Lead in Indiana's Soil


According to the U.S. Centers for Disease Control and Prevention, lead poisoning is the No. 1 preventable environmental cause of illness in children. Children between the ages of 1 and 3 are at the greatest risk of lead poisoning because their nervous systems are still developing, their bodies absorb more lead than adults, and they use hand-to-mouth activity to explore their world.

Most of the efforts to increase awareness about lead focus on lead-based paints. The spotlight has now shifted to soil around the home, which causes new concern for parents when they encourage their children to play in the dirt.

Indiana State University Sediment Geochemist Jennifer Latimer conducted a project last summer looking at the soil in the community garden at ISU. The results concluded that there were elevated lead levels. Since then, areas of the community garden with elevated levels have been repurposed into having a non-gardening function. Knowing the test was only a snapshot of property in Vigo County spawned Latimer’s curiosity to test more property.

“Our ultimate goal is to create a map of an average soil lead concentration from around Vigo County. We have partnered with the city to use the data they have collected for different purposes. We also want to provide free soil testing for residents so that we can try and understand what lead levels look like in neighborhoods all over,” Latimer said.

Lead, lead, everywhere …

There is naturally some lead in rock, therefore lead is naturally found in the soil. High concentrations of lead in soil comes from past environmental uses. It is often referred to as a legacy problem because lead is geochemically immobile and stays at the surface of the soil. Over past centuries, lead in soil has accumulated. Think of it this way: emissions from industrial activities like coal fired power plants, lead-based paint from older homes and lead from combustion leaded gasoline all put lead into the atmosphere. The soil then acts like a sponge, absorbing and accumulating decades of harmful lead into the surface layers.

Lead in your garden

Since lead resides in the top four-to-six inches of the soil, gardeners are at risk of consuming lead. Before I scare you away from gardening this year, let me tell you how to take a few extra steps so that your garden can become safer and healthier for the environment at the same time. First, have your soil tested. One can do so by contacting Latimer by email at ISU-lead@mail.indstate.edu or 812-237-2254.

Some guidelines on how to read the results:

• Lead is naturally present in soil at 10-30ppm.

• Less than 200ppm: Having anything higher than what is natural in soil can be alarming, but anything less than 200ppm has not been directly linked to negative health outcomes. Make sure all parts of your property are less than 200ppm. If some areas are higher, you may want to cover these areas with ground cover or mulch to prevent contaminated dust from blowing on your plants and food.

• 200-400ppm: Build a raised-bed garden and mulch the surrounding 10 feet to suppress any dust from blowing onto your food.

• 400-600ppm: Follow all recommendations listed above. Leafy green vegetables should either not be grown, or washed thoroughly because they have tiny hairs that trap soil particles. Root vegetables should be peeled and washed thoroughly.

• 600ppm or higher: Consider relocating your garden or overhaul your property to remove hazardous lead levels.

“Lead is not usually taken up by plants,” Latimer said. “If you are exposed to lead from your garden it is from the soil left on your vegetables. If you can clean or peel your vegetables, it decreases the lead consumption.”

Now what?

One can never be too cautious when dealing with lead. The side effects are damaging and can be life altering. If you believe you have been exposed to lead, consult your physician. In addition practice the following steps:

• Keep your property damp to prevent lead-rich dust from blowing in the air and potentially leading to exposure.

• Wash produce thoroughly.

• Put gardening clothes in a bag upon entering the house and wash separately.

• Leave gardening shoes outside.

• Wash hands and exposed body upon returning from the garden.

If the lead levels are extremely high on your property, don’t worry. You can still satisfy your need to garden by either obtaining a plot at a local community garden or by growing fruit trees. Fruit trees do not carry lead to the produce. Remember, by making a few changes to your yard, you can increase the safety to your yard, your kids and for yourself. Happy, safe, gardening!

- Jane Santucci