Vegetable selection makes a difference in heavy metal accumulation

In situations where heavy metals like lead and arsenic may be high in the soil, selecting certain vegetables to grow can lower the risk of heavy metal exposure.

Vegetable gardening can bring health benefits by growing and consuming fresh vegetables. In some cases, however, consuming the vegetables grown can be less than healthful. In situations where vegetables are grown in environments high in heavy metals, like lead and arsenic, they can actually concentrate these metals in their tissues. When humans eat these tissues, we further concentrate these chemicals, causing us harm.

Much research has been done looking at various crops and their relative abilities to accumulate heavy metals while growing. Certain vegetables are less likely to accumulate harmful levels of heavy metals than others. In general, heavy metals tend to accumulate in root, leaf and stem tissue. Those vegetables that arise from flowers and are botanically considered fruits are less likely to have harmful levels of heavy metals than leaf, stem or root crops. In areas where heavy metals are a concern in both soil and water, it is important to keep these things in mind when creating garden plans and selecting seeds.

The lists below outline vegetables that are the best choice for situations where heavy metals are a problem, and ones to avoid. Findings are from “Lead levels of edibles grown in contaminated residential soils: a field survey,” published in the Science of the Total Environment.

Low risk vegetables

(Assuming they are washed well with a food grade detergent and potable water before consumption.)

  • Tomatoes
  • Peppers
  • Beans
  • Zucchini

Moderate risk vegetables

  • Cucumbers
  • Melons

High risk vegetables

  • Potatoes
  • Carrots
  • Radishes
  • Onions
  • Collard greens
  • Swiss chard
  • Lettuce
  • Mint
  • Cilantro

For more information regarding safe growing practices in urban environments, contact your local Michigan State University Extension county office.

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