Soil lead and human health exposure risks: studies from Australia and the United States of America

Urban surface soils have been contaminated with lead (Pb) primarily from the former use of Pb additives in petrol and Pb paint, and in some instances from Pb smelters. These exposures continue to pose an ongoing risk to human health globally. Lead is a neurotoxin. When it is absorbed, inhaled or ingested, it can affect the development of the child’s nervous system causing lower intelligence quotient measures, Attention Deficit Hyperactivity Disorder (ADHD) and delinquent behaviors In a series of 8 published peer-reviewed papers (and one response to comments paper), this thesis assesses soil Pb contributions to blood Pb (PbB) in Australia and the USA. In addition, the study assesses the role of Pb additives in petrol (gasoline) as a potential source of blood PbB in children. In evaluating the potential role of petrol Pb additives for elevating children’s PbB levels and urban soil Pb levels, the spatial and temporal variation of Pb in atmospheric and household dusts were evaluated. The results from the thesis studies demonstrate that the historical use of leaded gasoline and Pb in exterior paints has contaminated urban soils to levels that pose a potential risk of harm to children. Leaded gasoline is a major source of Pb urban soils and house dust. Children’s PbB levels are associated spatially with soil Pb concentrations and temporally with atmospheric soil and Pb concentrations. Roadside soils contaminated with Pb are subject to re-suspension by vehicle movement, which causes dispersal into the urban environment. This thesis indicates that the paradigm that Pb paint is the sole primary source of Pb exposure in urban children is incorrect. Ongoing exposure from legacy deposition of Pb from petrol is also a major source of exposure in children and still poses a significant risk of harm.