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

Although bromodichloromethane (BDCM) had some use in the past as a solvent and fire extinguisher fluid, its present use is probably limited to that of a feedstock in laboratory-scale organic syntheses. Most BDCM present in the environment is a byproduct of drinking water chlorination. The general population might be exposed to BDCM via ingestion of chlorinated water and the inhalation of the volatilized compound from heated water used for cooking, bathing, and showering. Exposure by dermal contact might occur when swimming in chlorinated pools, bathing, or showering.

No studies were found that describe the absorption of BDCM via inhalation or dermal contact by either humans or animals. Laboratory animal studies indicate that the compound generally is well absorbed via the oral route. The pathways by which BDCM is metabolized are unknown. In laboratory animals, the compound is excreted unchanged in exhaled air or as a volatile metabolite, such as carbon dioxide. Little BDCM is excreted in urine or feces.

The chemical is acutely toxic to laboratory rodents via the oral route, with resulting development of lesions in the kidney, brain, adrenals and lung, and liver (fatty degeneration). Sub-chronic and chronic (oral route of administration) studies of BDCM in rodents indicate the liver and kidney as target organs.

Chronic oral administration of BDCM to rodents implicate the compound as a carcinogen. Exposed rats developed tumors of the liver (females only), kidney, and large intestine. Female mice developed liver tumors and male mice kidney tumors, but neither sex developed intestinal cancers. Epidemiological studies indicate there might be an association between the consumption of chlorinated drinking water and an increased cancer risk; however, many trihalomethanes (THMs) are present in disinfected water and it is not possible to attribute the increased risk to any one compound. EPA's Integrated Risk Information System (IRIS) classifies BDCM as "B2; probable human carcinogen."

No studies were found that describe the reproductive toxicity of this compound. At doses of BDCM that resulted in maternal toxicity, fetal rats developed defects in the sternebrae, but no other skeletal or visceral effects were noted. The effects on the sternebrae may be attributable to fetal toxicity.

An in vivo study in mice provides some evidence that BDCM can cause genetic damage. In vitro genotoxicity assays using human, mouse, and rat cells also indicate that this compound can exert genotoxic effects.

As of 2010, EPA has not developed a maximum contaminant level (MCL) for BDCM alone, but the total annual average trihalomethane amount for bromoform, chloroform, bromodichloromethane, and dibromochloromethane together should not exceed 80 mg/L for safe drinking water (EPA 2001).


Bromodichloromethane, CAS No. 75-27-4 Adobe PDF Logo
Report on Carcinogens, Fourteenth Edition. U.S. Department of Health and Human Services, Public Health Service, National Toxicology Program (NTP), 2016

Bromodichloromethane (CASRN 75-27-4)
U.S. EPA, Integrated Risk Information System (IRIS).

Toxicological Profile for Bromodichloromethane
Agency for Toxic Substances and Disease Registry (ATSDR), 2020

Stage 1 Disinfectants and Disinfection Byproducts Rule
U.S. EPA, Office of Water. EPA 816-F-01-014, 4 pp, 2001

For Further Information

Volatilization of Bromodichloromethane from Chlorinated Drinking Water as a Contributor to Residential Indoor Air Risk Adobe PDF Logo
Foster, S.J., J.P. Kurtz, and A.K. Woodland.
EnviroGroup Limited Web site, 2004

Ecological Toxicity

Very few studies are available for the ecological toxicity of BDCM. The Pesticide Action Network Pesticide Database gives references for some amphibian studies and one zooplankton study, but acute toxicity data for BDCM are not provided (Kegley et al. 2009).


Methane, Bromodichloro- : Identification, Toxicity, Use, Water Pollution Potential, Ecological Toxicity and Regulatory Information
Kegley, S.E., B.R. Hill, S. Orme, and A.H. Choi.
PAN Pesticide Database. Pesticide Action Network, San Francisco, CA, 2009

Other DNAPLs Toxicology Topics: