Background.Soil contamination from heavy metals and polycyclic aromatic hydrocarbons (PAHs) released during informal e-waste processing and disposal poses human and ecological health risks in Nigeria.Objectives.This study assesses the levels of heavy metals and PAHs in soils of e-waste dumpsites in Lagos and Ibadan, Nigeria.Methods.Composite soil samples were collected at depths of 0–15 cm, 15–30 cm and 30–45 cm from major e-waste dumpsites in Lagos and Ibadan and analyzed for lead (Pb), cadmium (Cd), copper (Cu), nickel (Ni), zinc (Zn), chromium (Cr) and PAHs to evaluate the potential contaminant contribution from e-waste activities. Control samples were collected at the Botanical Garden, University of Ibadan. Samples were analyzed for heavy metals after acid digestion using atomic absorption spectrophotometry, while PAHs were extracted using cold solvent extraction and quantified by gas chromatography-mass spectrometry. Blank determination and recovery studies were carried out for each metal. Contamination and ecological risks were assessed using soil contamination indices such as contamination factor, geo-accumulation and pollution load indices, and potential ecological risk index to categorize contaminant concentrations and associated impacts. Soil physico-chemical characteristics such as pH and total organic matter were also determined.Results.Metals concentrations in the dumpsite soils ranged from 114–2,840 mg/kg and not detectable - 6.50 mg/kg for Pb and Cd, and 42.8–5,390 mg/kg, 27.5–3,420 mg/kg, 11.0–128 mg/kg and 94.0–325 mg/kg for Cu, Zn, Ni and Cr, respectively. Serious metals accumulation was observed at every e-waste dumpsite, as shown by the pollution load index. The potential ecological risk values were between 584 and 10,402 at all of the dumpsites, signifying very high ecological risk. The total PAHs ranged from 1,756–2,224 μg/kg at the 0–15 cm level, 1,664–2,152 μg/kg at 15–30 cm and 278 μg/kg in the top- and sub-soil of the control site.Discussion.The total PAHs in the soil of e-waste dumpsites was significantly higher than in the control soil.Conclusions.The results of this study indicate that indiscriminate dumping and open burning of e-waste are potential sources of PAH and toxic metal emissions, which can pose serious human health and ecological risks.

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Canned foods are one of the most commonly consumed products, due to benefits like the taste, handiness and convenience derived from them. On the other hand, these dietary products may be a means of heavy metal exposure and toxicant. This study aimed to quantify metals content in some frequently consumed canned foods in Nigeria as a possible source of toxicity. Twenty-two different commonly consumed brands of canned foods (Sweet corn, Green peas, Corned beef, Hotdog, Mushroom, Tin tomato, Mixed fruit, Baked beans, Mackerel (tomato sauce canned fish), Sardine (canned fish in vegetable oil) and Red kidney were analyzed for Ni, Cr, Cu, Pb and Al using Atomic Absorption Spectrophotometer after wet digestion. The results showed that the heavy metals concentration in the samples under study ranged from 0.55 to 0.86mg/kg (Ni), 0.00 to 0.41mg/kg (Cr), 1.40 to 1.76 mg/kg (Pb), 0.07 to 0.2mg/kg (Cu) and 4.71 to 16.4mg/kg (Al). The levels of Pb, Ni and Al were above FAO/WHO recommended limit of 0.01mg/kg, 0.05mg/kg and 7mg/kg respectively. The presence of heavy metals like lead (Pb) above the permissible limit calls for caution during production and in the frequent consumption of canned foods which may lead to accumulation of metals, toxicity and the sequelae.

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/kg), respectively. The mean concentration of Pb was far above (four times higher than) the normal crustal average for soils while the other heavy metals were below the normal background level. The concentration of Pb is also the highest at the distance closest to the factory which indicate that Pb is the major heavy metal impacted on soils by the company which elevate the normal background level and thereby contaminate the soils and make it unfit for agricultural purposes as plant take up the leached metals and ultimately find its way into animals and human body through the food chain.