Difluorodibromomethane

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 LC_LO of 2,300 ppm [Comstock et al. 1953 cited by NIOSH 1974] and on the statement by Patty [1963] 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:

Species	Reference	LC50 (ppm)	LCLo (ppm)	Time	Adjusted 0.5-hr LC (CF)	Derived value
Mouse Rat	Chambers et al. 1950 Comstock and Oberst 1952	----- -----	54,630 55,000	15 min 15 min	43,158 ppm (0.79) 43,450 ppm (0.79)	4,316 ppm 4,345 ppm

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].

REFERENCES:

1. Chambers WH, Krachow EH, McGroth FP, Goldberg SB, Lawson LH, McNamee K [1950]. 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 [1952]. 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 [1953]. 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 [1974]. 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. [1963]. Industrial hygiene and toxicology. 2nd rev. ed. Vol. II. Toxicology. New York, NY: Interscience Publishers, Inc., p. 1328.