有机污染物对发光菌和鱼的毒性相关性研究

研究有机污染物对不同水生生物毒性的种间关系有助于探讨有机污染物对水生生物的毒性作用模式。本文应用1 470种有机化合物对发光菌的毒性数据和949种有机化合物对鱼的毒性数据,研究有机化合物对发光菌和鱼的种间毒性作用模式。结果表明,有机化合物对发光菌和鱼的毒性呈正相关,但种间相关性较差。通过计算毒性比率TR值表明多数类别有机化合物具有相似的种间毒性作用模式。基线和弱惰性化合物对发光菌和鱼的毒性均与辛醇水分配系数log Kow具有良好的线性关系,这说明基线和弱惰性化合物在发光菌和鱼体内的残余量CBR值均为一个常数。这些化合物对发光菌和鱼具有相似的毒性作用模式和生物吸收过程。另外,一些亲水性化合物的log TR值具有较大的种间差异,即对发光菌和鱼的毒性效应具有较大的种间差异,表明亲水性化合物对发光菌为反应型化合物,而对鱼为麻醉型化合物。有机化合物对发光菌和鱼的毒性种间相关性通过引入疏水性参数得到了一定的改善,这表明这些亲水性化合物毒性效应的种间差异有一部分归因于有机化合物在发光菌和鱼体内的生物富集不同,而不是由于与生物分子的反应性不同。这些亲水性化合物相对于鱼的腮和皮肤更容易通过发光菌的细胞膜,与生物分子发生化学反应,从而具有较高的毒性效应。Log Kow大于7的化合物对发光菌和鱼均具有较低的毒性,说明有机化合物在生物体内的富集能力对有机化合物剩余毒性的判别起着重要作用。

Investigation of Toxicity Correlation of Organic Pollutants between Vibrio fischeri and Fish

Investigation of the toxicity correlation between species plays a key role in the studying of the chemical toxic mechanisms to aquatic organisms. In this paper, the toxicity data of 1470 compounds to Vibrio fischeri and 949 compounds to fish were used to investigate the modes of action (MOAs) between species. The results showed that the toxicity relationship was poor in spite of there was a positive interspecies correlation. Analysis on the excess toxicity calculated from toxic ratios (TR) showed that many compounds had close toxicities and share the same MOAs between species. Linear relationships between the toxicities and octanol/water partition coefficient (log Kow) for baseline and less inert compounds indicate that the critical body residues (CBRs) approach a constant both to fish and V. fischeri for these compounds. These compounds shared the same toxic mechanisms and bio-uptake processes between species. On the other hand, some hydrophilic compounds have different MOAs with significantly different log TR values between species. These hydrophilic compounds were identified as reactive compounds to V. fischeri, but not to fish. The interspecies correlation was improved by the inclusion of log Kow into the correlation equation. This indicates that the differences in the toxic ratios between fish and V. fischeri for these hydrophilic compounds can be partly attributed to the differences of bioconcentration between species, rather than the differences of reactivity with the target macromolecules. These hydrophilic compounds may more easily pass through the cell membrane of V. fischeri than the gill and skin of fish, react with the target macromolecules and exhibit excess toxicity. The compounds with log Kow > 7 exhibiting very low toxicity to both species indicate that the bioconcentration potential of a compound plays a key part in the identification of excess toxicity.