Ethylene Oxide:

March 1, 2001

Ethylene Oxide: The Way We Choose to Go

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, 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.


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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EmployeesFacilities8 Hour (TWA) Result < 1 ppm PEL, < 0.5 ppm AL15 Minute (EL) Result < 5 ppm
202None detected-0.12 ppmNone detected-0.64 ppm


1. Describe how EO can be used cost-effectively and with minimal risk ofhazardous chemical exposure to personnel by following current OSHA EOregulations.
2. Describe the 3 OSHA established limits that protect workers from exposure toEO.
3. Demonstrate that you always use steam sterilization as the primarysterilization process in a healthcare facility because it is fast and the mostcost effective.
4. Discuss the value of written protocols (validation tools) to ensure criticalbehaviors are consistently and successfully met by personnel performing sterileprocessing functions.

Test Questions

1. EO is efficacious because it penetrates medical devices and permeatesporous materials.
2. EL monitoring is for 15 minutes and is accomplished when employees performtasks such as transferring a load to an aerator or changing a tank of a gasmixture.
3. Safe worker practices minimize worker exposure to EO.
4. Steam sterilization is the fastest and least expensive sterilization processavailable.
5. Load items into the EO sterilizer so that they touch the chamber walls,ceiling and operators hands when the cart or basket is transferred to theaerator.
6. Stack paper/plastic peel pouches to facilitate EO and humidity penetration.
7. Place an EO biological indicator in each load.
8. Incubate a positive biological indicator control each day you incubate aprocessed biological indicator to ensure correct incubation temperature,viability of spores and capability of media to promote growth.
9. Do not inspect items prior to storage or distribution.
10. Use a record keeping system to record load contents, sterilizationparameters, and monitoring results.

Validation Tool: Evaluation of Processed Devices Prior to Release


Objective: To ensure the processed peel pouch, wrapped package, wrapped tray,or closed container is properly evaluated for package integrity, verificationthat the device was processed, required information is visible, etc. prior torelease to the customer or distribution to storage.

Critical Behaviors
Successfully Met (Yes)?

1. Prior to examination and distribution of the sterilizer load contents, thepackaging of the medical devices and /or other products must be properly cooledand dried.
2. Prior to unloading, each individual processed item will be inspected. Thecriteria for inspection will be based upon the type of package enclosure (i.e.,peel pouch, wrapped package, wrapped tray, closed container).
3. Peel Pouch:

a. Package integrity (absence of holes, tears, etc.)?
b. Chemical indicator is processed (reached end point response)?
c. Visible and correct load/lot label?
d. Establish owner of package (OR, L&D, Diagnostic Imaging, etc.)?

4. Wrapped Packages:

a. Packaging material is firm around the device?
b. Sterilization tape adheres to and holds the sterilization wrap firm?
c. Sterilization wrap integrity (absence of holes, tears, etc.)?
d. Chemical indicator is processed (reached end point response)?
e. Visible and appropriately completed continuous quality improvement form?
f. Visible and correct load/lot label?
g. Establish owner of package (OR, L&D, Diagnostic Imaging, etc.)?

5. Wrapped Tray:

a. Packaging material is firm around the tray.
b. Sterilization tape adheres to and holds the sterilization wrap firm?
c. Sterilization wrap integrity (absence of holes, tears, etc.)?
d. Chemical indicator is processed (reached end point response)?
e. Visible and correct load/lot label?
f. Establish owner of package (OR, L&D, Diagnostic Imaging, etc.)?

6. Rigid Container System

a. Locking arrows properly inserted?
b. Chemical indicator is processed on arrow (reached end point response)?
c. Visible and correct load/lot label?
d. Paper filter holding mechanism(s) (top and bottom) is visible and properly aligned?
e. Tray name tag visible?
f. If applicable, "This Tray is INCOMPLETE" adhesive label visible?

Validation Tool: Proper Loading Techniques and Monitoring of a 3M E0Sterilizer


Objective: To ensure the preparation of a sterilization load has beenperformed according to recommended practices and guidelines. To monitor theunits progress during the sterilization cycle.

Critical Behaviors
Successfully Met

1. List all items to be processed and complete all other required informationon the EO Record Sheet.
2. Add load/label to each package.
3. Basket Loading Guidelines:

a. Loosely place items in the appropriate baskets to facilitate the sterilization process.
b Items must not touch chamber walls and ceilings or the operator's hands when the cart or basket is transferred from the sterilizer to the aerator.
c. Place packages on edge unless it is a perforated, wire-mesh-bottom tray or a rigid container. Place flat.
d. Place plastic/paper peel pouches on edge in wire baskets with plastic side of one facing paper side of the other.
e. If plastic/paper peel pouches are placed flat, place plastic side up. Do not stack.

4. Place the correctly labeled 3M Attest 1278 EO Pack in the center ofeach load in the bottom basket, if two baskets are required.
5. Insert appropriate 3M Steri-Gas cartridge (4-100 for 5XL and 8-170 for8XL) into cartridge holder in the sterilizer unit. The sound of a click is yourassurance that the cartridge has been properly installed.
6. Check the water level before each load. Fill if needed.
7. Carefully slide prepared baskets into the chamber using lift or cart.
8. Close the door and turn handle in downward clockwise motion to secure doorseal.
9. Check and select sterilization temperature setting. Warm is 55°C and cool is37°C.
10. Advance graph paper through vertical slot and place a load/label on thepaper graph.
11. Complete documentation on the EO record sheet.
12. Periodically monitor the progress of the sterilization cycle to ensure theunit is operating properly. Inspect the unit for mechanical or electronicmalfunction. Check for Error or Caution Codes (example: E76), printoutcorrectness or malfunction, etc. Refer to Users Manual for Error or CautionCodes. Follow instructions; call for service if noted. Notify the SupervisorASAP of the situation.

1. T
2. T
3. T
4. T
5. F
6. F
7. T
8. T
9. F
10. T

Validation Tool: EO Biological Monitoring Process


Objective: To demonstrate that conditions necessary for sterilization wereachieved by means of the biological monitoring process.

Critical Behaviors
Successfully Met (Yes)?

1. Place the appropriate load/label on the 3M Attest 1278 EO Pack.
2. Place the Attest EO pack in each load in the center of the bottom basket, iftwo baskets are required.
3. Start the sterilizer according to the manufacturer procedures.
4. Retrieve the Attest EO pack at the completion of the sterilization andaeration phases.
5. Remove the biological indicator from the Attest EO pack. Document the date,load number and sterilizer number on the information strip on the Attest EObiological indicator.
6. Record all required information on the EO Record Sheet.
7. Prepare the Attest EO biological indicator for incubation (followmanufacturer's procedure for crushing the ampule) and place in the dedicatedAttest EO biological incubator.
8. For a single day, one biological indicator control is required unless theload/lot number is different. If different, a new biological indicator controlis required.
The purpose of the control is to ensure correct incubation temperature,viability of spores and capability of media to promote growth. The positivecontrol must be yellow at 48 hours for the processed biological indicator testresults to be valid.
9. Biological indicator incubation must be monitored closely at time intervalsof no greater than 8 hours up to the 48th hour. Any color change in theprocessed biological indicator (purple to yellow) indicates a positive result.Alert the supervisor at once.
10. Following the final reading at or as soon after the 48th hour, record thecontrol and processed biological indicator results on the corresponding EORecord Sheet. The (+) symbol indicates a positive result and the (-) symbolrepresents a negative result.
11. Quarantine implantable items until the biological indicator results areavailable.
12. Place completed documents in appropriate file.

Continuing Education Credit for NICHSPDP

CEU Applicant Name:
State/Province: Zip Code:

For NICHSPDP certification only: NICHSPDP has awarded 1.0 CEU for completionof this continuing education lesson. Managers should administer the lesson andexamination to their employees. The test results should be kept with theemployee's continuing education records. Do not submit test or grades to theNICHSPDP. Do not submit this lesson to the NICHSPDP, since it has beenpre-approved. To obtain additional information: Contact the NICHSPDP, P.O. Box558, Annandale, NJ 08801, or phone 908-730-8902.

For IAHCSMM certified members only: IAHCSMM has awarded .1 credit hours forcompletion of this continuing education lesson. Departmentalmanagers/supervisors should administer the lesson and examination to theiremployees. The test results with an authorized signature should be kept with theemployee's continuing education records. Do not submit test grades or thislesson to IAHCSMM since it has been pre-approved. To obtain additionalinformation, contact the IAHCSMM, 213 West Institute Place, Suite 307, Chicago,IL 60610 (800) 962-8274.

In addition for the Nursing credits you will need to add the standardapplication form.

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