Starting a new garden? How to Test Your Soil for Lead
Soil contamination is more common than you think
Starting a new garden comes with such a sense of excitement. It can brighten up the landscape, promote a healthier lifestyle, and become a lifelong hobby! But before you hit your local nursery, you might want to consider the soil contaminants. It's always a good idea to check if the soil on your property might contain harmful chemicals like lead. What do you do if you suspect your soil may be contaminated? And how do you check? We've got you covered!
How lead can get into your soil
Lead can occur in soil naturally around a rate between 10-50 mg/kg, but because of past reliance on leaded products, contaminated sites may have lead levels anywhere from 150 mg/kg to 10,000 mg/kg (1). Although the widespread use of lead had been phased out over the years, lead does not break down over time so it's still the most common type of soil contaminant in urban areas (2).
The main ways lead can contaminate your soil is through lead paint or leaded gasoline. Until the 1970s, lead paint was commonplace indoors and outdoors in both residents and commercial properties. It was basically everywhere! As paint ages, it can flake off and leave behind tiny debris that can integrate into soil. Car exhaust from leaded gasoline could have also contaminated soil with lead, especially if the soil was located next to a particularly busy road (2). Even though lead gasoline was phased out in the 1980s, lead can still be present in the soil.
While lead does not bioaccumulate in plants, it does hold very tightly onto clay or organic matter and, unless disturbed, is found in the top 1-2 inches of soil (2). This means that produce that grows lower to the ground, like root vegetables or leafy greens, might be covered in lead-contaminated soil.
How you can test your soil
Even though it's a little more time consuming, testing your soil is definitely worth it for the peace of mind. Although you can buy soil testing kits at a home improvement store, they don't test for heavy metals. To test for lead and other heavy metals, you'll have to send your soil to a laboratory for more extensive testing. Luckily there are many laboratories that offer easy testing, like this one available to purchase on Amazon The EPA has also put together a list of labs for their National Lead Laboratory Accreditation Program that offer lead testing. You can also check with local universities or labs to see if they offer heavy metal soil testing- some good options include Perry Laboratory,Center for Agriculture, Food, and the Environment at UMass Amherst, or the Cornell Nutrient Analysis Laboratory. Tests usually cost between $15-100 and offer a detailed look at your soil and any contaminants.
Any result that shows lead above 150 mg/kg means you have high levels of lead in your soil and you should take action before planting and new plants. One of the easiest solutions is to switch to only gardening in raised garden beds with soil you bought at a nursery. If you'd prefer to plant in the ground and are able to, you should remove the top 4 inches of soil (just to be on the safe side) and replace it with store bought soil. It's also a good idea to only plant ornamental plants instead of edible produce.
There are also a lot of small, easy changes you can make if you suspect your soil might have high levels of lead. Thoroughly washing and peeling produce before eating it is a great way to limit your exposure. Since lead doesn't bioaccumulate in plants, getting as much soil off of your produce as possible will make it a lot harder to come into contact with lead. Always make sure to wash your hands and remove your shoes before entering your house. This is especially important for kids playing in soil, since their little bodies are more susceptible to lead poisoning but they also love putting their hands in their mouths and rolling around in the dirt!