[Objective] In order to provide a reference for safe and reasonable use of pyrethroids in cigarette production,the degradation behaviors of three kinds of pyrethroids in cigarette production environment were studied. [Method]Three kinds of pyrethroids( permethrin,cyfluthrin and cis-cypermethrin) were administrated to two media( cut tobacco and iron sheet surface) in cigarette production environment at MRLs concentration,and the first sampling was conducted at 24 d post administration. Afterwards,sampling was performed once every 7 d,with a total of six times. The degradation rates of insecticides in different media were calculated,and degradation models were established. [Result] The contents of three kinds of insecticides in two media gradually declined with the prolongation of time,and degradation rates presented the trend of fast-slow-fast; the degradation rates of permethrin,cyfluthrin and cis-cypermethrin in cut tobacco at 36 d post administration were 97. 14%,88. 89% and 95. 38%,respectively; the degradation rates on iron sheet surface were 29. 95%,48. 99% and 40. 24%,respectively.The half lives of three kinds of insecticides in cut tobacco were 1- 2 d,while those on iron sheet surface were 6- 10 d. [Conclusion]The contents of three kinds of insecticides in two media gradually declined with the prolongation of time,and their degradation regularity accorded with first order kinetic equation.
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