Ethylene oxide is a highly penetrating, chemically reactive flammable gas or liquid used widely as a sterilizer of medical equipment and supplies. It is also an important industrial chemical that is used as an intermediate in the production of ethylene glycol, solvents, surfactants, and multiple other industrial chemicals. Ethylene oxide liquid has a boiling point of 10.7°C (760 mm Hg) and is readily miscible with water and organic solvents. Ethylene oxide gas poses a risk for fire/explosion at concentrations greater than 2.6% in air.

Ethylene oxide is an alkylating agent and reacts directly with proteins and DNA to cause cell death. Direct contact with the gas causes irritation of the eyes, mucous membranes, and lungs. It is mutagenic, teratogenic, and carcinogenic (regulated as a carcinogen by OSHA and categorized by IARC as a known human carcinogen). It may be absorbed through intact skin.

The workplace permissible exposure limit (PEL) in air is 1 ppm (1.8 mg/m³) as an 8-hour time-weighted average (TWA). The air level immediately dangerous to life or health (IDLH) is 800 ppm. Occupational exposure above OSHA-determined trigger levels (0.5 ppm as an 8-hour TWA) requires medical surveillance (29 CFR 1910.1047). The odor threshold is approximately 500 ppm, giving the gas poor warning properties. High levels of ethylene oxide can occur when sterilizers malfunction or during opening or replacing ethylene oxide tanks. Exposure may also occur when fumigated or sterilized materials are inadequately aerated. A minute amount of ethylene oxide is produced endogenously in humans from the metabolism of ethylene. Levels are also increased by cigarette smoking.

1. Ethylene oxide is a potent mucous membrane irritant and can cause eye and oropharyngeal irritation, bronchospasm, and pulmonary edema. Cataract formation has been described after significant eye exposure. Exposure to ethylene oxide in solution can cause vesicant injury to the skin. Ethylene oxide can cause CNS depression, seizures, or coma.
2. Neurotoxicity, including convulsions and delayed peripheral neuropathy, may occur after exposure. Other suspected long-term neurologic sequelae include headaches and memory loss.
3. Cardiac arrhythmias can occur when ethylene oxide is used in combination with freon as a carrier gas.
4. Leukemia has been described in chronically exposed workers.
5. Hypersensitivity, similar to latex hypersensitivity, may occur with chronic dermal exposure to small amounts of ethylene oxide.

Is based on a history of exposure and typical upper airway irritant effects. Detection of ethylene oxide odor indicates significant exposure. Industrial hygiene sampling is necessary to document air levels.

1. Specific levels.
   1. Blood levels are transient and not commercially available. However, ethylene oxide forms irreversible hemoglobin adducts, and these adducts can be used as an estimate of the last 4 months of cumulative exposure. Most adduct testing has been performed by the ATSDR and the CDC, but large-scale commercial research testing is available through RTI International (www.rti.org). Individual testing may be available through local health departments in collaboration with the CDC.
   2. IgE testing for ethylene oxide hypersensitivity is commercially available from multiple laboratories.
2. Other useful laboratory studies include CBC, glucose, electrolytes, blood gases or pulse oximetry, chest radiography, and ECG.

1. Emergency and supportive measures. Monitor closely for several hours after exposure.
   1. Maintain an open airway and assist ventilation if necessary. Treat bronchospasm, anaphylaxis, and pulmonary edema if they occur.
   2. Treat coma, convulsions (p 23), and arrhythmias if they occur.
2. Specific drugs and antidotes. There is no specific antidote. Treatment is supportive.
3. Decontamination
   1. Remove the victim from the contaminated environment immediately and administer oxygen. Rescuers should wear self-contained breathing apparatus and chemical-protective clothing.
   2. Remove all contaminated clothing and wash exposed skin. For eye exposures, irrigate copiously with tepid water or saline.
4. Enhanced elimination. There is no role for these procedures.