1,1Dimethylhydrazine [factsheet]

1,1-DIMETHYLHYDRAZINE

Please Note: The main sources of information for this fact sheet are EPA's Health and Environmental Effects Profile for 1,1-Dimethylhydrazine and the International Agency for Research on Cancer (IARC) monographs of the carcinogenic risk to man of 1,1-dimethylhydrazine. 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literature, and the Registry of Toxic Effects of Chemical Substances (RTECS), a database of toxic effects that are not peer reviewed.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

* Individuals may be exposed to 1,1-dimethylhydrazine in the workplace. (1)

* Individuals may be exposed to 1,1-dimethylhydrazine in the ambient atmosphere from its use as rocket fuel and from spills, leaks, and venting during loading, transfer, and storage. (1)

* In the atmosphere, 1,1-dimethylhydrazine reacts with ozone and hydroxyl radicals to produce 1,1-dimethylnitrosamine, a potent carcinogen. (1)

Assessing Personal Exposure

* No information was located concerning the measurement of personal exposure to 1,1-dimethylhydrazine.

Health Hazard Information

Acute Effects:

* Acute (short-term) inhalation exposure of humans to 1,1-dimethylhydrazine has been observed to result in nose and throat irritation, mild conjunctivitis, nausea, and vomiting. (2,3)

* 1,1-Dimethylhydrazine is highly corrosive and irritating to the skin, eyes, and mucous membranes, and neurological symptoms were observed in a man burned by 1,1-dimethylhydrazine. (2,4)

* Central nervous system stimulation and convulsions have been reported in animals acutely exposed to 1,1-dimethylhydrazine by ingestion. (3)

* Acute animal exposure tests, such as the LC₅₀ and LD₅₀ tests in rats, mice, hamsters, rabbits, and guinea pigs, have demonstrated 1,1-dimethylhydrazine to have high acute toxicity from inhalation, oral, and dermal exposures. (5)

Chronic Effects (Noncancer):

* Liver damage in humans may occur from chronic (long-term) exposure to 1,1-dimethylhydrazine. (1)

* Hemolytic anemia and central nervous system effects, such as convulsive seizures, have been observed in animals chronically exposed to 1,1-dimethylhydrazine by inhalation. (1-3)

* Mild kidney damage has been observed in a chronic animal study. (1)

* The RfC is under review by EPA. (6)

* EPA has not established an RfD for 1,1-dimethylhydrazine. (6)

Reproductive/Developmental Effects:

* No information is available on the reproductive or developmental effects of 1,1-dimethylhydrazine in humans or animals.

Cancer Risk:

* Information on the carcinogenic effects of 1,1-dimethylhydrazine to humans is not available.

* Carcinogenic effects were observed in mice and rats exposed to 1,1-dimethylhydrazine by inhalation, but the carcinogenicity could not be definitively attributed to 1,1-dimethylhydrazine because of the presence of contaminants in the study. However, in another study, rats exposed to 1,1-dimethylhydrazine by inhalation developed skin, lung, pancreas, pituitary, and liver tumors. (1,7)

* By oral exposure, 1,1-dimethylhydrazine is carcinogenic in mice and hamsters. Lung tumors, as well as kidney and liver tumors, have been observed in mice orally exposed to 1,1-dimethylhydrazine. A high incidence of angiosarcomas located in various organs was also observed in the mice. (1)

* EPA considers 1,1-dimethylhydrazine to be a probable human carcinogen (cancer-causing agent) and has classified it as a Group B2 carcinogen. (8)

* EPA's Office of Air Quality Planning and Standards, for a hazard ranking under Section 112(g) of the Clean Air Act Amendments, has not assigned 1,1-dimethylhydrazine a ranking for carcinogenic hazard. The 1/ED₁₀ value for 1,1-dimethylhydrazine is 83 per (mg/kg)/d. (8)

Physical Properties

* The chemical formula for 1,1-dimethylhydrazine is C₂H₈N₂, and its molecular weight is 60.1 g/mol. (1,4,7)

* 1,1-Dimethylhydrazine is a colorless, flammable, hygroscopic liquid that gradually turns yellow upon contact with air and is miscible with water. (1,4,7)

* 1,1-Dimethylhydrazine has an ammonia-like fishy smell, with an odor threshold of 1.7 ppm. (1,7,9)

* The vapor pressure for 1,1-dimethylhydrazine is 157 mm Hg at 25 EC. (1)

Uses

* 1,1-Dimethylhydrazine is primarily used as a high-energy fuel in military applications, as a rocket propellant and fuel for thrusters, and small electrical power generating units. (1)

* 1,1-Dimethylhydrazine is also used in the manufacture of a plant growth regulator, in chemical synthesis, in photographic chemicals, as a stabilizer for fuel additives, and as an absorbent for acid gases. (1)

Health Data from Inhalation Exposure

Concentration (mg/m³)	Health numbers^a	Regulatory, advisory numbers^b	Reference
1000.0
_ _ _ _ 100.0	* LC₅₀ (hamsters) (964 mg/m³) * LC₅₀ (rats) (620 mg/m³) * LC₅₀ (mice) (423 mg/m³)		5 5 5
_ _ _ _ 10.0
_ _ _ _ 1.0		* OSHA PEL and MSHA standard (1 mg/m³)	5
_ _ _ _ 0.1		* NIOSH REL (0.15 mg/m³/2 h)	5
_ _ _ _ 0.01		* ACGIH TLV (0.025 mg/m³)	5

ACGIH TLVCAmerican Conference of Governmental and Industrial Hygienists' threshold limit value expressed as a time-weighted average; the concentration of a substance to which most workers can be exposed without adverse effects.

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.

MSHACMine Safety and Health Administration.

NIOSH RELCNational Institute of Occupational Safety and Health's recommended exposure limit; NIOSH-recommended exposure limit for an 8- or 10-h time-weighted-average exposure and/or ceiling.

OSHA PELCOccupational Safety and Health Administration's permissible exposure limit expressed as a time-weighted average; the concentration of a substance to which most workers can be exposed without adverse effect averaged over a normal 8-h workday or a 40-h workweek.

^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.

References

1. U.S. Environmental Protection Agency. Health and Environmental Effects Profile for 1,1-Dimethylhydrazine. EPA/600/x-84/134. Environmental Criteria and Assessment Office, Office of Health and Environmental Assessment, Office of Research and Development, Cincinnati, OH. 1984.

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

3. G.D. Clayton and F.E. Clayton, Eds. Patty's Industrial Hygiene and Toxicology. Volume IIA. 3rd revised ed. John Wiley & Sons, New York. 1981.

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

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. Integrated Risk Information System (IRIS) on 1,1-Dimethylhydrazine. Environmental Criteria and Assessment Office, Office of Health and Environmental Assessment, Office of Research and Development, Cincinnati, OH. 1993.

7. International Agency for Research on Cancer (IARC). IARC Monographs on the Evaluation of the Carcinogenic Risk of Chemicals to Man: Some Aromatic Amines, Hydrazine and Related Substances, N-Nitroso Compounds and Miscellaneous Alkylating Agents. Volume 4. World Health Organization, Lyon. 1974.

8. 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.

9. J.E. Amoore and E. Hautala. Odor as an aid to chemical safety: Odor thresholds compared with threshold limit values and volatilities for 214 industrial chemicals in air and water dilution. Journal of Applied Toxicology, 3(6):272-290. 1983.