Immediately Dangerous to Life or Health Concentrations (IDLH)
CAS number: 107–31–3
NIOSH REL: 100 ppm (250 mg/m3) TWA, 150 ppm (375 mg/m3) STEL
Current OSHA PEL: 100 ppm (250 mg/m3) TWA
1989 OSHA PEL: 100 ppm (250 mg/m3) TWA, 150 ppm (375 mg/m3) STEL
1993-1994 ACGIH TLV: 100 ppm (246 mg/m3) TWA, 150 ppm (368 mg/m3) STEL
Description of substance: Colorless liquid with a pleasant odor.
LEL: . . . 4.5% (10% LEL, 4,500 ppm)
Original (SCP) IDLH: 5,000 ppm
Basis for original (SCP) IDLH: The chosen IDLH is based on the
statement by ACGIH  that 5,000 ppm was considered the maximum concentration guinea pigs could tolerate for 60 minutes without serious disturbances [Schrenk et al. 1936].
Short-term exposure guidelines: None developed
ACUTE TOXICITY DATA:
Lethal concentration data:
|Species||Reference||LC50 (ppm)||LCLo (ppm)||Time||Adjusted 0.5-hr
|G. pig||Schrenk et al. 1936||-----||50,000||20 min||43,500 ppm (0.87)||4,350 ppm|
Lethal dose data:
|Species||Reference||Route||LD50 (mg/kg)||LDLo (mg/kg)||Adjusted LD||Derived value|
|Rabbit||Munch 1972||oral||1,622||-----||4,542 ppm||454 ppm|
Other animal data: It has been stated that 5,000 ppm was considered the maximum concentration that guinea pigs could tolerate for 60 minutes without serious disturbances [Schrenk et al. 1936].
Human data: No adverse effects were found in humans after exposure to 1,500 ppm for 1 minute [Schrenk et al. 1936].
|Revised IDLH: 4,500 ppm
Basis for revised IDLH: The revised IDLH for methyl formate is 4,500 ppm based on acute inhalation toxicity data in animals [Schrenk et al. 1936]. Also, this value is 10% of the lower explosive limit of 4.5%.
1. ACGIH . Methyl formate. In: Documentation of the threshold limit values for substances in workroom air. 3rd ed. Cincinnati, OH: American Conference of Governmental Industrial Hygienists, pp. 165-166.
2. Munch JC . Aliphatic alcohols and alkyl esters: narcotic and lethal potencies to tadpoles and to rabbits. Ind Med Surg 41:31-33.
3. Schrenk HH, Yant WP, Chornyak J, Patty FA . Acute response of guinea pigs to vapors of some new commercial organic compounds. XIII. Methylformate. Public Health Rep 51:1329-1335.