Why You Should Care About Soil Contamination If You're Starting a Garden in Your Backyard
Here's the dirt-y details you're going to want to know and what to do about it
Why should I care about my soil?
Believe it or not, the soil that you use matters! Soil in older neighborhoods tend to contain higher levels of lead since those houses were built before the ban of lead paint in 1978 (1). Most soil in urban areas also have residual lead from the days of leaded gasoline (don't worry, that has since been banned too!) (8). One of the concerns with heavy metals, especially lead, is that your vegetables can take in some of the metal during the growing process (1). You're probably getting the picture just from these two examples. BUT if you take away nothing else, here is the most important thing to know - a study by the University of Washington found that the benefits of urban gardening definitely outweigh any of the potential worries. This definitely doesn't mean that you can't take steps to make sure that you reap all the benefits and none of the yucky toxic chemicals (3).
What might be in my soil?
The biggest concern by far in soil used for home gardening is heavy metals, particularly lead, cadmium and arsenic (1). Heavy metals are concerning because while they do not have immediate effects, the buildup of these metals in your body can result in negative health effects over time. For instance, lead can slow down child brain and motor development, while cadmium buildup can result in kidney and lung damage (4). Children, pregnant women and individuals with health conditions are most vulnerable to heavy metals (4). Particulate matter (a.k.a. the different chemicals that float around in the air and blow around in the wind from things like car exhaust) can also build up on the surface of your produce (5). This is often why vegetables that are grown near a busy road have higher levels of heavy metals because of dirt and dust getting kicked up into the air and mixing with your soil (2).
What can I do to reduce the chance my vegetables will be contaminated?
- Get you soil tested if you can. This is especially important if you live in an older neighborhood as the chance of lead buildup in the soil is greater (1, 6). Testing generally costs between $10-20 and this is good not only to test for toxic compounds, but can help you know which crops to grow or how to amend your soil. Most land-grant universities in your state can test your soil for you, check here to see where the nearest university is to you.
- Bring in new safe topsoil and create raised beds - 6 to 12 inches of additional topsoil is recommended. Purchase soil that is Organic Materials Review Institute (OMRI) certified to guarantee the lowest lead levels in soil available for commercial purchase (7). Hey bonus, no more bending your back alllllll the way to the ground!
- If you're not sure, stay away from growing root vegetables and leafy greens as they absorb heavy metals more easily through the soil (5). Stick to growing vegetables like tomatoes, zucchini and beans which take in less heavy metals (5).
- Double or even triple wash all your produce before using to make sure all the yucky particulate matter and heavy metals in the soil are rinsed out (5).
- Don't forget to wash your hands after working in the garden! This will make sure that you don't ingest any contaminated soil when you're enjoying your fresh grown veggies.
Basically, don't let the worries of home gardening stop you from growing your own fresh vegetables! Even though there are some concerns, just by paying close attention to the type of soil you have and carefully choosing which vegetables to grow, you'll be A-okay!