| 摘要: | 美國於2002年修訂Clean Air Act，廢除醫療廢棄物現地焚化處理的專案申請，因廢棄物含氯量高達2.7%，加上專用焚化爐操作不穩定，使戴奧辛排放係數高達3000 μg I-TEQ/ton，為一般混燒焚化爐的40倍。我國目前醫療廢棄物大多採用專用焚化爐處理，物資回收率非常低。政府乃於「資源回收再利用推動計畫」中，規劃各類事業廢棄物於民國109年 (2020) 之回收率為45%。醫療廢棄物若要回收必先經過滅菌處理，但目前僅2.5%為滅菌處理，其他均受焚化。因此本研究旨在建立快速滅菌判讀法，探討其使用於滅菌處理之成效和可行性，期能藉此提昇我國醫療廢棄物之滅菌處理成效和物資回收率。
本研究前往廢棄物滅菌處理現場進行滅菌效能評估，使用化學指示劑 (chemical integrator, CI) 與生物指示劑 (biological indicators, BI)， 比較四個點放置的滅菌效能：(1) 鍋內冷點挑戰包 (CPC)、(2) 鍋內中心點挑戰包 (CPM)、(3) 袋內 (IB)、及 (4) 袋內之針筒內 (IBS)。BI可進行需時1~3小時之快速判讀，及需時24~48小時之顏色判讀，亦可將BI之孢子桿菌打出後，使用異營菌培養法 (heterotrophic plate count, HPC) 計數菌落數；CI則可由色變立即目測判讀。十個機組試驗結果顯示，有七個機組滅菌效能符合規定 (log kill≧5)，三個機組不符合規定；其中八個機組之CPC滅菌效能與其他三點無顯著性差異 (p>0.05)。因CPC之滅菌效能較低，可視為較保守之成效檢測點。若以HPC為對照，計算其他判讀法之敏感度 (sensitivity)，快速判讀為97.8%，顏色判讀為90.7%，CI判讀為95.6% (n=200)。
本研究進一步執行了軟袋、軟管及針筒等三種資源性廢棄物之滅菌成效評估，分別以兩種操作模式進行滅菌試驗：121oC重力式/60分鐘 (121G)、及135 oC真空式/45分鐘 (135V)。結果顯示121 G之試驗，兩種滅菌效能檢測，皆未達標準；135V則全部符合法規標準；此外CPC之滅菌效能較三種廢棄物塑膠為保守。
本研究實廠測試結果顯示：(1) 我國目前醫療廢棄物滅菌品質仍待改善，應建立滅菌效能測試準則並定期查核滅菌程序；(2) 含有指示劑之挑戰包為使用方便且較嚴謹之檢測方法；(3) 135V為良好之資源性醫療廢棄物回收利用之滅菌條件，而121G則無法符合標準。
The US Clean Air Act prohibits incineration of regulated medical wastes in general incinerators due to the high chlorine content (2.7%) of the wastes and the unstable operation conditions of the general incinerators. Under general conditions, the emission factor of dioxin can be as high as 3,000 μg I-TEQ/ton of medical wastes, i.e. 40 times of that from general refuse incineration. In Taiwan most medical wastes are being incinerated, resulting in very low material recovery. The Taiwan Environment Protection Administration has set a goal of recovery to be 45% for all types of municipal wastes by the year 2020. At present, only 2.5% of medical wastes are treated by sterilization and are recovered. The purpose of this study was to propose the use of a rapid readout method as an indicator of sterilization performance to sterilization of medical wastes and hence increase the recovery rate of medical waste materials.
This study tested the effectiveness of a sterilization indicator under field conditions in sterilization facilities throughout Taiwan. In each facility, the effectiveness of a chemical indicator (CI) and a biological indicators (BI) were compared at 4 sampling sites: 1) challenge pack at the cold spot (CPC), 2) challenge pack at the middle chamber (CPM), 3) inside the bag (IB), and 4) inside the syringe in bag (IBS). The BI was monitored as a rapid readout (1~3 hr) and as a color change (24 hr). The effectiveness of BI was also tested by heterogeneous plate counts (HPC) using a pour plate technique. The CI was scored by degrees of color changes. The test results indicated that, among 10 sets of autoclaves being tested, 7 sets met the national microbial reduction standard (log kill ≧ 5), and three sets did not. Using CPC as the reference site, in 8 autoclaves evaluated, there was no significant difference (p > 0.05) in log kill between CPC and the other three sampling sites. Since CPC site gave a lower log kill, it was considered a relatively conservative reference site. In comparison with HPC, the sensitivity was 97.8% for the BI rapid readout, 90.7% for the BI color change, and 95.6% for the CI readout.
In consideration of waste recycling, we also evaluated the sterilization efficiency for 3 types of plastic medical wastes (soft bag, soft tubing, and syringe) at two operating conditions: 121 oC/60 min by gravity displacement (121G) and 135 oC/45 min by vacuum displacement (135V). The results based on the two indication methods indicated that all the 121G tests failed to meet the national standard, whereas all the 135G tests complied with the standard. In addition, the sterilization efficiency of CPC was equivalent to those tested inside the three types of plastic wastes.
This study concluded that 1) the current practice of medical waste sterilization in Taiwan needs improvement, 2) standard operation and auditing procedure need to be established, 3) the use of challenge pack with CI and BI appeared to be a reliable and convenient method, and 4) sterilization at 135 oC by vacuum displacement for 45 minutes is a viable pretreatment method for medical waste recycling. |
