Sappington Keith G
US Environmental Protection Agency, Office of Research and Development, National Center for Environmental Assessment (8623D), 1200 Pennsylvania Avenue, N.W., Washington, DC 20460, USA.
Aquat Toxicol. 2002 Apr;57(1-2):101-13. doi: 10.1016/s0166-445x(01)00267-3.
The US is currently in the process of revising its freshwater, chronic aquatic life criterion for selenium. The fundamental issues being addressed include which environmental compartment(s) support the most reliable expression of the criterion, which form(s) of selenium should be measured in the medium (media) of choice, and which site-specific water quality (or other factors) should be linked to the expression of the criterion. Literature reviews and a recent workshop were conducted to assess the state of the science on various issues related to water-, tissue- and sediment-based criteria for selenium. Evaluation of many of these issues is ongoing. In terms of water column criteria issues, data limitations will likely restrict the expression of a criterion to operationally defined forms (e.g. total recoverable, dissolved). The specific identity of organoselenium in natural systems is lacking and may not be appropriately represented by free seleno-amino acids (e.g. selenomethionine). The available data do not appear to support quantitative relationships between chronic toxicity and water quality characteristics. In terms of a tissue-based criterion, reproductive tissue (ovary, egg) has been recommended as the tissue of choice, but practical concerns and data availability require consideration of other tissues (e.g. whole-body). Organoselenium (bound to peptides or proteins) is thought to be the form of greatest toxicological importance in fish, however, direct measurements of organoselenium compounds in tissues are very limited. Route of exposure (food vs. water uptake) may prove important for establishing diagnostic tissue residues for selenium based on laboratory data. Data on toxicological aspects of selenium in sediments appear sparse, particularly in relation to different sedimentary forms. Reliable assessments of bioaccumulation will likely be critical for making site-specific modifications to chronic selenium criteria, however, many technical issues for assessing bioaccumulation remain. The need for improved analytical methods for directly speciating organoselenium in various environmental media underpins many of the current data gaps. Improving analytical methodologies to enable affordable and reliable measurement of organoselenium compounds holds significant promise for advancing selenium ecotoxicological research.
美国目前正在修订其关于硒的淡水慢性水生生物标准。正在解决的基本问题包括哪些环境介质能最可靠地体现该标准，应在选定的介质中测量哪种形式的硒，以及哪些特定地点的水质（或其他因素）应与该标准的体现相关联。开展了文献综述和近期的研讨会，以评估与基于水、组织和沉积物的硒标准相关的各种问题的科学现状。对其中许多问题的评估仍在进行中。就水柱标准问题而言，数据限制可能会将标准的体现局限于操作定义的形式（例如总可回收量、溶解量）。天然系统中有机硒的具体特性尚不明确，游离硒代氨基酸（如硒代蛋氨酸）可能无法恰当地代表它。现有数据似乎并不支持慢性毒性与水质特征之间的定量关系。就基于组织的标准而言，生殖组织（卵巢、卵）已被推荐为首选组织，但实际问题和数据可得性要求考虑其他组织（如全身）。有机硒（与肽或蛋白质结合）被认为是鱼类中毒理学重要性最高的形式，然而，对组织中有机硒化合物的直接测量非常有限。暴露途径（通过食物摄取还是通过水摄取）可能对根据实验室数据确定硒的诊断性组织残留量很重要。关于沉积物中硒的毒理学方面的数据似乎很少，特别是与不同沉积形式相关的数据。对生物累积进行可靠评估可能对针对特定地点修改慢性硒标准至关重要，然而，评估生物累积的许多技术问题仍然存在。在各种环境介质中直接对有机硒进行形态分析的改进分析方法的需求是当前许多数据缺口的根本原因。改进分析方法以实现对有机硒化合物的经济且可靠的测量，对推进硒生态毒理学研究具有重大意义。
