It all started when a close friend refused to eat the rosemary I’d cut from my window box on the grounds that it was “polluted.” But before my friend’s momentous refusal, I admit I hadn’t thought once about the safety of eating what I was growing out there.
We’ll look at both the perceived and real threats of each in the next couple of weeks.
I just planted this tiny strawberry in my window box. Inorganic contaminants include arsenic, mercury, cadmium, and lead, the last being the biggest problem by far.
Photograph by Meredith Swinehart.
Soil Contamination from Lead
Photograph by Liesa Johannssen for Gardenista.
I can lean out the window to water my plants.
What’s worse, heavy car traffic tends to disturb soil and send it into the air—”atmospheric suspension” is the technical term—meaning it’s likely to contaminate even healthy nearby soils, settle on the surface of fruits and vegetables, and be inhaled into gardeners’ lungs.
Mint and oregano were my primary crops in last year’s window box, which is perched right over a busy street. Like lead, PAHs are found in greatest concentrations in cities; highest concentrations at industrial sites and lowest in rural areas.
Soil Contamination from PAHs
Photograph by Meredith Swinehart.
Perceived threat: Plants grown in contaminated soil will absorb the PAHs, making them unsafe to eat and potentially carcinogenic.