Levels of residues and dietary risk assessment of the fungicides myclobutanil, penconazole, tebuconazole, and triadimenol in squash

Abstract

Triazole fungicides may potentially harm human health. The 'quick, easy, cheap, effective, rugged, and safe' approach has become popular for extraction and cleanup during pesticide residue analysis. We aimed to (a) validate a method for the simultaneous determination of myclobutanil, penconazole, tebuconazole, and triadimenol in squash using LC-MS/MS and (b) determine the pre-harvest intervals (PHIs) and assess the related risk of consuming squash cultivated under open-field conditions in Saudi Arabia. Using acetonitrile as the extraction solvent and fourfold dilution in deionized water led to weak signal suppression (<-6.1%). The limits of quantitation ranged from 10 to 40 μg/kg. Mean recovery and relative standard deviation ranged from 81.7 to 96.3% and from 3.6 to 11.4%. The half-lives ranged from 2.22 to 3.83 days, and the dissipation followed first-order kinetics. The terminal residues of myclobutanil, penconazole, tebuconazole, and triadimenol were <0.771, <0.307, <0.459, and <0.954 mg/kg, respectively, 7 days after two or three applications of recommended dosages. The PHIs of 7.1-11.4, 8.7-13.1, 3.8-5.3, and 11.3-14.3 days are suggested after the application of the recommended dose and double the recommended dose. A consumer risk assessment based on estimated dietary intake indicated that the consumption of squash treated with the recommended doses does not pose a significant health risk.