一、背景

一般情况下，采用环氧乙烷灭菌的医疗器械应当对灭菌后相关残留物进行分析评价，因为残留量的多少与接触医疗器械的相关人员的健康息息相关。环氧乙烷是一种中枢神经抑制剂。若与皮肤接触迅速发生红肿，数小时后起泡，反复接触可致敏。液体溅入眼内，可致角膜灼伤。若长期少量接触，可见有神经衰弱综合征和植物神经功能紊乱。有报道表明，大鼠急性口服LD50为330mg/Kg，环氧乙烷可使小鼠骨髓染色体的畸变率提高[1]。有报道，与环氧乙烷接触的工作人员致癌率和死亡率较高。[2]2-氯乙醇若与皮肤接触，可出现皮肤红斑；可经皮吸收引起中毒。口服可致死。若慢性长期接触有可对中枢神经系统、心血管系统、肺造成损伤。国内外对于乙二醇的研究结果一致认为其本身毒性较低。其在体内代谢过程与乙醇相同，经过乙醇脱氢酶及乙醛脱氢酶的代谢，主要产物为乙醛酸、草酸和乳酸，毒性较高。因此，多项标准中均对经环氧乙烷灭菌后相关残留物有具体要求。如：GB/T 16886.7-2015《医疗器械生物学评价第7部分：环氧乙烷灭菌残留量》、YY0290.8-2008《眼科光学 人工晶状体 第8部分：基本要求》等标准中对环氧乙烷、2-氯乙醇的残留量的限值有详细规定。GB/T 16886.7-2015中明确表示，当使用环氧乙烷灭菌的医疗器械中存在2-氯乙醇时,其可允许残留量也有明确限值。因此，要从环氧乙烷的生产、运输、存储环节，医疗器械的生产环节、灭菌环节来综合分析常见残留物（环氧乙烷、2-氯乙醇、乙二醇）的产生。

二、灭菌残留物的分析

环氧乙烷的生产工艺分为氯醇法和氧化法。其中氯醇法为早期环氧乙烷生产方法。主要包含两个反应过程：一：C２H４＋HClO——CH２Cl-CH２OH；二：CH２Cl-CH２OH＋CaOH2——C2H4O＋CaCl2＋H2O。其反应过程中间产物为2-氯乙醇（CH２Cl-CH２OH）。因氯醇法技术落后，严重污染环境，加之产物对设备腐蚀严重，大部分厂家已经淘汰[4]。氧化法[3]分为空气法和氧气法。根据氧气纯度的不同，生产中的主要包含两个反应过程：一：2C2H4＋O2——2C2H4O；二：C2H4＋３O2——2CO2＋H2O。目前，环氧乙烷的工业生产主要采用以银为催化剂的乙烯直接氧化法工艺。因此，环氧乙烷的生产工艺是决定灭菌后对2-氯乙醇进行评价的一个因素。

参照GB/T 16886.7-2015标准中的相关规定执行环氧乙烷灭菌过程的确认和开发，根据环氧乙烷的物理化学特性，灭菌后大部分残留物以原形存在。影响残留量的因素主要包括医疗器械对环氧乙烷的吸附、包装材料及厚度、灭菌前后的温湿度、灭菌作用时间及解析时间、储存条件等，以上因素决定了环氧乙烷的逃逸能力。有文献[5]报道,环氧乙烷灭菌浓度通常选择300-1000mg.L-1。灭菌时环氧乙烷的损耗因素主要包括：医疗器械的吸附、在一定湿度条件的水解等。浓度在500-600mg.L-1是相对经济有效的，降低环氧乙烷的消耗与灭菌物品上的残留，节约了灭菌成本。

氯在化学工业中有着广泛的应用，许多产品与我们息息相关。既可作为中间体，如氯乙烯；也可作为终产品，如漂白剂。同时氯也存在于空气、水等环境中，对人体的危害也是显而易见的。因此，在相关医疗器械经环氧乙烷灭菌时，应当考虑综合分析产品的生产、灭菌、存储等环节，有针对性地采取相应的措施控制2-氯乙醇的残留量。

有文献报道[6]，创口贴经过环氧乙烷灭菌，解析72小时后，2-氯乙醇的含量达到近150µg/片，参照GB/T16886.7-2015的标准中规定的短期接触器械，2-氯乙醇对患者的平均日剂量不应超过9mg，其残留量远低于标准中的限值。

有研究[7]对3种缝合针线中环氧乙烷及2-氯乙醇的残留量进行测定，材质为尼龙线的带线缝合针，环氧乙烷的结果为未检出，2-氯乙醇结果为53.7µg.g-1。YY 0167-2005中规定了非吸收性外科缝线环氧乙烷检出限值，对2-氯乙醇未做规定。缝合线在生产过程中有大量工业用水的可能。我国地面水的四类水质是适用于一般工业保护区及人体非直接接触的用水区，普遍经过漂白粉处理，可控制水中的藻类及微生物，用于杀菌卫生防疫。其主要有效成分为次氯酸钙，是由氯气通入石灰石生成。次氯酸钙在空气中易降解，主要反应式为：Ca(ClO)2+CO2+H2O——CaCO3+2HClO。次氯酸在光照下易分解为盐酸和水，主要反应式为：2HClO+光照——2HCl+O2。氯负离子易吸附在缝合线中，在一定的弱酸性或弱碱性环境下，环氧乙烷开环与其生成2-氯乙醇。

有文献[8]报道，用丙酮超声提取人工晶状体样品残留的2-氯乙醇，利用气相色谱-质谱法测定，但并未检出。YY0290.8-2008《眼科光学 人工晶状体 第8部分：基本要求》中，规定人工晶状体上2-氯乙醇残留量每只每天不应超过2.0µg，每个晶状体总量不应超过5.0µg。GB/T16886.7-2015标准中提到2-氯乙醇残留引起的眼毒性是同等水平环氧乙烷的4倍。

综上所述，在评价医疗器械经环氧乙烷灭菌后的残留物时，对环氧乙烷、2-氯乙醇应重点关注，但也应根据实际综合分析其残留情况。

在医疗器械灭菌过程中，部分一次性使用医疗器械或包装材料的原材料包括聚氯乙烯（PVC），PVC树脂在加工中因树脂分解也会产生极少量的氯乙烯单体。GB10010-2009 医用软聚氯乙烯管材中规定了氯乙烯单体含量不能超过1µg.g-1。氯乙烯在催化剂（过氧化物等）或光、热作用下容易发生聚合，生成聚氯乙烯，统称为氯乙烯树脂。聚氯乙烯受热超过100°C或经过紫外线辐射照射会存在氯化氢气体逃逸的可能性。那么包装内氯化氢气体与环氧乙烷结合会生成一定量的2-氯乙醇。

乙二醇，性质稳定，不易挥发。环氧乙烷中的氧原子带两个孤对电子，具有较强的亲水性，在与氯负离子共存的情况下，更容易生成乙二醇。例如：C2H4O+NaCl＋H2O——CH２Cl-CH２OH+NaOH。此过程反应端为弱碱性，生成端为强碱性，这种反应发生率较低。发生率更高的是环氧乙烷遇水生成乙二醇：C2H4O+H2O——CH2OH-CH2OH，且环氧乙烷水合作用会抑制其与游离氯负离子的结合。

医疗器械生产、灭菌、存储、运输、使用等环节中，若引入氯负离子，存在环氧乙烷与其发生反应生成2-氯乙醇的可能性。由于生产环节中氯醇法已经被淘汰，那么其中间产物2-氯乙醇不会在直接氧化法中出现。医疗器械的生产环节，某些原材料对环氧乙烷、2-氯乙醇具有极强的吸附特性，那么灭菌后进行解析时必须考虑其残留量的控制。此外，医疗器械生产过程中，原料、添加剂、反应抑制剂等含有以氯化物形式存在的无机盐，在灭菌时，须考虑环氧乙烷在酸性或碱性条件下开环，发生SN2反应，与游离的氯负离子结合生成2-氯乙醇的可能性。

目前，常用检测环氧乙烷、2-氯乙醇、乙二醇的方法为气相法。环氧乙烷还可以用品红亚硫酸试液对比色法进行检测，但其缺点是检测结果的真实性受实验条件影响的因素较多，如实验环境温度37°C的恒定从而控制乙二醇的反应，显色处理后的待测液放置时间等。因此，在有资质的实验室，经过确认的方法学验证（包括准确度、精密度、线性、灵敏性等）对于残留量的定量检测有参考意义。

三、对审评工作的思考

环氧乙烷、2-氯乙醇、乙二醇是医疗器械进行环氧乙烷灭菌后常见的残留物。开展残留物评价，应考虑环氧乙烷的生产、存储、医疗器械的生产、灭菌等环节相关物质的引入。

实际医疗器械审评工作中还应关注两个问题：1、是否需要进行2-氯乙醇的残留量的检测。在环氧乙烷生产环节，若采用传统氯醇法，尽管在生产过程中会采取提纯、过滤等方法，环氧乙烷气体在一定程度上还是会含有中间产物2-氯乙醇，应对其残留量进行评价。若采用氧化法，没有2-氯乙醇的引入，但应考虑环氧乙烷反应过程中相关抑制剂、催化剂等的残留量。医疗器械在生产过程中大量使用工业用水，成品中也会吸附一定量的次氯酸、氯负离子，这些是残留物中可能存在2-氯乙醇的原因。还存在医疗器械的原材料及包装中是含有氯元素的无机盐或结构稳定、不易断键的高分子材料等情况，因此要综合分析2-氯乙醇残留量的风险是否一定需要检测来进行评价，若有充分的证据表明不会引入2-氯乙醇或低于检测方法的检测限，可以不考虑用检测来控制其风险。2、对于乙二醇的残留量的分析评估。与环氧乙烷、2-氯乙醇相比，乙二醇残留物接触毒性较低，但由于环氧乙烷生产、使用过程中还会接触二氧化碳和水，而环氧乙烷与水又容易生产乙二醇，灭菌后乙二醇的含量与环氧乙烷的纯度相关，也与包装、微生物中的水分及灭菌的温湿度环境相关，因此应根据实际情况考虑对乙二醇进行评价。

标准是医疗器械技术审评的工具之一，医疗器械技术审评工作要关注产品的设计研发、生产、存储、使用等各环节安全有效的基本要求，综合分析影响安全有效的因素，要做到理论联系实际，基于科学、基于事实，而不是直接引用标准，脱离产品设计、研发、生产、使用的实际情况。审评工作应当更加关注医疗器械生产质量体系对于相关环节的控制，同时现场审评也应当以“问题”为导向，充分发挥“眼睛”的作用从而达到提高审评质量，科学审评的目的。

参考文献:

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[2] 沈菊华.国内外环氧乙烷生产技术及市场分析.化工技术经济,2005年11月第23卷第11期

[3] 崔小明.环氧乙烷生产技术进展及市场分析.精细与专用化学品.2014年5月第22卷第５期

[4] 陈向华. 环氧乙烷的生产方法及应用.化工科技市场,2008,31（10）:33-36

[5] 李传秋.环氧乙烷灭菌效果及残留量的实验研究[J].食品与药品, 2014, 16(1):41-43

[6] 谭周飞.创口贴灭菌后经不同解析时间环氧乙烷和2—氯乙醇的清除效果分析. 中国药事2013年第 27卷第9期

[7] 尹庆和. 气相色谱法测定缝合针线中2一氯乙醇残留量. 中国药事2013年第 27卷第12期

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审评二部 贺伟罡 刘柏东 供稿

来源：国家药监局医疗器械技术审评中心

1、 Background

In general, the related residues after sterilization should be analyzed and evaluated for the medical devices sterilized with ethylene oxide, because the amount of residual is closely related to the health of the relevant personnel contacting with the medical devices. Ethylene oxide is a central nervous system inhibitor. If it contacts with skin, it will be inflamed rapidly and blister after several hours. Repeated contact can sensitize. The liquid splashes into the eye, may cause cornea burn. If a small amount of long-term contact, we can see neurasthenia syndrome and autonomic nerve dysfunction. It has been reported that acute oral LD50 of rats is 330 mg / kg, and ethylene oxide can increase the chromosome aberration rate of bone marrow in mice [1]. It has been reported that the workers exposed to ethylene oxide have higher carcinogenic rate and mortality. [2] If 2-chloroethanol is in contact with the skin, erythema may appear; it can be absorbed through skin and cause poisoning. Oral administration can cause death. If chronic long-term contact has, can cause damage to central nervous system, cardiovascular system, lung. The research results of ethylene glycol at home and abroad agree that its toxicity is low. The main products are glyoxylic acid, oxalic acid and lactic acid, with high toxicity. Therefore, a number of standards have specific requirements for the residues after ethylene oxide sterilization. For example, GB / T 16886.7-2015 biological evaluation of medical devices Part 7: ethylene oxide sterilization residue, yy0290.8-2008 ophthalmic optical intraocular lens part 8: basic requirements have detailed provisions on the limits of ethylene oxide and 2-chloroethanol residues. It is clearly stated in GB / T 16886.7-2015 that when 2-chloroethanol is present in medical devices sterilized with ethylene oxide, the maximum allowable residue also has a clear limit. Therefore, the production of common residues (ethylene oxide, 2-chloroethanol, ethylene glycol) should be comprehensively analyzed from the production, transportation and storage of ethylene oxide, the production and sterilization of medical devices.

2、 Analysis of sterilization residues

The production process of ethylene oxide is divided into chlorohydrin method and oxidation method. Among them, chlorohydrin method is the early production method of ethylene oxide. There are two main reaction processes: the first step is C2H4 + hclo-ch2cl-ch2oh; the second step is ch2cl-ch2oh + caoh2-c2h4o + CaCl2 + H2O. The intermediate product was 2-chloroethanol (ch2cl-ch2oh). Due to the backward technology of chlorohydrin method, serious environmental pollution and serious corrosion of products to equipment, most manufacturers have been eliminated [4]. Oxidation method can be divided into air method and oxygen method. According to the different oxygen purity, the production mainly includes two reaction processes: the first step: 2c2h4 + o2-2c2h4o; the second step: C2H4 + 3o2-2co2 + H2O. At present, ethylene oxide is mainly produced by direct oxidation of ethylene with silver as catalyst. Therefore, the production process of ethylene oxide is a factor determining the evaluation of 2-chloroethanol after sterilization.

According to the relevant provisions of GB / T 16886.7-2015, the confirmation and development of ethylene oxide sterilization process is carried out. According to the physical and chemical characteristics of ethylene oxide, most of the residues after sterilization exist in original form. The factors affecting the residual amount mainly include the adsorption of ethylene oxide by medical devices, packaging materials and thickness, temperature and humidity before and after sterilization, sterilization action time and analysis time, storage conditions and so on. These factors determine the escape ability of ethylene oxide. According to the literature [5], the sterilization concentration of ethylene oxide is usually 300-1000mg · L-1. The loss factors of ethylene oxide during sterilization mainly include: adsorption of medical devices, hydrolysis under certain humidity conditions, etc. The concentration of 500-600 mg · L-1 is relatively economic and effective, which can reduce the consumption of ethylene oxide and the residue of sterilization articles, and save the cost of sterilization.

Chlorine is widely used in chemical industry and many products are closely related to us. It can be used as an intermediate, such as vinyl chloride, or as an end product, such as bleaching agent. At the same time, chlorine also exists in the air, water and other environment, the harm to human body is obvious. Therefore, when the relevant medical devices are sterilized by ethylene oxide, comprehensive analysis of the production, sterilization and storage of the products should be considered, and corresponding measures should be taken to control the residual amount of 2-chloroethanol.

It has been reported in the literature [6] that the content of 2-chloroethanol reached nearly 150 μ g / tablet after 72 hours of ethylene oxide sterilization. Referring to the short-term contact device specified in GB / t16886.7-2015, the average daily dose of 2-chloroethanol to patients should not exceed 9mg, and its residual amount is far below the limit value in the standard.

Some studies [7] have determined the residual amount of ethylene oxide and 2-chloroethanol in three kinds of suture needle and suture. For suture needle with nylon thread, the result of ethylene oxide is not detected, and the result of 2-chloroethanol is 53.7 μ g.g-1. In YY 0167-2005, the detection limit of ethylene oxide for non absorbable surgical suture was specified, but 2-chloroethanol was not specified. It is possible to use a large amount of industrial water in the production process of suture. The four kinds of surface water quality in China are suitable for general industrial protection areas and water use areas not directly contacted by human body. After being treated with bleaching powder, the algae and microorganisms in the water can be controlled and used for sterilization, sanitation and epidemic prevention. Its main effective component is calcium hypochlorite, which is generated by chlorine gas flowing into limestone. Calcium hypochlorite is easy to degrade in air. The main reaction formula is Ca (CLO) 2 + CO2 + H2O - CaCO3 + 2hclo. Hypochlorous acid is easily decomposed into hydrochloric acid and water under light. The main reaction formula is: 2hclo + illumination - 2HCl + O2. In a certain weak acid or weak alkali environment, epoxy B is easy to adsorb in the suture