Dissipation and distribution of difenoconazole in bananas and a risk assessment of dietary intake.

The dissipation and terminal residues of difenoconazole in whole bananas and pulp were investigated under field conditions. The residual levels of difenoconazole in various parts of bananas grown in Guangdong, Hainan and Yunnan were determined by a GC-ECD detection method after simple, rapid pretreatment. The mean recovery was 80.66~107.40%, and the relative standard deviation was 3.36~9.84%. The results showed that the half-lives of difenoconazole in whole bananas and in the pulp were 12.16~13.33 days and 17.77~20.38 days, respectively. At harvest intervals of 28 and 35 days after the last application, the terminal residues of difenoconazole in whole bananas and pulp were 0.45~0.84 mg/kg and 0.19~0.37 mg/kg, respectively, which were lower than the maximum residue level established in China. The distribution of difenoconazole in banana pulp and peels was studied. The results showed that until harvesting, the residue in the peels was always 2.19~12.30 times larger than that in the pulp. Difenoconazole was mainly absorbed by the banana peels but did not easily penetrate into the pulp. Based on dietary risk assessment results, the residual levels of difenoconazole at the sampling interval of 28 days after the last application were within acceptable limits for chronic and acute dietary risks in different populations in China. This study can provide a reference for the safe and rational use of difenoconazole as a fungicide and for the future research and application of banana pulp and peels.