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Problem Areas with Ethylene Oxide Sterilization
PROBLEM AREAS WITH ETHYLENE OXIDE STERILIZATION John E. Doyle, B.S., and Robert R. Emst, M.S. The capability of ethylene oxide as a sterilant has been confirmed numerous times by investigators in the field. The principle stimulus to its continued development is the increasing requirement for a reliable method to sterilize heat-labile materials. Since medical progress stimulates a steady increase in the numbers and types of equipment and materials to be sterilized, the use of ethylene oxide will continue to be important. One wonders if the myriad of disposable items would have developed without using heat-labile materials; materials which could not have been used were it not for the capability of being sterilized with ethylene oxide. One is tempted to compare ethylene oxide sterilization with the classical processes such as dry heat or steam sterilization. Although the application of ethylene oxide is more complex and more expensive, one should recognize that all sterilization processes have their limitations. There is no overall process that will sterilize all materials. Most previous authors of ethylene oxide articles have emphasized the good attributes of ethylene oxide sterilization. In order to avoid the difficulties and pitfalls associated with this method, the emphasis will be on the ~
John E. Doyle is micrnhiology manager at Castle Research Laboratory and has been active for six years in research on the application of gaseous chemical and steam Sterilization and on the development of sterility indicators. He holds a B.S. degree from the University of Illinois. Robert R. Ernst is manager of the Castle Research Laboratory. He holds a B.S.M.E. degree from the L1. S. Merrhant Marine Academy; B.S. and M.S. degress from Pennsylvania State University. He has been active for nine years as a consultant for stmilization, and in the development of various sterilization processes, and chemical analytical procedures for determining ethylene oxide.
J u n e 1968
problems associated with ethylene oxide sterilization.
HISTORY The killing ability of ethylene oxide was first noted by Cotton and Roark in 1928 who used it as a fumigant against insects. The bactericidal action of the compound was established in 1929 by Schrader and Bossert.' Subsequently, there were several patents granted in relation to ethylene oxide and sterilization of food * Ethylene oxide received its greatest impetus from a series of papers by Phillips and Kaye which defined the efficiency of this agent against bacterial spores and vegetative There are several reviews which have summarized many aspects of ethylene oxide processes.'~
PHYSICAL, AND CHEMICAL PRO PERT1ES Ethylene oxide is a cyclic ether or the simplest epoxy compound, the structure of which may be represented as follows:
It is an extremely reactive colorless gas, with a boiling point of 10.8 degrees Centigrade at atmospheric pressure. It is flammable with air, the limits being 3.6 to 100 per cent by volume. However, there are nonflammable mixtures with carbon dioxide or chloro-fluorohydrocarbons. It is possible to sterilize with 100 per cent ethylene oxide, but there are the disadvantages of requiring expensive explosion-proof equipment, highly trained personnel, and higher insurance rates.'O
47
TOXICITY Ethylene oxide gas diffuses rapidly through a i d into materials. This property is advantageous for sterilkation. However, some materials may take up the gas so readily that long aeration times are necessary to elute the gas. Materials should be chosen b y the manufacturer of ethylene oxide sterilized items with this problem in mind. Some items such as polyethylene bags elute ethylene oxide in a few hours, whereas an item such as a silicone rubber prothesis required over 50 days for the ethylene oxide to become undetectable.ll
A possible problem area in ethylene oxide sterilization could be the possibility of the formation of toxic compounds. Ethylene oxide is readily soluble in water and tends to hydrolyze to toxic ethylene glycol. Allen, Meier, and Hoag reported on the toxicity of wood shavings to mice which had been treated with ethylene oxide.I2 Reyniers, Sacksteder and Ashburn reported on the formation of tumors in mice exposed to ethylene oxide treated bedding.13 Hirose, Goldstein and Baily 14 demonstrated hemolysis of the blood from plastic tubing exposed to ethylene oxide. However, the blood was in a static condition and no circulation was attempted. They concluded that aeration times of three to five days were necessary before using ethylene oxide sterilized tubing for clinical extracorporeal bypass. O’Leary and Guess l6 also recently reported on hemolysis of blood and death of cells in culture from materials exposed to ethylene oxide. However, they performed their tests immediately after ethylene oxide exposure, allowing no gas elution time other than during the vacuum phase of the sterilization cycle. They concluded that polypropylene was the best material for making a medical product which would require ethylene oxide sterilization. Recently, Adler reported on the presence of residual ethylene glycol and ethylene oxide in drugs.10
48
Wesley, Rourke, and Darbishire l’ reported that fumigation of foods with ethylene oxide produced toxic chlorohydrins. This was later confirmed by Ragelis, Fisher and Klimeck.lx That toxic chemicals could be produced in plastic or rubber items is a distinct possibility. The formulations of these materials and their additives (accelerators, additives, plasticizers, etc.) should be evaluated with the possibility of forming compounds with the highly reactive ethylene oxide. Some additives can even retard the sterilizing activity of ethylene oxide.l9 In the same vein, the ethylene oxide or freon compounds, under certain conditions, could leach additives which could be toxic to humans. Another type of toxicity possible with the use of ethylene oxide is skin reaction. The pure liquid, if applied to the skin, evaporates too rapidly to cause burns. However, if articles such as rubber gloves, which contain dissolved ethylene oxide, are confined against the skin, burns can occur. Aeration for up to one day is recommended for such materials. The inhalation toxicity of ethylene oxide is about that of ammonia. With proper room air exchange, there is little problem. However, situations should not be allowed where the gas could be vented in a confined area.
HUMIDITY The importance of optimum humidity (30 per cent to 40 per cent) at room temperature was discovered by Kaye and Phillips 2O and confirmed by Ernst and ShullZ1 for higher temperatures. Because of diffusion it is desirable to humidify the sterilizer chamber to levels above the recommended optimum. This is especially important at higher sterilizing temperatures. At 130 degrees F., 45 to 50 per cent RH is all that can be tolerated short of actually wetting materials. There have been some reports, however, of sterilization with no humidity provision. This is because the environment and the materials themselves can
AORN Journal
sometimes provide sufficient (but usually not optimum) humidity for sterilization to occur. However, this available humidity is highly uncoiltrollable and call result in sterilization skips if the material or environment is excessively dry. Consequently, for reliable sterilization, it is necessary to have a humidity control. The gas must be heated before admission to the sterilizer or the cold influx of gas can condense the moisture thereby reducing the humidity below sterilizing levels.D
relatively cool door, and 2) as a straw colored oily liquid which appears in piping associated with steam under heat and pressure. This oily liquid eventually continues to polymerize to form a resin-like solid. The polymer is usually water soluble and can be periodically flushed away. Good maintenance will keep accumulations to a minimum. Plastic covers on materials that are being sterilized will adequately protect them from damaging p o l ~ m e r s . ~
PERMEATION The permeation characteristic of materials to moisture and to ethylene oxide are important considerations. The polymers such as polyethylene, polyvinyl chloride, and polypropylene are readily permeated by ethylene oxide, but not by moisture. On the other hand, nylon, mylar and cellophane are highly permeable to moisture but less to ethylene oxide. The choice of packaging materials can be an important consideration. The permeation of laminates by moisture and gas can be severely limited. Laminates of more than one plastic (i.e. a polyethylene-cellophane laminate) are very difficult to permeate.
TESTING FOR STERILITY There are two general methods of testing for sterility; one is the use of sterility indicators, the other is testing a certain number of the items which have been sterilized (according to the methods in the U. S. Pharmacopeia) . The indicators of sterilization are usually chemical or biological. The chemical indicators usually change in color after a certain ethylene oxide exposure time. Their major limitation is that they do not indicate the complex relationship of ethylene oxide exposure-temperature-humidity required to sterilize. Their advantage is immediate indication of ethylene oxide exposure, but not necessarily sterilization.
POLYMERIZATION EFFECTS Polymerization can also be a problem area with ethylene oxide. There are many poIymerization catalysts such as steel, stainless steel, glass, lead, hydrochloride of tin, iron, aluminum, carbonic acid and alkalies. Polymerization rates also increase under increased pressure, increased temperature, and in the presence of water vapor. Thus, gas transmission lines can become clogged and valves may cease to function by the accumulation of polymer. Polymer can also cause severe damage to unprotected materials. Ethylene oxide polymerization is noted in many forms: 1) as a white powder where water has a tendency to accumulate by condensation such as near the
The only true and acceptable indication of sterility is performed with a biological indicator. The biological indicator is usually designed to provide a safety factor for the sterilization process. Bacillus subtilis var. niger spores are usually chosen. These spores have a greater resistance than most microorganisms which would be present by natural contamination such as pathogens. Bacillus stearothermophilus spores should not be used since they are easily killed by ethylene oxide. By adjusting the contamination level of the test organism, a safety factor is provided which will assure sterility of the product to be sterilized if prescribed sterilization parameters are followed. To further guarantee sterility, indicators are placed in strategically difficult-tosterilize locations within the sterilizer.
June 1968
49
If one wishes to make his own biological sterility indicators he should be very careful to wash the suspension several times to eliminate the residual culture niedia. The microorganism could become severely resistant to ethylene oxide as reported by Doyle and Ernst.22 Ethylene oxide is primarily used to sterilize clean materials. It is unrealistic to monitor sterility with excessively protected microorganisms. The use of flamed alcohol dipped forceps for transferring biological sterility indicators to culture media should be discouraged. Viable spores sometimes accumulate by one means or another in the alcohol and remain viable. These spores, picked up by the transfer forceps will also survive the flaming procedure and cause contamination of the sterility indicators.28 The recommendation is to use individually sterilized forceps for each transfer. Sterility testing by taking a statistical sampling of the material processed and placing the samples in culture media is rarely performed in hospitals, but continually done in industry. The major problem area here is to
transfer the samples without contamination occurring, giving a false indication of nonsterility. The items that are sterilized with ethylene oxide are usually plastic materials. These materials can easily pick u p an electrostatic charge. Microorganisms which have the opposite charge can become attracted to them readily. Baribo, Avens, and O’Neill, 24 described how bacterial spores can become attracted to plastic food containers by an electrostatic charge. Consequently, sterile plastic isolators are recommended for sterility transfers of product samples. CONCLUSION The use of ethylene oxide as a sterilant has been confirmed numerous times by previous investigators. The use of this agent will undoubtedly increase as the influx of heat labile items proliferate. The problems associated with flammability (100 per cent ethylene oxide), toxicity, humidity, permeation, polymerization and sterility test procedures should be considered so that they may be avoided.
REFERENCES 1. Cotton, R. T., and Aoark, R. C., “Ethylene-oxide gas as a fumigant,” Ind. Eng. Chem., Vol. 20, 1928, pp. 805-806. 2. Schrader, H., and Bossert, E., “Fumigant composition,” U. S. Patent 2,037,439, 1936. 3. Gross, P. M., and Dixon, L. F., “Method of sterilizing,” U. S. Patent 2,075,845, 1937. 4. Griffith, C. L., and Hall, L. A., “Sterilizing foodstuff,” U. S. Patent 2,107,697, 1938. 5. Phillips, C. R., “The sterilizing action of gaseous ethylene oxide. 11. Sterilization of contaminated objects with ethylene oxide and related compounds: time, concentration and temperature relationship,” Ant. J. Hyg., Vol. 50, 1949, pp. 280-288. 6. Kaye, S., and Phillips, C. R., “The sterilizing action of gaseous ethylene oxide. IV. The effect of moisture,” Am. J . Hyg., Vol. 50, 1949, pp. 296-306. 7. Phillips, C. R., and Kaye, S., “Sterilizing action of gaseous ethylene oxide. I. Review,” Am. J. Hyg., Vol. 50, 1949, pp. 270-279. 8. Bruch, C. W., “Gaseous sterilization,” Ann. Rev. Microbiol., Vol. 15, 1961, pp. 245-262. 9. Ernst, R. R., and Doyle, J. E., “Sterilization with gaseous elhylene oxide: A review of chemical and physical factors,” Biotech. and Bioeng., Vol. 10, 1968, pp. 1-31.
SO
10. Alquire, D. E., “Sterilization with 100 per cent ethylene oxide,” Bull. Parent. Drug Assor., Vol. 17. 1963, pp. 1-8. 11. Ernst, R. K., Unpublished data. 12. Allen, R. C., Meier, H., and Hoag, W. G., “Ethylene glycol produced by ethylene oxide sterilization and its effect on blood-clotting factors in an inbred strain of mice,” Nature, Vol. 193, 1962, pp. 387-388. 13. Reyniers, J. A., Sackstetler, M. R., and Ashburn, L. L., “Multiple tumors in female germfree inbred albino mice exposed to bedding treated with rthylenc oxide,” Nut. Cancer Inst., Vol. 32, 1%4, pp. 10451057. 14. Hirose, T., Goldstein, R., and Bailey, C. P., “Hemolysis of blood due to exposure to different types of plastic tubing and the influence of ethylene oxide sterilization,” J . of Thoracic and Cardiouascular Surgery, Vol. 45, 1963, pp. 245-251. 15. O’Leary, R. K., and Guess, W. L., “Toxicological studies on certain medical grade plastics sterilized by ethylene oxide,” J. Phnrm. Sci., Vol. 57, 1968, pp. 12-17. 16. Alder, N., “Residual ethylene oxide and ethylent glycol in ethylene oxide sterilized pharmaceuticals,” J. Pharm. Sci., 1965, Vol. 54, pp. 735-742.
,4OKN .I mi rnril
17. Wesley, F., Rourke, B., and Darbishire, O., “The formation of persistent chlorohydrins in foodstuffs tiy fumigation with ethylene oxide and with propylene oxide,” J. Food Sci., Vol. 30, 1965, pp. 10371042. 18. Ragelis, E. P., Fisher, B. S., and Klimeck, B. A., “Note on the determination of chlorohydrins in funds fumigated with ethylene oxide and with propylene oxide,” I . of the A.O.A.C., Vol. 49, 1966, pp. 963.965. 19. Ernst, R. R., and Doyle, J. E., “Limiting factors in ethylene oxide gaseous sterilization,” Develop. Ind. Microbiol., Vol. 9 (to be published in 1968). 20. Kaye, S., and Phillips, C. R., “The sterilizing action of gaseous ethylene oxide. IV. The effect of
moisture,” Am. J . Hyg., Vol. 50, 1949, pp. 296-306. 21. Emst, R. R., and Shull, J. J., “Ethylene oxide gaseous sterilization. I. Concentration and temperature effects,” Appl. Microbiul., Vol. 10, 1962, pp. 337-341. 22. Doyle, J. E., and Ernst, R. R., “The influence of various pretreatments (carriers, desiccation and relative cleanliness) on the destruction of Bacillus subtilis var. niger spores with gaseous ethylene oxide,” I. Pharm. Sci., 1968 (to be published). 23. Doyle, J. E., Unpublished data. 24. Baribo, L. E., Avens, J. S., and O’Neill, R. D., “Effect of electrostatic charge on the contamination of plastic food containers by airborne bacterial spores,” Vol. 14, 1966, pp. 905-913.
A N A GUIDELINES FOR AN ACTION PROGRAM FOR STATE AND DISTRICT COMMITTEES ON EMERGENCY HEALTH PREPAREDNESS Emergency-disaster health preparedness is defined broadly as the mobilization of all health resources to administer immediate and preventative health care to both the injured and well population affected by upheaval of natural phenomena, civil strife, or war. The Association has prepared guidelines to assist nurses to make a contribution to maximum population survival following disasters. Essential to this purpose is the preparation and utilization of nurses who will function effectively during disasters. The health personn,el employed by public and private health facilities andlor orgnnizations are a potential health personnel reservoir for utilization in emergencies. Health facilities and organizations have an obligation to plan and develop medical care programs which operate as integral units of an overall state plan incorporating all allied medical professions. It is essential thnt state and district nurses’ associations assume responsibility for leadership in the preparation, utilization and allocation of all available nurse manpower capable of functioning in natural, civil, or war-caused disasters. This document (available from A N A Order Department, 10 Columbus Circle, New York, New York 10019) is a suggested framework to assist state and district organizations to assume positions of leadership in state and local communities as spokesmen, planners, educators and evaluators of nursing preparedness in disaster and national defense.
June 1968
51
John E. Doyle is micrnhiology manager at Castle Research Laboratory and has been active for six years in research on the application of gaseous chemical and steam Sterilization and on the development of sterility indicators. He holds a B.S. degree from the University of Illinois. Robert R. Ernst is manager of the Castle Research Laboratory. He holds a B.S.M.E. degree from the L1. S. Merrhant Marine Academy; B.S. and M.S. degress from Pennsylvania State University. He has been active for nine years as a consultant for stmilization, and in the development of various sterilization processes, and chemical analytical procedures for determining ethylene oxide.
J u n e 1968
problems associated with ethylene oxide sterilization.
HISTORY The killing ability of ethylene oxide was first noted by Cotton and Roark in 1928 who used it as a fumigant against insects. The bactericidal action of the compound was established in 1929 by Schrader and Bossert.' Subsequently, there were several patents granted in relation to ethylene oxide and sterilization of food * Ethylene oxide received its greatest impetus from a series of papers by Phillips and Kaye which defined the efficiency of this agent against bacterial spores and vegetative There are several reviews which have summarized many aspects of ethylene oxide processes.'~
PHYSICAL, AND CHEMICAL PRO PERT1ES Ethylene oxide is a cyclic ether or the simplest epoxy compound, the structure of which may be represented as follows:
It is an extremely reactive colorless gas, with a boiling point of 10.8 degrees Centigrade at atmospheric pressure. It is flammable with air, the limits being 3.6 to 100 per cent by volume. However, there are nonflammable mixtures with carbon dioxide or chloro-fluorohydrocarbons. It is possible to sterilize with 100 per cent ethylene oxide, but there are the disadvantages of requiring expensive explosion-proof equipment, highly trained personnel, and higher insurance rates.'O
47
TOXICITY Ethylene oxide gas diffuses rapidly through a i d into materials. This property is advantageous for sterilkation. However, some materials may take up the gas so readily that long aeration times are necessary to elute the gas. Materials should be chosen b y the manufacturer of ethylene oxide sterilized items with this problem in mind. Some items such as polyethylene bags elute ethylene oxide in a few hours, whereas an item such as a silicone rubber prothesis required over 50 days for the ethylene oxide to become undetectable.ll
A possible problem area in ethylene oxide sterilization could be the possibility of the formation of toxic compounds. Ethylene oxide is readily soluble in water and tends to hydrolyze to toxic ethylene glycol. Allen, Meier, and Hoag reported on the toxicity of wood shavings to mice which had been treated with ethylene oxide.I2 Reyniers, Sacksteder and Ashburn reported on the formation of tumors in mice exposed to ethylene oxide treated bedding.13 Hirose, Goldstein and Baily 14 demonstrated hemolysis of the blood from plastic tubing exposed to ethylene oxide. However, the blood was in a static condition and no circulation was attempted. They concluded that aeration times of three to five days were necessary before using ethylene oxide sterilized tubing for clinical extracorporeal bypass. O’Leary and Guess l6 also recently reported on hemolysis of blood and death of cells in culture from materials exposed to ethylene oxide. However, they performed their tests immediately after ethylene oxide exposure, allowing no gas elution time other than during the vacuum phase of the sterilization cycle. They concluded that polypropylene was the best material for making a medical product which would require ethylene oxide sterilization. Recently, Adler reported on the presence of residual ethylene glycol and ethylene oxide in drugs.10
48
Wesley, Rourke, and Darbishire l’ reported that fumigation of foods with ethylene oxide produced toxic chlorohydrins. This was later confirmed by Ragelis, Fisher and Klimeck.lx That toxic chemicals could be produced in plastic or rubber items is a distinct possibility. The formulations of these materials and their additives (accelerators, additives, plasticizers, etc.) should be evaluated with the possibility of forming compounds with the highly reactive ethylene oxide. Some additives can even retard the sterilizing activity of ethylene oxide.l9 In the same vein, the ethylene oxide or freon compounds, under certain conditions, could leach additives which could be toxic to humans. Another type of toxicity possible with the use of ethylene oxide is skin reaction. The pure liquid, if applied to the skin, evaporates too rapidly to cause burns. However, if articles such as rubber gloves, which contain dissolved ethylene oxide, are confined against the skin, burns can occur. Aeration for up to one day is recommended for such materials. The inhalation toxicity of ethylene oxide is about that of ammonia. With proper room air exchange, there is little problem. However, situations should not be allowed where the gas could be vented in a confined area.
HUMIDITY The importance of optimum humidity (30 per cent to 40 per cent) at room temperature was discovered by Kaye and Phillips 2O and confirmed by Ernst and ShullZ1 for higher temperatures. Because of diffusion it is desirable to humidify the sterilizer chamber to levels above the recommended optimum. This is especially important at higher sterilizing temperatures. At 130 degrees F., 45 to 50 per cent RH is all that can be tolerated short of actually wetting materials. There have been some reports, however, of sterilization with no humidity provision. This is because the environment and the materials themselves can
AORN Journal
sometimes provide sufficient (but usually not optimum) humidity for sterilization to occur. However, this available humidity is highly uncoiltrollable and call result in sterilization skips if the material or environment is excessively dry. Consequently, for reliable sterilization, it is necessary to have a humidity control. The gas must be heated before admission to the sterilizer or the cold influx of gas can condense the moisture thereby reducing the humidity below sterilizing levels.D
relatively cool door, and 2) as a straw colored oily liquid which appears in piping associated with steam under heat and pressure. This oily liquid eventually continues to polymerize to form a resin-like solid. The polymer is usually water soluble and can be periodically flushed away. Good maintenance will keep accumulations to a minimum. Plastic covers on materials that are being sterilized will adequately protect them from damaging p o l ~ m e r s . ~
PERMEATION The permeation characteristic of materials to moisture and to ethylene oxide are important considerations. The polymers such as polyethylene, polyvinyl chloride, and polypropylene are readily permeated by ethylene oxide, but not by moisture. On the other hand, nylon, mylar and cellophane are highly permeable to moisture but less to ethylene oxide. The choice of packaging materials can be an important consideration. The permeation of laminates by moisture and gas can be severely limited. Laminates of more than one plastic (i.e. a polyethylene-cellophane laminate) are very difficult to permeate.
TESTING FOR STERILITY There are two general methods of testing for sterility; one is the use of sterility indicators, the other is testing a certain number of the items which have been sterilized (according to the methods in the U. S. Pharmacopeia) . The indicators of sterilization are usually chemical or biological. The chemical indicators usually change in color after a certain ethylene oxide exposure time. Their major limitation is that they do not indicate the complex relationship of ethylene oxide exposure-temperature-humidity required to sterilize. Their advantage is immediate indication of ethylene oxide exposure, but not necessarily sterilization.
POLYMERIZATION EFFECTS Polymerization can also be a problem area with ethylene oxide. There are many poIymerization catalysts such as steel, stainless steel, glass, lead, hydrochloride of tin, iron, aluminum, carbonic acid and alkalies. Polymerization rates also increase under increased pressure, increased temperature, and in the presence of water vapor. Thus, gas transmission lines can become clogged and valves may cease to function by the accumulation of polymer. Polymer can also cause severe damage to unprotected materials. Ethylene oxide polymerization is noted in many forms: 1) as a white powder where water has a tendency to accumulate by condensation such as near the
The only true and acceptable indication of sterility is performed with a biological indicator. The biological indicator is usually designed to provide a safety factor for the sterilization process. Bacillus subtilis var. niger spores are usually chosen. These spores have a greater resistance than most microorganisms which would be present by natural contamination such as pathogens. Bacillus stearothermophilus spores should not be used since they are easily killed by ethylene oxide. By adjusting the contamination level of the test organism, a safety factor is provided which will assure sterility of the product to be sterilized if prescribed sterilization parameters are followed. To further guarantee sterility, indicators are placed in strategically difficult-tosterilize locations within the sterilizer.
June 1968
49
If one wishes to make his own biological sterility indicators he should be very careful to wash the suspension several times to eliminate the residual culture niedia. The microorganism could become severely resistant to ethylene oxide as reported by Doyle and Ernst.22 Ethylene oxide is primarily used to sterilize clean materials. It is unrealistic to monitor sterility with excessively protected microorganisms. The use of flamed alcohol dipped forceps for transferring biological sterility indicators to culture media should be discouraged. Viable spores sometimes accumulate by one means or another in the alcohol and remain viable. These spores, picked up by the transfer forceps will also survive the flaming procedure and cause contamination of the sterility indicators.28 The recommendation is to use individually sterilized forceps for each transfer. Sterility testing by taking a statistical sampling of the material processed and placing the samples in culture media is rarely performed in hospitals, but continually done in industry. The major problem area here is to
transfer the samples without contamination occurring, giving a false indication of nonsterility. The items that are sterilized with ethylene oxide are usually plastic materials. These materials can easily pick u p an electrostatic charge. Microorganisms which have the opposite charge can become attracted to them readily. Baribo, Avens, and O’Neill, 24 described how bacterial spores can become attracted to plastic food containers by an electrostatic charge. Consequently, sterile plastic isolators are recommended for sterility transfers of product samples. CONCLUSION The use of ethylene oxide as a sterilant has been confirmed numerous times by previous investigators. The use of this agent will undoubtedly increase as the influx of heat labile items proliferate. The problems associated with flammability (100 per cent ethylene oxide), toxicity, humidity, permeation, polymerization and sterility test procedures should be considered so that they may be avoided.
REFERENCES 1. Cotton, R. T., and Aoark, R. C., “Ethylene-oxide gas as a fumigant,” Ind. Eng. Chem., Vol. 20, 1928, pp. 805-806. 2. Schrader, H., and Bossert, E., “Fumigant composition,” U. S. Patent 2,037,439, 1936. 3. Gross, P. M., and Dixon, L. F., “Method of sterilizing,” U. S. Patent 2,075,845, 1937. 4. Griffith, C. L., and Hall, L. A., “Sterilizing foodstuff,” U. S. Patent 2,107,697, 1938. 5. Phillips, C. R., “The sterilizing action of gaseous ethylene oxide. 11. Sterilization of contaminated objects with ethylene oxide and related compounds: time, concentration and temperature relationship,” Ant. J. Hyg., Vol. 50, 1949, pp. 280-288. 6. Kaye, S., and Phillips, C. R., “The sterilizing action of gaseous ethylene oxide. IV. The effect of moisture,” Am. J . Hyg., Vol. 50, 1949, pp. 296-306. 7. Phillips, C. R., and Kaye, S., “Sterilizing action of gaseous ethylene oxide. I. Review,” Am. J. Hyg., Vol. 50, 1949, pp. 270-279. 8. Bruch, C. W., “Gaseous sterilization,” Ann. Rev. Microbiol., Vol. 15, 1961, pp. 245-262. 9. Ernst, R. R., and Doyle, J. E., “Sterilization with gaseous elhylene oxide: A review of chemical and physical factors,” Biotech. and Bioeng., Vol. 10, 1968, pp. 1-31.
SO
10. Alquire, D. E., “Sterilization with 100 per cent ethylene oxide,” Bull. Parent. Drug Assor., Vol. 17. 1963, pp. 1-8. 11. Ernst, R. K., Unpublished data. 12. Allen, R. C., Meier, H., and Hoag, W. G., “Ethylene glycol produced by ethylene oxide sterilization and its effect on blood-clotting factors in an inbred strain of mice,” Nature, Vol. 193, 1962, pp. 387-388. 13. Reyniers, J. A., Sackstetler, M. R., and Ashburn, L. L., “Multiple tumors in female germfree inbred albino mice exposed to bedding treated with rthylenc oxide,” Nut. Cancer Inst., Vol. 32, 1%4, pp. 10451057. 14. Hirose, T., Goldstein, R., and Bailey, C. P., “Hemolysis of blood due to exposure to different types of plastic tubing and the influence of ethylene oxide sterilization,” J . of Thoracic and Cardiouascular Surgery, Vol. 45, 1963, pp. 245-251. 15. O’Leary, R. K., and Guess, W. L., “Toxicological studies on certain medical grade plastics sterilized by ethylene oxide,” J. Phnrm. Sci., Vol. 57, 1968, pp. 12-17. 16. Alder, N., “Residual ethylene oxide and ethylent glycol in ethylene oxide sterilized pharmaceuticals,” J. Pharm. Sci., 1965, Vol. 54, pp. 735-742.
,4OKN .I mi rnril
17. Wesley, F., Rourke, B., and Darbishire, O., “The formation of persistent chlorohydrins in foodstuffs tiy fumigation with ethylene oxide and with propylene oxide,” J. Food Sci., Vol. 30, 1965, pp. 10371042. 18. Ragelis, E. P., Fisher, B. S., and Klimeck, B. A., “Note on the determination of chlorohydrins in funds fumigated with ethylene oxide and with propylene oxide,” I . of the A.O.A.C., Vol. 49, 1966, pp. 963.965. 19. Ernst, R. R., and Doyle, J. E., “Limiting factors in ethylene oxide gaseous sterilization,” Develop. Ind. Microbiol., Vol. 9 (to be published in 1968). 20. Kaye, S., and Phillips, C. R., “The sterilizing action of gaseous ethylene oxide. IV. The effect of
moisture,” Am. J . Hyg., Vol. 50, 1949, pp. 296-306. 21. Emst, R. R., and Shull, J. J., “Ethylene oxide gaseous sterilization. I. Concentration and temperature effects,” Appl. Microbiul., Vol. 10, 1962, pp. 337-341. 22. Doyle, J. E., and Ernst, R. R., “The influence of various pretreatments (carriers, desiccation and relative cleanliness) on the destruction of Bacillus subtilis var. niger spores with gaseous ethylene oxide,” I. Pharm. Sci., 1968 (to be published). 23. Doyle, J. E., Unpublished data. 24. Baribo, L. E., Avens, J. S., and O’Neill, R. D., “Effect of electrostatic charge on the contamination of plastic food containers by airborne bacterial spores,” Vol. 14, 1966, pp. 905-913.
A N A GUIDELINES FOR AN ACTION PROGRAM FOR STATE AND DISTRICT COMMITTEES ON EMERGENCY HEALTH PREPAREDNESS Emergency-disaster health preparedness is defined broadly as the mobilization of all health resources to administer immediate and preventative health care to both the injured and well population affected by upheaval of natural phenomena, civil strife, or war. The Association has prepared guidelines to assist nurses to make a contribution to maximum population survival following disasters. Essential to this purpose is the preparation and utilization of nurses who will function effectively during disasters. The health personn,el employed by public and private health facilities andlor orgnnizations are a potential health personnel reservoir for utilization in emergencies. Health facilities and organizations have an obligation to plan and develop medical care programs which operate as integral units of an overall state plan incorporating all allied medical professions. It is essential thnt state and district nurses’ associations assume responsibility for leadership in the preparation, utilization and allocation of all available nurse manpower capable of functioning in natural, civil, or war-caused disasters. This document (available from A N A Order Department, 10 Columbus Circle, New York, New York 10019) is a suggested framework to assist state and district organizations to assume positions of leadership in state and local communities as spokesmen, planners, educators and evaluators of nursing preparedness in disaster and national defense.
June 1968
51