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May 1994
Immediately Dangerous to Life or Health Concentrations (IDLH)

Methyl formate

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 [1971] 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


Lethal concentration data:


SpeciesReferenceLC50 (ppm)LCLo (ppm)TimeAdjusted 0.5-hr


Derived value
G. pigSchrenk et al. 1936 -----50,00020 min43,500 ppm (0.87)4,350 ppm

Lethal dose data:


SpeciesReferenceRouteLD50 (mg/kg)LDLo (mg/kg)Adjusted LDDerived value
RabbitMunch 1972oral1,622-----4,542 ppm454 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 [1971]. 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 [1972]. 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 [1936]. Acute response of guinea pigs to vapors of some new commercial organic compounds. XIII. Methylformate. Public Health Rep 51:1329-1335.

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