Metals in Agbogbloshie e-waste recycling site, Accra, Ghana: distribution, bioaccessibility and health risk assessment

Due to the scarcity of information on the impacts of e-waste on terrestrial and aquatic systems, this study was designed to provide current and timely information on solid and aqueous phase contamination around two informal e-waste recycling sites in Agbogbloshie (Accra, Ghana) and Ashaiman (Tema, Ghana). Field procedures involved sampling 180 urban soil samples, 88 surface dust samples, 96 surface water samples, 21 sediment samples, 32 agricultural soils and 49 leafy vegetables in Agbogbloshie and control sites. Thirteen soil samples were collected in Ashaiman Fitter Line e-waste recycling site. Samples were analysed for total and bioaccessible metal concentrations and mineralogy. Elevated metal concentrations were found in soil and surface dust. Garden soil and leafy vegetables were not contaminated. Dissolved elements were found in small concentrations in the surface waters. Quartz was the dominant mineral in the dust, with albite, anglesite, calcite and tenorite. Bioavailability of metals in selected samples of floor dust, garden soils and leafy vegetables were determined using in vitro extraction employing simulated gastric solutions. Copper, zinc and lead were more bioaccessible in vegetables than in surface dust. Iron had the smallest bioaccessible fraction in both soil and vegetables. Lead in urban soils from burn area topsoils, burn area subsoils, dismantling area topsoils and dismantling area subsoils posed non-carcinogenic risks to children and adults in Agbogbloshie. Lead in soils from Ashaiman posed non-carcinogenic risks to children but not adults. Copper concentrations posed significant non-carcinogenic risks to children from burn area topsoils, burn area subsoils, dismantling area topsoils, and also in Ashaiman soil. Carcinogenic risks from arsenic ingestion of contaminated burn area subsoils and dismantling area topsoils was significant for children living in Agbogbloshie. Similarly, soils in Ashaiman posed carcinogenic risks to children living near the e-waste site.