Immediately Dangerous to Life or Health Concentrations (IDLH)
CAS number: 74–89–5
NIOSH REL: 10 ppm (12 mg/m3) TWA
Current OSHA PEL: 10 ppm (12 mg/m3) TWA
1989 OSHA PEL: Same as current PEL
1993-1994 ACGIH TLV: 5 ppm (6.4 mg/m3) TWA, 15 ppm (19 mg/m3) STEL
Description of substance: Colorless gas with a fish- or ammonia-like odor.
LEL: . . 4.9% (10% LEL, 4,900 ppm)
Original (SCP) IDLH: 100 ppm
Basis for original (SCP) IDLH: The chosen IDLH is based on the severe respiratory tract irritation produced by methylamine. Deichmann and Gerarde  stated that inhalation of methylamine vapors (greater than 100 ppm) causes irritation of the nose and throat, followed by violent sneezing, burning sensation of the throat, coughing, constriction of the larynx and difficulty in breathing, pulmonary congestion, and edema of the lungs.
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|
|Mouse||Izmerov et al. 1982||1,860||-----||2 hr||2,977 ppm (1.6)||298 ppm|
Human data: It has been reported that transient irritation of the eyes, nose, and throat has resulted from brief exposures to concentrations of 20 to 100 ppm; the odor was intolerable at 100 to 500 ppm [Clayton and Clayton 1981]. Inhalation of methylamine vapors (at concentrations greater than 100 ppm) has caused irritation of the nose and throat, followed by violent sneezing, burning sensation of the throat, coughing, constriction of the larynx and difficulty in breathing, pulmonary congestion, and edema of the lungs [Deichmann and Gerarde 1969].
|Revised IDLH: 100 ppm [Unchanged]
Basis for revised IDLH: Based on acute inhalation toxicity data in humans [Clayton and Clayton 1981; Deichmann and Gerarde 1969], the original IDLH for methylamine (100 ppm) is not being revised at this time.
1. Clayton GD, Clayton FC, eds. . Patty’s industrial and toxicology. 3rd rev. ed. Vol. 2B. Toxicology. New York, NY: John Wiley & Sons, Inc., pp. 3135-3173.
2. Deichmann WB, Gerarde HW . Methylamines (monomethylamine; dimethylamine; trimethylamine). In: Toxicology of drugs and chemicals. New York, NY: Academic Press, Inc., p. 385.
3. Izmerov NF, Sanotsky IV, Sidorov KK . Toxicometric parameters of industrial toxic chemicals under single exposure. Moscow, Russia: Centre of International Projects, GKNT, p. 81.