The aim of this study was to carry out a bio-accessibility based risk assessment of polycyclic aromatic hydrocarbon (PAHs) in soils from sites of different anthropogenic activities in Lagos, Nigeria. Using an in vitro gastrointestinal model-Fed Organic Estimation Human Simulation Test method (FOREShT)), the concentration of bio-accessible 16 priority US Environmental Protection Agency (USEPA) PAHs in soils were determined. Total concentration of 16 priority USEPA PAHs was also determined. The concentration range was 702 to 253,922 ng g-1 and 92-760 ng g-1 for total and bio-accessible PAHs respectively. For persons involved with activities at these sites no health risk were observed, based on bio-accessibility values of PAHs. Mean daily intake of PAHs from these soils were below the oral mean daily intake threshold for PAHs in food. Also, overall estimated theoretical cancer risk (2.

Diet has been established as a major source of exposure to PAHs for humans especially nonsmokers. Therefore their presence in plants constitutes a major health concern. This research aims to determinine the concentration and profile of sixteen US-EPA priority PAHs in tropical edible vegetables (Corchorus olitorius (Ewedu), Celosia argentea (Soko), Amaranthus cruentus L (Grain amaranthus/ Tete), Telfairia occidentale (Ugwu), Basella alba (Amunu tutu/White Spinash), Lactuca Sativa (Lettuce), Allium ascalonicum (Spring Onions/Alubasa elewe), Talinum Triangulare (Water leaf)), grown on potted contaminated soils. Vegetable grown on potted contaminated soils and contaminated soils were extracted using n-hexane/acetone mixture in ultrasonic bath. The extract was purified using a C18 solid-phase extraction cartridge (5 mL). The resultant extract was separated and the PAHs quantified on an Agilent 6890 Gas chromatography/mass spectrometer (GC/MS). Total PAH concentration in contaminated soils and plants grown on them were 200-250,000 ng g-1 and 100-5,000 ng g-1, respectively. Concentration of PAHs in plant roots was generally higher than in the stems. PAH concentration in plant stems was also generally higher than in plant leaves. Two and three ringed PAHs which are the less toxic were dominant in most of the plant parts. One of the vegetable samples Telfairia occidentale (Ugwu) consistently grew on all the soils samples which suggest it possess some potential for phyto remediation.

Soils from 12 sites in Lagos area, Nigeria impacted by anthropogenic activities were extracted by ultrasonication and analysed for the concentration of 16 priority polycyclic aromatic hydrocarbons (PAHs) by gas chromatograph-mass spectrometer (GC-MS). The concentration of the sum of PAHs ranged from 0.2 to 254 μg/g at these sites. The sum benzo[a]pyrene-equivalent dose (BaPeq) at the sites ranged from 0.0 (K, forest soil) to 16.7 μg/g (C, the lubricating oil depot soil). Mean daily intake (MDI) for the composite soils samples when compared that of food revealed that some of the individual PAH in samples from sites A (Dump site), C (Depot and loading point for used for black oil), F (Dump site), G(petroleum depot), H (Roadside) and L (Car park) exceeded the recommended the recommended MDI threshold for food, indicating some risk associated with activities on these sites based on this ingestion estimate exceeded value. 8.2 × 10(-6), 7.1 × 10(-7), 1.2 × 10(-4), 4.9 × 10(-7), 7.3 × 10(-7), 1.4 × 10(-5), 7.9 × 10(-5), 4.6 × 10(-6), 3.4 × 10(-7), 2.4 × 10(-7), 2.2 × 10(-7) and 1.1 × 10(-4) estimated theoretical cancer risk (ER) for an adult with a body weight of 70 kg working on sites were composite soil samples A, B, C, D, E, F, G, H, I, J, K and L respectively were sampled. The ER from occupational exposure to surface soil based on oral ingestion were all higher than the target risk of 1 × 10(-6) for normal exposure but were all within the 1 × 10(-4) for extreme exposure for most of the sites except for site C and L. The differences in concentration and risk were related to the different activities (e.g., handling of petroleum products, open burning, bush burning) undertaken at these locations. However, it should be noted here that the resultant risk could be overestimated, since these calculations were based on an exhaustive extraction technique which may be different from uptake by the human guts (bioavailability study).