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
19931994 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  that the rat 2hour LC50 is 21 ppm [Kimmerle and Eben 1964].
Shortterm exposure guidelines: None developed
ACUTE TOXICITY DATA:
Lethal concentration data:
|Dodd et al. 1986|
Dodd et al. 1986
Dood et al. 1986
Kimmerle & Eben 1964
Lethal dose data:
|Vernot et al. 1977|
Vijayarachavan & Kaushik 1987
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
|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].
1. ACGIH . 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 . Acute inhalation studies with methyl isocyanate vapor. I. Methodology and LC50 determinations in guinea pigs, rats, and mice. Fundam Appl Toxicol 6:747755.
3. Kimmerle G, Eben A . Zur toxicitat von methylisocyanat und dessen quantitativer bestimmung in der luft (Toxicity of methyl isocyanate and its quantitative determination in the air). Arch Toxikol 20:235241 (in German).
4. Mellon . Special report 2623. Pittsburgh, PA: Mellon Institute (March 13, 1963).
5. Vernot EH, MacEwen JD, Haun CC, Kinkead FR . Acute toxicity and skin corrosion data for some organic and inorganic compounds and aqueous solutions. Toxicol Appl Pharmacol 42:417423.
6. Vijayarachavan R, Kaushik MP . Acute toxicity of methyl
isocyanate and ineffectiveness of sodium thiosulphate in preventing
its toxicity. Indian J Exp Biol 25:531534.
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