Dissipation of pesticides used on covered crops in Eastern Sicily.

Dissipation rates of the fungicides vinclozolin, chlorothalonil and hexaconazole, used in a few Sicilian greenhouse productions (autumn and spring aubergine and tomato), and the insecticide endosulphan, used on a field covered crop (grape), were investigated by gas chromatography-electron capture detection (GC-ECD). Residues were evaluated either on washed or not washed fruits. The used extraction-cleanup and determination methods allowed the assessment of pesticide dissipation in considered trials with good recoveries, selectivity, sensitivity and repeatability. Residue contents were found to be greater than expected, probably because abiotic and biotic degradation processes were reduced under the protected environment. The thermoclimatic difference between autumnal and spring growing exerted a positive influence on degradation of pesticides. Washing procedure induced a noteworthy reduction of residue levels on aubergine and tomato, but not on grape. Degradation rates of active ingredients were influenced by initial concentrations. Higher levels of residues were measured in tomato compared to aubergine. Vinclozolin dissipation was lower than that of the other tested fungicides. In these conditions, the use of active ingredients characterized by slower dissipation rates should be limited. Consequently, the safety period to elapse before harvesting should be increased to minimize the risk of consumer exposure to expected pesticide residues.