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)

Environmental Occurrence

Halogenated Alkanes


The majority of chloroform used in the United States was in the production of the refrigerant chlorodifluoromethane (R-22). As part of the Montreal Protocol, this use will be phased out. Chloroform was and in some cases still is widely used by chemical companies in the production of other chemicals. The compound also has been used as an industrial solvent in the extraction and purification of antibiotics, alkaloids, and vitamins, as well as an extraction solvent for oils, greases, fats, gums and adhesives, rubber, and waxes. In the past, chloroform was used in fire extinguishers to lower the freezing temperature of carbon tetrachloride, and as a general inhaled anesthetic for surgery; however, it is not used for those purposes today. (ATSDR 1997 and HSDB).

Chloroform enters the environment from multiple routes, including chemical companies, paper mills, and sewage treatment plants. The chemical can enter the air directly from factories that make or use it, and by evaporating from soil or water that contain it. Chloroform can enter soil and water from wastewater containing chloroform and from spills and leaks from storage and waste sites. Chlorine typically is added to drinking water, wastewater, and spa and swimming pool water to destroy bacteria, and chloroform can form as a result.

EPA's Toxics Release Inventory, which does not cover all industrial sources, reports the release of 707,006 pounds of chloroform to the environment in 2007; almost 600,000 pounds were air emissions, and about 8,800 pounds were releases to surface water. In 1997, the total amount of chloroform released was 7,470,742 pounds. The decrease in release volume between 1997 and 2007 probably reflects the implementation of the Montreal Protocol ban on R22, which reduced the demand for chloroform.

In a U.S. Geological Survey nationwide assessment of public and private water wells, Zogorski et al. (2006) found that chloroform was the chemical most frequently detected in domestic and public water supply wells-albeit at very low levels (less than the MCL). He also found that chloroform is the chemical most frequently detected in samples taken from aquifers.

Chloroform is produced naturally by the tropical red algae, Asparagopsis armata, and by the red seaweed, A. taxiformis (HSDB).


Chloroform, CASRN: 67-66-3
PubChem, National Center for Biotechnology Information.

The Quality of Our Nation's Waters: Volatile Organic Compounds in the Nation's Ground Water and Drinking-Water Supply WellsAdobe PDF Logo
Zogorski, J., J.M. Carter, T. Ivahnenko, W.W. Lapham, M.J. Moran, B.L. Rowe, P.J. Squillace, and P.L. Toccalino.
U.S. Geological Survey Circular 1292, 112 pp, 2006

For Further Information

Adobe PDF LogoChloroform, 67-66-3
Technology Transfer Network, Air Toxics Web Site Hazard Summary.
U.S. EPA, Office of Air and Radiation, 2000

Chloroform in the Hydrologic System: Sources, Transport, Fate, Occurrence, and Effects on Human Health and Aquatic Organisms
Ivahnenko, T. and J.E. Barbash.
U.S. Geological Survey Scientific Investigations Report 2004-5137, 46 pp, 2004

Concise International Chemical Assessment Document 58: Chloroform
Watts, P., G. Long, and M.E. Meek.
World Health Organization, Geneva, 2004

Disinfectants and Disinfectant By-Products
International Programme on Chemical Safety (IPCS), Environmental Health Criteria 216, World Health Organization, Geneva, 2000

Occurrence of Trihalomethanes in the Nation's Ground Water and Drinking-Water Supply Wells, 1985-2002
Schaap, B.D., and J.S. Zogorski.
U.S. Geological Survey Scientific Investigations Report 2006-5068, 65 pp, 2006

Toxicological Profile for Chloroform
Agency for Toxic Substances and Disease Registry (ATSDR), 343 pp, 1997