Adverse health effects caused by lead (Pb) exposure have been extensively documented. Lead in residential soils has long been recognized as a principal source of excess Pb absorption in young children. Weathering, chipping, scraping, sanding, and sandblasting of structures bearing Pb-based paints result in Pb becoming entrained in soils that are continuously tracked inside the house in the form of dust, which remains the primary route of chronic human exposure driving the health risk.

The hazard imposed by Pb within soils is dependent on soil properties and the geochemical forms of Pb in soils. Soil properties such as pH, soil organic matter, clay and carbonate contents can affect the geochemical form of Pb and consequently, Pb bioaccessibility and human bioavailabity. Therefore, this study was performed to assess varying geochemical forms of Pb and hence its availability in Pb contaminated residential soils with different physio-chemical properties. An extensive field survey and subsequent collection of soils from 10 residential sites in San Antonio, TX (with alkaline pH) as well as 10 residential sites with acidic pH from Baltimore, were conducted. Soils were analyzed for texture, pH, salinity (EC), Cation Exchange Capacity (CEC), total iron, aluminum, Pb, extractable iron, aluminum, Pb, total and extractable calcium and magnesium, total and extractable P, Soil Organic Matter (SOM), total carbon. Results showed that soils collected from San Antonio were alkaline (pH ranging from 7.43 to 7.87), whereas those from Baltimore were acidic (pH ranging from 5.16 to 6.25). Generally, San Antonio samples had relatively high salinity (EC ranging from 217-1051 µS/cm), high clay content (7.33% - 65.22%), moderate to high SOM (5.23% - 12.89%), and high total Pb concentration, with the highest being 7768 mg/Kg. Baltimore samples were characterized by low salinity (EC ranging from 97-715 µS/cm), low clay content (2.1% - 5.2%), low SOM (0.64% - 2.27%), and the highest total Pb concentration of 5373 mg/Kg). Studies to identify the various geochemical forms of lead in San Antonio and Baltimore soils are currently in progress.