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)

Chemistry and Behavior

Halogenated Alkanes

Methanes

Bromodichloromethane

BromodichloromethaneBromodichloromethane (BDCM, CAS 75-27-4) has a vapor pressure of 50 mm Hg at 20oC (ATSDR 1989) and is a nonflammable liquid (Air Liquide 2001). The log Koc of BDCM is about 1.8, the log Kow is 2.1, and the Henry's constant is 2.41 e-3 atm-m3/mole. The solubility of the chemical is about 4,500 mg/L, and its specific gravity is about 1.98 at 20oC (ATSDR 1989). The toxicological profile for BDCM developed by the Agency for Toxic Substances and Disease Registry contains a useful summary table Adobe PDF Logo of the compound's physical properties.

The relatively low calculated Koc value for BDCM in soil indicates that it is likely to move quickly through soil and sediment (ATSDR 1989, Howard 1990).

Volatilization is the most important removal process for BDCM released to surface waters (ATSDR 1989). Howard (1990) reports that the half life of the chemical in rivers and streams has been estimated to be between 33 minutes and 12 days, with a typical half life of 35 hours. Modeling information in the record for BCDM in the Hazardous Substances Data Bank (HSDB) indicates that its half life in a model lake is estimated as 5 days.

Because of the low Kow of BDCM, bioaccumulation is not expected to occur to any significant extent (ATSDR 1989, Howard 1990, HSDB). The compound is readily degraded by microbial action under anaerobic conditions (Howard 1990) and can also be degraded by cometabolism under denitrification conditions (Wahman et al. 2005). Fram et al. (2003) state that methanes with three or more halogen atoms seem to be more difficult to metabolize in aerobic environments than methanes with one or two halogen atoms. Aerobic metabolism of trihalomethanes has not been observed definitively, and bromoform (CHBr3) has been found to be resistant to biodegradation in several aerobic aquatic environments.

When released to the atmosphere, hydroxyl radicals are expected to degrade BDCM with a half life of two to three months (ATSDR 1989). Direct photolysis below the ozone layer is not expected to occur (ATSDR 1989, Howard 1990).

References

Bromodichloromethane, CASRN: 75-27-4
Hazardous Substances Data Bank (HSDB)
TOXNET, National Library of Medicine Web site.

Cometabolism of Trihalomethanes by Nitrosomonas europaea
Wahman, D., L. Katz, and G. Speitel, Jr.
Applied and Environmental Microbiology 71(12):7980-7986(2005)

Handbook of Environmental Fate and Exposure Data for Organic Chemicals, Volume 2: Solvents
Howard, P. (ed).
CRC Press, 546 pp, 1990

Material Safety Data Sheet: Bromodichloromethane
Fisher Scientific, 2007

Processes Affecting the Trihalomethane Concentrations Associated with the Third Injection, Storage, and Recovery Test at Lancaster, Antelope Valley, California, March 1998 through April 1999
Fram, M., B. Bergamaschi, K. Goodwin, R. Fujii, and J. Clark.
U.S. Geological Survey Water-Resources Investigations Report 03-4062, 83 pp, 2003

Toxicological Profile for Bromodichloromethane
Agency for Toxic Substances and Disease Registry (ATSDR), 89 pp, 1989

For Further Information

DNAPL Site EvaluationAdobe PDF Logo
Cohen, R. and J. Mercer.
EPA 600-R-93-022, 369 pp, 1993

This document has a broad discussion of DNAPL site evaluation and contains a comprehensive table of physical properties of selected DNAPL chemicals, including BDCM, in its Appendix A.