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1 This article was downloaded by: [Janssen Pharmaceutica], [Daniel Caldwell] On: 11 November 2014, At: 07:00 Publisher: Taylor & Francis Informa Ltd Registered in England and Wales Registered Number: Registered office: Mortimer House, Mortimer Street, London W1T 3JH, UK Applied Industrial Hygiene Publication details, including instructions for authors and subscription information: Evaluation of an Add-on Local Exhaust Ventilation System for an Ethylene Oxide (ETO) Sterilizer Daniel J. Caldwell a a U.S. Army Published online: 25 Feb To cite this article: Daniel J. Caldwell (1989) Evaluation of an Add-on Local Exhaust Ventilation System for an Ethylene Oxide (ETO) Sterilizer, Applied Industrial Hygiene, 4:4, 88-91, DOI: / To link to this article: PLEASE SCROLL DOWN FOR ARTICLE Taylor & Francis makes every effort to ensure the accuracy of all the information (the Content ) contained in the publications on our platform. However, Taylor & Francis, our agents, and our licensors make no representations or warranties whatsoever as to the accuracy, completeness, or suitability for any purpose of the Content. Any opinions and views expressed in this publication are the opinions and views of the authors, and are not the views of or endorsed by Taylor & Francis. The accuracy of the Content should not be relied upon and should be independently verified with primary sources of information. Taylor and Francis shall not be liable for any losses, actions, claims, proceedings, demands, costs, expenses, damages, and other liabilities whatsoever or howsoever caused arising directly or indirectly in connection with, in relation to or arising out of the use of the Content. This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. Terms & Conditions of access and use can be found at

2 Evaluation of an Add-on Local Exhaust Ventilation System for an Ethylene Oxide (ETO) Sterilizer Downloaded by [Janssen Pharmaceutica], [Daniel Caldwell] at 07:00 11 November 2014 Daniel J. Caldwell U.S. Army An add-on local exhaust ventilation (LEV) system was evaluated as an engineering control measure during a follow-up study of high ethylene oxide (ETO) exposures at a U.S. Army medical center. Baseline breathing zone and general area samples were collected to characterize ETO exposure, and existing general ventilation was evaluated. ETO-contaminated air was recirculated back to the sterilizer area by the air-conditioning system. This recirculation, coupled with a positive differential air pressure in the sterilizer area, caused the ETO to migrate to other areas. General area sample results ranged from 0.95 to 2.80 pprn as a time-weighted average, with peak real-time exposures greater than 50 ppm. Breathing zone sample results exceeded the Occupational Safety and Health Administration action level for nine of ten individuals sampled (7 of 10 if the lower confidence limit (LCL] is applied to the sample results), with five individuals exposed to ETO concentrations greater than the PEL(3 greater than the PEL if the LCL is applied). An off-the-shelf LEV system was installed; then samples were again collected and compared to those obtained previously. Only one breathing zone sample showed a detectable level of ETO. The LEV system was able to overcome the positive differential air pressure in the Central Material Supply and the recirculating air-conditioning system to control ETO emissions effectively. Caldwell, D. J.: Evaluation of an Add-on Local Exhaust Ventilation System for an Ethylene Oxide (DO) Sterilizer. Appl. Ind. Hyg. 4:88-91; Introduction In June 1984, the Occupational Safety and Health Administration (OSHA) issued the Final Standard concerning occupational exposure to ETO,(l) which reduced the permissible exposure limit (PEL) from 50 pprn to 1 ppm as an 8-hour time-weighted average (TWA) concentration and set an action level of 0.5 ppm for airborne concentrations of ETO. The standard was amended in June 1988 to include a short-term excursion limit of 5 pprn averaged over a 15-minute sampling period. Because of the carcinogenic potential of ETO, the National Institute for Occupational Safety and Health (NIOSH) recommended that ETO exposures not exceed 50 ppm-minutes, e.g., 5 pprn for a maximum of 10 minutes per day.(*) The OSHA standard cites requirements for, among other things, methods to control exposure, personal protective equipment, medical surveillance, signs and labels, emergency procedures, and recordkeeping. In instances where it is demonstrated that employee exposures are above the action level, employers are obligated to comply with requirements set forth in the standard. In response to the OSHA standard, the U.S. Army Health Services Command implemented a basline ETO sampling program which collected data on breathing zone exposures of personnel exposed to ETO at 34 Army hospitals in the United States.(j) A follow-up study of ETO exposures that exceeded the PEL was conducted at an Army Medical Center in order to determine the cause and prescribe corrective actions. Breathing zone and general area samples were collected to characterize ETO exposures, and existing general ventilation for the Central Material Supply (CMS) was evaluated. The building was heated by a hot water radiator system; the only mechanical general ventilation consisted of an auxiliary air-conditioning system that had been installed in Air from the CMS was returned to the air-conditioning unit and recirculated back to the CMS. This recirculation, coupled with positive differential air pressure in the linen room and sterilizer area, caused the ETO to migrate from the sterilizer area to other areas of the CMS. Engineering Controls The most effective method for reducing ETO exposures to below the action level is the provision of engineering controls. General dilution ventilation has been the traditional engineering control method recommended for reducing ETO exposures in the hospital;(*) however, it does not effectively control the transient high concentration emissions incident to typical sterilizer operations. Envirogard is a registered trademark of the American Sterilizer Company, Erie, PA MIRAN is a registered trademark of Foxboro Analytical, Inc., Foxboro, MA ORB0 is a registered trademark of Supelco, Inc., Bellefonte, PA 3M is a registered trademark of the Minnesota Mining and Manufacturing Company, lnc., St. Paul, MN. Reference to specific brands, equipment, or the above mentioned trade names in this article does not imply endorsement by the author or the US. Army but is intended only to assist in identification of a specific product. 88 APPL. IND. HYG. VOL. 4, NO. 4. APRIL 1989

3 Downloaded by [Janssen Pharmaceutica], [Daniel Caldwell] at 07:00 11 November 2014 The need for local exhaust ventilation (LEV) as a supplemental control measure for ETO sterilizers has been well documented.(5,6) Recommended control measures specify LEV for controlling emissions from the sterilizer door, the floor drain, the pressure relief valve, ETO cylinder connections, and from the aerat~r.(~.~) An aerator is a heated, ventilated cabinet in which sterilized items are placed after removal from the sterilizer and allowed to off-gas for a specified period of time, usually 16 hours, to reduce the residual level of ETO. Current Army guidelines stipulate that air from a room in the CMS which contains an ETO sterilizer should not be recirculated and that local exhaust ventilation be provided to capture ETO emissions at their ~ource.(~>~) Neither of these criteria were met at the medical center. Air from the CMS was returned to the air handling unit and recirculated back to the CMS. This, coupled with a positive differential air pressure in the sterilizer area, caused the ETO to migrate to other areas of the CMS. Since ground for a new medical center had been broken, installation of an off-the-shelf LEV system was thought to be a cost effective control method for reducing personnel exposure to ETO. The EnvirogardB System The Envirogard@ system, a LEV engineering control measure designed to reduce ambient ETO levels, is offered by the American Sterilizer Company as a retrofit option for existing sterilizers and as standard equipment on new sterilizers. The system consists of an auxiliary local exhaust ventilation system and a poststerilization control modification. The LEV system consists of a blower, manifold assembly, liquid'gas separator, door vent adapter, flexible ductwork, and exhaust vent adaptor (Figure 1). The control modification is designed to reduce the ETO level in the chamber at the end of the programmed sterilization cycle. Two poststerilization vacuum cycles, which exhaust the sterilizer chamber, and a repeating 20-minute dynamic air flush through the chamber minimize the amount of ETO remaining in the sterilizer and prevent ETO buildup from load desorption due to delayed door opening. This system, standard on new AMSCO sterilizers, has been shown to control ETO exposures to below the OSHA action Ie~eL(7,~) EXHAUST 'r HOOD 1 ETHYLENE \MANIFOLD Study Methodology This study consisted of two parts: Phase 1, which was performed prior to installation of the Envirogard system, and Phase 2, which measured ETO concentrations after the Envirogard was installed. The ETO concentrations measured during Phase 1 were used as baseline exposure levels to evaluate the effectiveness of the Envirogard system as a control measure by comparing general area and breathing zone ETO concentrations measured during Phase 2. Findings and Discussion Sterilization of heat sensitive supplies was performed in the CMS area in an AMSCO single door sterilizer which used a 12 percent ETO, 88 percent dichlorodifluoromethane ga5 mixture. The ETO concentration in front of the gas sterilizer was measured with a MIRAN@ infrared spectrophotometer in order to obtain real-time exposure data and identify peak exposure periods. The ETO concentrations measured before the Envirogard was installed ranged between 3.3 ppm and 7.2 ppm averaged over the approximately 4-hour sampling period; peak concentrations exceeded 50 ppm during the chamber exhaust portion of the sterilization cycle. The air in the CMS was also sampled for ETO in the breathing zone of exposed personnel and from the locations listed in Figure 2. These locations were chosen to characterize ETO exposure in the vicinity of the sterilizer and aerators, the area with the highest potential for exposure, and to determine the extent of ETO migration from the sterilizer area. All general area samples were collected with ORBO-78@ ethylene oxide sorbent tubes. This tube was developed by the US. Army Environmental Hygiene Agency (USAEHA) and is now commercially available. The ORE30-78 tube is impregnated with hydrogen bromide and simultaneously absorbs and derivatizes ETO to 2-bromoethanol, which is subsequently analyzed with a gas chromatograph equipped with an electron capture detector. The tube can be used for short- or long-term sampling, is unaffected by high (90%) relative humidity, and does not require refrigeration after collection of the sample.@) The breathing zone samples were taken with 3M@ Model 3550 and 3551 ethylene oxide ASSEMBLY I CONTROL DAMPER 1 VALVE EXHAUST FAN I II OXIDE I/ STERILIZER LIQUID/GAS SEPARATOR ii FLOOR DRAIN FIGURE 1. Envirogard local exhaust system. APPL. IND. HYG. VOL. 4, NO. 4 * APRIL

4 ~ ~~ ~ I 1 - d A 6 STERILE SUPPLY A 4 Downloaded by [Janssen Pharmaceutica], [Daniel Caldwell] at 07:00 11 November 2014 LINEN RUDM FIGURE 2. monitors, which are passive samplers that also derivatize ETO as it is collected.(10) The model 3550 monitors were analyzed by 3M, while the Model 3551 monitors were analyzed by the USAEHA Results are presented in Tables I and 11. Results of Personal Sampling Table I lists the results of breathing zone samples collected during both phases of the study. The sample periods encompassed the entire period of potential ETO exposure, e.g., from the time the sterilization cycle was started to well after the transfer of sterilized items to the aerator. The lower and upper confidence limits (95%) were calculated using a coefficient of variation of 8.8 percent derived from the USAEHA data and found to be 0.86 ppm and 1.14 ppm, respectively.(ll) Before installation of the Envirogard system, approximately one-half of the samples showed ETO exposure concentrations greater than 1 ppm. With only one exception, the remainder of the exposures were above the OSHA action level of 0.5 ppm. The highest ETO exposure measured after the Envirogard was installed was 0.04 ppm, less than one-tenth the OSHA action level. It is noteworthy that 10 of the 11 sample results were less than the minimum detectable level of ETO. TABLE 1. Breathing Zone Samples Before individual Sampling Pericd Results Sampled (min) (PPm) STERILIZER MECHANICAL ACCESS AREA * SAMPLE foint Location of sample points Central Material Services. After Sampling Period Results (min) (PPm) 314 < c ~ < < < ~ ~ < <0.04 Results of Area Sampling Table I1 presents the results of general area samples collected throughout the CMS by sample point location (Figure2) and compares results before and after installation of the Envirogard as 7wIA exposures calculated over the duration of comparable sample periods that covered the entire period of potential exposure. The lower and upper confidence limits (95%), calculated using a coefficient of variation of 3.3% (USAEHA data), were found to be 0.95 ppm and 1.05 ppm. TABLE II. General Area Samples BeforeA Sample Sampling Period Results Point (min) (PPm) c O E OC lC oc ( Office Mechanical Access Area After% Sampling Period Results (min) (PPm) 243 < < < <O.l 418 <0.1 c 397 <O.lC < < ASamples were collected on two consecutive days BSamples were collected during two &hour shifts on the same day CThis result is an average of multiple samples collected at the same time in a sampling tunnel OThis short-term sample was collected during the exhaust phase of the sterilizer cycle and included exposure during the transfer 01 sterilized items to the aerator EThis short-term sample was collected immediately after the preceding sample Both short-term samples were collected concurrently with the 258-minute sample 90 AWL. /NO. HYG. VOL. 4, NO. 4. APRIL 1989

5 Downloaded by [Janssen Pharmaceutica], [Daniel Caldwell] at 07:00 11 November 2014 Samples collected before the Envirogard was installed show that ETO concentrations exceeded the OSHA PEL in the sterile supply area (sample points 1 and 2), in the instrument room (sample point 3), in the vicinity of the sterilizer (sample point 4), and in the hallway between the linen room and decontamination room (sample point 6). The ETO concentration in the linen room (sample point 5) and CMS office (sample point not shown) were below the PEL but exceeded the OSHA action level. The results listed for sample point 4 are the averages of two to four samples collected simultaneously in a sampling tunnel. The three-foot-long by four-inch-square plexiglass sampling tunnel employed a fan to mix the air and draw it through the tunnel, thus ensuring that each of the ORB0 tubes was sampling the same ETO concentration. The standard deviation computed from the sample tunnel data was approximately 0.15 ppm. The calculated lower and upper confidence limits, 0.75 ppm and 1.25 ppm, while greater than the confidence limits calculated from laboratory data, are still within the 25 percent NIOSH accuracy criterion. Results from samples collected from the same locations after installation of the Envirogard show that ETO concentrations were under the OSHA action level in areas normally occupied by CMS personnel. Additionally, all sample results were less than the minimum detectable level except for one sample, which was collected in the sterilizer mechanical access area (sample point 7). The mechanical access area is kept locked, and the key is controlled by the CMS supervisor; therefore, personnel exposure to ETO is unlikely to occur. Real-time measurements made in front of the sterilizer with the MIRAN showed no ETO present. Conclusions General area and breathing zone ETO concentrations throughout the CMS exceeded the OSHA PEL or action level before installation of the Envirogard system. Both general area and breathing zone ETO concentrations were under the OSHA PEL and action level and were, in most cases, nondetectable after the Envirogard system was installed. The Envirogard system, when properly installed, is an effective engineering control measure for controlling ETO emission from sterilizers. References 1. Occupational Exposure to Ethylene Oxide; Final Standard, 29 CFR Pan 1910 as amended. Fed. Reg. 49:25734 (June 22, 1984). 2. US. Department of Health and Human Services: Recommended Exposure Levels for Ethylene Oxide. NIOSH Policy Statement ( June 27, 1984). 3. US. Army Environmental Hygiene Agency: Baseline Ethylene Oxide Exposures, U.S. Army Health Services Command, October 1984-July Medical Systems Safety and Health Study No (5 September 1985). 4. US. Department of Health and Human Services: Guidelines for Construction and Equipment of Hospital and Medical Facilities. DHHS Pub. No. (HRS-M-HF) 84-1 (1984). 5. Mortimer, V.D.; Kercher, S.L.; O Brien, D.M.: Effective Controls for Ethylene Oxide-A Case Study. Appl. Ind. Hyg. 1:15 (1986). 6. American Sterilizer Company: Ethylene Oxide Gas Guidelines. Pub. No. DB Erie, PA (1985). 7. Department of the Army: Interior Mechanical Design Conditions for Army and Air Force Medical Facilities. Engineer Technical Letter (4 October 1983). 8. Department of the Army: Exhaust Systems for Ethylene Oxide Sterilizer System. Engineer Technical Letter (11 December 1985). 9. Esposito, G.G.; Williams, K.; Bongiovanni, R.: Determination of Ethylene Oxide in Air by Gas Chromotography. Anal. Chem (1984). 10 Loving, TJ.; Allen, RO.; Mosher, TJ.: An Evaluation of the Accuracy and Reliability of Ethylene Oxide Diffusion Badge Monitors. Med. Instrum (1984). 11 US. Department of Health, Education, and Welfare: Statistical Methods for the Determination of Noncompliance with Occupational Health Standards. DHEW Pub. No. (NIOSH) (1975). Received 4/24/87; review decision 5/26/87; revision 9/21/88; accepted 9/28/88 APPL. IND. HYG. VOL. 4, NO. 4. APRIL