| Objective: Pyraflufen-ethyl is a new type of herbicide, which be widely applied in agriculturalindustry. The study through chonic toxicity test, observing the general toxicity, which canprovide a relatively complete set of data for the common chemical toxicity assessment.Method:640SPF SD rats (weight of40~50g, half male and half female) were randomlydivided into groups with zero, low, middle and high dose feed of Pyraflufen-ethyl for comparingwith each other. Each group has160rats, half male and half female. The contents ofPyraflufen-ethyl in feeds for groups with dose of zero to high are0mg/kg,80mg/kg,400mg/kgand2000mg/kg respectively. Dose feeding for the groups of rats will last for104consecutiveweeks. During the feeding period, water drinking is free for rats. Detailed records of dying anddead rats were made while observing the activity, appearance and physical signs of the rats daily.From the1th week to the13th week, weights and feeds volumes of the rats were recorded onWednesday weekly. From the14th week to the104th week weights and feed volumes of the ratswere recorded on Wednesday for every4week. In the26th,52th and78th week, rats foranatomy were chose (20rats per one group with half male and half female, and single gendertesting number n=10). In the104th week, the team took all survived rats of all groups (singlegender testing number n>10) and conducted blood biochemical tests, urine routine test, andorgan coefficient calculation after anatomy and organ weighting, as well as histopathological test.The team used single factor analysis of variance (ANOVA) for the measurement of data such asbody weight, feed intake, blood index, organ weight, and used Dunnett to test and compare thesignificance of difference between dose fesd groups and control group, used X2examine methodfor statistics collecting of clinical signs and death. Fisher was used for probability checking inpathological anatomy findings and histological findings, and software of SPSS12.0was alsobeen used for data analysis.Results: Weights decreases in high dose groups were obvious, comparing with the control group.In medium dose group, only female rats had low intake rate of feed from the1th week to the26th week, while in high dose group, the intake rates of feed of both male and male were low. Sometimes, medium and high dose of testing subject could lead to the changes in rats withincrease of AST, BUN, CHOL contents, and decrease in ALB, T-BIL, GLU, TG and CHE, thuscertain toxicological significance was fund. By comparing the organ weights and organcoefficient of medium and high dose groups with that of the control group, the differences wereobvious, and mainly on liver, kidney, testis, renicapsule, thymus gland. The histopathological testshowed that the toxic targeted organ was kidney, and rats of medium and high dose groups hadpathologic damages in52th,104th week in renal tubular epithelial cells degeneration, or aschronic renal disease, renal interstitial inflammation, etc.Conclusion: In this experiment, no harmful effects of Pyraflufen-ethyl on SD rats were fundduring the104week long chronic toxicity test. Dose (NOAEL) in the test:80mg/kg of feed forboth male and female rats, calculated as Pyraflufen-ethyl in content:7.45mg/kg/day for femaleand5.84mg/kg/day for male. The minimum dose with harmful effect:400mg/kg of feed,calculated as Pyraflufen-ethyl in content:38.32mg/kg/day for female and29.17mg/kg/day forfemale. Target organ of the testing subject was kidney. |
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