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Urban Gardens and Soil Contaminants

Betsy Wieland, Andy Leith and, Carl Rosen (March, 2010)

Summary

Lead (Pb), Cadmium (Cd), and Arsenic (As) are the main contaminants of concern because of their widespread occurrence in urban environments. Other contaminants may be a concern if the site or nearby properties have a history of industrial or commercial use. Although soil tests for Pb, Cd and As are relatively inexpensive (less than $100 for all three), tests for other contaminants can be much more expensive. If soil contamination is a concern, raised bed gardens are the most effective alternatives to using the native soil. Ingestion of soil and dust is the main route of exposure to soil contaminants. Reduce the risk of exposure by washing and peeling root crops, and washing and removing the outer leaves or bottoms of leafy green crops. Reduce children’s exposure by covering bare soil with mulch or sod. Increasing the organic matter content and pH of the garden soil can limit the amount of contamination taken up by the crops.