Use of a physiologically based extraction test to estimate the human bioaccessibility of potentially toxic elements in urban soils from the city of Glasgow, UK

Abstract

A simple, two-stage, physiologically based extraction has been applied to assess the human bioaccessibility of potentially toxic elements (PTE) in 20 urban soils from a major UK city. Chromium and iron bioaccessibilities were found to be markedly higher in the intestinal phase, whilst lead and zinc bioaccessibilities were higher in the stomach. Copper and manganese bioaccessibilities were generally similar under both extraction conditions. Principal component analysis was used to study relationships amongst bioaccessible element concentrations and land use. Distinctions could be observed between the distributions of the urban metals-copper, lead and zinc-and metals predominantly of geogenic origin, such as iron. There was no clear delineation between roadside soils and soils obtained from public parks. Bioaccessible analyte concentrations were found to be correlated with pseudototal (aqua regia soluble) analyte concentrations for all elements except iron. Results of the BCR sequential extraction did not, in general, provide a good indication of human bioaccessibility. Comparison of bioaccessible PTE concentrations with toxicological data indicated that lead is the element of greatest concern in these soils but that levels are unlikely to pose a health risk to children with average soil intake.

Experimental determination of the oral bioavailability and bioaccessibility of lead particles

“…Bruce et al measured a bioaccessibility of 47% for the mine wastes at the end of the gastric phase, and these values dropped to 7% at the end of the intestinal phase [94]. The same range of decrease in bioaccessibility was observed in other studies [67,113-115]. Results using Pb-ISE and DPASV in chyme following GI in vitro digestion showed that the free Pb 2+ is indeed negligible, and that most of the Pb was present as Pb-phosphate and Pb-bile complexes in dynamic equilibrium with solubilized Pb [85].…”

Assessing bioaccessible fractions of arsenic, chromium, lead, selenium and zinc in coal fly ashes

“…gastric and intestine pH, sample mass-to-fluid ratio, stomach mixing, stomach emptying rate and intestinal transit rates, were chosen on the basis of previous studies (Ruby et al 1996(Ruby et al , 1999Hamel et al 1998;Rodriguez et al 1999;Roe and Klinck 2007;Wragg et al 2007;Sialelli and Urquhart 2010). The details of PBET procedure are shown in Fig.…”

“…Wragg and Cave (2002) demonstrated the PBET as a practical methodology for in vitro measurement of the bioaccessibility of metals and metalloids. The PBET has been applied to soils, mussel tissues, airborne dusts, mine-waste contaminated soils, mining wastes and magnetic fractions of coal fly ashes (Bruce et al 2007;Roe and Klinck 2007;Wragg et al 2007;Navarro et al 2008;Lu et al 2009;Sialelli and Urquhart 2010).…”

Heavy metals in soils along unpaved roads in south west Cameroon: Contamination levels and health risks

“…Gastric juice was prepared using 2.5 g pepsin (Pocrine gastric mucosa), 1 g tri-sodium citrate, 1 g DL Malic acid and 840 lL lactic acid syrup. These were diluted with DDW, acidified to pH 1.5 using concentrated hydrochloric acid and made up to 2 L (Intawongse and Dean 2008;Sialelli et al 2010;Li and Zhang 2013). The intestinal phase solution comprised 500 mg pancreatin and 175 mg of bile salts per litre of gastric juice solution neutralised to pH 7 with solid sodium hydrogen carbonate (NaHCO 3 ) (Sialelli et al 2010 andZhang 2013).…”