In March, Michelle Obama delighted locavores when she planted an "organic" vegetable garden on the White House's South Lawn. For years, Alice Waters, Michael Pollan, and other sustainable food activists had been pushing the idea as a way to reseed interest in do-it-yourself agriculture. Less than two months later, the National Park Service disclosed that the garden's soil was contaminated with toxic lead, and the plot's educational value took on a new flavor as the New York Times and other papers discussed how to make urban backyards that are laced with old lead-based paint safe for growing kale and cauliflower. But those stories might have fingered the wrong culprit.
Starting in the late 1980s and continuing for at least a decade, the South Lawn was fertilized by ComPRO, a compost made from a nearby wastewater plant's solid effluent, a.ka. sewage sludge. Sludge is controversial because it can contain traces of almost anything that gets poured down the drain, from Prozac flushed down toilets to lead hosed off factory floors. Spreading sludge at the White House was a way for the EPA to reassure the public that using it as a fertilizer for crops and yards (instead of dumping it in the ocean, as had been common practice) would be safe. "The Clintons are walking around on poo," the EPA's sludge chief quipped in 1998, "but it's very clean poo."