Dissipation pattern and risk assessment of the synthetic pyrethroid Lambda-cyhalothrin applied on tomatoes under dryland conditions, a case study

Résumé

The present study was carried out to develop and validate an analytical method for the detection and quantification of lambda-cyhalothrin, a synthetic pyrethroid insecticide, in tomato using gas chromatography-electron capture detector (GC-ECD). The study has meant to ascertain lambda-cyhalothrin dissipation behavior under dry land conditions. The analytical method was validated using blank tomato spiked at 0.01, 0.1 and 0.5 mg/kg, with satisfactory recoveries ranging between 92.3 to 95.1 % and relative standard deviations (RSDs) < 13.4 %. Good linearity was achieved, with a determination coefficient (R 2) of 0.999 for the 0.005–2.0 mg/L concentration range. The limits of detection and quantification were 0.005 and 0.01 mg/kg, respectively. Dissipation pattern of lambda-cyhalothrin applied on open field grown tomato was also assessed using the same method. Lambda-cyhalothrin residues declined very quickly following first-order rate kinetics with half-life of 3.12 days. At harvest time, 14 days after final application, the remaining residues of lambda-cyhalothrin were below CODEX maximum residue limit (MRL) of 0.05 mg/kg. Exposure of lambda-cyhalothrin has been assessed and compared to acceptable daily intake (ADI). The assessment of consumers’ exposure was based on the international estimated daily intake (IEDI) compared to acceptable daily intake (ADI). The long-term risk assessment was performed by calculating the hazard quotient (HQ). Since the HQChronic of lambda-cyhalothrin never exceeded 1.2 %, the tomato fruits could be considered safe for human consumption 14 days after application of lambda-cyhalothrin at the recommended dose.

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