Characterization of oral bioaccessibility of Potentially Toxic Elements (PTEs) in urban area of Belfast

Urban environments have been modified significantly since the industrial revolution, due to the release of many Potentially Toxic Elements (PTEs) and their accumulation in topsoil. Belfast, the largest city in Northern Ireland, is historically recognised for both linen production and shipbuilding. A recent study using the Tellus geochemical dataset (McIlwaine et al., 2016) demonstrated the relationship between historical development zones in Belfast and PTEs concentrations, suggesting the PTEs are of both geogenic and anthropogenic origin. In some areas of the city, concentration of PTEs including As, Cd, Cr, Pb, Ni, Pb, V, Zn exceed current “Suitable 4 Use Levels” (Nathanail et al., 2015) for the protection of human health. However, not all these contaminants in soil are available for uptake by humans. Oral bioaccessibility testing can be used to refine the risks posed to human health by measuring the fraction of a contaminant that is released in the digestive tract. A subset of 100 samples from across the metropolitan area of Belfast was selected from the archive of Tellus samples held by Geological Survey of Northern Ireland (GSNI). This subset was chosen to include soils overlying the main bedrock formations, a wide variety of contaminant concentrations and different land uses. The Unified BARGE Method (UBM), an in-vitro method which simulates the human gastro-intestinal tract and validated against in-vivo studies for As, Cd, Pb, and Sb (Denys et al., 2012) was used to undertake bioaccessibility testing on selected samples. The outcomes of this research are used to provide data on the behaviour of PTEs and their oral bioaccessibility in urban soil across Belfast and to improve decision making regarding contaminated land management.