Determination of Worker Exposure to Instantaneously Emitted Ethylene Oxide in Sterilization Facilities

Abstract

In typical hospital settings, sterilizer operators can be exposed to extremely high concentrations of ethylene oxide (EtO) for very short time periods, although calculated values of time-weighted average exposure are usually below occupational exposure limits. This is a result of an extended average time and because of the absence of an appropriate sampling method to determine EtO concentrations for extremely short periods. The purpose of the study was to determine actual peak values of EtO emission and the time delay of peak values in routine sterilizer operations. A province wide survey included 26 exposure episodes at 18 hospitals where EtO sterilizers were routinely used. A remote-controlled sequential sampler with air bags was used to sample ambient air for 3 to 5 seconds. An infrared spectrophotometer was used to determine the EtO concentrations. Peak EtO concentrations occurred 20 seconds after the doors of portable and tabletop sterilizers were opened; however, there was a considerable delay of peak occurrence to 78 seconds in a built-in sterilizer. An aerodynamic model of EtO emission was proposed and verified for a built-in sterilizer operated in a confined room. A peak value of EtO emission reached 24 ppm or 58 percent of the provincial short-term (15 minutes) exposure limit of 50 ppm immediately after the sterilizer door was cracked open.