Hydrazine

Hydrazine was first synthesized in 1887 and found its industrial destiny as a rocket propellant [1]. It powered the Titan II missiles, the Apollo lunar module descent engine, and remains in use today for attitude control thrusters on satellites and spacecraft, and in fuel cells. It is also used in agricultural fungicides and as a chemical intermediate in pharmaceuticals and polymer production [2]. The drinking water connection is indirect but significant: chloramine, used as a secondary disinfectant by many utilities because it generates fewer regulated trihalomethanes than chlorine, can degrade to form hydrazine as a byproduct — particularly when the water temperature is high or contact time is long. This pathway puts hydrazine in drinking water at low concentrations in many communities [3].

Occupational inhalation is the primary high-dose route — hydrazine vapor is generated during aerospace propellant handling, pharmaceutical synthesis, and agricultural chemical manufacturing [1]. At aerospace facilities, liquid hydrazine is loaded into spacecraft propulsion systems, creating potential spill and vapor exposure. Industrial workers using hydrazine as a corrosion inhibitor in boiler water treatment are another occupational group [2]. Water exposure is the primary community pathway: chloramine-disinfected municipal water systems may have trace hydrazine from disinfectant degradation. The EPA monitoring data suggests this pathway is widespread at low but not zero concentrations. Cigarette smoke contains hydrazine [3].

Hydrazine is a probable human carcinogen (IARC Group 2A), with clear animal evidence for lung, liver, and nasal tumors and supporting occupational evidence for lung cancer in aerospace workers [1]. The primary toxic mechanism involves metabolic activation to reactive species that alkylate DNA and proteins, generating lipid peroxidation and oxidative stress in liver cells. The liver is the primary target organ for chronic toxicity [2]. Acute high-level hydrazine exposure is a medical emergency: it causes seizures (by depleting pyridoxine/vitamin B6, which is required for GABA synthesis), liver failure, and pulmonary edema. The treatment for acute hydrazine poisoning is high-dose vitamin B6 [3].

Aerospace industry workers who handle liquid hydrazine propellants face the highest occupational risks [1]. Pharmaceutical and agricultural chemical plant workers who use hydrazine as a synthesis intermediate have significant exposures. Boiler water treatment workers and industrial maintenance workers who handle hydrazine-based corrosion inhibitors are also occupationally exposed [2]. General population exposure through chloramine-disinfected drinking water is low but widespread — the EPA monitors this pathway.

If your water utility uses chloramine disinfection (ask or check your annual water quality report), you may have trace hydrazine exposure [1]. A granular activated carbon (GAC) or reverse-osmosis filter will reduce hydrazine in drinking water. For occupational use: enclosed systems for hydrazine transfer and handling, NIOSH-approved supplied-air respirators, and impermeable gloves and coveralls are essential — hydrazine is readily absorbed through skin as well as by inhalation [2]. Skin contact should be avoided and decontaminated immediately. Occupational monitoring should include annual liver function tests and lung function testing for workers with chronic low-level exposures [3].