Cranfield University, School of Water, Energy and Environment, Cranfield MK43 0AL, UK.
Cranfield University, School of Water, Energy and Environment, Cranfield MK43 0AL, UK.
Sci Total Environ. 2018 Feb 15;615:708-723. doi: 10.1016/j.scitotenv.2017.09.321. Epub 2017 Oct 17.
Understanding the distribution, behaviour and interactions of complex chemical mixtures is key for providing the evidence necessary to make informed decisions and implement robust remediation strategies. Much of the current risk assessment frameworks applied to manage land contamination are based on total contaminant concentrations and the exposure assessments embedded within them do not explicitly address the partitioning and bioavailability of chemical mixtures. These oversights may contribute to an overestimation of both the eco-toxicological effects of the fractions and the mobility of contaminants. In turn, this may limit the efficacy of risk frameworks to inform targeted and proportionate remediation strategies. In this review we analyse the science surrounding bioavailability, its regulatory inclusion and the challenges of incorporating bioavailability in decision making process. While a number of physical and chemical techniques have proven to be valuable tools for estimating bioavailability of organic and inorganic contaminants in soils, doubts have been cast on its implementation into risk management soil frameworks mainly due to a general disagreement on the interchangeable use of bioavailability and bioaccessibility, and the associated methods which are still not standardised. This review focuses on the role of biotic and abiotic factors affecting bioavailability along with soil physicochemical properties and contaminant composition. We also included advantages and disadvantages of different extraction techniques and their implications for bioavailability quantitative estimation. In order to move forward the integration of bioavailability into site-specific risk assessments we should (1) account for soil and contaminant physicochemical characteristics and their effect on bioavailability; (2) evaluate receptor's potential exposure and uptake based on mild-extraction; (3) adopt a combined approach where chemical-techniques are used along with biological methods; (4) consider a simplified and cost-effective methodology to apply at regulatory and industry setting; (5) use single-contaminant exposure assessments to inform and predict complex chemical mixture behaviour and bioavailability.
理解复杂化学混合物的分布、行为和相互作用是提供必要证据以做出明智决策和实施稳健修复策略的关键。目前应用于管理土地污染的许多风险评估框架都是基于污染物总量，而其中嵌入的暴露评估并未明确解决化学混合物的分配和生物可利用性问题。这些疏忽可能导致对各部分的生态毒性效应以及污染物迁移性的高估。反过来，这可能会限制风险框架在提供针对性和适度修复策略方面的有效性。在这篇综述中，我们分析了生物可利用性及其监管纳入方面的科学依据，以及在决策过程中纳入生物可利用性所面临的挑战。虽然许多物理和化学技术已被证明是估算土壤中有机和无机污染物生物可利用性的有价值工具，但由于对生物可利用性和生物有效性的可互换使用以及相关方法仍未标准化存在普遍分歧，因此对其在风险管理土壤框架中的实施提出了质疑。本综述重点讨论了影响生物可利用性的生物和非生物因素以及土壤物理化学性质和污染物组成。我们还介绍了不同提取技术的优缺点及其对生物可利用性定量估算的影响。为了将生物可利用性纳入特定地点的风险评估，我们应该：（1）考虑土壤和污染物的物理化学特性及其对生物可利用性的影响；（2）根据温和提取来评估受体的潜在暴露和吸收；（3）采用化学技术与生物方法相结合的综合方法；（4）考虑采用简化且具有成本效益的方法在监管和行业环境中应用；（5）使用单一污染物暴露评估来了解和预测复杂化学混合物的行为和生物可利用性。
