U.S. EPA Contaminated Site Cleanup Information (CLU-IN)

U.S. Environmental Protection Agency
U.S. EPA Technology Innovation and Field Services Division

Dense Nonaqueous Phase Liquids (DNAPLs)


Halogenated Alkanes


Human Health Toxicity

Bromochloromethane (BCM), also referred to as Halon-1011, was formerly used as an aircraft fire-extinguisher fluid and in portable extinguishers, but it is no longer manufactured. Unlike other halomethanes, BCM is unlikely to be generated as a drinking water disinfection byproduct.

Laboratory rodent studies indicate that BCM is rapidly absorbed via inhalation and dermal contact. Oral absorption of the compound by rodents is assumed by the development of systemic toxic effects after oral dosing. Absorbed BCM is distributed to blood, liver, and muscle, but the greatest concentrations appear in fat tissue.

The Agency for Toxic Substances and Disease Registry (ATSDR) has not posted a toxicological profile for this compound. A case report of firefighters occupationally exposed to BCM mentions the development of gastric irritation and possibly compound-related central nervous system (CNS) effects such as headache, drowsiness, and loss of consciousness. Laboratory rodents develop symptoms of CNS toxicity in response to acute inhalation exposure to the compound, as well as degenerative changes in the liver.

There are no chronic toxicity studies of the effects of BCM on humans or laboratory animals. EPA's Integrated Risk Information System (IRIS) assigns Halon 1011 the weight-of-evidence classification "D; not classifiable as to human carcinogenicity."

No studies are available for the human reproductive or developmental toxicity of BCM. One rodent study reported that sub-chronic inhalation exposure of guinea pigs and rabbits to the chemical resulted in decreased spermatogenesis; however, the significance of this effect was not evaluated.

BCM has been reported as giving positive results in both bacterial and mammalian in vitro genotoxicity assays.


Bromochloromethane (CASRN 74-97-5)
U.S. EPA, Integrated Risk Information System (IRIS).

Chlorobromomethane, CASRN: 74-97-5
PubChem, National Center for Biotechnology Information.

Health and Environmental Effects Document for Bromochloromethane
U.S. EPA, Office of Environmental Criteria and Assessment.
EPA 600-8-91-016, 106 pp, 1990

Ecological Toxicity

No ecological toxicity studies are available for BCM for either terrestrial or aquatic receptors. An LC50 value of 67 mg/L for the common carp, Cyprinus carpio, and a freshwater acute criterion/guideline of 11 mg/L is given in Rowe et al. (1997).


Summary of Published Aquatic Toxicity Information and Water Quality Criteria for Selected Volatile Organic CompoundsAdobe PDF Logo
Rowe, B.L., S.J. Landrigan, and T.J. Lopes.
U.S. Geological Survey Open-File Report 97-563, 66 pp, 1997

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