Using Caution Around Ethylene Oxide

Abstract

I would like to comment on Becky Crossley's “Troubleshoot It” column (November/December 2011 issue of BI&T) concerning ethylene oxide (ETO). The article raised a number of excellent points, but there were some that I felt needed amplification, since ETO is and will be a part of our sterile processing world for years to come, and, if it is not managed properly, can be a real hazard. Note that my company, H&W Technology, LLC, formerly manufactured FDA-cleared ETO control systems, and still do for industry. We sit on the relevant AAMI standards committees for this type of sterilization, so I am speaking from an informed position.There are good reasons to be cautious when working around ethylene oxide, and engineering controls must be maintained for its safe use. The one, overriding regulation is promulgated by the Occupational Safety and Health Administration (OSHA) in 29 CFR 1910.1047. It says that the action level for ethylene oxide is a time-weighted average of 0.5 PPM, that no employee shall be exposed to more than 1 PPM in an eight-hour time-weighted average, and that the maximum 15-minute exposure is 5 PPM average. That's the law. If your facility is not measuring to make certain that these limits are observed, it should be.Safety features built into all ETO sterilizers built in the past 20–25 years make them quite safe in normal usage and if maintained properly. These features include door locks/interlocks, which Ms. Crossley mentions, integrated ventilation systems, and controllers that will not allow an uncontrolled release of ETO into the environment if the sterilizer is working at all. Most ETO sterilizers these days operate under a vacuum at all times, so opening the door becomes impossible. Even on rather old machines (those from the 1980s), the door switch will lock out the valve that delivers the ETO to the sterilizer chamber, making it nearly impossible for ETO to be released when the door is open. (Anything can, and will happen, but this is good safety engineering at work.)AAMI ST41 and AAMI ST79 are quite explicit on the needs for room ventilation (number of air changes per hour and negative pressure relative to the surrounding area) to remove ETO from the work areas, and are, as U.S. National Standards, a requirement for healthcare facilities. Also, scrubbers and thermal burners destroy the ethylene oxide, which is the only toxin in the exhaust stream from these sterilizers. These devices convert the ETO into carbon dioxide and water. The scrubbers/thermal burners should be the only path for the exhaust of the sterilizer to release to the environment if the system is properly designed and maintained.In the current state of the art, and with proper equipment maintenance, ETO may be used safely. If anything goes wrong in a cycle, only persons with specific training on the machines and ETO safety should be allowed to deal with the problem and remove the goods, which must be aerated or reprocessed.I think that the article raised excellent points and hope that my contribution to it will add to the demystification of this process. Remember, all sterilization processes are hazardous. If they weren't, they wouldn't sterilize. The point is to know enough about the process to keep it where it needs to be—inside the sterilizer chamber—and away from the staff and patients.