ETHYLENE OXIDE

Ethylene oxide
(1,2 Epoxyethane; oxacyclopropane; dimethylene oxide)
CAS 75-21-8

C₂ H₄O

Colorless liquid or gas
bp 10.7 °C, mp -111.3 °C
Miscible with water

Sweet odor detectable at 257 to 690 ppm (mean = 420 ppm)

1.5 at bp (air = 1.0)

1095 mmHg at 20 °C

-20 °C

429 °C

LD₅₀ oral (rat) 72 mg/kg

LC₅₀ inhal (rat) 800 ppm (1600 mg/m³)

PEL (OSHA) 1 ppm (2 mg/m³)

TLV-TWA (ACGIH) 1 ppm (2 mg/m³)

OSHA "select carcinogen"; highly flammable; severe irritant.

Ethylene oxide is a severe irritant to the eyes, skin, and respiratory tract and exhibits moderate acute toxicity by all routes of exposure. Symptoms of overexposure by inhalation may be delayed and can include nausea, vomiting, headache, drowsiness, and difficulty breathing. Ethylene oxide can cause serious burns to the skin, which may only appear after a delay of 1 to 5 hours. This substance may also be absorbed through the skin to cause the systemic effects listed above. Eye contact can result in severe burns. Ethylene oxide is not considered to have adequate warning properties.

Ethylene oxide is listed by IARC in Group 2A ("probable human carcinogen") and is classified as a "select carcinogen" under the criteria of the OSHA Laboratory Standard. There is some evidence from animal studies that ethylene oxide may be a developmental and reproductive toxin in both males and females. Exposure to this substance may lead to sensitization.

Ethylene oxide is an extremely flammable substance (NFPA rating = 4). Ethylene oxide vapor may be ignited by hot surfaces such as hot plates and static electricity discharges, and since the vapor is heavier than air, it may travel a considerable distance to an ignition source and flash back. Ethylene oxide vapor forms explosive mixtures with air at concentrations of 3 to 100% (by volume). Carbon dioxide or dry chemical extinguishers should be used for ethylene oxide fires. Ethylene oxide may explode when heated in a closed vessel.

Ethylene oxide can undergo violent polymerization, which can be initiated by contact with metal surfaces, strong acids or bases, alkali metals, iron oxide or chloride, and aluminum chloride.

Because of its carcinogenicity, flammability, and reactivity, ethylene oxide should be handled using the "basic prudent practices" of Chapter 5.C, supplemented by the additional precautions for work with compounds of high chronic toxicity (Chapter 5.D) and extremely flammable substances (Chapter 5.F). In particular, work with ethylene oxide should be conducted in a fume hood to prevent exposure by inhalation, and appropriate impermeable gloves and splash goggles should be worn at all times to prevent skin and eye contact. Ethylene oxide should be used only in areas free of ignition sources and should be stored in the cold in tightly sealed containers placed within a secondary container.

In the event of skin contact, immediately wash with soap and water and remove contaminated clothing. In case of eye contact, promptly wash with copious amounts of water for 15 min (lifting upper and lower lids occasionally) and obtain medical attention. If ethylene oxide is ingested, obtain medical attention immediately. If large amounts of this compound are inhaled, move the person to fresh air and seek medical attention at once.

In the event of a spill of liquid ethylene oxide, remove all ignition sources, soak up the ethylene oxide with a spill pillow or absorbent material, place in an appropriate container, and dispose of properly. In the event of accidental release of ethylene oxide gas, evacuate the area and eliminate the source of the release, such as a leaking cylinder, if possible. Respiratory protection may be necessary in the event of a large spill or release in a confined area.

Excess ethylene oxide and waste material containing this substance should be placed in an appropriate container, clearly labeled, and handled according to your institution's waste disposal guidelines.

The information in this LCSS has been compiled by a committee of the National Research Council from literature sources and Material Safety Data Sheets and is believed to be accurate as of July 1994. This summary is intended for use by trained laboratory personnel in conjunction with the NRC report Prudent Practices in the Laboratory: Handling and Disposal of Chemicals. This LCSS presents a concise summary of safety information that should be adequate for most laboratory uses of the title substance, but in some cases it may be advisable to consult more comprehensive references. This information should not be used as a guide to the nonlaboratory use of this chemical.

Copyright 1995 National Academy of Sciences. All rights reserved.