Thursday, July 2, 2009

Take the lead out of gardening

Did you hear that lead was detected in soil from the White House vegetable garden? I wasn't surprised. Although lead is not widely in use today, prior to 1978, it was a common additive in paint and gasoline. Lead was widely deposited in urban soils through car exhaust and flaking paint from building exteriors. In rural and formerly rural areas, lead may be present in soil from the historic use of lead-containing pesticides like lead arsenate. (If your neighborhood has streets with names like "orchard" or "farm", you probably live on former farmland.)

Since lead is a metal, it is persistent in soil. Unlike a volatile compound (think gasoline fumes), lead tends to stay put. Some of this lead may be bioavailable, meaning it can enter your plants and, ultimately, you and your family.

But don’t let your concerns about lead exposure dampen your enthusiasm for gardening with your kids! There are easy steps that you can take to limit this problem:

• Locate your garden away from roads and buildings. This 1995 study showed that soils in some inner-city front yards in Washington, DC were contaminated with lead; the source was traced to paint.

• Consider importing fresh topsoil for your garden. You can work this soil into your planting beds or use containers and elevated planters.

• Make sure that you and your children wash your hands after gardening and remove your shoes before coming into the house. Wipe the feet of pets that have been in the garden with you.

• Wash all fruits and vegetables thoroughly before eating them. Ingesting contaminated soil poses a greater human health risk than eating foods grown in contaminated soil.

• Studies have shown that leafy greens (like lettuce) and roots (such as carrots and onions) are the most likely to uptake metals. If you are concerned about the soil in your garden, you may want to grow fruits, like tomatoes, which are less likely to become contaminated.

At 93 parts per million, the lead levels found in the White House garden are actually quite low for urban soils; values over 400 ppm lead might raise an eyebrow. To learn more about the possible risks of lead exposure from gardening, check out:

"Leaden Gardens" from ScienceNews

"Lead in the Home Garden and Urban Soil Environment" from the University of Minnesota Extension Office

And to learn more about lead and lead poisoning, visit:

"Blood-Lead Level Basics: What You Really Need to Know" from Washington Parent

Public Health Statement for Lead from the Agency for Toxic Substances and Disease Registry.

A portion of this article appeared previously in Natural Family Online.

Photo credit: Leon Brooks,

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