Urban gardening is a fundamentally positive trend. However, the toxins that plants extract from city soil and deliver to hungry human mouths form an unsavory dark side to the movement. As the popularity of urban gardens increases, publicizing safe gardening practices is critical.
Although the public is generally aware of the risks of growing plants in metropolitan soil, explicit guidelines to garden siting and information regarding vegetable toxin absorption have heretofore been unclear and insufficiently disseminated. A recent study published in the journal Environmental Pollution by researchers from the Technical University of Berlin helps clarify these issues.
The study yielded three primary insights. First, it confirmed vegetables' tendency to extract heavy metals from soil. For example, many tested vegetables contained dangerously high levels of lead, which is widely known to cause developmental disorders, brain damage, and generally punish the body's organs.
Second, the entire spectrum of vegetables involved tested positive for contaminants, contradicting the belief that some vegetables are safer choices for dangerous soils. Fortunately, the study's final conclusion points to a primary problem, as well as a potential solution. Gardens closest to high traffic flow are the most toxic. But barriers of foliage or buildings between gardens and traffic significantly reduced levels of heavy metals.
Based on the results of this study, we can extrapolate some key guidelines to safe urban gardening. Research the land in which you plan to plant. Check the city land planning office for information concerning what went down on the ground you're considering. If you really want to get your hands dirty, enlist nearby health/environmental agencies or a local university's agricultural department to conduct some basic soil tests. If you find contamination, plant in pots or raised beds lined with protective sheets. Finally, if you are near a high traffic avenue, build a wall or thick hedge to defend against toxic dusts.
With these guidelines in mind, the benefits of urban gardening - cleaner
air, fresher produce, exercise outdoors, urban beautification, and a
deeper connection to nature - begin to outweigh the potential risks.
"Rooftop Garden" by Jim Crossley on Flickr courtesy of Creative Commons Licensing.