摘要
為了因應健康風險評估應用趨勢與強化現有常用之風險基礎生命週期評估(Risk-based LCA)內人體健康衝擊方法，研究中提出生命週期風險評估以確切評估連續且多樣汙染源的排放及其對應受體間的關係。生命週期風險評估以健康風險分析為分析方法的基礎，利用生命週期思考連結評估標的內所有汙染源-受體關係，最後合計評估標的之族群風險作為總人體健康衝擊。此方法保留了生命週期思考的優點:以功能單位標的物的流向流量，串連範疇邊界內所有程序(含直接與間接)，以避免危害衝擊的轉移；與風險分析方法的優點: 連結汙染源與各利害關係人間，污染物濃度非均質地隨著時間空間坡降，在不等的暴露量下探討敏感受體。此方法藉由調整評估標的內空間與時間的限制，量化評估標的施行時細部的執行變異，更仔細量化方案間各利害關係人之危害程度，增加執行可行性，用以整合評估各方案對其影響受體之危害，提供較低人體健康衝擊的方案，以便提供更詳細的資訊。 生命週期風險評估將五個階段，含目標定義、範疇界定、盤查分析、生命週期風險分析與闡釋，分成18個步驟，其中除了整合探討目標定義、範疇界定與闡釋外，盤查分析與生命週期風險分析皆需依直接汙染源與間接汙染源分別量化各汙染源-受體健康風險。透過生命週期風險評估可量化評估標的各方案之直接/間接個別風險、族群風險與平均個別風險，用以比較各方案總健康風險、方案內各汙染源-受體衝擊、評估範疇內風險轉移等，提供管理者作為評估標的執行之決策基礎。 研究中以底渣再利用為案例分析，冀能利用研究中建立之生命週期風險再次審視底渣再利用管理之人體健康危害並減低現行執行時各單位對底渣再利用於健康風險的疑慮。以族群風險連結所有程序之危害，總族群風險排序為情境C、情境B、情境A與情境D；而平均個別風險排序則與總族群風險不同，其排序為情境B、情境A、情境C與情境D。以程序探討，底渣工作人員的危害最大，其個別風險介於1.0E-07~1.0E-02之間，呼吸為主要暴露途徑；其次為情境C中的道路使用期鄰近居民，鉻與砷之滲出汙染了飲用水與食物鏈灌溉水，已影響到道路鄰近居民，其個別風險略大於1.0E-08，可見長期使用底渣再利用於道路鋪設，其危害之顯而易見的。然而，道路使用期20年危害的鄰近居民個別風險(1.09E-08)相較掩埋場鄰近居民(1.51E-10)大2個量級，但考慮道路鋪設時間即可將鄰近居民個別風險降至1.0E-13，由此可見就個別風險而言，道路鋪設期可考慮於相關規範以降低一般居民危害。另一方面，由14個汙染源-受體連結比較研究中所提之四項情境，可以發現各情境之汙染源間風險轉移，若採取底渣再利用應用於道路鋪設(不限制鋪設時間)，則汙染源風險將由掩埋場轉至底渣再利用處理廠；另一方面，道路鋪設時間若增長，則風險不單只是個人增加，暴露人口數亦隨之增加而造成受體間風險轉移。 研究中以底渣再利用為案例，透過生命週期風險評估整合評估範疇內所有受體之族群風險，即便受體不同且暴露特性差異甚遠，卻實整併了空氣、水體與土壤，多樣介質擴散尺度之健康衝擊。且除了跨介質合計各方案所有受體健康危害，仍可維持健康風險評估原有特色，提供暴露及汙染源-受體關係等資訊，供管理者作為評估標的執行之決策基礎。
並列摘要
The temporal and spatial considerations have yet to be integrated into risk-based LCA, whereas life-cycle thinking has yet to be captured in RA. In order to maintain the link between source and receptor through RA, and consider a life cycle, the method in this study focuses on integrating life cycle thinking into RA to develop the life cycle risk assessment methodology (LCRA) in this study. Because LCRA assessed risks from a life cycle perspective of the concerned linkage sources, it was helpful to identify important sources, contaminants, receptors and exposure pathways along the life cycle of activities. Analyses of different scenarios are assessed as the alternative of bottom ash reuse in road paving or landfill, and the harm of bottom ash reuse is assessed by LCRA to avoid the risk shift. When the population risks over the entire life cycle considered in this study are used as a decision criterion, the ranking was D, A, B and C; on the other hand, the ranking of average individual risk became D, C, A and B. The source-receptors in these four scenarios were also discussed: with higher exposure, the individual risks of laborers (1.0E-07~1.0E-02) were higher than residents through exposure to Cr and Cd via inhalation and dermal contact. as for the residents, the highest individual risk occurred in road paving (1.09E-08) due to leakage of Cr to groundwater, and the ingestion of drinking water and food chain contaminated by groundwater use were the main exposure pathways. The results also showed risk shift between different stages; among four scenarios, the individual risk of residents living near the road was 100 times greater than the residents near the landfill which keeps bottom ash for 20 years. However, the individual risk of residents living near landfill is 1000 times greater than the residents near the road when a high frequency of road maintenance (2 years) was used. This indicated that different reuse scenarios would result in risk shift between life stages and receptors, and using duration of pavement would be a factor for risk management. By calculating and population risks associated various receptors resulting from a source at each life stage and aggregating population risks along the life cycle, we obtain total risks. The total population risks as well as information of individual risk at each stage and average individual risk for various alternatives can be used to rank the alternatives and identify important factors for environmental management.