety Card: Hydrogen Cyanideexternal icon
- IPCS INCHEM, CICADS 61: Hydrogen Cyanide and Cyanidesexternal icon
- OECD Global Portal to Information on Chemical Substances