The impact of soil particle size and bioaccessibility on children and adult lead (Pb) exposure via the incidental soil ingestion pathway was assessed in 16 pen-urban contaminated soils. A comparison of Pb distribution across 4 particle size fractions (<50 mu m, <100 mu m, <250 mu m and <2 mm) found increasing Pb concentrations associated with decreasing particle size fractions. Lead enrichment in the <50 mu m particle size fraction was up to 5 times the concentration observed in the bulk soil. When gastric phase Pb bioaccessibility was determined in the <50, <100 and <250 mu m particle size fractions using the SBRC assay, Pb bioaccessibility also increased with decreasing particle size fraction for 6 of the 16 soils tested. Assessment of children and adult Pb exposure indicated that particle size and bioaccessibility had a significant influence on the contribution of incidental soil ingestion to daily Pb intake values. Although the <250 mu m particle size fraction is recommended for incidental soil ingestion calculations, using this fraction has the potential to underestimate Pb exposure due to the preferential adhesion of smaller particles to hands with elevated Pb concentrations. (C) 2011 Elsevier B.V. All rights reserved.