Immediately Dangerous to Life or Health Concentrations (IDLH)
CAS number: 67–56–1
NIOSH REL: 200 ppm (260 mg/m3) TWA, 250 ppm (325 mg/m3) STEL [skin]
Current OSHA PEL: 200 ppm (260 mg/m3) TWA
1989 OSHA PEL: 200 ppm (260 mg/m3) TWA, 250 ppm (325 mg/m3) STEL [skin]
1993-1994 ACGIH TLV: 200 ppm (262 mg/m3) TWA, 250 ppm (328 mg/m3) STEL [skin]
Description of substance: Colorless liquid with a characteristic pungent odor.
LEL: . . . 6.0% (10% LEL, 6,000 ppm)
Original (SCP) IDLH: 25,000 ppm
Basis for original (SCP) IDLH: The chosen IDLH is based on the statement by Patty  that it probably would be dangerous for men to be exposed to the vapors of methyl alcohol in concentrations of the order of 30,000 to 50,000 ppm for as much as 30 to 60 minutes.
Existing short-term exposure guidelines: National Research Council [NRC 1985] Emergency Exposure Guidance Levels (EEGLs):
10-min EEGL: 800 ppm
30-min EEGL: 400 ppm
1-hour EEGL: 200 ppm
24-hour EEGL: 10 ppm
ACUTE TOXICITY DATA:
Lethal concentration data:
|Species||Reference||LC50(ppm)||LCLo(ppm)||Time||Adjusted 0.5-hrLC (CF)||Derived value|
|Cat||Flury & Wirth 1933||—–||33,082||6 hr||76,090 ppm (2.3)||7,609 ppm|
|Mouse||Izmerov et al. 1982||—–||37,594||2 hr||60,150 ppm (1.6)||6,015 ppm|
|Rat||NPIRI 1974||64,000||—–||4 hr||128,000 ppm (2.0)||12,800 ppm|
Lethal dose data:
|Species||Reference||Route||LD50(mg/kg)||LDLo(mg/kg)||Adjusted LD||Derived value|
|Rat||Larionov & Broitman 1975||oral||5,628||—–||29,621 ppm||2,962 ppm|
|Mouse||Smith & Taylor 1982||oral||7,300||—–||38,421 ppm||3,842 ppm|
|Rat||Smyth et al. 1941||oral||12,880||—–||67,789 ppm||6,779 ppm|
|Rabbit||WHO 1970||oral||14,200||—–||74,737 ppm||7,474 ppm|
Other animal data: RD50 (mouse), 41,514 ppm [Alarie 1981].
Human data: Two human studies showed no effects at vapor concentrations ranging from 160 to 1,000 ppm [McAllister 1954; MDOH 1937]. It has been stated that it probably would be dangerous to be exposed to concentrations of the order of 30,000 to 50,000 ppm for as much as 30 to 60 minutes [Patty 1963]. It has been reported that the lethal oral dose is between 143 and 6,422 mg/kg [Arena 1970; Deichmann and Gerarde 1969; Handa 1983]. [Note: An oral dose of 143 to 6,422 mg/kg is equivalent to a 70-kg worker being exposed to about 7,000 to 225,000 ppm for 30 minutes, assuming a breathing rate of 50 liters per minute and 100% absorption.]
|Revised IDLH: 6,000 ppmBasis for revised IDLH: The revised IDLH for methyl alcohol is 6,000 ppm based on acute inhalation toxicity data in animals [Izmerov et al. 1982]. This may be a conservative value due to the lack of relevant acute toxicity data for workers exposed to concentrations between 1,000 and 30,000 ppm. However, this value is also 10% of the lower explosive limit of 6%.|
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