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Ethylene Oxide

Introduction

Ethylene oxide (EtO) is primarily used to produce several industrial chemicals, most notably ethylene glycol. It is also used as a sterilant and fumigant in the health care and medical fields. EtO has also been used:

• To manufacture polyester 
• To produce nonionic surfactants, ethanolamines, glycol ethers, diethylene glycol and triethylene glycol 
• As a fumigant in agricultural products 
• As a primary ingredient in antifreeze 
• In flame retardants 
• As an accelerator for maturing tobacco leaves

Ethylene oxide (C2H4O) is a colorless gas at room temperature and normal pressure. At 10.4°C or at higher pressure it is a liquid with a characteristic ether-like odor. Ethylene oxide is completely miscible with water, alcohol, acetone, benzene, ether and most organic solvents. Its vapors are highly flammable and explosive. It is relatively stable in aqueous solutions or when diluted with carbon dioxide or halocarbons, but it may undergo slow polymerization during storage. EtO is highly reactive and potentially explosive when heated or in the presence of alkali metal hydroxides and highly active catalytic surfaces. Incomplete combustion releases carbon monoxide.

Exposure Limits

The Occupational Health and Safety Administration (OSHA) has set the 8-hour time-weighted average (TWA) as one (1) part ethylene oxide per million parts of air (1 ppm). The excursion limit is five (5) parts ethylene oxide per million parts air (5 ppm) as averaged over a sampling period of fifteen (15) minutes.

Exposure Monitoring

According to Title 29 Code of Federal Regulations 1910.1047 Ethylene Oxide Standard, each employer who has a workplace or work operation covered by this standard shall perform initial monitoring to accurately determine the airborne concentrations of ethylene oxide to which employees may be exposed. If the monitoring reveals employee exposure at or above the action level (0.5 ppm calculated as an eight (8)-hour time-weighted average), the employer shall repeat such monitoring for each such employee at least every six months. If the monitoring reveals employee exposure above the 8-hour TWA (1 ppm) or above the 15-minute excursion limit (5 ppm), the employer shall repeat such monitoring for each such employee at least every three months.

The employer may discontinue TWA monitoring for those employees whose exposures are below the action level during the initial monitoring or are below the action level in at least two consecutive measurements taken at least seven days apart after the initial monitoring. However, an employer must implement monitoring whenever there is a change in the production, process, control equipment, personnel or work practices that may result in new or additional exposures to ethylene oxide or when the employer has any reason to suspect that a change may result in new or additional exposures.

Effects of Overexposure

Both human and animal studies suggest that EtO is a potential occupational carcinogen causing leukemia and other cancers. Ethylene oxide has also been linked to reproductive damage, including spontaneous abortions; cytogenetic damage; neurological effects ranging from nausea and dizziness to peripheral paralysis; and tissue irritation.

First Aid

Eyes: If ethylene oxide contacts the eyes, immediately flush the eyes with large amounts of water, occasionally lifting the upper and lower lids. Flush the eyes for at least 15 minutes.

Skin: If ethylene oxide contacts the skin, immediately flush with water for at least 15 minutes. May need to treat for possible skin burns and/or frostbite damage (cryogenic injury).

Inhalation: If ethylene oxide is inhaled, remove the exposed person to fresh air, restore and/or support his or her breathing as needed. Observe for pulmonary edema and treat accordingly.

Ingestion: Is unlikely.

Get medical help for all exposures. Seek prompt medical assistance for further treatment, observation and support after first aid. If a significant level of EtO has been inhaled, hospitalization and observation for 72 hours is recommended to determine if there is delayed pulmonary edema.

Personal Protective Equipment

Personal protective equipment must be used in conjunction with engineering and administrative controls to prevent ethylene oxide exposure.

Safety goggles should always be worn when working with ethylene oxide. If splashing of aqueous ethylene oxide solution may occur, wear a face shield as a supplementary protective measure.

Protective clothing should be worn when handling ethylene oxide. Butyl rubber, 4H/Silvershield™ and Kappler Responder® are materials that provide adequate protection from contact with Ethylene Oxide.

OSHA has outlined guidelines in 29 CFR 1910.1047(g)(3) for respiratory protection. A full facepiece respirator with an EtO approved canister, frontor back-mounted is required if the concentration is equal to or less than 50 ppm. When the concentration of EtO is equal to or less than 2000 ppm, a positivepressure supplied air respirator, equipped with a full facepiece, hood or helmet, or a continuous-flow supplied air respirator (positive pressure) equipped with hood, helmet or suit, is required. Whenever the concentration is above 2000 ppm or the concentration is unknown (such as in emergencies), a positive-pressure self-contained breathing apparatus (SCBA), equipped with a full facepiece or a positive-pressure full facepiece supplied air respirator equipped with an auxiliary positive-pressure self-contained breathing apparatus is required.

Commonly Asked Questions

Sources for More Information

Occupational Health and Safety Administration Title 29 Code of Federal Regulations 1910.1047

Agency for Toxic Substances and Disease Registry (ATSDR): Division of Toxicology
1600 Clifton Road NE, Mailstop E-29 
Atlanta, GA 30333
Phone: 888-422-8737 
Fax: (404) 498-0057

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