Contaminated urban soils can be used in edible gardening, with certain safety measures

Researchers from Kansas State University conducted a six-year long study to evaluate the safety in using contaminated soils to grow food in urban environments.  The land typically used for vegetable gardens are abandoned lots or areas near industrial centers which have a higher risk of contaminants.  Soils typically had elevated levels of lead, arsenic, zinc, and/or polycyclic aromatic hydrocarbons and plants evaluated were categorized by edible part: root crops, leaf crops, and fruit crops.

garden by Arthur E. Miller, USDA APHIS PPQ, Bugwood.org

Root crops, carrots, beet roots, and radishes, had elevated levels of contaminants, but they were still very low and are considered to be very low risk.  Leaf and fruit crops had an even lower risk than root crops, very little contaminants were found within the vegetable but there were occasions where contaminated dust was on the surface of the of the food.  This dust could be washed away with simply cleaning the food prior to consumption.  The overall observation has been that the bioavailability of the contaminants is very low.  Some best management practices for growing food on suspected contaminated soils include:

• Test soil for pH and nutrients and amend as needed
• Add organic matter and clean soil to dilute any possible contaminants
• Remember that, while very little of the contaminants are in the vegetables, they are still in the soil and proper clothing should be worn to minimize contact with the soil.

Source Article: Study: With proper care, contaminated urban soils are safe for gardening