WHAT IS ETHYLENE OXIDE ?
Ethylene oxide is a colorless
gas with a sweet odor. Ethylene Oxide exists as a colourless
liquid below 10 degrees Celcius. It is an
extremely flammable gas. The gas is slightly heavier than air and may
spread long distances. Distant ignition and flashback are possible. The
liquid can accumulate static charge by splashing or agitation. Ethylene
oxide can decompose explosively. Cylinders and closed containers may
rupture violently if heated. It is a compressed gas. It is also
dangerously reactive. Ethylene oxide may polymerize or decompose
violently when exposed to high temperatures or contaminants (e.g. acids
Ethylene Oxide is also known as Dihydrooxirene,
Dimethylene oxide, EO, EtO,
Ethene oxide, Oxacyclopropane,
Oxane, Oxidoethane , Oxirane, Oxyde d'éthylène.
WHERE IS ETHYLENE OXIDE USED?
Ethylene Oxide (EtO) is produced in large
volumes and is primarily used as a chemical intermediate in the
manufacture of several industrial chemicals including textiles, detergents,
polyurethane foam, antifreeze, solvents, medicinal products, adhesives,
and other related products. The most notable product involving the use of
sizable quantities of Ethylene Oxide Ethylene Glycol. It is also used as
a fumigant in certain agricultural products and as a sterilizing agent
for food (spices), cosmetics, medical equipment as well as for the
sterilization of surgical tool and plastic devices in hospitals that
cannot be sterilized by steam..
Over the past 50 years, there have been many incidents in both EtO production plants and EtO
consuming plants resulting in major plant damage, as well as fatalities.
There have also been a significant number of EtO
WHAT ARE THE HEALTH HAZARDS OF ETHYLENE OXIDE
Ethylene Oxide possesses several physical and health hazards that
merit special attention. EtO is both flammable
and highly reactive. Acute exposures to EtO gas
may result in respiratory irritation and lung injury, headache, nausea,
vomiting, diarrhea, shortness of breath, and cyanosis. Chronic exposure
has been associated with the occurrence of cancer, reproductive effects,
mutagenic changes, neurotoxicity, and
Ethylene Oxide is very toxic and may be fatal if inhaled. It is
irritating to the respiratory tract and is a central nervous system
depressant. This means that high concentrations may cause headache,
nausea, dizziness, drowsiness, and in co-ordination. Solutions cause skin
irritation and probably cause eye irritation. Ethylene oxide is a cancer hazard
- It can cause cancer, based on human information. It is also a possible
reproductive hazard (It may harm reproductive capability, based on animal
information) and a mutagen (It may cause inheritable genetic
COMPOSITION AND PURITY OF ETHYLENE OXIDE:
Ethylene Oxide (EtO) is a high purity chemical
(99.7% or higher). Impurities may include acetaldehyde, acetic acid,
acetylene, and inorganic and organic chlorides. It is also available as an non-flammable mixture with nitrogen or carbon
dioxide. Historically, mixtures with dichlorodifluoromethane
(Fluorocarbon 12) were available, but environmental concerns have led to
the use of other flame retardant diluent gases.
EtO is shipped as a liquid under its own vapour pressure of 50 kPa
at 21.1 deg C in compressed gas cylinders, special containers, such as
insulated steel drums, portable tanks or insulated single-unit tank cars.
WHAT ARE THE FIRE AND EXPLOSION DANGERS
ASSOCIATED WITH ETHYLENE OXIDE?
Ethylene Oxide is an extremely flammable gas (above 10 degrees C) or
liquid (below 10 degrees C) that will readily ignite at room temperature.
Liquid can accumulate static charge by splashing or agitation. Gas can be
ignited by a static charge. Solutions containing greater than 4 wt%
ethylene oxide (EO) are flammable. The gas is
slightly heavier than air and can travel a considerable distance to a
source of ignition and flash back to a leak or open container.
Explosive decomposition may occur. The gas forms explosive mixtures with
air over an extremely wide range. Although the gas itself has a high
minimum ignition energy (approximately 1000 millijoules),
air mixtures have an extremely low minimum
ignition energy (0.06 millijoules) and easily
ignite. Once ignited, pure liquid EtO will burn
explosively at or below the surface and a propagating flame may be
The heat of a fire may cause spontaneous polymerization, which can cause
containers to rupture violently. EtO can burn
in sealed containers if ignited. Under fire conditions, an EtO pipeline may undergo internal decomposition.
Explosions will occur if gas or vapours are
ignited in a confined area.
HOW CAN I WORK WITH ETHYLENE OXIDE SAFELY?
EtO is a very toxic (cancer hazard, mutagen),
compressed, extremely flammable gas. EtO is
also dangerously reactive. Before handling, it is extremely important
that engineering controls are operating and that
protective equipment requirements and personal hygiene measures
are being followed. Control access to designated handling area. Post
appropriate warning signs. Only authorized personnel should have access
to EtO. They should be properly trained
regarding its hazards and its safe use. Maintenance and emergency
personnel should be advised of potential hazards.
Prevent release of gas into workplace air. Closed handling systems for
processes involving EtO should be used. To
reduce the fire/explosion hazard, consider the use of an inert gas in the
container or storage vessel. If a closed handling system is not possible,
use in smallest possible amounts in appropriate labelled,
containment devices (e.g. fume hood). Containment devices should be made
of smooth, unbreakable, compatible material. Maintain containment devices
at appropriate air flow and negative pressure. Check regularly.
Eliminate all ignition sources (e.g. sparks, open flames, hot surfaces).
Keep away from heat. Post "NO SMOKING" signs. It is very
important to keep areas where EtO is used clear
of other materials which can burn (e.g. cardboard, sawdust).
Immediately report leaks or ventilation failures. Unprotected persons
should avoid all contact with EtO and
contaminated equipment. If EtO is released,
immediately put on a suitable respirator and leave the area until the
severity of the release is determined. In case of leaks or spills, escape-type
respiratory protective equipment should be available in the work area. EtO is extremely reactive. Prevent exposure to
elevated temperatures and absolutely no contact with even trace amounts
of incompatible materials. Do not use with incompatible materials such as
oxidizing agents, acids, bases and alcohols.
Use non-sparking ventilation systems, approved explosion-proof equipment
and intrinsically safe electrical systems in areas of use. Consider the
installation of leak and fire detection equipment along with a suitable,
automatic fire suppression system. Keep aisles and exits free of
obstruction. Do not use near welding operations, flames or hot surfaces.
Do not perform any welding, cutting, soldering, drilling or other hot
work on an empty vessel, container or piping until it has been thoroughly
decontaminated. To prevent sparking, generously wet hard surfaces before
they are chipped, ground, etc, in potentially hazardous areas. Do not
heat compressed gas cylinders. Inspect cylinders for leaks before
handling. During transfer operations, cylinders and vessels should be
electrically grounded and bonded to prevent the build-up of a static
charge. Leave cylinder cap on cylinder until cylinder is secured and
ready for use. Always secure cylinders to a wall, rack or other solid
structure in an upright position. Do not handle cylinders with oily
hands. Regularly check cylinders for evidence of corrosion or leakage.
Make sure cylinders are labelled clearly. Use
the appropriate pressure regulator. Ensure equipment is compatible with
cylinder pressure and contents. Follow supplier recommendations.
Before connecting the cylinder for use, make sure that back feed from the
system into the cylinder is prevented. Suck-back into cylinder may cause
explosion. Prevent cylinder entry tube from being inserted in a liquid or
gas without a vacuum-break or other protective device.
Avoid damaging cylinders. Do not open cylinder if damaged. Never use
excessive force when opening. Open cylinder valve slowly to prevent rapid
decompression and damage to valve seat. Keep cylinder valves clean and
free from contaminants. Make sure valves on gas cylinders are fully
opened when gas is used. Open and shut valves at least once a day, while
cylinder is in use, to avoid valve 'freezing'. Shut flow off at cylinder
valve and not just at the regulator after use. Replace outlet caps or
plugs and cylinder caps as soon as cylinder is disconnected from
Keep empty cylinders under slightly positive pressure. Do not use
cylinders as rollers or for any other purpose than to contain the gas as
supplied. Move cylinders by hand truck or cart designed for that purpose.
Do not drop cylinders or permit them to bang against each other. Do not
lift cylinders by the cap or with a lifting magnet.
Follow handling precautions on Material Safety Data Sheet. Have suitable
emergency equipment for fires and leaks readily available. Practice good
housekeeping. Maintain handling equipment. Comply with applicable
WHAT CAN BE DONE TO CONTROL HAZARDOUS CONDITIONS?
Engineering control methods to reduce hazardous exposures are preferred.
Methods include mechanical ventilation (local exhaust), process or
personnel enclosure, control of the process conditions and process
modification (e.g. substitution of a less hazardous material).
Administrative controls and personal protective equipment may also be
Because of the high potential hazard associated with EtO,
stringent control measures such as enclosure (closed handling systems) are
recommended. A combined sterilization/aeration facility should be used
wherever possible. To reduce the fire hazard, consider the use of an
inert gas in the handling system. Use non-sparking, grounded ventilation
system separate from other exhaust ventilation systems. Exhaust directly
to the outside. Supply sufficient replacement air to make up for air
removed by exhaust systems. Use approved explosion-proof equipment and
intrinsically safe electrical systems in areas of use. Consider the
installation of leak and fire detection equipment along with a suitable,
automatic fire suppression system.