Advancing environmental risk assessment of selenium (ERASe)

硒（Se）是加拿大水生环境中的优先污染物。它是一种必需的微量营养素，但由于必需性和毒性之间的范围非常窄，特别是在鱼类中，因此具有极端的毒理学危害。与其他微量元素不同，硒在水生系统中的暴露和吸收主要通过饮食发生。它通过微生物从无机形式转化为有机形式，并可在高等营养类群中积累至毒性水平。硒在水生态系统中营养转移的复杂性，造成了许多不确定性和争论的环境风险评估。虽然联邦监测法规最近增加了硒的物质清单，由工业废水和接收水生环境进行监测，仍然存在显着的研究差距，阻碍客观评估其潜在的危害水生野生动物在特定地点的条件下。了解影响加拿大水生环境中硒循环的关键因素对于准确评估水生物种的毒理学风险至关重要，从而为行业和监管机构提供更好，更有效的工具来保护生态系统，而不会过度惩罚释放硒的行业。该项目的总体目标是开发一种先进的，国家的最先进的风险评估方法硒在加拿大资源行业的预测建模要求的支持。利用实验室和现场的方法，控制硒的转化和同化的关键过程，以及它的转移沿着有代表性的水生食物链将进行研究。此外，直接摄取这种食物基础的本地鱼类的早期生命阶段的相对敏感性（即，生物膜），它们对硒的敏感性，从母亲转移的硒，和相关的潜在机制的毒性将进行研究。基于这些结果，我们将开发一个改进的和现场验证的模型，准确和客观的预测暴露于饲料硒及其对本地鱼类的影响。这将使预测水生生态系统的监管相关性的基础上，不同鱼类物种的机械毒性信息（不良后果途径）。

Selenium (Se) is a priority pollutant in Canadian aquatic environments. It is an essential trace nutrient but represents an extreme toxicological hazard due to the very narrow range between essentiality and toxicity, especially in fish. Unlike other trace elements, exposure to and uptake of Se in aquatic systems occurs predominantly through the diet. It is transformed from inorganic to organic forms by microorganisms and can accumulate to toxic levels in higher trophic taxa. The complexity in the trophic transfer of Se in aquatic ecosystems has created much uncertainty and debate regarding its environmental risk assessment. Although federal monitoring regulations recently added Se to the list of substances to be monitored by industry in effluent and receiving aquatic environments, there remain significant research gaps that hamper objective assessment of its potential hazard to aquatic wildlife under site-specific conditions. Understanding of the key factors influencing Se cycling in Canadian aquatic environments will be critical for accurately assessing the toxicological risks to aquatic species, and thus, provide industries and regulators with better and more efficient tools to protect ecosystems without overly penalizing industries that release Se. The overall goal of this project is to develop an advanced, state-of-the-art risk assessment approach for Se in support of the Canadian resource industry's predictive modeling requirements. Using laboratory and field approaches key processes that govern the transformation and assimilation of Se, and its transfer along representative aquatic food chains will be researched. Also, the relative sensitivity of early life stages of native fish species that directly ingest this food base (i.e., biofilm), their sensitivity to Se resulting from maternal transfer of Se, and the associated underlying mechanisms of toxicity will be investigated. Based on these results we will develop an improved and field validated model for accurate and objective prediction of the exposure to dietary Se and its effects on native fish species. This will enable prediction of aquatic ecosystem responses of regulatory relevance based on mechanistic toxicity information across diverse fish species (adverse outcome pathways).