Biotoxic Effect Of Endosulfan On Grass Carp Ctenopharyngodon Idellus

Fish is one of the main economic resources, which plays a very important role in the body of water, such as the ecological balance of aquatic ecosystems, the normal flow of energy, stoffkreislauf, the increasing of the productivity of the water body and enhancing the economic performance. As a kind of typical persistent organic pollutants, endosulfan, the organochlorine pesticide, was widely used in agricultural production and it is still being used widely in some areas of China. Endosulfan would through the surface runoff, leaching and wet/dry deposition into the water, which will have direct impact on aquatic macroohytes and planktonic algae, and at the same time, it will bring a certain amount of toxic effects to fish and other aquatic animals. Because of its long half-life period, better migration abilities and higher enrichment, endosulfan is widely detectable in the water body. Therefore, the safety evaluation of endosulfan in the aquatic ecosystem is very important.In this study, indicator organism is the Ctenopharyngodon idellus. The study use the way of traditional environmental toxicology to test the acute toxicity of endosulfan. On the basis of mastering its median lethal concentration, through the way of subacute toxicity test, the research can assay the impact of endosulfan on the detoxification system enzymes, antioxidant defense system and genetic damage of the Ctenopharyngodon idellus, systematically discussed the ecotoxicity and the genetic toxicity of endosulfan.1. Used method of static state, the median lethal concentration LC50of the endosulfan for the Ctenophaiyngodon idellus was found3.82μg/L in24h,2.52μg/L in48h,1.86μg/L in72h,1.42μg/L in96h, with safe concentration (SC) of0.33μg/L. The test fish exposed to endosulfan showed increase in mortality with the increase in the concentration, indicating a significant dose-response relationship. According to Class standards on toxic chemicals in fish, endosulfan as highly toxic to fish should be paid particular attention in use to avoid harm to aquatic organisms. 2. The experiment was designed to have four treatments, that is, CK and three levels of endosulfan concentration (A:0.18, B:0.36and C:0.71μg/L). Samples of the fish were taken for analysis separately after they lived in these treatments for24,72,120and168h. Results show that in Treatments B and C the activity of APND was significantly higher after24h, but inhibited significantly after72h as compared to CK. It was inhibited to a significant extent after120h in all the treatments. On the whole the activity of ERND was induced by the exposure, whereas the activity of GST was induced at the initial stage and then turned to be inhibited. In Treatments B and C the activity of GST peaked after72h of exposure and afterwards declined gradually with the duration of exposure, till168h when it turned to be inhibited, while in Treatment A, it peaked after120h and declined afterwards, too, till168h when it turned off to be equal to that in CK.3. The activities of SOD, CAT and GSH-Px in liver and muscle of Ctenopharyngodon idellus were significantly affected after24h exposure, showing a slow decrease after induction, then the SOD activities was significantly lower than the controls level, while the GSH-Px activities with no significant differences between the controls. The LPO level was rising when the antioxidant enzymes are affected in the same time, the MDA contents were increased, and reached the highest value after96h exposure.4. The NM showed that frequencies of micronuclei, nuclear anomalies and total nuclear anomalies in Ctenopharyngodon idellus erythrocytes increased with endosulfan exposure concentrations, showing an obvious dose-response relationship. During a certain exposure period (≤96h), micronuclei, nuclear anomalies and total nuclear anomalies in exposure groups showed a time-effect relationship. After96h, prolongation of exposure time no longer led to further increase of micronuclei, nuclear anomalies and total nuclear anomalies in higher concentration groups (0.36μg/L and0.71μg/L). In SCGE Test, the damage the exposure of the fish to endosulfan brought to DNA of its liver cells was significant in the exposure of0.18～0.71μg/L after24～168h. Endosulfan can causes genetic damage to the DNA of liver cells of the fish. Liner regression analysis showed that the time-effect and dose-response of liver cell DNA damage of Ctenopharyngodon idellus after endosulfan exposure were significant.