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Ethylene Oxide

Document Number: 176
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
| Q. |
What are some synonyms for ethylene oxide? |
| A. |
Ethylene oxide is also known as EtO, ETO, EO, dihydrooxirene,
dimethylene ooxide, 1,2- epoxyethane, epoxyethane, ethene oxide,
oxacyclopropane, oxane, oxidoethane, oxirane and oxyde d'ethylene. |
| Q. |
With so many names for ethylene oxide, is there a way it is
uniquely identified? |
| A. |
The Chemical Abstracts Service (CAS) has assigned the CAS Registry
Number 75-21-8. Even though CAS in the United States assigns this number,
it is used as a unique identifier worldwide. |
| Q. |
How might I be exposed to ethylene oxide? |
| A. |
You are not likely to be exposed to EtO in the general environment. You
may be exposed to EtO if you work where it is produced or used. Healthcare
workers, such as technicians, nurses and physicians in hospitals and
clinics may have contact with EtO because it is used to sterilize medical
equipment and supplies. Since EtO is used as a fumigant to spray
agricultural products, farmers or farm workers where ethylene oxide is
used may be exposed. |
| Q. |
What are the effects of overexposure? |
| A. |
Skin contact with ethylene oxide can result in blisters and burns that
may appear to be similar to frostbite. Exposure to high levels of EtO in
air has resulted in seizures and cataracts in people. Exposure to lower
levels has resulted in problems with hand/eye coordination and eye and
nose irritation. In animals, kidney damage has been seen at levels of 100
ppm, while lower levels (50 ppm) have resulted in decreased physical
activity. |
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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Please Note: The information contained in this
publication is intended for general information purposes only. This
publication is not a substitute for review of the applicable government
regulations and standards, and should not be construed as legal advice
or opinion. Readers with specific questions should refer to the cited
regulation or consult with an attorney.
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