A.Carl Rosen, a soil scientist at the University of Minnesota, responds: In general, plants do not take up large quantities of lead even when grown in soil with elevated lead levels; however, lead levels in plants will increase as the soil lead level increases. The amount of lead taken up depends on the type of plant being grown. Lead accumulates more in leafy vegetables like lettuce and in root crops like carrots than in the fruiting part of plants like tomatoes, squash, and strawberries.
The only way to know if soil is safe for gardening is to have it tested; the homeowners can contact their local extension service for the name of a reputable lab. Some states use 500 ppm (parts per million) as the cutoff for vegetable gardens; in Minnesota we use 300 ppm.
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