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Hydrogen cyanide																				Related Pages
										May 1994
Immediately Dangerous to Life or Health Concentrations (IDLH)
**CAS number:** 74–90–8
**NIOSH REL:** 4.7 ppm (5 mg/m3) STEL [skin]
**Current OSHA PEL:** 10 ppm (11 mg/m3) TWA [skin]
**1989 OSHA PEL:** 4.7 ppm (5 mg/m3) STEL [skin]
**1993-1994 ACGIH TLV:** 10 ppm (11 mg/m3) CEILING [skin]
**Description of Substance:** Colorless or pale-blue liquid or gas (above 78°F) with a bitter, almond-like odor.
**LEL:**. . 5.6% (10% LEL, 5,600 ppm)
**Original (SCP) IDLH:** 50 ppm
**Basis for original (SCP) IDLH:** The chosen IDLH is based on the statements by Patty [1963] that 45 to 54 ppm is “tolerated by man for 0.5 to 1 hour without immediate or late effects; 110 to 135 ppm, however, may be fatal after 0.5 to 1 hour or later, or dangerous to life [Flury and Zernik 1931; Dudley et al. 1942].”
**Short-term exposure guidelines:** None developed
**ACUTE TOXICITY DATA:**
**Lethal concentration data:**

**Species**
    **Reference**
    **LC50** **(ppm)**
    **LCLo** **(ppm)**
    **Time**
    **Adjusted 0.5-hr** **LC (CF*)**
    **Derived value**Mammal
    AAPCO 1966
    -----
    200
    5 min
    103 ppm (0.52)
    10 ppmMamma
    Arena 1970
    -----
    36
    2 hr
    60 ppm (1.67)
    6.0 ppmHuman
    Dudley et al. 1942
    -----
    107
    10 min
    71 ppm (0.67)
    7.1 ppmRat
    Dudley et al. 1942
    503
    -----
    5 min
    259 ppm (0.52)
    26 ppmMouse
    Dudley et al. 1942
    323
    -----
    5 min
    166 ppm (0.52)
    17 ppmRabbit
    Gates et al. 1946
    -----
    759
    1 min
    216 ppm (0.28)
    22 ppmCat
    Gates et al. 1946
    -----
    759
    1 min
    216 ppm (0.28)
    22 ppmRat
    Hartzell et al. 1985
    275
    -----
    15 min
    213 ppm (0.77)
    21 ppmRat
    Hartzell et al. 1985
    170
    -----
    30 min
    170 ppm (1.0)
    17 ppmHuman
    Izmerov et al. 1982
    -----
    357
    2 min
    131 ppm (0.37)
    13 ppmRat
    Levin et al. 1987
    160
    -----
    30 min
    160 ppm (1.0)
    16 ppmRat
    Vernot et al. 1977
    323
    -----
    5 min
    166 ppm (0.52)
    17 ppmHuman
    WHO 1970
    -----
    179
    1 hr
    231 ppm (0.69)
    23 ppm*Note: Conversion factor (CF) was determined with "n" = 2.7 [ten Berge et al. 1986].
 **Other animal data:** The median effective concentrations to produce incapacitation (EC50s) in rats have been determined to be 139 ppm and 115 ppm in 15 and 30 minutes, respectively [Hartzell et al. 1985].
 **Other human data:** It has been reported that 45 to 54 ppm can be tolerated for 0.5 to 1 hour without immediate or delayed effects while 110 to 135 ppm may be fatal after 0.5 to 1 hour or later, or dangerous to life [Flury and Zernik 1931].
 
 **Revised IDLH:** 50 ppm [Unchanged] **Basis for revised IDLH:** Based on acute inhalation toxicity data in humans [Flury and Zernik 1931], the IDLH for hydrogen cyanide (50 ppm) is not being revised at this time.**REFERENCES:**
1. AAPCO [1966]. Pesticide chemicals official compendium. Topeka, KS: Association of the American Pesticide Control Officials, Inc., p. 596.
2. Arena JM [1970]. Poisoning; toxicology, symptoms, treatments. 2nd ed. Springfield, IL: C.C. Thomas, *2*:73.
3. Dudley HC, Sweeney TR, Miller JW [1942]. Toxicology of acrylonitrile (vinyl cyanide). II. Studies of effects of daily inhalation. J Ind Hyg Toxicol *23*:255-258.
4. Flury F, Zernik F [1931]. Schädliche gase dämpfe, nebel, rauch- und staubarten. Berlin, Germany: Verlag von Julius Springer, p. 404 (in German).
5. Gates M, Williams J, Zapp JA [1946]. Arsenicals. In: Summary technical report of Division 9, NRDC. Vol. 1. Chemical warfare agents, and related chemical problems. Part I. Washington, DC: Office of Scientific Research and Development, National Defense Research Committee, pp. 83-114.
6. Hartzell GE, Priest DN, Switzer WG [1985]. Modeling of toxicological effects of fire gases. II. Mathematical modeling of intoxication of rats by combined carbon monoxide and hydrogen cyanide. J Fire Sci *3*:115-128.
7. Izmerov NF, Sanotsky IV, Sidorov KK [1982]. Toxicometric parameters of industrial toxic chemicals under single exposure. Moscow, Russia: Centre of International Projects, GKNT, p. 75.
8. Levin BC, Paabo M, Gurman JL, Harris SE [1987]. Effects of exposure to single or multiple combinations of the predominant toxic gases and low oxygen atmospheres produced in fires. Fundam Appl Toxicol *9*:236-250.
9. Patty FA, ed. [1963]. Industrial hygiene and toxicology. 2nd rev. ed. Vol. II. Toxicology. New York, NY: Interscience Publishers, Inc., p. 1998.
10. ten Berge WF, Zwart A, Appelman LM [1986]. Concentration-time mortality response relationship of irritant and systematically acting vapours and gases. J Haz Mat *13*:301-309.
11. Vernot EH, MacEwen JD, Haun CC, Kinkead ER [1977]. Acute toxicity and skin corrosion data for some organic and inorganic compounds and aqueous solutions. Toxicol Appl Pharmacol *42*:417-423.
12. WHO [1970]. Technical report series 30. Geneva, Switzerland: World Health Organization.

			
							
								Page last reviewed:  December 4, 2014						Content
							source: 	National Institute for Occupational Safety and Health NIOSH Publications & Products
Immediately Dangerous To Life or Health (IDLH) Values
Table of IDLH Values
Criteria for Determining IDLH Values
Historical Documentation
Original (SCP) Values
Abbreviations for IDLH Documentation
Abbreviations for Journal Titles Follow NIOSH Facebook
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