Ethylene Oxide:

Ethylene Oxide:
The Way We Choose to Go

By R. Michael Festa

Ethylene Oxide (EO) sterilization is used in our facilities because it isefficacious, safe to use, and the most cost-effective low temperaturesterilization process. Selection and use of present sterilization methods werebased upon efficacy of the process, safety and cost effectiveness. The use ofwritten protocols ensures that sterile processing functions are consistentlyperformed according to best practices, current regulatory requirements, andmanufacturer's written instructions.

Efficacy: EO is particularly efficacious because it not onlypenetrates medical devices, but it permeates porous materials.¹ Inaddition, it is an alkalyating agent that does not change the surface ofmaterial. Our facility has chosen EO as our only low temperature sterilizationprocedure because of its 50-year history of reliability and recognizedeffectiveness as a sterilant. Neal Danielson states in Ethylene Oxide Use inHospitals that EO sterilizers provide a degree of assurance of sterility ofmany orders of magnitude.²

Safety: EO can be used in a safe and effective manner. OSHA hasthree established limits that protect workers from exposure to EO. In 1984, twoexposure levels were established. The first was the permissible exposure limitor PEL. An employee cannot be exposed to more than 1 part per million (ppm) ofethylene oxide over an 8-hour time weighted average. The second level is anaction level or Al. If an employee is exposed to less than 0.5 ppm over an8-hour time weighted average, then some provisions of the standard do not haveto be followed as frequently, such as employee monitoring. In 1988, anadditional requirement called the excursion limit, or EL, was established. Thatvalue is 5 ppm over a 15-minute sampling period.

To determine the PEL and AL levels in our facility, ethylene oxide dosimeterbadges are placed on employees for 8 hours. Excursion limit or EO monitoring, onthe other hand, is task related. For the EL testing in our facility, badges areplaced on employees for 15 minutes while they are performing the task ofunloading and transferring the contents of a processed, unaerated load to theaerator. Testing is performed at the time of each new employee's orientation.Any additional testing would be performed upon request of an employee or ifthere were a change in production, process, etc., where such a change wouldrequire additional testing per current OSHA regulations. Also, additionaltesting is required when an employee is exposed to more than 0.5 ppm of EO overan 8-hour time weighted average.

EL testing is also required when other tasks are performed such as removingthe biological indicator from the load, unloading the aerator, and handling ofthe materials during this time. If the sterilizer is an EO mixture type using anexternal cylinder tank, additional monitoring of employees will need to beperformed during maintenance activities such as tank or tank line changes. Thisis required since higher exposures occur during these times.² If youare considering using an EO sterilization system, read the OSHA regulations (CFR29, Part 1910.1047), available on the Internet at www.osha.gov., to becomecomfortable and knowledgeable of personnel and environmental requirements.Understanding the requirements will help in making an informed decision aboutthis well-publicized sterilization method.

Current and past staff testing at our facilities:

The exposure values, obtained from our facility testing, are way below thePEL, AL and EL limits so our facilities are exempt from the additional OSHApersonal monitoring requirements. These low values are a result of using theupdated 3M Steri-Vac 5XL and 8XL EO Sterilizers that have local exhaustand continuous purge features. The Sterilizers are located in the mainprocessing area of the department, not a separate room, where there is 10-airexchanges/hour and dedicated venting of the sterilizer and aerators. Inaddition, the staff is trained to follow recommended safe work practices. Aninexpensive duct sail switch is connected to a bell and light system as theventilation failure detector for the sterilizers and aerators. A dedicated ventline exhausts EO to the outside during the sterilization process. Use of the 3MSteri-Vac 5XL and 8XL sterilization systems negates the need for an expensivecontinuous area monitoring system.

Cost Effectiveness

We have remained committed to using the 100% 3M Steri-Vac EO sterilizersystems as our only low temperature sterilization system because in a costanalysis it was determined to be the most cost effective low temperaturesterilization process per load when compared to the other low temperaturesterilization methods. In part, the review included a comparison of labor,supply, preventative and service costs. Other financial and non-financialfactors included its influence on operations, available surgical and medicalinstrumentation/equipment resources and their reuse time requirements. Thepresent strategy is to use steam sterilization to the greatest extent possible.With the introduction of steam sterilizable endoscopic system components,primarily scopes and cameras, and the expected introduction of other samecategory medical devices in the near future, the need for the more expensive andcomplex low temperature sterilization methods will be diminished. We willcontinue to use 100% EO for our low temperature sterilization processes becauseit is efficacious, safe, and cost effective.

Validation Tools

The use of written protocols (in the form of a validation tool) ensures thatcritical knowledge and competencies are successfully met. For each function, theemployee is expected to verbalize an understanding and perform a returndemonstration of the written protocol up to three times, before being validatedto perform the function independently.

Sterile processing department validation tools are used fordecontamination/cleaning, preparation/packaging, inspection and assembly ofsurgical and medical instrumentation/devices, high level disinfection andsterilization, to mention a few. The validation tools for proper loadingtechnique and monitoring of a 3M EO sterilizer, EO biological monitoring processand evaluation of processed devices prior to release are listed here. Validationtools are also used to instruct and validate knowledge of how to respondappropriately in the event of an EO-dedicated venting system failure or an EOspill, leaks or fire.

Summary

In conclusion, EO can be used safely and cost-effectively, with minimal riskof hazardous chemical exposure to personnel by following recommended practicesand meeting current OSHA EO regulations. The use of steam sterilization as theprimary sterilization process is your best choice because it is efficient, themost cost effective and is now capable of processing a wider range of medicaldevices. As sterile processing professionals we must consistently performrecommended best practices, current regulatory requirements and followmanufacturer's written instructions. The use of written protocols (validationtools) facilitates instruction and training to ensure critical behaviors areconsistently and successfully met by personnel performing critical andnon-critical sterile processing functions.

R. Michael Festa is the Director of Sterile Process of the HealthEast St.Joseph's Hospital in St. Paul, Minn. He has more than 18 years of experience inthe sterile processing management field and is known for his innovative and costeffective approaches to improving the quality of the sterile processingservices.

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