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Hydrogen cyanide

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-hrLC (CF*) Derived value
Mammal AAPCO 1966 —– 200 5 min 103 ppm (0.52) 10 ppm
Mamma Arena 1970 —– 36 2 hr 60 ppm (1.67) 6.0 ppm
Human Dudley et al. 1942 —– 107 10 min 71 ppm (0.67) 7.1 ppm
Rat Dudley et al. 1942 503 —– 5 min 259 ppm (0.52) 26 ppm
Mouse Dudley et al. 1942 323 —– 5 min 166 ppm (0.52) 17 ppm
Rabbit Gates et al. 1946 —– 759 1 min 216 ppm (0.28) 22 ppm
Cat Gates et al. 1946 —– 759 1 min 216 ppm (0.28) 22 ppm
Rat Hartzell et al. 1985 275 —– 15 min 213 ppm (0.77) 21 ppm
Rat Hartzell et al. 1985 170 —– 30 min 170 ppm (1.0) 17 ppm
Human Izmerov et al. 1982 —– 357 2 min 131 ppm (0.37) 13 ppm
Rat Levin et al. 1987 160 —– 30 min 160 ppm (1.0) 16 ppm
Rat Vernot et al. 1977 323 —– 5 min 166 ppm (0.52) 17 ppm
Human 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.

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