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Subchapter 7. General Industry Safety Orders
Group 16. Control of Hazardous Substances
Article 110. Regulated Carcinogens
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§5220. Ethylene Oxide, Appendix A

Substance Safety Data Sheet for Ethylene Oxide


(A) Substance: Ethylene oxide.

(B) Synonyms: dihydrooxirene, dimethylene oxide, EO, 1, 2-epoxyethane, EtO, ETO, oxacyclopropane, oxane, oxidoethane, alpha/beta-oxidoethane, oxiran, oxirane.

(C) Ethylene oxide can be found as a liquid or vapor.

(D) EtO is used in the manufacture of ethylene glycol, surfactants, ethanolamines, glycol ethers, and other organic chemicals. EtO is also used as a sterilant and fumigant.

(E) Appearance and color: Colorless liquid below 10.7° C (51.3° F) or colorless gas with an ether-like odor detectable at approximately 700 parts EtO per million parts of air (700 ppm).

(F) Permissible exposure limit: Exposure may not exceed 1 part EtO per million parts of air averaged over the 8-hour work day.

(G) Short term exposure limit: Exposure may not exceed 5 parts EtO per million parts of air averaged over a sampling period of 15 minutes.


(A) Routes of exposure. Ethylene oxide can cause bodily harm if you inhale the vapor, if it comes into contact with your eyes or skin, or if you swallow it.

(B) Effects of overexposure.

(1) Ethylene oxide in liquid form can cause eye irritation and injury to the cornea, frostbite, and severe irritation and blistering of the skin upon prolonged or confined contact. Ingestion of EtO can cause gastric irritation and liver injury. Acute effects from inhalation of EtO vapors include respiratory irritation and lung injury, headache, nausea, vomiting, diarrhea, shortness of breath, and cyanosis (blue or purple coloring of skin). Exposure has also been associated with the occurrence of cancer, reproductive effects, mutagenic changes, neurotoxicity, and sensitization.

(2) EtO has been shown to cause cancer in laboratory animals and has been associated with higher incidences of cancer in humans. Adverse reproductive effects and chromosome damage may also occur from EtO exposure.

(C) Reporting signs and symptoms: You should inform your employer if you develop any signs or symptoms that you suspect are caused by exposure to EtO.


(A) Eye exposure: If EtO gets into your eyes, wash your eyes immediately with large amounts of water, lifting the lower and upper eyelids. Get medical attention immediately. Contact lenses should not be worn when working with this chemical.

Section 3400(d) of the General Industry Safety Orders requires that where the eyes or body of any person may be exposed to injurious corrosive materials (such as liquid EtO or EtO-containing solutions), suitable facilities for quick drenching or flushing of the eyes and body shall be provided within the work area for immediate emergency use.

(B) Skin exposure: If EtO gets on your skin, immediately wash the contaminated skin with water. If EtO wets your clothing, including your shoes, remove the clothing immediately and wash the skin with water using an emergency deluge shower. Get medical attention immediately. Thoroughly wash contaminated clothing before reusing. Contaminated leather shoes or other leather articles should not be reused and should be discarded.

(C) Inhalation: If large amounts of EtO are inhaled, the exposed person must be moved to fresh air at once. If breathing has stopped, perform cardiopulmonary resuscitation. Keep the affected person warm and at rest. Get medical attention immediately.

(D) Swallowing: When EtO has been swallowed, give the person large quantities of water immediately. After the water has been swallowed, try to get the person to vomit by having him or her touch the back of the throat with his or her finger. Do not make an unconscious person vomit. Get medical attention immediately.

(E) Rescue: Move the affected person from the hazardous exposure. If the exposed person has been overcome, attempt rescue only after notifying at least one other person of the emergency and putting into effect established emergency procedures. Do not become a casualty yourself. Understand your emergency rescue procedures and know the location of the emergency equipment before the need arises.


(A) Respirators: You may be required to wear a respirator in emergencies, during nonroutine activities, while your employer is installing engineering controls for the reduction of EtO exposures, or when engineering controls are not feasible. As of the effective date of the EtO regulation, only air supplied positive-pressure, full-facepiece respirators are approved for protection against EtO. If air-purifying respirators are worn in the future, they must have a label issued by the National Institute for Occupational Safety and Health (NIOSH)under the provisions of 42 CFR part 84 stating that the respirators have been approved for use with ethylene oxide. For effective protection, respirators must fit your face and head snugly. Respirators should not be loosened or removed in work situations where their use is required.

EtO does not have a detectable odor except at levels well above the permissible exposure limit. If you can smell EtO while wearing a respirator, proceed immediately to fresh air. If you experience difficulty breathing while wearing a respirator, tell your employer.

(B) Protective clothing: You may be required to wear impermeable clothing, gloves, a face shield, or other appropriate protective clothing to prevent skin contact with liquid EtO or EtO-containing solutions. Where protective clothing is required, your employer must provide clean garments to you as necessary to assure that the clothing protects you adequately.

Replace or repair protective clothing that has become torn or otherwise damaged.

EtO must never be allowed to remain on the skin. Clothing and shoes which are not impermeable to EtO should not be allowed to become contaminated with EtO, and if they do, the clothing should be promptly removed and decontaminated. Once EtO penetrates shoes or other leather articles, they should not be worn again.

(C) Eye protection: You must wear splashproof safety goggles in areas where liquid EtO or EtO-containing solutions may contact your eyes. In addition, contact lenses should not be worn in areas where eye contact with EtO can occur.


(A) EtO is a flammable liquid, and its vapors can easily form explosive mixtures in air.

(B) EtO must be stored in tightly closed containers in a cool, well-ventilated area, away from heat, sparks, flames, strong oxidizers, alkalies and strong bases, acids, and acetylide-forming metals such as copper, silver, mercury and their alloys.

(C) Sources of ignition such as smoking materials, open flames and some electrical devices are prohibited wherever EtO is handled, used, or stored in a manner that could create a potential fire or explosion hazard.

(D) You should use non-sparking tools when opening or closing metal containers of EtO, and containers must be bonded and grounded in the rare instances in which liquid EtO is poured or transferred.

(E) Impermeable clothing wet with liquid EtO or EtO-containing solutions may be easily ignited and should be washed down with water before removal. If you are wearing clothing which is not impermeable to EtO and are splashed with liquid EtO or EtO-containing solution, you should immediately remove the clothing while under an emergency deluge shower.

(F) If your skin comes into contact with liquid EtO or EtO-containing solutions, you should immediately use an emergency deluge shower to remove the EtO.

(G) You should not keep food, beverages, or smoking materials in regulated areas where employee exposures are above the permissible exposure limit.

(H) Fire extinguishers and emergency deluge showers for quick drenching should be readily available, and you should know where they are and how to operate them.

(I) Ask your supervisor where EtO is used in your work area and for any additional plant safety and health rules.


(A) Each year, your employer is required to inform you of the information contained in this standard and appendices for EtO. In addition, your employer must instruct you in the proper work practices for using EtO, in emergency procedures, and in the correct use of protective equipment.

(B) Your employer is required to determine whether you are being exposed to EtO. You or your representative has the right to observe employee measurements and to record the results obtained. Your employer is required to inform you of your exposure. If your employer determines that you are being overexposed, he or she is required to inform you of the actions which are being taken to reduce your exposure to within permissible exposure limits.

(C) Your employer is required to keep records of your exposures and medical examinations. The exposure records must be kept by the employer for at least thirty (30) years. Medical records must be kept for the period of your employment plus thirty (30) years.

(D) Your employer is required to release your exposure records to you and your designated representative and to release your medical records to your physician or designated representative upon your written request in accordance with the provisions of Section 3204, Access to Employee Exposure and Medical Records.


This section of Appendix A, for informational purposes, sets forth EPA's recommendations for modifications in workplace design and practice in hospitals and health care facilities for which the Environmental Protection Agency has registered EtO for uses as a sterilant or fumigant under the Federal Insecticide, Fungicide, and Rodenticide Act, 7 U.S.C. 136 et seq. Published in the Federal Register as mandatory provisions by the EPA at 49 FR 15268 on April 18, 1984 and relegated to advisory status at 49 FR 25675 on June 22, 1984 (concurrent with OSHA's publication of the Federal standard for occupational exposure to EtO), these recommended workplace design and workplace practices are intended to help reduce the exposure of hospital and health care workers to EtO to 1 ppm. For the purposes of this appendix, EPA language which could be misinterpreted to impose mandatory provisions for workplace design and work practices has been amended, primarily by the replacement of "must" by "should," in the recommendations which follow:


(a) Installation of gas line hand valves. Hand valves should be installed on the gas supply line at the connection to the supply cylinders to minimize leakage during cylinder change.

(b) Installation of capture boxes. Sterilizer operations result in a gas/water discharge at the completion of the process. This discharge is routinely piped to a floor drain which is generally located in an equipment or an adjacent room. When the floor drain is not in the same room as the sterilizer and workers are not normally present, all that is necessary is that the room be well ventilated.

A "capture box" should be installed in those workplace layouts where the floor drain is located in the same room as the sterilizer or in a room where workers are normally present. A "capture box" is a piece of equipment that totally encloses the floor drain into which the discharge from the sterilizer is pumped. The "capture box" should be vented directly to a non-recirculating or dedicated ventilation system. Sufficient air intake should be allowed at the bottom of the box to handle the volume of air that is ventilated from the top of the box. The "capture box" can be made of metal, plastic, wood or other equivalent material. The box is intended to reduce levels of EtO discharged into the work room atmosphere. The use of a "capture box" is not needed if: (1) the vacuum pump discharge floor drain is located in a well ventilated equipment or other room where workers are not normally present; or (2) the water sealed vacuum pump discharges directly to a closed sealed sewer line (check local plumbing codes).

If it is impractical to install a vented "capture box" and a well ventilated equipment or other room is not feasible, a box that can be sealed over the floor drain may be used if: (1) The floor drain is located in a room where workers are not normally present and EtO cannot leak into an occupied area; and (2) the sterilizer in use is less than 12 cubic feet in capacity (check local plumbing codes).

(c) Ventilation of aeration units.

[i] Existing aeration units. Existing units should be vented to a non-recirculating or dedicated ventilation system or vented to an equipment or other room where workers are not normally present and which is well ventilated. Aerator units should be positioned as close as possible to the sterilizer to minimize the exposure from the off-gassing of sterilized items.

[ii] Installation of new aerator units (where none exist). New aerator units should be vented as described above for existing aerators.

(d) Ventilation during cylinder change. Workers may be exposed to short but relatively high levels of EtO during the change of gas cylinders. To reduce exposure from this route, users should select one of three alternatives designed to draw off gas that may be released when the line from the sterilizer to the cylinder is disconnected:

[i] Location of cylinders in a well ventilated equipment room or other room where workers are not normally present.

[ii] Installation of a flexible hose (at least 4" in diameter) to a non-recirculating or dedicated ventilation system and located in the area of cylinder change in such a way that the hose can be positioned at the point where the sterilizer gas line is disconnected from the cylinder.

[iii] Installation of a hood that is part of a non-recirculating or dedicated ventilation system and is positioned no more than one foot above or behind the point where the change of cylinders takes place.

(e) Ventilation of sterilizer door area. One of the major sources of exposure to EtO occurs when the sterilizer door is opened following the completion of the sterilization process. In order to reduce this avenue of exposure, a hood or metal canopy closed on each end should be installed over the sterilizer door. The hood or metal canopy should be connected to a non-recirculating or dedicated ventilation system or one that exhausts gases to a well ventilated equipment or other room where workers are not normally present. A hood or canopy over the sterilizer door should be installed for use even with those sterilizers that have a purge cycle.

(f) Ventilation of sterilizer relief valve. Sterilizers are typically equipped with a safety relief device to release gas in case of increased pressure in the sterilizer. Generally, such relief devices are used on pressure vessels. Although these pressure relief devices are rarely opened for hospital and health care sterilizers, it is suggested that they be designed to exhaust vapor from the sterilizer by one of the following methods:

[i] Through a pipe connected to the outlet of the relief valve ventilated directly outdoors at a point high enough to be away from passers-by, and not near any windows that open, nor near any air conditioning or ventilation air intakes.

[ii] Through a connection to an existing or new non-recirculating or dedicated ventilation system.

[iii] Through a connection to a well ventilated equipment or other room where workers are not normally present.

(g) Ventilation systems: Each hospital and health care facility that uses EtO for the sterilization of equipment and supplies should have a ventilation system which enables compliance with the recommendations of section (b) through (f) in the manner described in these sections. Thus, each affected hospital and health care facility should have or install a non-recirculating or dedicated ventilation system or have available a well ventilated equipment or other room where workers are not normally present in which to vent EtO.

(h) Installation of alarm systems. An audible and visual indicator alarm system should be installed to alert personnel of ventilation system failures, i.e., when the ventilation fan motor is not working.


All the workplace practices discussed in this unit should be permanently posted near the door of each sterilizer prior to use by any operator.

(a) Changing of supply line filters. Filters in the sterilizer liquid line should be changed when necessary by the following procedure:

[i] Close the cylinder valve and the hose valve.

[ii] Disconnect the cylinder hose (piping) from the cylinder.

[iii] Open the hose valve and bleed slowly into a proper ventilating system at or near the in-use supply cylinders.

[iv] Vacate the area until the line is empty.

[v] Change the filter.

[vi] Reconnect the lines and reverse the valve position.

[vii] Check hoses, filters, and valves for leaks with a fluorocarbon leak detector (for those sterilizers using the 88 percent chlorofluorocarbon and 12 percent ethylene oxide mixture).

(b) Restricted access area.

[i] Areas involving use of EtO should be designated as restricted access areas. They should be identified with signs or floor marks near the sterilizer door, aerator, vacuum pump floor drain discharge, and in-use cylinder storage.

[ii] All personnel should be excluded from the restricted area when certain operations are in progress, such as discharging a vacuum pump, emptying a sterilizer liquid line, or venting a non-purge sterilizer with the door ajar or other operations where EtO might be released directly into the face of workers.

(c) Door opening procedures.

[i] Sterilizers with purge cycles. A load treated in a sterilizer equipped with a purge cycle should be removed immediately upon completion of the cycle (provided no time is lost opening the door after cycle is completed). If this is not done, the purge cycle should be repeated before opening door.

[ii] Sterilizers without purge cycles. For a load treated in a sterilizer not equipped with a purge cycle, the sterilizer door should be ajar 6" for 15 minutes, and then fully opened for at least another 15 minutes before removing the treated load. The length of time of the second period should be established by peak monitoring for one hour after the two 15-minute periods suggested. If the level is above 10 ppm time-weighted average for 8 hours, more time should be added to the second waiting period (door wide open). However, in no case should the second period be shortened to less than 15 minutes.

(d) Chamber unloading procedures.

[i] Procedures for unloading the chamber should include the use of baskets or rolling carts, or baskets and rolling tables to transfer treated loads quickly, thus avoiding excessive contact with treated articles and reducing the duration of exposures.

[ii] If rolling carts are used, they should be pulled not pushed by the sterilizer operators to avoid off-gassing exposure.

(e) Maintenance. A written log should be instituted and maintained documenting the date of each leak detection and any maintenance procedures undertaken.

[i] Leak detection. Sterilizer door gaskets, cylinder and vacuum piping, hoses, filters, and valves should be checked for leaks under full pressure with a fluorocarbon leak detector (for 12/88 systems only) every two weeks by maintenance personnel. Also, the cylinder piping connections must be checked after changing cylinders. Particular attention in leak detection should be given to the automatic solenoid valves that control the flow of EtO to the sterilizer. Specifically, a check should be made at the EtO gasoline entrance port to the sterilizer, while the sterilizer door is open and the solenoid valves are in a closed position.

[ii] Maintenance procedures. Sterilizer/aerator door gaskets, valves, and fittings should be replaced when necessary as determined by maintenance personnel in their bi-weekly checks; in addition, visual inspection of the door gaskets for cracks, debris, and other foreign substances should be conducted daily by the operator.

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