Dense Nonaqueous Phase Liquids (DNAPLs)

Halogenated Alkenes

1,3-Dichloropropene

Human Health Toxicity

1,3-dichloropropene (1,3-DCP) is a soil fumigant that is typically injected into soil before the crops are planted to control nematode worms. Early formulations of this pesticide incorporated chemical additives, such as chloropicrin and epichlorohydrin, to stabilize and enhance the effect. These additives may have confounded the toxicological studies that employed these early formulations because it is not clear which effects were attributable to 1,3-DCP itself. The cis and trans isomers of 1,3-DCP are present in pesticide formulations in roughly equal quantities, so human exposures to the chemical are to a mixture of both isomeric forms.

Residents living in close proximity to treated fields may be exposed to 1,3-DCP through several exposure pathways. Residents who use well water as a source of drinking water and for other domestic purposes could be exposed if ground water wells in the vicinity of sprayed fields are contaminated with 1,3-DCP. 1,3-DCP volatilizes from treated fields and may present an inhalation risk to local residents. Residues of 1,3-DCP have not been found in crops grown on fumigated soil. Pesticide applicators, people involved in the manufacture and distribution of 1,3-DCP, and spill cleanup workers may be exposed to the chemical through inhalation or dermal exposure.

1,3-DCP is rapidly absorbed via the respiratory and gastrointestinal tracts, and the vapor may be absorbed through skin. The absorbed chemical is widely distributed throughout the body, but is metabolized primarily in the liver. Metabolic by-products of 1,3-DCP are excreted in urine. Animal studies suggest that 1,3-DCP is not retained in tissues.

Case reports of acute human exposure have shown inhalation of 1,3-DCP after a spill to cause irritation, cough, chest pain, and breathing difficulties in exposed workers. Accidental ingestion of the chemical by one individual has resulted in death from multiple organ failure. Death was preceded by acute gastrointestinal distress, tachycardia, sweating, hypervolemia, and finally respiratory distress.

Three human cases of cancer (one leukemia and two non-Hodgkin's lymphoma) that developed after exposure to 1,3-DCP have been reported, but the evidence does not provide a basis for inferring that the chemical was responsible. The formulation of the pesticide involved in these cases is unknown and the presence confounding factors cannot be ruled out.

A chronic (2-year) feeding study in rats found decreased body weight in the test subjects and histopathological changes in the forestomach, plus a mild basal cell hyperplasia suggestive of chronic irritation. A 13-week, sub-chronic feeding study of 1,3-DCP in mice also found decreased body weight in the test animals without a decline in food consumption. Kidney changes were observed in male mice at the highest dose used. Histopathological changes in rat nasal tissues were observed in a chronic inhalation study, but this was the only treatment-related change seen. Male mice exposed to 1,3-DCP by inhalation showed an increase in lung mass at the highest dose used. Hyperplasia of the bladder at the higher test doses also occurred, and changes in the nasal tissues of the mice were found.

A two-generation inhalation study of 1,3-DCP in rats did not find significant adverse reproductive effects. Two studies performed on rats and rabbits did not find evidence of developmental toxicity for the compound.

EPA concludes that although the human data for assessing potential human carcinogenicity are inadequate, 1,3-DCP is characterized as a "likely" human carcinogen. This characterization is based on the tumors observed in chronic animal studies of oral and inhalation exposures to 1,3-DCP. 1,3-DCP is mutagenic, and it is suggested that its mechanism of action may be genotoxic.

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Adapted from:

1,3-Dichloropropene (DCP) (CASRN 542-75-6)
Integrated Risk Information System
U.S. EPA, 2000

R.E.D. Facts 1,3-Dichloropropene
Office of Prevention, Pesticides and Toxic Substances
U.S. EPA Report: EPA-738-F-98-014, 1998

Toxicological Profile for Dichloropropenes
Agency for Toxic Substances and Disease Registry (ATSDR)
Department of Health and Human Services, Atlanta, GA, 2008

Ecological Toxicity

Median lethal concentration (LC₅₀) studies suggest 1,3-DCP to be moderately toxic to fish, such as the sheepshead minnow, largemouth bass, bluegill, rainbow trout, walleye, and most of the life stages of the fathead minnow with the exception of very small, young fish of this species. The pesticide is classified as highly toxic to young sheepshead minnow of the size 16mm long and 0.05 g weight.

Other studies of aquatic organisms indicate that 1,3-DCP is moderately toxic to Daphnia (water flea), the ramshorn snail, the early life stages of the stonefly, and Chironomid larvae. This pesticide is moderately to highly toxic to zooplankton species, such as the opossum shrimp.

1,3-DCP is not expected to bioaccumulate.

Human Health References

1,3-Dichloropropene (DCP) (CASRN 542-75-6)
Integrated Risk Information System
U.S. EPA, 2000

An EPA developed and maintained database that contains toxicological data and discussions of effects for a variety of chemicals of regulatory interest.

Environmental Health Criteria Document 146: 1,3-Dichloropropene, 1,2-dichloropropane and mixtures
International Programme on Chemical Safety (IPCS), 1993

This monograph covers chemical/physical properties, production, fate and transport, and toxicology of 1,3-DCP.

Peer Review on 1,3-Dichloropropene (Telone II) and Copper: Meeting Summary
International Toxicity Estimates for Risk (ITER), 1998

A discussion of the results of the application of EPA risk methodology by Dow Agrosciences to determine the risk of 1,3-DCP.

Public Health Goal for 1,3-Dichloropropene in Drinking Water
Office of Environmental Health Hazard Assessment
California Environmental Protection Agency (CalEPA), 1999

A discussion of the health effects of 1,3-DCP for the purpose of providing the scientific basis for setting a maximum contaminant level in drinking water for California.

R.E.D. Facts 1,3-Dichloropropene
Office of Prevention, Pesticides and Toxic Substances
U.S. EPA Report: EPA-738-F-98-014, 1998

Brief eight-page discussion of pesticide use, potential exposure, and toxicity for re-registration purposes.

Toxicological Profile for Dichloropropenes
Agency for Toxic Substances and Disease Registry (ATSDR)
Department of Health and Human Services, Atlanta, GA, 2008

This profile provides information on human health effects, fate and transport, production, and uses of 1,3-DCP.

Toxicological Review of 1,3-Dichloropropene (CAS No. 542-75-6)
U.S. EPA
Report: EPA/635/R-00/001, 2000.

An 83 page report that provides Support of 1,3-DCP Summary Information on the Integrated Risk Information System (IRIS).

Ecological References

1,3-Dichloropropene. Pan Pesticide Database
Kegley, S, B. Hill, and S. Orme
Pesticide Action Network, San Francisco, CA, 2007

A web page that describes physical/chemical properties and provides information similar to a materials data safety sheet plus multiple links to other web sites that contain information on 1,3-DCP.