3种氯酚对噬热四膜虫的毒性效应

以原生动物噬热四膜虫作为受试生物,研究了3种氯酚的急性毒性和遗传毒性及环境因子对污染物的生物效应,探讨了水体硬度对3种氯酚生物毒性的影响.结果表明,3种氯酚毒性大小依次为五氯酚(PCP)>2,4,6-三氯酚(2,4,6-TCP)>2,4-二氯酚(2,4-DCP),表明随着氯原子数目的增加,生物毒性增强.硬度实验结果显示随水体硬度升高,3种氯酚对四膜虫的急性毒性先降低后增加,但不同的水体硬度下2,4-DCP对四膜虫的24、48、72和96 h EC50值分别为3.69、3.54、3.02和2.34 mg·L-1;2,4,6-TCP分别为3.23、2.83、2.56和1.97 mg·L-1;PCP分别为0.63、0.45、0.34和0.28 mg·L-1,3种氯酚的EC50值分别在同一数量级上,表明对四膜虫的毒性影响不大.采用单细胞凝胶电泳技术(SCEG)研究了3种氯酚对四膜虫核DNA的损伤作用,结果显示氯酚类化合物具有细胞毒性,彗星实验可以较好地指示氯酚类化合物的遗传毒性.

Toxicity of Three Chlorophenols to Protozoa Tetrahymena thermophila

Using Tetrahymena thermophila as the indication organism, the single acute toxicity and genotoxicity induced by 2,4-dichlorophenol (2,4-DCP), 2,4,6-trichlorophenol (2,4,6-TCP) and pentachlorophenol (PCP) were determined. The results showed that the 24, 48, 72 and 96-hour EC₅₀ values of 3 individual CPs to T. thermophila were 3.69, 3.54, 3.02, 2.34 mg·L^-1; 3.23,2.83, 2.56, 1.97 mg·L^-1 and 0.63, 0.45, 0.34, 0.28 mg·L^-1, respectively, which revealed that the acute toxicity of CPs increased with the number of chlorine on benzene ring. Effects of water hardness on the acute toxicities of 2,4-DCP, 2,4,6-TCP and PCP to T. thermophila were evaluated. It showed that the effect of water hardness on the acute toxicities of the three CPs to T. thermophila had a certain influence, but the impact was relatively insignificant. The results in the SCGE showed that there were significant differences (P<0.05) between the control and treatment groups at various concentrations of the three CPs. It recommended that the comet assay of T. thermophila was sensitive to the three detected CPs and could be a useful tool for screening and detecting of environmental genotoxins.