When you see dirt in Chicago, you’re probably looking at lead pollution. Thanks to decades of avoidable but profitable use of lead paint and leaded gasoline, this invisible toxin has penetrated the ground everywhere, especially near old houses and areas with heavy traffic.
Natural soil contains about 20 parts of lead per million parts of soil. That’s the “background” level, but different jurisdictions have different opinions about how much should be considered safe in practice. In the squeaky-clean state of Minnesota bare soil with more than 100 parts of lead per million is supposed to be covered with sod, mulch, or tarp. In 2001 the U.S. EPA concluded from the available evidence that children shouldn’t play on dirt with more than 400 parts per million. The city of Chicago considers bare soil accessible to children a hazard if it contains over 1,000 parts per million. The EPA’s standard for bare soil where children won’t be playing is 1,200.
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Can you protect yourself and your kids and have your veggies too? Yes, say Finster, Gray, and Binns. But you have to garden differently:
Dunn says the Resource Center simply doesn’t grow its organic produce in actual city soil. Instead his outfit practices a variation on container gardening, laying down a clay barrier between three and six inches thick, then adding eighteen inches’ worth of composted restaurant waste from the center’s composting facility (at 1325 E. 70th) as a growing medium. Clay isn’t impermeable forever, but Dunn estimates it should work to separate the plant roots from leaded soil for ten years or so. The Resource Center’s produce is sold to some of the pickiest restaurants in town–the Dining Room at the Ritz-Carlton and Frontera Grill, among others. If you want to garden badly enough there’s always a way.
