Arsenic transformations in the human environment

众所周知，砷是一种有毒物质和致癌物质。我们建议研究环境中砷的化学形态如何变化，以及这些变化如何影响暴露在砷中对人类的潜在有害影响。我们的目标之一是研究砷的化学形态的变化，从土壤和植物中发现的有毒无机砷，到蘑菇中发现的无毒砷甜菜碱。通过这样做，我们希望分离出负责将砷从有毒形式转变为无毒形式的确切生物体和机制。我们还将测定杂货店常见的蘑菇以及其他食品中的砷形态，包括饲料食品，这是一种越来越受欢迎的食品趋势。此外，我们亦会研究如何利用湿地植物，特别是木贼，从水和土壤中清除大量砷。(马尾)。对于这些研究，我们将使用我们拥有专业知识的工具：一种基于同步加速器的X射线分析方法(称为X射线吸收光谱分析)，辅以传统测试方法来表征砷的分布；以及一种称为生物可及性的测试方法。生物可及性测试使我们能够在实验室中模拟人类或动物的胃肠环境，并给出人类胃和肠道中可溶的砷的量。拟议的工作将使人们深入了解水和土壤中砷污染的可能解毒和补救战略，以及加拿大人在食品供应中可能面临的砷暴露和风险。

Arsenic is well known as a poison and a cancer-causing agent. We propose to study how the chemical form of arsenic changes in the environment, and how these changes influence the potential for harmful effects to humans when they are exposed to arsenic. One of our objectives is to study the change of arsenic’s chemical form, from toxic inorganic arsenic, found in soil and plants, to non-toxic arsenobetaine, found in mushrooms. In doing this we hope to isolate the exact organisms and mechanisms that are responsible for changing arsenic from a toxic to a non-toxic form. We will also determine the arsenic forms in mushrooms commonly found in grocery stores, as well as other food products, including foraged foods, an increasingly popular food trend. We will also study the removal of arsenic from water and soil using wetland plants that take up large concentrations of arsenic, specifically Equisetum sp. (horsetails). For these studies we will use tools in which we have expertise: a synchrotron-based X-ray analysis method (called X-ray absorption spectroscopy), complemented by conventional testing methods, to characterize the distribution of arsenic; and a testing method called bioaccessibility. Bioaccessibility testing allows us to mimic the gastro-intestinal environment of humans or animals in a laboratory, and gives us the amount of arsenic that is soluble in the human stomach and intestines. The proposed work will give insight into possible detoxification and remediation strategies for arsenic contamination of water and soil, as well as the possible arsenic exposures and risks that Canadians may face in their food supply.