Immediately Dangerous to Life or Health Concentrations (IDLH)
CAS number: 74–97–5
NIOSH REL: 200 ppm (1,050 mg/m3) TWA
Current OSHA PEL: 200 ppm (1,050 mg/m3) TWA
1989 OSHA PEL: Same as current PEL
1993-1994 ACGIH TLV: 200 ppm (1,060 mg/m3) TWA
Description of Substance: Colorless to pale-yellow liquid with a chloroform-like odor.
LEL: . . Noncombustible Liquid
Original (SCP) IDLH: 5,000 ppm
Basis for original (SCP) IDLH: Patty  reported that light narcosis could be produced in animals at 3,000 ppm, and pulmonary edema and deaths during exposure at 27,000 ppm; delayed deaths occurred after exposure to 20,000 ppm [Comstock et al. 1953]. Patty  also reported that guinea pigs survived 1-hour exposures but 1 of 3 guinea pigs died after 2-hour exposures to 8,000 to 10,000 ppm [Matson and Dufour 1948]. NIOSH  cited 1,550 ppm as the mouse LCLO [Svirbely et al. 1947]. Scheel (member of the Standards Completion Program Respirator Committee), in an evaluation of the work of Van Stee , determined a cardiac toxicity concentration for chlorobromomethane of 7,000 ppm. Based on an evaluation of the toxicological data cited above, an IDLH of 5,000 ppm was chosen.
Short-term exposure guidelines: None developed
ACUTE TOXICITY DATA
Lethal concentration data:
|Species||Reference||LC50(ppm)||LCLo(ppm)||Time||Adjusted 0.5-hrLC (CF*)||Derivedvalue|
|Comstock et al. 1952Comstock and Oberst 1953
Comstock and Oberst 1953
Matson and Dufour 1948
Matson and Dufour 1948
Svirbely et al. 1947
|15 min15 min
|18,720 ppm (0.65)18,850 ppm (0.65)
17,550 ppm (0.65)
47,600 ppm (2.38)
19,040 ppm (2.38)
15,600 ppm (5.2)
|1,872 ppm1,885 ppm
*Note: Conversion factor (CF) was determined with “n” = 1.6 [ten Berge et al. 1986].
Lethal dose data:
|Species||Reference||Route||LD50(mg/kg)||LDLo(mg/kg)||Adjusted LD||Derived value|
|RatMouse||Deichmann and Gerarde 1969Svirbely et al. 1947||oraloral||5,0004,300||———-||6,506 ppm5,595 ppm||651 ppm560 ppm|
Human data: None relevant for use in determining the revised IDLH.
|Revised IDLH: 2,000 ppmBasis for revised IDLH: The revised IDLH for chlorobromomethane is 2,000 ppm based on acute inhalation toxicity data in animals [Comstock et al. 1952; Comstock and Oberst 1953; Matson and Dufour 1948]. This may be a conservative value due to the lack of relevant acute toxicity data for workers.|
1. Comstock C, Fogleman RW, Oberst FW . Acute narcotic effects of monochloro-monobromomethane vapor in rats. AMA Arch Ind Hyg Occup Med 7:526-528.
2. Comstock CC, MacNamee JK, Ozburn EE, Fogelman RW, Oberst FW . Monochloro-monobromomethane: inhalation toxicity, pathology, and symptomatology in rats and mice. Army Chemical Center, MD: Chemical Corps Medical Laboratories, Research Report #113.
3. Comstock CC, Oberst FW . Comparative inhalation toxicities of four halogenated hydrocarbons to rats and mice in the presence of gasoline fires. AMA Arch Ind Hyg Occup Med 7:157-167.
4. Deichmann WB, Gerarde HW . Methylene chlorobromide (bromochloromethane). In: Toxicology of drugs and chemicals. New York, NY: Academic Press, Inc., pp. 390-391.
5. Matson AF, Dufour RE . The life hazards and nature of the products formed when chlorobromomethane extinguisher liquid is applied to fires. Chicago, Il: Underwriter’s Laboratories Inc., Bulletin of Research No. 42, p. 19.
6. NIOSH . PA52500. Bromochloromethane. 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. 476.
7. Patty FA, ed. . Industrial hygiene and toxicology. 2nd rev. ed. Vol. II. Toxicology. New York, NY: Interscience Publishers, Inc., pp. 1271-1272.
8. Svirbely JL, Highman B, Alford WC, von Oettingen WF . The toxicity and narcotic action of mono-chloro-mono-bromo-methane with special reference to inorganic and volatile bromide in blood, urine and brain. J Ind Hyg Toxicol 29:382-389.
9. ten Berge WF, Zwart A, Appelman LM . Concentration-time mortality response relationship of irritant and systematically acting vapours and gases. J Haz Mat 13:301-309.
10. Van Stee EW . A review of the toxicology of halogenated fire extinguishing agents. Wright-Patterson Air Force Base, Ohio: Aerospace Medical Division, Aerospace Medical Research Laboratory, Air Force Systems Command, AMRL-TR-74-143.