A total of 23 pesticides from different chemical groups in 160 different domestic vegetables collected from four major big supermarkets located in Al-Qassim region, Saudi Arabia, were identified by gas chromatography with mass spectrometry (GC-MS). Residues were found in 89 of the 160 samples and 53 samples were above the maximum residue levels (MRLs). The most frequently found pesticides were carbaryl followed by biphenyl and then carbofuran. Cabbage was the most positive and violated MLRs (16 and 11 samples), followed by carrot and green pepper (12 and 7 samples), cucumber (12 and 6 samples), egg-plant (12 and 5 samples), squash (11 and 7 samples), lettuce (11 and 6 samples) and tomato (11 and 4 samples). The highest concentrations were found in lettuce (ethiofencarb, 7.648), followed by tomato (tolclofos-methyl, 7.312 mg/kg), cabbage (chlropyrifos, 6.207 mg/kg), carrot (heptanophos, 3.267 mg/kg), green pepper (carbaryl, 2.228 mg/kg) and egg-plant (carbaryl, 1.917 mg/kg). These findings pointed to the following recommendation: the need for a monitoring program for pesticide residues in vegetables cultivated under greenhouse conditions at the national level to protect consumers' health.
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