Lead Paint Risk - Gardening with Contaminated Soils
by Denise
If you want to grow a backyard garden in the city, you may want to have your soil tested. Ordinarily, most surface soils in the U.S. contain between 7 to 20 parts per million (ppm) lead. If there's more lead present, it's usually the result of lead contamination. Anything above 300 ppm exceeds the EPA standards. Some states set the level even lower at 100 ppm.
Soils in the city are more likely to be contaminated, both from lead paint chips or dust and exhaust from gas before lead was banned in 1995. There are certain locations around your home that are at higher risk for lead contamination. The side of the driveway is often contaminated from the exhaust expelled over the area through years of warming up the car. And the area between the wall and the drip line under the eaves is a common area of contamination, usually caused by leaching from the paint on the walls for from direct flaking or chalking of paint into the soil.
If your soil is contaminated, there are several strategies you can use to keep your produce from your garden safe to eat.
- Excavate and remove the top three feet of contaminated soil. Replace the soil with a mixture of compost and top soil. This can be an expensive option and time consuming as well if you aren't able to bring in equipment to do the work for you.
- Build raised beds. Line the bottom of each bed with landscape fabric. Then fill with new compost and top soil. The landscape fabric will discourage roots from reaching down into the contaminated soil.
- If you can't afford raised beds, only grow plants that don't accumulate lead in their fruits in the contaminated soil. For example, tomatoes, cucumbers, climbing beans and squash are good choices because they also like an alkaline soil high in calcium, which makes lead harder for the plants to absorb.
The primary concern if you know your soil has lead present is to ensure that no lead dust gets onto the produce. There is also the risk of tracking lead contaminated mud and dirt into your home from a contaminated garden. Mulch is a cost effective answer to both problems.
Using a mulch will prevent mud from splashing up onto the plants. Mulching your garden paths will prevent you from tracking mud. Mulch offers other advantages as well. It cuts down on the amount of weeds, so pulling up weeds won't bring lead dust to the surface. It reduces the risk any children will play in the dirt. And it nourishes the soil.
Even when you use mulch, you'll also want to be especially careful about washing your produce. Add 1% vinegar or 0.5% soap to the wash water to ensure any lead goes down the drain.
Finding out that you have lead in your soil doesn't mean you have to give up on having a garden. It just means you have to be careful with how you handle the soil and adopt practices that reduce the risk of the lead being ingested.
