Evaluation of pesticide residue dynamics in Chinese cabbage, head cabbage and cauliflower.

Pesticide residues from the time of application until harvest were analysed for 20, 17 and 18 active insecticidal and fungicidal substances in Chinese cabbage, head cabbage and cauliflower, respectively. In total, 40 mathematical models of residue degradation were developed using a first-order kinetic equation, and from these models it was possible to forecast the action pre-harvest interval for a given action threshold for low-residue production in Brassica vegetables as a percentage of the maximum residue level. Additionally, it was possible to establish an action pre-harvest interval based on an action threshold of 0.01 mg kg for the production of Brassica vegetables for baby food. Among the evaluated commodities, the speed of residue degradation was highest in head cabbage, medium in Chinese cabbage and lowest in cauliflower. The half-lives of pesticide in various vegetables were also determined: they ranged from 1.55 to 5.25 days in Chinese cabbage, from 0.47 to 6.54 days in head cabbage and from 1.88 to 7.22 days in cauliflower.