Immediately Dangerous to Life or Health Concentrations (IDLH)
CAS number: 75–61–6
NIOSH REL: 100 ppm (860 mg/m3) TWA
Current OSHA PEL: 100 ppm (860 mg/m3) TWA
1989 OSHA PEL: Same as current PEL
1993-1994 ACGIH TLV: 100 ppm (858 mg/m3) TWA
Description of Substance: Colorless, heavy liquid or gas (above 76 F) with a characteristic odor.
LEL:. . Noncombustible Liquid/Nonflammable Gas
Original (SCP) IDLH: 2,500 ppm
Basis for original (SCP) IDLH: The chosen IDLH is based on the rat LCLO of 2,300 ppm [Comstock et al. 1953 cited by NIOSH 1974] and on the statement by Patty  that 4,000 ppm for 15 minutes caused significant pulmonary damage in rats [Chambers et al. 1950].
Short-term exposure guidelines: None developed
ACUTE TOXICITY DATA
Lethal concentration data:
|Chambers et al. 1950|
Comstock and Oberst 1952
|43,158 ppm (0.79)|
43,450 ppm (0.79)
Other animal data: It has been reported that 4,000 ppm for 15 minutes caused significant pulmonary damage in rats [Chambers et al. 1950]. Fatalities were noted in rats after exposures of to 2,300 ppm for 6 hours/day, 5 days/week for 7 weeks [Comstock et al. 1953].
Human data: None relevant for use in determining the revised IDLH.
|Revised IDLH: 2,000 ppm
Basis for revised IDLH: The revised IDLH for difluorodibromomethane is 2,000 ppm based on inhalation toxicity data in animals [Chambers et al. 1950; Comstock et al. 1953].
1. Chambers WH, Krachow EH, McGroth FP, Goldberg SB, Lawson LH, McNamee K . An investigation of the toxicity of proposed fire extinguishing fluids. Part III. The pathology in rats produced by inhalation of vapors of proposed fire extinguishing compounds. Army Chemical Center, MD: U.S. Army Chemical Corps, Medical Division Research Report No. 23, p. 33.
2. Comstock CC, Oberst FW . Comparative inhalation toxicities of carbon tetrachloride, monochloromonobromomethane, difluorodibromomethane and trifluoromonobromomethane to rats and mice in the presence of gasoline fires. Army Chemical Center, MD: U.S. Army Chemical Corps Medical Laboratories, Research Report No. 107. p. 52.
3. Comstock CC, Kerschner J, Oberst FW . Toxicology of inhaled trifluoromonobromomethane and difluorodibromomethane vapors from subacute and chronic exposures of rats and dogs. Army Chemical Center, MD: U.S. Army Chemical Corps, Medical Laboratory Research Report No. 180, p. 6.
4. NIOSH . PA75250. Methane, dibromodifluoro-. In: The toxic substances list, 1974 ed. Rockville, MD: U.S. Department of Health, Education, and Welfare, Public Health Service, Center for Disease Control, National Institute for Occupational Safety and Health, DHEW (NIOSH) Publication No. 74-134, p. 477.
5. Patty FA, ed. . Industrial hygiene and toxicology. 2nd
rev. ed. Vol. II. Toxicology. New York, NY: Interscience
Publishers, Inc., p. 1328.
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