First Assessment of Multi-Residue Pesticide Occurrence in Commercial Wheat Flour from Al-Bayda City, Libya: Physicochemical Quality and Dietary Health Risk Assessment

Abstract

Wheat flour is the primary dietary staple in Libya, yet comprehensive pesticide residue monitoring data for commercial flour remains no peer-reviewed studies have been published. This study provides the first multi-residue pesticide assessment of commercial wheat flour from Al-Bayda City, northeastern Libya, integrating gas chromatography–triple quadrupole mass spectrometry (GC-TSQ-MS, SIM mode) screening 18 compounds across five flour samples, and liquid chromatography–tandem mass spectrometry (LC-MS/MS, QuEChERS, EN 15662:2018) analysis of six samples at an EGAC-accredited laboratory (FDSC, Egypt; ISO/IEC 17025:2017, CAB #022136). Physicochemical parameters were simultaneously characterized for five samples including moisture, ash, protein, wet gluten, Zeleny sedimentation, falling number, and heavy metals (Cd, Pb). Eleven unique pesticide compounds were detected. Key findings: Malathion detected in 4/5 GC-MS samples (20.98–36.90 µg/kg); Fenitrothion in 5/5 samples (21.10–35.22 µg/kg); Permethrin in 5/5 samples (22.33–30.89 µg/kg); Deltamethrin in 4/5 samples (35.58–45.22 µg/kg); Chlorpyrifos-methyl in 4/5 samples (22.19–30.44 µg/kg); Piperonyl butoxide (PBO) quantified by LC-MS/MS in one sample at 0.032 mg/kg. All detected concentrations were below Codex Alimentarius and EU MRLs, except fenitrothion and dichlorvos, which exceeded their default MRL of 0.01 mg/kg. Health risk assessment confirmed negligible chronic dietary risk for Libyan adults (THQ = 0.0183) and children (THQ = 0.0276). Physicochemical parameters were within Libyan standard specifications, confirming commercial acceptability. These results establish an initial reference datasetfor wheat flour in eastern Libya, consistent with post-harvest grain storage insecticide use.