Dissipation kinetics and risk assessment of pyraclostrobin after open field application in cucumber under Egyptian conditions

Pyraclostrobin is a strobilurin fungicide and widely used in Egypt for the protection of cucumber cultivation from several high-risk diseases. We have investigated (1) consumer safety after pyraclostrobin treatment in cucumbers and (2) its residue behavior. Supervised field trials were conducted to estimate the dynamics and terminal residues of pyraclostrobin in cucumbers grown under Egyptian climatic conditions and several agricultural practices, including worst case scenarios. For the determination of residues in fruits, a QuEChERS (quick, easy, cheap, effective, rugged, and safe)-based protocol coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) was employed and successfully validated at a limit of quantification (LOQ) of 0.001 mg kg(-1). The decline of pyraclostrobin residues in fruits fit a first-order decay process with a calculated t(1/2) of 2.26 days and a significant degradation (99%) after 14 days. A consumer risk assessment was performed employing both FAO/WHO and EFSA approaches. No significant health risks after the consumption of treated cucumbers were identified.