Transfer of pesticides and metabolites in corn: Production, processing, and livestock dietary burden

Corn stover is widely used in livestock feed but has received limited attention regarding its potential risks. In this study, pesticide residues were monitored across 12 provinces in China, and terminal residues of four pesticides, chlorantraniliprole, thiamethoxam, epoxiconazole, and pyraclostrobin, were tested. In addition, the silage processing experiment was conducted. All processing factors (PF) were <1, indicating pesticide degradation. The physicochemical properties of pesticides, especially log P, were related to degradation efficiency. Pesticides with higher log P values showed higher PFs (0.43 to 0.85), indicating lower degradation efficiency. The dietary burden of livestock before and after silage processing was calculated using OECD livestock dietary burden calculator. Results showed that after silage fermentation, the dietary burden was reduced by 28.8 % to 79.2 %. Throughout the entire production and processing process, the fastest degradation of all pesticides in whole corn was primarily observed from the pesticide application time to the harvest time, with some pesticides also showing accelerated degradation during subsequent processing stages. Therefore, in actual production, especially for pesticides which are difficult to degrade, appropriate extension of the safety interval or selection of suitable processing methods can be taken to further reduce pesticide residues in agricultural products.