Because airborne heavy metals and particulates are not likely to be absorbed by plants through their leaves, urban air contamination is not considered a major concern for urban-grown food. The exception is for farm and garden sites close to freeways, as freeway driving can produce toxic tire dust. In these instances, farmers should considering using a closed growing method, such as greenhouse production, or other barriers.
In all instances, regardless of proximity to freeways, all crops should be washed thoroughly before sale or consumption to remove any contaminants settled on plant leaves.
It should be noted that airborne particulates will settle on soils and contribute to soil contamination, and urban farmers should follow the precautionary measures and safe gardening practices outlined in Factsheet #7, Dealing with Contaminated Soils.
For more information about air pollution, visit the United States Environmental Protect Agency’s website on air and radiation at http://epa.gov/air/ and the New York State Department of Environmental Conservation’s website section on Chemical and Pollution Control at http://www.dec.ny.gov/.
Plants can absorb contaminants and toxins from their water sources, and using contaminated potable water for washing crops can also make produce unsafe to eat. To determine your water safety, follow these steps (from the Essential Urban Farmer by Novella Carpenter and Willow Rosenthal, Penguin Books, 2011):
- Learn about your water table, and particularly how high it is, by contacting your local water district office. If it is high enough to be reached by plant roots, plants could absorb toxins.
- Evaluate your land-use history, and particularly any previous industrial or factory activities in your area that might have polluted groundwater sources.
- If a city or regional company supplies water, contact the company for data on heavy metals and other types of water contamination.
- Get your water source tested.
Water Testing Services
Cornell Cooperative Extension’s “Water Quality Information for Consumers” website provides many resources about water testing and contamination and home treatment at http://waterquality.cce.cornell.edu/.
Cornell University also provides a listing of certified potable and non-potable water testing laboratories in New York State, available for download at http://www.gaps.cornell.edu/weblinks.html.
The University of Missouri Extension provides a guide to interpreting water analysis report results at http://extension.missouri.edu/p/WQ101 (Copyright 1993 to 2011 University of Missouri. Published by MU Extension, all rights reserved).