Cerium Chloride Induces Acute,Subchronic And Chronic Toxicity In Gobiocypris Rarus

Rare earth elements are widely used in industry,agriculture,medicine and other fields because of their excellent physical and chemical properties,which lead to them entering into the ecological environment in a large number of ways.As rare earth elements enter into the organism and accumulate in a certain amount,it will cause toxicity to the organism.However,studies on the toxicity of cerium were few,and the test animals used in these researches were not the Chinese native recommended materials.Gobiocypris rarus,an endemic species of China,is one of the recommended test organisms in the Guidelines for the testing of chemicals.So,in this study,the toxic effects of cerium chloride on Gobiocypris rarus were researched by acute toxicity,subchronic toxicity and chronic toxicity.The results were shown as follows:1.The median lethal concentration(96h:LC₅₀)of Ce³⁺in G.rarus was 1.07 mg/L and its 95%confidence interval was from 0.986 to 1.168 mg/L.The safe concentration(SC),no observed effect concentration(NOEC),lowest observed effect concentration(LOEC)and maximum acceptable toxicant concentration(MATC)value of Ce³⁺was 0.11,0.50,0.72 and 0.60 mg/L,respectively.2.Conclusion analysis of toxicity test of embryo yolk sac larvae:(1)When exposed for 36h,the number of spontaneous movements of rare Carassius auratus in 0.04 mg/L group decreased very significantly(P<0.01)compared with the control group;the 0.32mg/L group increased significantly(P<0.05).(2)When exposed for 48h,The fetal heart rate in 0.02 and 0.32 mg/L group increased significantly(P<0.05);When exposed for 72h,0.02,0.04 and 0.08 mg/L group decreased very significantly(P<0.01),the 0.32mg/L group increased significantly(P<0.05);When exposed for 84h,the 0.16,0.32 and 0.50mg/L group increased significantly(P<0.05).(3)After 72h of exposure,the hatchability of 0.02 mg/L group increased very significantly(P<0.01),the 0.08 mg/L group increased significantly(P<0.05);After 96h of exposure,the 0.02 and 0.04 mg/L group decreased significantly(P<0.05).(4)After 168h of exposure,the cumulative mortality in 0.02,0.16,0.32 and 0.50 mg/L group was increased very significantly(P<0.01).(5)After 168h exposure,the area of pericardium in 0.08,0.16 and 0.50 mg/L group increased significantly or very significantly(P<0.05 or P<0.01);The area of yolk sac in 0.04 0.16,0.32 and 0.50 mg/L group increased very significantly(P<0.01).(6)At the end of the test(168h exposure),the body length of 0.02-0.50 mg/L group decreased very significantly(P<0.01);the weight in 0.02,0.04,0.32 and 0.50 mg/L group lossed very significantly(P<0.01),the 0.16 mg/L group increased significantly(P<0.05).3.After 28 days of chronic toxicity test,the results of histological structure of gill and liver of Carassius auratus compared with the control group were as follows:The average length of gill segments in 0.50 mg/L group decreased significantly(P<0.05);The average width of gill segments in 0.08-0.50 mg/L group increased significantly or very significantly(P<0.05 or P<0.01);The average area of gill in 0.08-0.32 mg/L group was increased significantly or very significantly(P<0.05 or P<0.01).The obvious pathological features of gill are the distortion of small piece epithelium,hyperplasia,edema and exfoliation necrosis of gill filament epithelium.The symptoms of liver include capillary swelling and congestion,hepatocyte vacuolation,nucleolysis and large area necrosis and so on.4.At the end of 28d chronic toxicity test,the analysis of antioxidant stress indexes of Carassius auratus showed that:(1)Compared with the control group,the MDA content of hepatopancreas in 0.16 mg/L group decreased significantly(P<0.05),the 0.32 mg/L group increased very significantly(P<0.01).(2)The SOD activity of hepatopancreas in0.04,0.08 and 0.16 mg/L group decreased significantly or very significantly(P<0.05 or P<0.01);The SOD activity in 0.32 mg/L group increased very significantly(P<0.01);The0.50 mg/L group decreased very significantly(P<0.01).(3)The Cat activity in 0.04,0.08and 0.16 mg/L group decreased significantly or very significantly(P<0.05 or P<0.01);The 0.32 mg/L group increased very significantly(P<0.01);the 0.32 mg/L group decreased very significantly(P<0.01).