Jump to main content.

Cyanide, free Quickview (CASRN 57-12-5)

Health assessment information on a chemical substance is included in IRIS only after a comprehensive review of toxicity data by U.S. EPA health scientists from several Program Offices, Regional Offices, and the Office of Research and Development.

Disclaimer: This QuickView represents a snapshot of key information. We suggest that you read the IRIS Summary to put this information into complete context.

For definitions of terms in the IRIS Web site, refer to the IRIS Glossary.

Status of Data for Cyanide, free

File First On-Line: 01/31/1987; Last Significant Revision: 09/28/2010

Category (section)
Last Revised
Oral RfD Assessment Yes 09/28/2010
Inhalation RfC Assessment No
Carcinogenicity Assessment Yes 03/01/1991
  • 57-12-5
  • Carbon nitride ion
  • Cyanide ion
  • Cyanure
  • Cyanide
  • Free cyanide
  • RCRA Waste Number p030
  • Cyanide, free
  • Isocyanide
  • Cyanide anion
Revision History
Date Section Description
09/28/2010 I.A. Updated RfD with data from Hydrogen Cyanide and Cyanide Salts Assessment
Chronic Health Hazard Assessments for Noncarcinogenic Effects

Reference Dose for Chronic Oral Exposure (RfD)

Critical Effect
Point of Departure*
Decreased cauda epididymis weight in male F344/N rats. The RfD for cyanide, free is presented in section I.A.3 of the hydrogen cyanide and cyanide salts IRIS Summary. (other effect: Weight loss, thyroid effects and myelin degeneration. ) : x10 6.3 x10-4 mg/kg-day

* The Point of Departure listed serves as a basis from which the Oral RfD was derived. See Discussion of Conversion Factors and Assumptions for more details.

Note: The RfD for Cyanide, free was calculated using toxicological data for CN-. Please see Toxicological Review of Hydrogen Cyanide and Cyanide Salts (PDF)(154 Pages, 905K, about PDF)

Top of page

Reference Concentration for Chronic Inhalation Exposure (RfC)

Not Assessed under the IRIS Program.

Top of page

Carcinogenicity Assessment for Lifetime Exposure
  • Weight-of-Evidence Characterization
    • D (Not classifiable as to human carcinogenicity)
  • Weight-of-Evidence Narrative:
    • Pertinent data regarding carcinogenicity have not been located in the available literature.
    • This may be a synopsis of the full weight-of-evidence narrative. See IRIS Summary.

Quantitative Estimate of Carcinogenic Risk from Oral Exposure

  • Not Assessed under the IRIS Program.

Quantitative Estimate of Carcinogenic Risk from Inhalation Exposure

  • Not Assessed under the IRIS Program.

Top of page

Recent Additions | Advanced Search | IRIS Home | Environmental Assessment | Research

Local Navigation

Jump to main content.