title: Factors controlling the oral bioaccessibility of anthropogenic Pb in polluted soils.
abstract: In human risk assessment, ingestion of soil is considered a major route of toxic Pb exposure. A large body of research has focussed on the measurement of the 'total' Pb contents in sediment, soil and dust as a measure for the exposure to lead. We report that Pb bioaccessibility (i.e. the maximum bioavailability), determined with an in vitro test, does not necessarily depend on the total Pb content. In contrast, the Pb bioaccessibility is initially controlled by the chemical form and particle size of the Pb source, which in turn determine its solubility. Furthermore, when anthropogenic Pb resides within the soil, it may form new, more stable, minerals and/or binds to organic matter, clay, reactive iron or other reactive phases, changing its bioaccessibility. The bioaccessible Pb fraction of 28 soils, polluted with various Pb sources (including residues of Pb bullets and pellets, car battery Pb, city waste and diffuse Pb), was determined with an in vitro-test and varied from 0.5% to 79.0% of total Pb. The highest Pb bioaccessibility (60.7% to 79.0%) was measured in soils polluted with residues of Pb bullets and pellets (shooting range), while the lowest Pb bioaccessibility (0.5%-8.3%) was measured in soils polluted with city waste (including remnants of Pb glazed potsherds and rooftiles, Pb based paint flakes, and Pb sheets). Bioaccessibility of Pb was correlated with pH, organic matter and reactive Fe. These results indicate that soil characteristics play an important role in the oral bioaccessibility of lead in polluted soils. Instead of basing human risk assessment solely on total Pb contents we propose to incorporate in vitro bioaccessibility tests, taking factors such as soil pH, organic matter content and reactive iron content into account. This approach will result in a better insight into the actual risks of Pb polluted soils to children.
authors.affiliation: GeoConnect, Meester Dekkerstraat 4, 1901 PV Castricum, The Netherlands. Electronic address: n.walraven@geoconnect.nl.
authors.forename: N
authors.initials: N
authors.lastname: Walraven
authors.affiliation: Rijksinstituut voor Volksgezondheid en Milieu (RIVM), P.O. Box 1, 3720 BA Bilthoven, The Netherlands. Electronic address: martine.bakker@rivm.nl.
authors.forename: M
authors.initials: M
authors.lastname: Bakker
authors.affiliation: Rijksdienst voor Archeologie, Cultuurlandschap en Monumenten, P.O. Box 1600, 3800 BP Amersfoort, The Netherlands. Electronic address: B.van.Os@cultureelerfgoed.nl.
authors.forename: B J H
authors.initials: BJ
authors.lastname: van Os
authors.affiliation: BRGM, 3 avenue Claude-Guillemin, BP 36009, 45060 Orléans Cedex 2, France. Electronic address: g.klaver@brgm.nl.
authors.forename: G Th
authors.initials: GT
authors.lastname: Klaver
authors.affiliation: University Utrecht, Faculty of Geosciences, P.O. Box 80021, 3508 TA Utrecht, The Netherlands. Electronic address: j.b.m.middelburg@uu.nl.
authors.forename: J J
authors.initials: JJ
authors.lastname: Middelburg
authors.affiliation: VU University Amsterdam, Faculty of Earth and Life Sciences, Petrology, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands. Electronic address: g.r.davies@vu.nl.
authors.forename: G R
authors.initials: GR
authors.lastname: Davies
mesh_terms: D004781:Environmental Exposure / Q000706:statistics & numerical data*; D004787:Environmental Pollution / Q000706:statistics & numerical data*; D006801:Humans; D007854:Lead / Q000032:analysis*; D012987:Soil / Q000737:chemistry; D012989:Soil Pollutants / Q000032:analysis*
chemical_list: D012987:Soil; D012989:Soil Pollutants; D007854:Lead
keywords: Bioaccessibility; Factors; Isotopes; Lead; Oral; Pollution; Soil; Sources