A Study On Acute Toxicity And Accumulative Toxicity Of Melamine In Mice

In September,2008,with the outburst of melamine and related problem milk powder incident,people came to get acquainted with the public safety of melamine as a kind of food addictives.Infants consumed these contaminated milk powder would develop calculus of kidney.Until this report,researches on toxicity of melamine mainly focused on its effects on kidney and lacked a relative systematic one.To thoroughly analysis its toxicity on animals and human being, we designed this experiment.In this experiment,we take Kunming (KM) mice as animal model to study the characteristics of acute or accumulation melamine intoxication.And the toxicological mechanism injury and biochemical indicators in blood examined.Acute toxicity test methods:60 mice were randomLy divided into control group andâ… ,â…¡,â…¢,â…£,â…¤5treatments groups of 10 each,male and female in half,housed separately.With melamine (Melamine) as a drug source, intragastric administration by way of a one-time exposure according to total body weight,5 groups were exposed by 5 different intragastric concentration gradient doses as 4500mg/kg,6534mg/kg, 9487mg/kg,13775mg/kg,20000mg/kg,while the control group was given equal volume of ultrapure water,for acute toxicity test.During the clinical trial,we recorded clinical symptom and mortality of experimental mice,calculated the organ index Dead mice were autopsied for observation and histological examination and blood biochemical parameters determined.Acute toxicity test results showed that:Modified Kou-type method showed melamine median lethal dose in mice (LD50) is 12086mg/kg,its 95% confidence interval range is 9817-14879mg/kg,indicated that melamine is micro-poisonous substance.And about 14 hours exposed to melamine mice exhibit apparent clinical symptoms, mainly the spiritual malaise, loss of appetite, lying with eyes closed, breathing difficulties,seizures,and with the elevated of the consumed dose,time of onset of symptoms became earlier and more severer,demonstrated dose-effect relationship.Experimental observation of melamine's toxicity showed that it can also cause liver,spleen, kidney pathological changes and blood biochemical indicators changes.The toxic effects and extent have positive correlation with dose.Note the liver, spleen and kidney may be the major target organ of melamine poisonousness. Accumulative toxicity test method:40 mice were randomLy divided into 2 groups:treatment group has 30 mouse and control group has 10 mouse. Male and female in each group were the same in number.Using incremental exposure method, take 1/10 of LD50 dose as the initial dose,daily exposure,4d for a period,increasing 1.5 times each time,20 to 28 days continuously exposure.This trial ceased when half of all mice were perished,K values were evaluated. Experiment with materials mixing method, and exposure to increasing doses.During the clinical trial,we recorded clinical symptom and mortality of experimental mice,calculated the organ index Dead mice were autopsied for observation and histological examination and blood biochemical parameters determined.Accumulation of toxicity test results showed that:Storage coefficient of melamine in mice is 4.36,which according to accumulative grading standards is moderate accumulation.Cardiac index,liver index,lung and kidney index of poisoned mice though differed but all higher than that of the control group.The main pathological damages seen in mice were kidneys,liver, spleen,lung and other organs.Liver damage,liver cirrhosis was observed cord disorders,degeneration,and hepatocyte swelling, necrosis;renal tubular epithelial cell degenerated,necrosis and tubular proteinuria as well as the phenomenon of melamine crystals appeared. Pulmonary capillary congestion, compensatory emphysema.Spleen cell necrosis, collapse of the immune system resulting the shrinkage of spleen.For blood biochemical indicators,total protein,albumin, A/G value, alkaline phosphatase,Valley GTP reducted,globulin,aspartate aminotransferase,lactic dehydrogenase, serum urea nitrogen,serum creatinine increased,indicating that melamine do harm to liver and kidney.According to the results of this experiment,melamine is no doubt a toxicant no matter to animals or human beings.The consumption of this chemical will result in heart,liver,spleen,lung and kidney lesion,especially liver and kidney.