Friday, September 24, 2010


This study1 was conducted to determine the consequences of a
ventilation pump failure in an Andersen AN74i sterilizer. Of
particular concern was possible operator exposure to ethylene oxide
(EO) in the vicinity of the sterilizer. Measurements taken at the
cycle’s peak concentration of EO resulted in an undetectable level
(< 1 part per million).
The temperature inside the sterilization liner bag measured at 24.3
to 25oC. The relative humidity ranged from 42.4 to 60.5 percent.
The test room itself had no air changes. Performing the test in an
unventilated room increases the risks associated with a
malfunction of this kind. Andersen Products, Inc. recommends
that the sterilizer be installed in a room with at least 10 air
changes per hour. Operation of the sterilizer in a room with no
air changes constitutes a gross misuse of the system.
AN74i Sterilizer
PAN-TY cable ties and Thomas & Betts cable tie tool
Andersen Sniffer™ with nylon gas sampling bags
Gas sampling pump and collection bag
Shimadzu gas chromatograph and analyzer
1.0ml gas-tight syringes for gas injection into GC
Standard Load:
• 10 AN10 Andersen Tubes sealed in 4.5” PolyEthylene/PolySurlyn
• 2 Patient Gowns wrapped in CSR wrap
• 1 AN42 Sump Pump wrapped in CSR wrap
• 6 Pairs of Latex Gloves sealed in Seal and Peel
• 10 Cotton-Tipped Applicators sealed in Seal and Peel
• 30 PPE Sutures inserted in aluminum pouches sealed in a self-seal
7”x13” paper plastic pouch
• 4 Hemostats sealed in Seal and Peel
• 12 Syringes (3 large, 3 medium and 6 small) sealed in a self-seal
7”x13” paper plastic pouch
• 10 Glass Vials (amber with rubber stoppers) sealed in a self-seal
7”x13” paper plastic pouch
• 1 x Humidichip placed in a Humiditube
• Cox Recorder
• AN79 (17.6ml) Anprolene Ampoule
The study was conducted to measure possible operator exposure
levels to EO should there be a vent pump failure. It has been
previously established that the highest concentration of EO

occurred inside the liner bag at 2.5 hours after activating the
ampoule. This test simulated a vent pump failure 2.5 hours
into the AN74i sterilization cycle.
For the study, one 17.6ml ampoule was activated (broken)
inside the sterilization liner bag after the initial purge of the
sterilization liner bag was completed. Samples of air were
collected using a 1.0ml gas-tight syringe at approximately 18
inches (45.4 cm) from the cabinet. Samples were taken at 2.5
hours after the activation of the ampoule and again 40
minutes later after the vent pump has been disabled.
A gas chromatograph (GC) was used to test the concentration
of ethylene oxide in the air samples.
15 minute OSHA STEL levels
Operator Breathing
Zone Air Sample
149-164 min. into cycle 5ppm <1.0ppm2
174-189 min. into cycle 5ppm <1.0ppm2
While the gas concentration increased inside the sterilizer
cabinet, no EO was detected outside the cabinet 40 minutes
after the ventilation pump was disabled. At the peak
concentration of EO inside the cabinet and sterilization liner
bag, the gas chromatograph reading was less than 1.0 ppm
(undetectable) These measurements are below OSHA short
term exposure limit allowed of 5.0 ppm.
The operator is not at risk for ethylene oxide exposure should
a vent pump fail during an AN74i cycle, even at times of
peak EO concentration. Actual measured EO levels were less
than 1 part per million, well below the OSHA short-term
exposure level (STEL) allowable limit of 5.0 ppm over a 15-
minute time period.

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