Polycyclic aromatic hydrocarbons (PAHs) in leafy vegetables consumed in southern Nigeria: concentration, risk assessment and source apportionment.

Abstract

Four commonly consumed leafy vegetables, obtained from four major cities in southern Nigeria, were analysed for their polycyclic hydrocarbon (PAH) content using gas chromatography coupled with mass spectrometry (GC-MS). The estimated daily intake (EDI), margin of exposure (MOE), hazard index (HI) and total cancer risk (TCR); principal component analysis (PCA) and diagnostic ratios (DRs) were respectively used for risk evaluation and source identification of the detected PAHs. The results showed that the mean concentration (µg kg-1) of ∑16 PAHs in the vegetables ranged from 532 to 2261. The EDI values ranged from 459 to 4876, 1809 to 8378, 2733 to 13,036 and 4143 to 12,568ngkg-1 bw day-1 for benzo[a]pyrene (BaP), PAH2, PAH4, and PAH8 for children exposure respectively, and from 115 to 1219, 452 to 2095, 683 to 3259 and 1036 to 3142ngkg-1 bw day-1 for adult exposure respectively. The estimated MOE values were < 10,000, indicating that the vegetables were unsuitable for consumption. The HI values were < 1, suggesting that there were no potential non-carcinogenic risks, but the total cancer risk values (> 1 × 10-6) designated carcinogenic risk of PAHs with consumption of these vegetables. The DR and PCA result showed that PAHs originated from high-temperature pyrogenic processes and vehicular emissions.