1,2Dibromo3chloropropane [factsheet]

1,2-DIBROMO-3-CHLOROPROPANE

(DBCP)

Please Note: The main sources of information for this fact sheet are EPA's Integrated Risk Information System (IRIS), which contains information on inhalation chronic toxicity of DBCP and the RfC, and EPA's DBCP Health Advisory. Other secondary sources include the Hazardous Substances Data Bank (HSDB), a database of summaries of peer-reviewed literature, and the Registry of Toxic Effects of Chemical Substances (RTECS), a database of toxic effects that are not peer reviewed.

Environmental/Occupational Exposure

* Human exposure to DBCP most likely results from the inhalation of contaminated air in occupational settings and ingestion of contaminated drinking water. (1)

* In the past, release of DBCP to the environment occurred primarily from its fumigant and nematocide uses; because of the cancellation of all DBCP uses outside of Hawaii, environmental exposure is expected to decline with time. (1)

Assessing Personal Exposure

* No information was located regarding the measurement of personal exposure to DBCP.

Health Hazard Information

Acute Effects:

* Acute (short-term) exposure to DBCP produces moderate depression of the central nervous system and pulmonary congestion after exposure by inhalation and gastrointestinal distress and pulmonary edema after oral exposure in humans. (1)

* In rats acutely exposed to DBCP by inhalation, scarring of kidney tissue, pulmonary irritation, liver damage, CNS damage, and death have resulted. (2)

* Dermal exposure to DBCP may irritate the skin and eyes in humans and animals. (3,4)

* Tests involving acute exposure of animals, such as the LC₅₀ and LD₅₀ tests in rats, mice, rabbits, and guinea pigs, have demonstrated DBCP to have high acute toxicity from inhalation, oral, and dermal exposure. (5)

Chronic Effects (Noncancer):

* Chronic (long-term) exposure to DBCP by inhalation has been reported to affect the kidneys and liver in rats and mice. (4)

* The RfC for DBCP is 0.0002 mg/m³ based on testicular effects in rabbits. (4)

* EPA has medium confidence in the study on which the RfC was based due to the lack of reporting respiratory effects; medium confidence in the database because although chronic studies in two different species exist, the available reproductive studies were limited and there is uncertainty about occurrence of respiratory tract effects relative to testicular effects; and, consequently, medium confidence in the RfC.

* EPA has not established an RfD for DBCP. (4)

Reproductive/Developmental Effects:

* Chronic exposure to DBCP primarily causes male reproductive effects. Decreased sperm counts have been observed in men occupationally exposed to DBCP; birth defects, prematurity, mortality, or spontaneous abortions were not associated with paternal exposure to DBCP. (2,4)

* Testicular effects and decreased sperm count were observed in rabbits chronically exposed to DBCP by inhalation. (4)

* Birth defects were not observed in rats exposed to DBCP by gavage (experimentally placing the chemical in their stomachs). (2,4)

Cancer Risk:

* Human data are inadequate on DBCP and cancer. The available studies involve multiple chemicals and do not control for confounding factors. (1,2,4)

* High incidences of tumors in the nasal cavity of rats and mice and in the lungs of mice have been observed when exposed to DBCP by inhalation. (2)

* Carcinoma of the forestomach and mammary adenocarcinoma have been reported in rats exposed to DBCP by gavage (experimentally placing the chemical in their stomachs). (2)

* EPA has classified DBCP as a Group B2, probable human carcinogen. (2)

* EPA's Office of Air Quality Planning and Standards, for a hazard ranking under Section 112(g) of the Clean Air Act Amendments, has ranked DBCP in the nonthreshold category. The 1/ED₁₀ value is 79 per (mg/kg)/d and this would place it in the medium category under Superfund's ranking for carcinogenic hazard. (6)

Physical Properties

* The chemical formula for DBCP is C₃H₅Br₂Cl, and the molecular weight is 236.36 g/mol. (2,3,7,8)

* DBCP occurs as a colorless liquid when pure, and commercial grades as a dark-amber to dark-brown liquid that is slightly soluble in water. (2,3,7)

* DBCP has a pungent odor with an odor threshold of 0.3 mg/m³. (1,2)

* The vapor pressure for DBCP is 0.8 mm Hg at 21 EC, and its log octanol/water partition coefficient (log K_ow) is 2.43. (2,7)

Uses

* DBCP is primarily used as a soil fumigant and nematocide for pineapples in Hawaii. All other uses were cancelled by the EPA since 1979. (1,2)

* DBCP is also used as an intermediate in the synthesis of organic chemicals. (1)

Health Data from Inhalation Exposure

Concentration (mg/m³)	Health numbers^a	Regulatory, advisory numbers^b	Reference
1,000.0
_ _ _ _ 100.0	* LC₅₀ (rats) (996 mg/m³)		5
_ _ _ _ 10.0
_ _ _ _ 1.0	* LOAEL^c (rabbits) (9.4 mg/m³)		5
_ _ _ _ 0.1	* NOAEL^c (rabbits) (0.94 mg/m³)		5
_ _ _ _ 0.01
_ _ _ _ 0.001
_ _ _ _ 0.0001	* RfC (0.0002 mg/m³)		5

LC₅₀ (Lethal Concentration₅₀)CA calculated concentration of a chemical in air to which exposure for a specific length of time is expected to cause death in 50% of a defined experimental animal population.

LOAELCLowest-observed-adverse-effect level.

NOAELCNo-observed-adverse-effect level.

RfCCReference concentration.

^a Health numbers are toxicological numbers from animal testing or risk assessment values developed by EPA.

^b Regulatory numbers are values that have been incorporated in Government regulations, while advisory numbers are nonregulatory values provided by the Government or other groups as advice.

^c The LOAEL and NOAEL are from the critical study used as the basis for the EPA RfD.

References

1. U.S. Department of Health and Human Services. Hazardous Substances Data Bank (HSDB, online database). National Toxicology Information Program, National Library of Medicine, Bethesda, MD. 1993.

2. U.S. Environmental Protection Agency. DBCP Health Advisory. Office of Drinking Water, Washington, DC. 1987.

3. The Merck Index. An Encyclopedia of Chemicals, Drugs, and Biologicals. 11th ed. Ed. S. Budavari. Merck and Co. Inc., Rahway, NJ. 1989.

4. U.S. Environmental Protection Agency. Integrated Risk Information System (IRIS) on 1,2-Dibromo-3-chloropropane. Environmental Criteria and Assessment Office, Office of Health and Environmental Assessment, Office of Research and Development, Cincinnati, OH. 1993.

5. U.S. Department of Health and Human Services. Registry of Toxic Effects of Chemical Substances (RTECS, online database). National Toxicology Information Program, National Library of Medicine, Bethesda, MD. 1993.

6. U.S. Environmental Protection Agency. Technical Background Document to Support Rulemaking Pursuant to the Clean Air ActCSection 112(g). Ranking of Pollutants with Respect to Hazard to Human Health. EPAB450/3-92-010. Emissions Standards Division, Office of Air Quality Planning and Standards, Research Triangle Park, NC. 1994.

7. International Agency for Research on Cancer (IARC). IARC Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Humans: Some Halogenated Hydrocarbons. Volume 20. World Health Organization, Lyon. 1979.

8. M. Sittig. Handbook of Toxic and Hazardous Chemicals and Carcinogens. 2nd ed. Noyes Publications, Park Ridge, NJ. 1985.