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Methyl isocyanate																				Related Pages
										May 1994
Immediately Dangerous to Life or Health Concentrations (IDLH)
**CAS number:** 624–83–9
**NIOSH REL:** 0.02 ppm (0.05 mg/m3) TWA [skin]
**Current OSHA PEL:** 0.02 ppm (0.05 mg/m3) TWA [skin]
**1989 OSHA PEL:** Same as current PEL
**1993-1994 ACGIH TLV:** 0.02 ppm (0.047 mg/m3) TWA [skin]
**Description of substance:** Colorless liquid with a sharp, pungent odor.
**LEL:** . . . 5.3% (10% LEL, 5,300 ppm)
**Original (SCP) IDLH:** 20 ppm
**Basis for original (SCP) IDLH:** The chosen IDLH is based on the statement by ACGIH [1971] that the rat 2-hour LC50 is 21 ppm [Kimmerle and Eben 1964].
**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**Rat MouseG. pigRat
    Dodd et al. 1986 Dodd et al. 1986Dood et al. 1986Kimmerle & Eben 1964
    6.1 12.25.421
    ----- ---------------
    6 hr 6 hr6 hr2 hr
    14 ppm (2.3) 28 ppm (2.3)12 ppm (2.3)34 ppm (1.6)
    1.4 ppm 2.8 ppm1.2 ppm3.4 ppm**Lethal dose data:**
 
 **Species**
    **Reference**
    **Route**
    **LD50 (mg/kg)**
    **LDLo (mg/kg)**
    **Adjusted LD**
    **Derived value**Mouse Rat
    Vernot et al. 1977 Vijayarachavan & Kaushik 1987
    oral oral
    120 51.5
    ----- -----
    354 ppm 152 ppm
    35 ppm 15 ppm**Human data:** Volunteers experienced eye irritation and lacrimation after 1 to 5 minutes at 2 ppm, with more marked irritation at 4 ppm; exposures were unbearable at 21 ppm [Kimmerle and Eben 1964]. In another study, volunteers noted eye irritation and lacrimation at 5 ppm in less than 50 seconds [Mellon 1963].
 
 **Revised IDLH:** 3 ppm **Basis for revised IDLH:** The revised IDLH for methyl isocyanate is 3 ppm based on acute inhalation toxicity data in humans [Kimmerle and Eben 1964; Mellon 1963].**REFERENCES:**
1. ACGIH [1971]. Methyl isocyanate. In: Documentation of the threshold limit values. 3rd ed. Cincinnati, OH: American Conference of Governmental Industrial Hygienists, p. 167.
2. Dodd DE, Fowler EH, Snellings WM, Pritts IM, Baron RL [1986]. Acute inhalation studies with methyl isocyanate vapor. I. Methodology and LC50 determinations in guinea pigs, rats, and mice. Fundam Appl Toxicol *6*:747-755.
3. Kimmerle G, Eben A [1964]. Zur toxicitat von methylisocyanat und dessen quantitativer bestimmung in der luft (Toxicity of methyl isocyanate and its quantitative determination in the air). Arch Toxikol *20*:235-241 (in German).
4. Mellon [1963]. Special report 26-23. Pittsburgh, PA: Mellon Institute (March 13, 1963).
5. Vernot EH, MacEwen JD, Haun CC, Kinkead FR [1977]. Acute toxicity and skin corrosion data for some organic and inorganic compounds and aqueous solutions. Toxicol Appl Pharmacol *42*:417-423.
6. Vijayarachavan R, Kaushik MP [1987]. Acute toxicity of methyl isocyanate and ineffectiveness of sodium thiosulphate in preventing its toxicity. Indian J Exp Biol *25*:531-534.

			
							
								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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