Deposition, dissipation, metabolism and dietary risk assessment of chlorothalonil in open field-planted cabbage

Chlorothalonil is a fungicide commonly used to prevent and control leafy vegetable diseases. The residual distribution of chlorothalonil on cabbage is unclear and rarely reported. The spatiotemporal distribution of chlorothalonil was used to understand its environmental behavior in cabbage. The results of open-field experiments demonstrated that chlorothalonil was distributed primarily on the second and third layers of rosette leaves and the first layer of bulb leaves. The chlorothalonil residues on cabbage followed the order of winter > fall > summer, and heading stage > rosette stage > seedling stage. Chlorothalonil on cabbage underwent -OH substitution forming 4-hydroxychlorothalonil, and reductive dechlorination forming 2,4,5-trichloro-1,3-isophthalonitrile, 2,5-dichloro-1,3-isophthalonitrile, and 5-chloro-1,3-isophthalonitrile. The residues of chlorothalonil in the outermost leaves of cabbage bulb pose an unacceptable risk to human health via dietary exposure. This study contributes to better understanding on the fate and transformation chlorothalonil in cabbage and potential risks to human health via dietary consumption.