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Methyl bromide
May 1994
Immediately Dangerous to Life or Health Concentrations (IDLH)
CAS number: 74–83–9
NIOSH REL: None established; NIOSH considers methyl bromide to be a potential occupational carcinogen as defined by the OSHA carcinogen policy [29 CFR 1990].
Current OSHA PEL: 20 ppm (80 mg/m3) CEILING [skin]
1989 OSHA PEL: 5 ppm (20 mg/m3) TWA [skin]
1993-1994 ACGIH TLV: 5 ppm (19 mg/m3) TWA [skin]
Description of substance: Colorless gas with a chloroform-like odor at high concentrations.
LEL: . . . 10% (10% LEL, 10,000 ppm)
Original (SCP) IDLH: 2,000 ppm
Basis for original (SCP) IDLH: The chosen IDLH is based on the statement by Patty [1963] that rats survived 2,600 ppm for 24 minutes [Irish et al. 1940].
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 |
|---|---|---|---|---|---|---|
| MouseRabbit
Rat Rat Mouse G. pig |
Alexeeff et al. 1985Bakhishev 1973
Bakhishev 1975 Honma et al. 1985 Izmerov et al. 1982 Sayers et al. 1929 |
1,2007,316
2,833 302 390 —– |
———-
—– —– —– 300 |
1 hr30 min
30 min 8 hr 2 hr 9 hr |
1,500 ppm (1.25)7,316 ppm (1.0)
2,833 ppm (1.0) 755 ppm (2.5) 624 ppm (1.6) 780 ppm (2.6) |
150 ppm732 ppm
283 ppm 76 ppm 62 ppm 78 ppm |
Other animal data: It has been reported that rats have survived an exposure to 2,600 ppm for 24 minutes [Irish et al. 1940].
Human data: It has been stated that 220 ppm can be endured for several hours without serious effects [Clarke et al. 1945].
| Revised IDLH: 250 ppmBasis for revised IDLH: The revised IDLH for methyl bromide is 250 ppm based on acute inhalation toxicity data in humans [Clarke et al. 1945]. This may be a conservative value due to the lack of relevant acute toxicity data for workers exposed to concentrations above 220 ppm. [Note: NIOSH recommends as part of its carcinogen policy that the “most protective” respirators be worn for methyl bromide at any detectable concentration.] |
REFERENCES:
1. Alexeeff GV, Kilgore WW, Munoz P, Watt D [1985]. Determination of acute toxic effects in mice following exposure to methyl bromide. J Toxicol Environ Health 15:109-123.
2. Bakhishev GN [1973]. Relative toxicity of aliphatic halohydrocarbons to rats. Farmakol Toksikol 8:140-143 (in Russian).
3. Bakhishev GN [1975]. Relationship between chemical structure and toxicity for some halogenated aliphatic hydrocarbons. Fiz Akt Vesh 7:35-36 (in Russian).
4. Clarke CA, Roworth CG, Holling HE [1945]. Methyl bromide poisoning. An account of four recent cases met with in one of H.M. ships. Brit J Ind Med 2:17-23.
5. Honma T, Miyagawa M, Sato M, Hasegawa H [1985]. Neurotoxicity and metabolism of methyl bromide in rats. Toxicol Appl Pharmacol 81:183-191.
6. Irish DD, Adams EM, Spencer HC, Rowe VK [1940]. The response attending exposure of laboratory animals to vapors of methyl bromide. J Ind Hyg Toxicol 22(6):218-230.
7. Izmerov NF, Sanotsky IV, Sidorov KK [1982]. Toxicometric parameters of industrial toxic chemicals under single exposure. Moscow, Russia: Centre of International Projects, GKNT, p. 81.
8. Patty FA, ed. [1963]. Industrial hygiene and toxicology. 2nd rev. ed. Vol. II. Toxicology. New York, NY: Interscience Publishers, Inc., p. 1252.
9. Sayers RR, Yant WP, Thomas BGH, Berger LB [1929]. Physiological response attending exposure to vapors of methyl bromide, methyl chloride, ethyl bromide, and ethyl chloride. Public Health Bulletin 185:1-56.