Food Safety in Pb-Enriched Garden Soils.

Mean Pb concentration in uncontaminated surface soils of the United States is about 22 mg/kg while Pb concentrations in urban soils may range from 50 to about 3,000 mg kg^-1. When Pb-enriched soil is used for urban gardening, exposure to Pb in soils primarily happens in two ways, direct exposure to Pb-contaminated soil (such as soil ingestion) or indirect exposure to Pb from soil-plant-human. Over the past 7 years, we gathered data regarding contaminant uptake by food crops grown on several urban brownfield sites slated for community gardens. Our research indicated, if managed properly, the pathway from soil-plant-human can be kept at minimum. Lead and other contaminants were consistently diluted by the addition of large amounts of compost thus reducing the potential risk of soil contaminant transfer to humans through consumption of vegetables grown at these sites. Results also showed that via addition of some compost types bioavailability of Pb as well as chemistry of Pb can be changed, especially over time. Significant surface contamination of produce samples (removed via thorough cleaning) indicated that surface contamination with contaminated dust may potentially affect food safety.