Disinfection is serious business, especially now during the COVID-19 global pandemic, when the need to disinfect and sterilize everything from offices to ventilators is so important. This article is about ethylene oxide, a frequently used but potentially hazardous sterilizing agent.
Abbreviated as EtO (or less commonly EO), ethylene oxide is used for sterilization in many medical, dental, veterinary, and animal surgical facilities. This is because it is efficient and performs at low temperatures compared to steam sterilization. In addition, EtO is very compatible with the polymer-based single use medical devices, procedure kits, and surgical trays, as well as most surgical instruments.
However, ethylene oxide is very toxic and highly flammable. Ethylene oxide sterilizer use requires precise installation, rigorous maintenance, and employee protections.
Ethylene oxide is a gas at room temperature with a boiling point of 10.7°C (51°F) and flammable limits in air from three to 100 percent, a very wide range. The vapor density is one and a half times that of air, therefore the vapors will tend to sink to the floor (or lowest available levels) and accumulate, spreading to the nearest ignition source.
EtO is also a serious health hazard. It is colorless with a characteristic sweet, ether-like odor. However, be warned—if you can smell it, you are breathing a toxic concentration hundreds of times greater than the exposure limit, given the OSHA occupational permissible exposure limit is only 1 ppm for a regular eight-hour work shift and the reported odor threshold is between 500 and 700 ppm. Therefore, odor is a very poor warning property for EtO.
Exposures occur by inhalation or skin absorption and can have severe results. Inhalation exposure symptoms include eye pain, sore throat, blurred vision, difficulty breathing, dizziness, and convulsions. Acute effects may lead to central nervous system depression, pulmonary edema, respiratory distress, and coma.
Liquid EtO can produce irritation or blistering of the skin or frostbite, from rapid evaporation and resultant cooling. EtO exposure may also produce allergic sensitization, with future exposure causing hives or life-threatening allergic reactions.
Ethylene oxide is designated as a suspected human carcinogen that may cause leukemia and other cancers. EtO is also linked to spontaneous abortion, genetic damage, nerve damage, muscle weakness, and peripheral paralysis.
Evaluating the hazards
Occupational use of ethylene oxide is regulated by the OSHA standard, 29CFR1910.1047. Employers must perform initial monitoring in each area where EtO is used to accurately determine the airborne concentrations to which employees might be exposed. For employees exposed at or above the PEL, monitoring is required every three months.
Wednesday, Nov 25, 2020
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