Advancing environmental risk assessment of selenium (ERASe)

硒（Se）是加拿大水生环境中的主要污染物。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，它代表了一种极端的毒理学危害。与其他微量元素不同，硒在水生系统中的暴露和吸收主要是通过饮食发生的。它通过微生物从无机形式转化为有机形式，并可在高营养分类群中积累到有毒水平。硒在水生生态系统中营养转移的复杂性给其环境风险评估带来了诸多不确定性和争议。尽管联邦监测条例最近将硒添加到工业在废水和接收水生环境中监测的物质清单中，但仍存在重大的研究空白，妨碍了在特定地点条件下客观评估其对水生野生动物的潜在危害。了解加拿大水生环境中影响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和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为Se开发一种先进的、最先进的风险评估方法，以支持加拿大资源行业的预测建模需求。利用实验室和现场方法，研究控制硒转化和同化的关键过程，以及硒在代表性水生食物链中的转移。此外，还将研究直接摄入这种食物基（即生物膜）的本地鱼类生命早期的相对敏感性，它们对硒的敏感性是由母体硒转移引起的，以及相关的潜在毒性机制。基于这些结果，我们将建立一个改进的和现场验证的模型，以准确和客观地预测饲料硒暴露及其对本地鱼类的影响。这将使基于不同鱼类的机械毒性信息（不良后果途径）的水生生态系统反应的调控相关性预测成为可能。

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).