Study finds that tomatoes, but not farm workers are safe from soil lead

Urban agriculture is booming, but there's often a hidden danger lurking in city soils: lead. A recent University of Illinois study showed universally elevated lead levels in soils across Chicago, an urban ag hotspot.

Scientists don't know much about how vegetables and other crops take up and accumulate lead in real-world settings, but new U of I research in Chicago backyard gardens shows tomatoes are likely safe to eat, even when grown in highly lead-contaminated soils.

"There was so little lead accumulation in the fruits, we estimate the average adult male would have to eat almost 400 pounds of tomatoes per week to reach toxic levels," says Andrew Margenot, assistant professor in the Department of Crop Sciences at U of I and co-author on the new study. "However, a lower body-weight child of about 60 pounds would need to eat 'only' 80 pounds of tomatoes per week—still quite a bit, but a lower threshold of consumption."

It's good news for urban agriculture, but there's a potential caveat for home gardeners and other urban agriculturalists.

"It's not the fruits I worry about, it's the practices of tillage and planting. That's where you get exposed," Margenot says. "If you magically have no exposure to contaminated soils to get to the fruit stage, or if you mulch the heck out of the soil and wear a suit and respirator, you're golden. But, of course, we all know it doesn't happen that way."

Read the complete research at www.phys.org.

George P. Watson et al, Fruit lead concentrations of tomato (Solanum lycopersicum L.) grown in lead-contaminated soils are unaffected by phosphate amendments and can vary by season, but are below risk thresholds, Science of The Total Environment (2022). DOI: 10.1016/j.scitotenv.2022.155076 George P. 


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