Hydrazines (1,2-Dimethylhydrazine, 1,1-Dimethylhydrazine, Hydrazine) are extremely toxic nitrogen compounds that are colorless and have an ammonia or fish-like odor. Hydrazine is used in many industries including petroleum refining, photographic processing, semiconductor manufacturing, soldering, and weapons manufacturing. Hydrazines are also a component of rocket fuel and, in addition, can be found in certain medications including hydralazine, isoniazid, and phenelzine. It is sometimes found at hazardous waste sites. Hydrazine exposure may occur via aerosol inhalation, or via liquid ingestion or dermal absorption. The consequences of exposure are severe and may include death.

Aerosol exposure and inhalation include irritation of the eyes, nose, throat, and skin; dyspnea; dizziness; and nausea. Direct contact with the liquid form can produce chemical burns of the skin, eyes, and mucous membranes.

After inhalation or absorption of large quantities of hydrazine, there may be lethargy, confusion, tremors, seizures, coma, and death. Delayed findings may include hepatitis, nephritis, pulmonary edema, liver necrosis, and GI hemorrhage. Seizures and renal failure may also occur after prolonged exposure.

The Immediately Danger to Health or Life (IDHL) air concentration of hydrazine is 50 ppm. The National Institute of Occupational Safety and Health (NIOSH) considers hydrazine a potential carcinogen.