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

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 12,568 ng kg-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 3142 ng kg-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.

Risk of human exposure to metals in some household hygienic products in Nigeria.

This study presents data on the levels and risk of human exposure to Cd, Pb, Cr, Ni, Cu, Co, Mn, Zn and Fe in some popular brands of household hygienic products (HHPs) available in Nigeria. The HHPs were digested with a mixture of HNO3, HCl and HClO4 in a ratio of 1:3:1 and the concentrations of the selected metals were quantified by atomic absorption spectrophotometry. The metal concentrations (in µg g-1) in these products ranged from 0.4 to 5.4, <0.09-47.0, <0.12-43.7, <0.06-7.5, <0.12-9.5, <0.06-15.0, <0.09-24.5, 9.0-675 and 62.4-434 for Cd, Pb, Cr, Cu, Co, Ni, Mn, Zn and Fe respectively. The systemic exposure dosages for the metals, arising from the use of these HPPs, were less than their respective provisional tolerable daily intake/recommended dietary allowance values. The household hygienic products are safe to use by humans based on the margin of safety values that were all above 100. However, the products contained significant levels of toxic (Cd and Pb), allergenic (Ni and Cr) and other low toxicity metals (Mn, Zn and Fe), which could be a potential threat to the environment.