Contents lists available at ScienceDirect Environmental Research journal homepage: www.elsevier.com/locate/envres Estimates of potential childhood lead exposure from contaminated soil using the US EPA IEUBK Model in Sydney, Australia Mark A.S. Laidlaw a, ⁎ , Shaike M. Mohmmad b , Brian L. Gulson c , Mark P. Taylor d , Louise J. Kristensen e , Gavin Birch b a Centre for Environmental Sustainability and Remediation (EnSuRe), School of Science, RMIT University, PO Box 71, Bundoora, Victoria, Australia - 3083 b Environmental Geology Group, School of Geosciences, Sydney University, Sydney, NSW 2006, Australia c Department of Environmental Sciences, Faculty of Science and Engineering, Macquarie University, Sydney, NSW 2109, Australia d Department of Environmental Sciences, Faculty of Science and Engineering, Macquarie University, Sydney, NSW 2109, Australia e Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093, USA ARTICLE INFO Keywords: Sydney Blood Lead Soil Toxicity Australia ABSTRACT Surface soils in portions of the Sydney (New South Wales, Australia) urban area are contaminated with lead (Pb) primarily from past use of Pb in gasoline, the deterioration of exterior lead-based paints, and industrial activities. Surface soil samples (n=341) were collected from a depth of 0–2.5 cm at a density of approximately one sample per square kilometre within the Sydney estuary catchment and analysed for lead. The bioaccessibility of soil Pb was analysed in 18 samples. The blood lead level (BLL) of a hypothetical 24 month old child was predicted at soil sampling sites in residential and open land use using the United States Environmental Protection Agency (US EPA) Integrated Exposure Uptake and Biokinetic (IEUBK) model. Other environmental exposures used the Australian National Environmental Protection Measure (NEPM) default values. The IEUBK model predicted a geometric mean BLL of 2.0 ± 2.1 μg/dL using measured soil lead bioavailability measurements (bioavailability =34%) and 2.4 ± 2.8 μg/dL using the Australian NEPM default assumption (bioavailability =50%). Assuming children were present and residing at the sampling locations, the IEUBK model incorporating soil Pb bioavailability predicted that 5.6% of the children at the sampling locations could potentially have BLLs exceeding 5 μg/dL and 2.1% potentially could have BLLs exceeding 10 μg/dL. These estimations are consistent with BLLs previously measured in children in Sydney. 1. Introduction 1.1. Soil investigations in the Sydney area Environmental contamination of air, dust and soils in Australia is derived from a range of industrial sources, which peaked in the 1970s and declined thereafter (Kristensen et al., 2017). The largest anthro- pogenic source of Pb emissions was Australian motor vehicles using petrol containing tetramethyl and tetraethyl Pb additives from 1932 to 2002 (Kristensen, 2015). Atmospheric emissions of Pb to the entire Australian continent from leaded petrol were calculated to total 240,510 t over seven decades of use, attaining a maximum of 7869 t in 1974 (Kristensen, 2015). Kristensen (2015) calculated that approxi- mately 68,000 t of lead were emitted into the atmosphere from leaded petrol in the state of New South Wales (NSW) between 1958 and 2002. From 1980 to 2001 leaded gasoline contributed approximately 90% to Pb in Sydney air (Chiaradia et al., 1997). Other sources of environ- mental lead include Australian paint, which were up to 50% Pb by volume before the 1950s, thereafter several mandated reductions reduced the allowable concentration to 0.1% (by weight) in 1997 (AGFOEE, 2017). Rouillon et al. (2017) showed that soil around houses in Sydney with painted exteriors built before 1970 were markedly more contaminated than non-painted houses and houses that were built from the 1970s onwards. The Pb from past petrol lead emissions, industrial sources and the deterioration of exterior lead-based paints have been deposited and concentrated in surface soils and urban areas of Australia (Gulson et al., 1995a; Olszowy et al., 1995; Laidlaw and Taylor, 2011; Harvey et al., 2017; Rouillon et al., 2017; Kristensen et al., 2017). Birch et al. (2011) systematically sampled soil Pb concentrations in surface soils (0–2.5 cm) at 491 locations across the Sydney estuary catchment (480 km 2 ; Fig. 1). One soil sample was collected in each 1 km 2 grid and sampling sites (one per grid square) were selected http://dx.doi.org/10.1016/j.envres.2017.04.040 Received 17 March 2017; Received in revised form 28 April 2017; Accepted 29 April 2017 ⁎ Corresponding author. E-mail addresses: mark.laidlaw@rmit.edu.au (M.A.S. Laidlaw), mo.6janu2005@yahoo.com (S.M. Mohmmad), brian.gulson@mq.edu.au (B.L. Gulson), mark.taylor@mq.edu.au (M.P. Taylor), lkristensen@ucsd.edu (L.J. Kristensen), gavin.birch@sydney.edu.au (G. Birch). Environmental Research 156 (2017) 781–790 0013-9351/ © 2017 Elsevier Inc. All rights reserved. MARK