The dog days of summer are here. August rolls in hot and humid, and with it a bounty of produce from the postage stamp-sized garden plots that pepper the urban landscape. There is a joy to sitting down to a summer supper that includes sweet tomatoes, bright basil, roasted beets, and other delights you have grown yourself. Before you feast on your harvest, however, it is important to understand that urban gardens may also contain toxic levels of lead that can cause brain and nervous system damage in children and neurological and gastrointestinal problems in adults.
Lead enters urban gardens in two primary ways – through soil that has been contaminated from lead-based paint chips on nearby buildings and homes and from auto emissions or lead dust that settles on vegetation. Homes and buildings built prior to 1950 are the biggest culprits for lead-based paint and research in urban areas has shown that the highest concentrations of lead are found around the foundations of these buildings and within a few feet of busy roads.
While getting your soil tested is the definitive way to determine whether or not you have a lead problem, most people cannot afford to have their soil professionally removed and replaced, or decontaminated. If you suspect you may have lead in your soil or in your surrounding neighborhood you can still exercise your green thumb and grow some food. There are simple steps you can take to ensure that you are not feeding your family lead-contaminated crops:
- Locate your garden as far away from buildings and busy roads as possible. This eliminates both the chance that the soil has been contaminated by lead chips and also reduces the risk of lead dust settling onto crops.
- Plant fruiting crops such as tomatoes, squash, okra, eggplant, and corn, which tend not to accumulate lead even when grown in contaminated soil.
- Use raised beds lined with landscaping fabric and filled with fresh, organic soil for plantings of herbs, leafy greens, and root vegetables like carrots, beets, and potatoes. Lead concentrates in the leaves of plants – the parts of herbs and lettuces you eat - and even a vigorous washing of root vegetables may not guarantee you’ve removed all contaminated soil.
- If you have a space in your yard that you’d like to garden in, but are concerned about lead levels, consider researching phytoremediation. This is a practice in which particular plants that are superstars at removing lead from the soil are grown specifically for that purpose for one or two seasons prior to planting food crops. Indian mustard, spinach, sunflowers, and blue fescue excel at this, but make sure that you remove the plants at the end of the growing season and dispose of them in a way that will not recontaminate the soil (i.e. don’t put them in your compost pile).
- Already have bushels of carrots, beets, and potatoes growing in questionable soil? Wash your root vegetables vigorously and peel them before eating to remove all contaminated soil. Consider keeping these crops off the plates of young children.
These suggestions might be prudent for all urban gardeners to keep in mind. When living in dense city spaces, it is difficult to control for or be aware of every potential source of lead contamination. Following these tips will help you savor your summer harvest in a way that is also safe and healthy.