Predicting the fate and effects of tributyltin in marine systems.
Predicting the fate and effects of tributyltin in marine systems.
复制标题
预测海洋系统中三丁基锡的命运和影响。
DOI：
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发表时间：
2000
影响因子：
6
通讯作者：
J. Meador
中科院分区：
文献类型：
--
作者：
J. Meador
现有数据表明，当使用平衡分配方法、毒代动力学模型 (1CFOK) 和临界身体残留 (CBR) 方法的一些假设和原则时，沉积物-水分配、生物累积和三丁基锡 (TBT) 的毒性反应是可以预测的。由于 TBT 是可电离的，因此其形态受到 pH 值的强烈影响，这似乎会导致辛醇-水分配系数发生较大变化。在海洋系统和高 pH 值的淡水系统中，TBT 主要以氢氧化物形式存在，这可以解释疏水性及其 EqP 行为。沉积物中的有机碳（> 0.2%）似乎是沉积物-水分配的主要控制因素。海洋环境中的平衡有机碳归一化沉积物-水分配系数（Koc）约为32,000（log10 Koc约为4.5），该系数是通过直接测量确定的，并通过孔隙水中脂质归一化生物浓缩因子（BCF）与生物群-沉积物积累因子（BSAF）之间的关系得到证实。海洋系统中TBT沉积物-水分配遵循EqP的结论得到了其Kow和Koc之间的相似性以及沉积物-水分配系数（Kp）与沉积物TOC之间的相关性的支持，这是有机碳对孔隙水浓度影响的结果。尽管控制组织残留物和脂质含量的摄取和消除速率似乎与积累的 TBT 量无关，但物种特异性 BSAF 对于检查生物积累、沉积物-水分配和毒性反应很有用。虽然 TBT 是疏水性的，并且似乎有在脂质中积累的倾向，但吸收和消除的速率，而不是热力学，似乎控制着全身组织的浓度。几个物种的 BCF 和 BSAF 值远远超过简单热力学分配的预测值，并且基于毒代动力学系数对观察到的和预测的生物累积值进行比较，这些结果支持用毒代动力学方法预测组织残留。这一观察结果与 EqP 的假设相反，即在平衡条件下吸收途径没有影响。对于 TBT，似乎动力学决定了组织残留，而体脂仅对于调节毒性反应很重要，而不是生物累积量。与中性疏水性有机化合物不同，这种毒物的毒代动力学在不同物种中变化很大，但在预测生物累积量和由此产生的毒性反应方面相对准确。为了使 CBR 方法发挥作用，对于给定的生物反应，相对恒定的组织残留物是必要的。一些研究支持 CBR 方法，因为某些生物效应（例如死亡率和生长抑制）会在相对恒定的 TBT 组织浓度下发生。对于 TBT，影响 50% 个体的致命全身组织浓度 (LR50) 几乎没有变化，在一系列物种中的干重约为 48 微克/克（166 纳摩尔/克）。 LC50 和生物浓缩因子 (BCF) 的直接证据和相关性支持这一观察结果。生长受损是一种亚致死反应，似乎也与相对恒定的组织浓度有关，这也已通过直接测量和间接通过 BCF 和 LOEC 回归得到证明。对于几个物种来说，与生长受损相关的最低观察到的组织残留效应 (LOER) 约为 3 微克/克（10.4 纳摩尔/克）干重。由于将生长障碍和组织浓度联系起来的研究数量很少，因此需要更多的研究来证实这些值。 （摘要已被截断）
The available data indicate that sediment-water partitioning, bioaccumulation, and the toxicity responses for tributyltin (TBT) are predictable when using some of the assumptions and tenets of the equilibrium partitioning method, toxicokinetic modeling (1CFOK), and critical body residue (CBR) approach. Because TBT is ionizable, its speciation is strongly affected by pH, which appears to cause large variations in the octanol-water partition coefficient. In marine systems, and in freshwater systems with high pH, TBT occurs predominantly in the hydroxide form, which may explain the hydrophobic properties and its EqP behavior. Organic carbon in sediment (> 0.2%) appears to be the major controlling factor for sediment-water partitioning. The equilibrium organic carbon-normalized sediment-water partition coefficient (Koc) in marine environments is approximately 32,000 (log10 Koc approximately 4.5), which was determined from direct measurement and confirmed by the relationship between the lipid-normalized bioconcentration factor (BCF) in porewater and the biota-sediment accumulation factor (BSAF). The conclusion that sediment-water partitioning of TBT in marine systems follows EqP is supported by the similarity between its Kow and Koc and the correlation between the sediment-water partition coefficient (Kp) and sediment TOC, which results from the influence of organic carbon on pore-water concentrations. Even though the rates of uptake and elimination control tissue residues and lipid content appears to have no bearing on the amount of TBT that is accumulated, the species specific BSAF is useful for examining bioaccumulation, sediment-water partitioning, and the toxicity response. Although TBT is hydrophobic and appears to have a propensity to accumulate in lipid, the rates of uptake and elimination, not thermodynamics, appear to control whole-body tissue concentrations. Support for a toxicokinetic approach for predicting tissue residues is found in BCF and BSAF values for several species that are far in excess of that predicted by simple thermodynamic partitioning and in the comparisons of observed and predicted bioaccumulation values based on toxicokinetic coefficients. This observation is counter to the assumption of EqP that the route of uptake is of no consequence under equilibrium conditions. For TBT, it appears that kinetics determine tissue residues and that body lipid is important only for regulating the toxic response, not the amount bioaccumulated. Unlike those for neutral hydrophobic organic compounds, the toxicokinetics for this one toxicant are highly variable in diverse species but relatively accurate in predicting the amount bioaccumulated and the resulting toxicity response. For the CBR approach to be useful, a relatively constant tissue residue for a given biological response is necessary. Several studies support the CBR approach because certain biological effects, such as mortality and growth inhibition, occur at a relatively constant TBT tissue concentration. For TBT, the lethal whole-body tissue concentration affecting 50% of individuals (LR50) exhibits little variation, occurring at approximately 48 micrograms/g (166 nmol/g) dry weight in a range of species. Direct evidence and correlation of the LC50 and the bioconcentration factor (BCF) support this observation. Impaired growth, a sublethal response, also appears to be associated with a relatively constant tissue concentration, which has also been demonstrated by direct measurement and indirectly by regression of the BCF and LOEC. The lowest-observed-effect tissue residue (LOER) associated with impaired growth for several species was approximately 3 micrograms/g (10.4 nmol/g) dry wt. Because of the small number of studies linking growth impairment and tissue concentrations, additional studies are needed to confirm these values. (ABSTRACT TRUNCATED)