Lead-contaminated soil originates from a variety of sources and impacts our most vulnerable populations. People can be exposed to lead in many different ways, we are looking at the causes of lead-contaminated soil currently as well as in the past.
Historically, lead was an incredibly useful resource for a variety of reasons. It was used in construction, energy, and transportation as a vital heavy metal.
Most soil contamination comes from sources like:
- leaded gasoline
- lead-based paint
- mining/smelting
- fishing weights
- stained glass use lead in production
These often leak into highways or create lead-contaminated dust through the company and consumer waste.
The National Institute of Health explains how a major source of lead in the air was leaded gasoline exhaust. Lead in the air then contaminates the soil and stays there for a long time. Other historical lead sources like paint have contaminated the soil after years of degradation and weathering that causes lead chips to fall into the soil.
As the dangers of lead have become more well-known, many more policies have been put in place and several of these companies have been shut down, but their impact is still felt today; lots of modern lead in the soil can be traced back to historical sources.
The Washington State Department of Health explains how current sources include:
- lead-based paint deteriorating on buildings and playground equipment
- busy roads (leaded gasoline)
- underground storage tank leaks
- recycling facilities for lead-acid batteries
- lead ore mining/smelting dust
These sources are found all across the world and are especially detrimental in low-income communities that don’t have the funding to replace or clean up these contamination sites.
Lead-Soil Concentrations in the US
Map of USGS Mean Data for Geogenic Soil Lead Concentrations in the US. *average values for each state are used in the map above, in ppm.
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If you are working outside with soil with these above factors, you can become exposed to certain lead levels from these sources. This is especially a risk for young children in urban areas and near homes built before 1978. The CDC furthers that “Young children tend to put their hands, which may be contaminated with lead dust from soil, into their mouths” (CDC). Eating produce grown in lead-contaminated soil is another modern cause of lead poisoning.
Gardening, playing in bare soil, consuming fruit and vegetables grown in contaminated soil, and ingesting soil are all causes of soil-based lead poisoning which is why it is important to test the soil around you in case of exposure. Below is a recommended soil level limit to help when growing food in gardens that you should test for.
- It is safe to consume any food crops grown in soil at 0-100 ppm.
- From 100-350 ppm you are safe to grow legumes, fruiting, and leafy vegetables but avoid growing root crops in these conditions.
- Anywhere from 400-900 ppm you should not grow root crops or leafy vegetables, but legumes and fruiting vegetables are safe to grow. You should also keep your children out of the garden at this range.
- Beyond 900 ppm is a toxic level of lead that is not recommended to grow crops in the soil.
In general, high modern lead levels in soil can be traced back to historical contamination.
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Works Cited
Centers for Disease Control and Prevention. (2022, December 16). Lead in soil. Centers for Disease Control and Prevention. https://www.cdc.gov/nceh/lead/prevention/sources/soil.htm
Common sources of lead poisoning. Washington State Department of Health. (n.d.). https://doh.wa.gov/community-and-environment/contaminants/lead/common-sources-lead-poisoning#:~:text=Lead%20can%20get%20in%20soil%20from%3A%201%20Deteriorating,mining%20and%20milling%2C%20smelting%2C%20municipal%20solid%20waste%20incinerators.
Dignam, T., Kaufmann, R. B., LeStourgeon, L., & Brown, M. J. (2019). Control of lead sources in the United States, 1970-2017: Public health progress and current challenges to eliminating lead exposure. Journal of public health management and practice : JPHMP. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6522252/#:~:text=Historically%2C%20the%20major%20source%20of,beginning%20in%20the%20early%201920s.
Sources of lead. Sources of Lead | Lead Poisoning | Health & Senior Services. (n.d.). https://health.mo.gov/living/environment/lead/sources.php
