A chemical thermodynamics-based approach to quantifying contaminant exposure

这笔拨款将支持一个独特的基础研究项目，该项目建立在化学热力学原理的基础上，以推进化学暴露评估，特别是对污染物生物放大的理解。生物放大是指生物体体内的脂质标准化污染物浓度高于它们所吃食物中的污染物浓度的过程。可以说，这是最有效的污染物放大过程；即使是很小的排放量和相对较低的环境浓度也会导致体内高度暴露于生物放大污染物。由于伦理考虑限制了可以进行的调查类型，因此对人类和野生动物物种的生物放大的坚实机制理解一直难以捉摸。采用无创或微创分析化学方法与动力学建模相结合的创新方法，我们将进行一系列研究，以阐明与饮食，消化和污染物相关的因素如何影响生物放大。我们将使用硅基平衡装置来量化配对食物和粪便样本的污染物容量，从而可以估计野生动物物种和人类的生物放大潜力。我们将比较饲喂相同饲料的不同食肉动物的生物放大潜力，研究北极熊在分解代谢和合成代谢阶段生物放大潜力的季节性变化，并量化摄入不可消化脂肪替代品和微塑料引起的污染物生物放大潜力的下降。依托人类志愿者，我们将进一步研究不同消化效率（如受肠道微生物群的影响）引起的生物放大潜力的个体间差异，以及不同饮食组成引起的生物放大潜力差异。通过将实验结果整合到食物链生物积累模型中，并将这些模型与全球尺度的环境命运和运输计算联系起来，我们将确定面临最高暴露于特定有机污染物危险的陆地和海洋野生动物种群，即生物放大物质金矿中的全球金丝雀。我们将进一步使用模型来估计人类食物消化和同化能力的变异性对人群中暴露的生物标志物（例如血液中生物放大污染物的浓度）的测量变异性的影响。虽然生物积累评估是有效化学品管理的核心，但判断生物放大的经验基础严重偏向于鱼类和实验动物。通过以前所未有的非侵入性方式研究生物放大，我们将通过生成生物放大物质最危险的生物体的信息，大大增强生物积累评估。

This grant will support a unique program of basic research that builds on the principles of chemical thermodynamics to advance chemical exposure assessment in general and the understanding of contaminant biomagnification in particular. Biomagnification is the process through which organisms can have higher lipid-normalized concentrations of contaminants in their bodies than are prevalent in the food they eat. It is arguably the most potent contaminant amplification process; even small emissions and relatively low environmental concentrations can lead to high internal exposure to biomagnifying contaminants. Because ethical considerations limit the type of investigations that can be conducted, a solid mechanistic understanding of biomagnification in humans and wildlife species has been elusive. Adopting innovative approaches that combine non-invasive or minimally invasive analytical chemistry methods with kinetic modelling, we will conduct a series of studies to elucidate how factors related to diet, digestion and contaminants influence biomagnification. We will use silicone-based equilibrium devices to quantify the capacity of paired food and feces samples for contaminants, which allows for an estimation of biomagnification potential in wildlife species and humans. We will compare the biomagnification potential of different carnivores being fed the same diet, investigate seasonal changes in the biomagnification of polar bears during catabolic and anabolic phases, and quantify the decrease in the biomagnification potential for contaminants caused by the ingestion of non-digestible fat substitutes and microplastics. Relying on human volunteers we will further study interindividual differences in biomagnification potential caused by different digestion efficiencies, e.g. influenced by the gut microbiome, and the differences in biomagnification caused by variable diet composition. By integrating the experimental findings into food chain bioaccumulation models and linking those models with global scale environmental fate and transport calculations, we will identify the terrestrial and marine wildlife populations that are in danger of experiencing the highest exposure to particular organic contaminants, i.e. the global canaries in the goldmine for biomagnifying substances. We will further use models to estimate the influence of the variability in human food digestion and assimilation capabilities on the measured variability in biomarkers of exposure (e.g. concentrations of biomagnifying contaminants in blood) within a population. Whereas bioaccumulation assessment is central to effective chemical management, the empirical basis for judging biomagnification has been heavily biased towards fish and lab animals. By studying biomagnification non-invasively in ways that had never been possible before, we will greatly enhance bioaccumulation assessment through generating information on those organisms most at risk from biomagnifying substances.