Evaluation Of The Application Of Medical Ethylene Oxide Sterilizer in Fumigation Sterilization Of Cultural Relics

1. Introduction
Ethylene oxide (EO) has been widely used in the field of disinfection and sterilization since the 1950s and is currently recognized as one of the most reliable chemical gas sterilizers. In the 1980s, ethylene oxide gas fumigation technology began to be applied to the cultural relics protection industry, mainly for the sterilization of organic material cultural relics such as textiles, calligraphy and painting, bamboo, wood and ivory carvings. However, due to the toxicity of ethylene oxide, its residual problem has always been a hot topic of research.

In the field of medical device sterilization, the application of ethylene oxide has mature standards, such as ISO 10993-7:2008. However, the cultural relics protection industry has not yet formed a unified sterilization specification. In addition, the fragility and non-renewability of cultural relics require that the sterilization process must strictly control conditions to ensure the safety of cultural relics. This study uses a medical ethylene oxide sterilizer to explore the best sterilization conditions for cultural relics protection by evaluating the sterilization effect, material influence and residual amount.

 

2. Materials and methods
2.1 Experimental materials
Paper materials: cotton rice paper, pure rice paper, mechanical book paper, etc.

Packaging materials: rice paper, non-woven fabrics, PE self-sealing bags, PVC plastic cylinders, etc.

Instruments and equipment: 3M ethylene oxide sterilizer, microscopic infrared analyzer, spectrophotometer, etc.

Reagents: ethylene oxide gas, Bacillus subtilis black variant biological indicator, PDA culture medium, etc.

2.2 Experimental methods
Evaluation of paper material performance: Test the tensile strength and folding resistance of paper before and after sterilization, analyze the microscopic infrared spectrum and color change.

Evaluation of the penetration effect of packaging materials: Place biological indicators in different packaging materials, and observe the sterilization effect after sterilization.

Residual amount evaluation: Use ISO 100993-7:2008 standard to detect the residual amount of ethylene oxide after different exhaust times.

 

3. Results and analysis

3.1 Effect of ethylene oxide on paper material performance
The experimental results show that after ethylene oxide sterilization, the tensile strength and folding resistance of paper did not change significantly (Table 1). Microscopic infrared spectrum analysis shows that the chemical composition of paper before and after sterilization is basically the same, indicating that ethylene oxide has little effect on the material of organic cultural relics. In addition, color tests show that the color difference (△E value) of Chinese painting pigments before and after sterilization is less than 5, which does not exceed the range that can be distinguished by the human eye.

Paper test result
Testing materials	Tensile strength(kN/m)		Folding endurance (times)
Testing materials	Before E0	After EO	Before E0 action	After EO action
Specially clean 2011	2.85	3.36	16	16
Cotton material alum paper	1.05	0.972	7	7
Cotton material 2009	0.973	0.791	16	15
Clean leather 2008	1.23	1.28	4	4
Mechanical book paper	1.72	1.79	65	68

3.2 Ethylene oxide penetration effect of different packaging materials
The experiment found that ethylene oxide can penetrate a variety of packaging materials such as rice paper, non-woven fabrics, and PE ziplock bags, and the sterilization effect is good. Among them, PVC plastic tubes and paper-plastic ziplock bags can effectively block external humidity while maintaining sealing, and are suitable for packaging sterilization of humidity-sensitive cultural relics.

3.3 Analysis of residual amount after ethylene oxide sterilization
By extending the exhaust time to 12 hours, the ethylene oxide residual amount can be reduced to a safe level (<4 mg/m³). The experiment also found that wood materials have a strong adsorption capacity for ethylene oxide, and the loading amount needs to be appropriately reduced and the exhaust time needs to be extended.

 

4. Discussion
This study verifies the applicability of medical ethylene oxide sterilizers in cultural relic protection. During the sterilization process, the control of temperature and humidity is crucial. The conditions of 37℃ and RH60% can not only ensure the sterilization effect, but also reduce the damage to cultural relics. In addition, the choice of packaging materials not only affects the sterilization effect, but also prolongs the preservation time of cultural relics.

However, the toxicity of ethylene oxide still needs to be taken seriously. It is recommended to ventilate for one week after sterilization before storage, and strictly control the contact time of operators. Future research can further optimize the sterilization parameters to meet the needs of cultural relics of different materials.

 

5. Conclusion
Medical ethylene oxide sterilizer has significant advantages in cultural relic protection:

The sterilization effect is reliable and has little impact on the material of cultural relics.

Automated operation improves safety.

The choice of packaging materials can effectively avoid secondary contamination.

It is recommended to formulate personalized sterilization plans based on the characteristics of cultural relic materials and further promote standardization research.

 

6. References
Liu Endi, et al. Research on the application of ethylene oxide fumigation disinfection on cultural relics. Shaanxi Cultural Museum, 1986.

ISO 10993-7:2008. Biological evaluation of medical devices.

Guo Zhun, et al. Discussion on risk control of ethylene oxide sterilization residues. China Medical Device Information, 2011.

(Note: This article is a simplified version. For the complete study, please refer to the original article.)