Arsenic transformations in terrestrial animals

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或动物的潜在有害影响。我们将通过首先测量人类或动物可能接触到的样本中存在的砷化学形式来实现这一点。我们还将确定砷变化的原因，重点是它们是否作为解毒反应发生。我们将使用两种我们擅长的工具：基于同步加速器的X射线吸收光谱学，辅以传统的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环境中模拟人类或动物的胃肠环境，并给出可在胃和肠道中溶解的砷的量。我们将采取的第一步是开发能够识别砷硫形态的传统测试方法，使我们能够在砷浓度太低而无法通过XAS研究的样品中对这些形态进行量化。我们的第二步将是通过结合常规(包括开发的砷硫分析方法)和XAS方法来确定鸟类、哺乳动物和昆虫中砷的化学形态。第三步是测量其中一些样品中可溶于胃肠道环境(可生物获取)的砷的化学形态，这将有助于我们确定人类或动物是否面临暴露于砷的有害影响的风险。

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 or animals when they are exposed to arsenic. We will do this by first measuring the arsenic chemical forms present in samples that humans or animals may be exposed to. We will also determine the reasons for the arsenic changes with a focus on whether they occur as detoxification responses. We will use two tools that we have expertise in: synchrotron-based 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 environment and gives us the amount of arsenic that is soluble in the stomach and intestines. The first step we will undertake will be to develop conventional testing methods that can identify arsenic-sulfur species, allowing us to quantify these species in samples whose arsenic concentrations are too low to study by XAS. Our second step will be to determine the chemical forms of arsenic in birds, mammals and insects, by combined conventional (including the methods developed for arsenic-sulfur analysis) and XAS methods. The third step is to measure the arsenic chemical forms that are soluble in the gastro-intestinal environment (bioaccessible) in some of these samples, which will help us to determine if humans or animals are at risk of harmful effects from arsenic exposure.