Comparison of Soil Pb in Vitro Bioaccessibility and in Vivo Bioavailability with Pb Pools from a Sequential Soil Extraction

Abstract

In this study, 15 soils ranging in Pb content from 32 to 6330 mg kg(-1) were subjected to in vitro gastrointestinal extractions with and without added powdered milk. Before and after treatment, Pb in the soils was fractionated according to a 7-step sequential extraction procedure. A subset of five soils and Pb acetate was used for a minipig dosing study. The amount of bioaccessible Pb determined with the in vitro system ranged from 3 to 20% without powdered milk and from 11 to 56% with powdered milk. The higher bioaccessibility of Pb in the in vitro model with addition of powdered milk was related to a depletion of Pb in the organic Pb pool and indicates that soluble milk constituents compete with soil organic ligands for Pb. The absolute and relative bioavailabilities of Pb in the minipig dosing experiment were not related to bioaccessible Pb determined in any of the two in vitro systems. However, relative bioavailabilities in liver, kidney, and total uptake were highly correlated to Pb in the third fraction of the sequential extraction that is attributed to easily reducible Mn oxides. These results indicate that reductive processes in the intestine may be more relevant for Pb absorption than the initial solubilization in the acidic stomach.

Lead bioaccessibility in 12 contaminated soils from China: Correlation to lead relative bioavailability and lead in different fractions

“…As pH increased from1.2-2.5 inthe gastric phase to 5.5-7.0 in the intestinal phase, solublePbin the gastric phase isprobably absorbed by soilsand Fe oxides [23,36]. In the intestinal phase , average Pbbioaccessibilityin soils using UBM, SBRC, IVG, and…”

“…Compared to limited in vivoPb-RBA studies, manystudies investigated Pbfractions in soils using sequential extraction [23,24]. The methodofTessier et al [25]is the most widely used, which operationally separatesPb into5 fractions, i.e., exchangeable Pb, and Pb associated with carbonates, Fe/Mn oxides, organic matter, and residualfractions, showing decreasing bioavailability.…”

“…The methodofTessier et al [25]is the most widely used, which operationally separatesPb into5 fractions, i.e., exchangeable Pb, and Pb associated with carbonates, Fe/Mn oxides, organic matter, and residualfractions, showing decreasing bioavailability. For example, Pb inthe carbonate and Fe/Mn oxides bound fractionsis more bioavailable than Pbinthe residual fraction [26,27].However, correlations between Pb fractionation by sequential extraction and Pb bioaccessibilityare rarely established [23,28].…”

An inter-laboratory trial of the unified BARGE bioaccessibility method for arsenic, cadmium and lead in soil

“…The key contaminants included in this work are arsenic (As), lead (Pb) and cadmium (Cd) as they are potentially harmful to human health (ATSDR, 2007b;ATSDR, 2007a;ATSDR, 2008) and the most common elements undergoing bioaccessibility research Ruby et al, 1993;Ruby et al, 1996;Albores et al, 2000;Oomen et al, 2002;Marschner et al, 2006;Chan et al, 2007;Datta et al, 2007;Drexler and Brattin, 2007;Finzgar et al, 2007;Hansen et al, 2007;Juhasz et al, 2007aJuhasz et al, , 2007bLjung et al, 2007;Sarkar et al, 2007;Subacz et al, 2007;Turner and Ip, 2007;Van de Wiele et al, 2007;Beak et al, 2008;Moseley et al, 2008;Girouard and Zagury, 2009;Morman et al, 2009;Nagar et al, 2009;Poggio et al, 2009;Smith et al, 2009;Zhang et al, 2009;Demetriades et al, 2010;Juhasz et al2010). …”

The distribution of sequentially extracted Cu, Pb, and Zn fractions in Podzol profiles under dwarf pine of different stages of degradation in subalpine zone of Karkonosze Mts (central Europe)

“…A commonly used, relatively simple BCR method, developed by the Community Bureau of Reference (Ure et al 1993;Mossop and Davidson 2003) determines four fractions of metals (acid soluble, reducible, oxidizable, and residual). A method by Zeien andBruemmer (1989, 1991), which is more laborious, provides greater insight into the mechanisms of metal binding in soils and, therefore, has been widely applied to both nonpolluted and variously polluted soils (Karczewska 1996;Wenzel and Jockwer 1999;Kabała and Szerszeń 2002;Marschner et al 2006;Rao et al 2008;Kabala et al 2011). The Zeien and Brümmer method involves the determination of seven operationally defined fractions, believed to correspond with the following species of metals: (1) mobile, (2) exchangeable and specifically bound, (3) bound to manganese oxides, (4) organically bound, (5) occluded in amorphous FeO x , (6) occluded in crystalline FeO x , and (7) residual.…”