If you’re concerned that your soil has high lead, you can collect a soil sample and send it to a laboratory to be tested.
You’ll need to specify what you want the soil tested for. Total soil lead concentration is the first test to get if you’re concerned. This information is included when you have your soil tested for total metal concentrations. Testing for total metals is done by dissolving your soil in concentrated acid. A standard method for this is the U.S. EPA 3050 extraction. But many labs will use a standard soil fertility test in lieu of measuring total metal concentrations.
Here are some labs where you can send your soil to be tested for total lead concentration:
- Penn State University: http://www.aasl.psu.edu/EnvirSoilTests.HTM
- Colorado State University: http://www.soiltestinglab.colostate.edu/
- Cornell University (choose “Environmental Analysis following US EPA SW-846”): http://cnal.cals.cornell.edu/analyses/index.html
- Purdue University: http://www3.ag.purdue.edu/counties/marion/Pages/SoilSamplingTesting.aspx
What do the results mean?
The total soil lead concentration that is cause for concern varies by whom you ask. The U.S. EPA says that you should start thinking about lead if the total concentration is above 400 parts per million in a child’s play area or 1200 parts per million in the rest of the yard. These limits are based on the potential for children to eat soil, rather than on the soil’s likelihood of contaminating homegrown produce.
Soil lead concentrations limits have not been established to protect people from eating plants grown in lead-contaminated soil, because plants generally take up almost no lead. The primary way you can be exposed to lead from plants grown on lead-contaminated soil is by eating plants that have not been fully washed.
In other words, washing vegetables before you eat them is the best way to reduce any chance of lead exposure. Washing your hands and your kid’s hands before meals is another easy and effective way to the reduce chances for lead exposure.
You should be aware, however, that total soil lead concentrations are not always a good measure of the portion of lead that can cause harm. It’s very hard to show that lead in soil is the reason children have elevated blood lead. Other factors, such as lead paint in older homes and household dust, can have much bigger impacts.
How important the soil is for lead poisoning depends on how high the lead concentration is in the soil, how much bare soil is around, how much time your children spend outside playing in the soil, and so on. 400 parts per million soil lead in Louisiana will be more dangerous than the same concentration in North Dakota, because North Dakota soils are snow-covered and frozen for much of the year and kids have no access to them.
- U.S. EPA: Information on redeveloped properties or “brownfields”
- University of Minnesota Extension: Lead in the Home Garden and Urban Soil Environment
- Oregon State University Extension: Reducing lead hazard in garden and landscape soils and Evaluating and Reducing Lead Hazard in Gardens and Landscapes (pdf).
- Purdue University: Soil Testing for Heavy Metals (Lead) (also includes good information on gardening