【摘要】 临界浓度反映的是有机污染物对生物体的体内毒性效应,是评价有机污染物对水生生物毒性的一个重要指标,对水生环境风险评价具有重要的意义.本文根据目前国内外在该领域的研究现状和本课题组的研究成果,系统地总结了有机污染物在鱼体内临界浓度的计算方法,不同毒性作用模式下的临界浓度、生物富集因子与临界浓度的关系以及影响临界浓度的因素.目前研究结果表明,麻醉型化合物在鱼体内临界浓度在较窄一个范围内变化,趋近于常数,非极性麻醉型化合物的临界浓度要高于极性麻醉型,反应型化合物的临界浓度低于麻醉型化合物;有机污染物在鱼体内的临界浓度与生物富集过程密切相关;生物富集因子与疏水性的关系,生物有机体的大小、脂含量,化合物的暴露时间,代谢转化及毒性数据测定的准确性都会对临界浓度的测定或计算产生影响.更多还原

【Abstract】 The internal concentration represented by critical body residue(CBR) is an ideal indicator of the intrinsic toxicity of a chemical that can be used to assess toxicity to aquatic organisms. In this study, we systematically summarized the method for calculation of CBR in fish, CBR values with different modes of toxic action, the relationship between CBR and BCF, and the factors influencing the CBR based on the progress in this field as a result of studies conducted worldwide and our own investigations. The CBRs could be calculated by the LC50 and BCF based on the toxicokinetic model. The modes of toxic action of fish are usually recognized based on classification of organic compounds as acting by non-polar narcosis(baseline compounds), polar narcosis(less inert compounds), or reactive and specific acting mechanisms. Baseline toxicity is associated with chemicals acting narcosis mechanism, which is the reversible suppression of physiological function brought about by hydrophobic binding of chemicals to cell membranes and proteins. The CBRs to fish for narcotic chemicals vary in a narrow range and are close to constant. The CBRs for non-polar narcotic chemicals are higher than those for polar narcotic chemicals. Moreover, non-polar and polar narcotic compounds have different underlying mechanisms. Polar compounds intercalate less deeply into membranes, leading to lower CBR values than non-polar narcotic compounds. Reactive compounds interact and/or react with biological molecules, leading to enhanced toxicity relative to that associated with narcosis, and their CBRs are lower than those of narcotic compounds. Because the CBRs of narcotic compounds are close to constant, their toxicities are mainly affected by bioconcentration and linearly related to hydrophobicity. Conversely, the CBRs of reactive compounds are closely related to the reactivity of chemicals with biomolecules at the target site, with different values being observed for different reactive compounds. Their toxicities are not only related to the bioconcentration factor, but also to the descriptors used to describe the reactivity of chemicals with biomolecules(CBRs). Many factors can affect the CBRs of chemicals. For example, linear models of the relationship between log BCF and log Kow can underestimate the log BCF for compounds with log Kow < 0.5 and overestimate the log BCF for compounds with log Kow > 7, resulting in larger errors for CBRs calculated from the BCF and LC50 of highly hydrophilic and hydrophobic compounds. Organism size, lipid content, exposure time, metabolism and transformation, and uncertainty of toxic data can also affect the calculation or determination of CBRs.更多还原