Residualdynamicsandriskassessmentoffosthiazateinsugarcaneandsoil

An effective method was developed for the determination of fosthiazate residue in sugar cane and soil. Field trials were designed to evaluate the dissipation and residue of fosthiazate in sugar cane and soil in Guangdong Province and Guangxi Province. The dietary exposure and risk assessment were also conducted. The samples were extracted by acetonitrile, cleaned up by NH₂-solid phase extraction and detected by GC-FPD. The results showed that, in terms of sugar cane samples, good average recoveries of 83%-84% with relative standard deviations of 2.6%-3.4% at the spiked level of 0.01, 0.1 and 1 mg/kg were achieved. As for soil samples, recoveries of 84%-86% with RSDs 4.1%-6.7% were obtained. The limit of detection (LOD) was 0.01 mg/kg and the limit of quantification (LOQ) was 0.01 mg/kg. The results demonstrated that residue of fosthiazate in sugar cane decreased first, then increased, and finally decreased again. The maximum concentration were 0.027 mg/kg which was detected 14-21 d after the application. Dissipation of fosthiazate in soil was in accordance with the first order kinetic equation with half-lives from 8.6 to 9.6 d. The terminal residue was below 0.01 mg/kg at harvest time. The acute dietary intake risk probability of fosthiazate was 225%, which was hazardous to people. It is necessary to combine the metabolic behavior data of fosthiazate in human body for comprehensive evaluation. The chronic dietary intake risk probability of fosthiazate was 57%, which was not hazardous to people.