Lead in US Soils: Brief Intro & A Look at WNY
This article will briefly orient us to lead contamination in soils, with an eye on western New York. The next article explores interesting facts about lead's chemical interactions with soil and plants.
When Americans think of lead contamination, Flint, Michigan is the town that probably comes to mind. It's important that this story of community-wide lead contamination due to corrupt, racist water supply decisions by the state government made national news. Our media and government should be focusing attention on environmental justice issues like this. However, this story may have misled other communities into assuming that, since their town hasn't made the news, they must not be at high risk. Unfortunately, lead poisoning is a common problem across the US, particularly in cities and older communities like western NY.
In a 2017 national report, Buffalo was named one of "the most dangerous lead hotspots in America.” In Buffalo’s most affected neighborhoods, lead poisoning rates were found to be eight times higher than those in Flint during its crisis (McLeod).
Why is lead such a problem?
The human body "confuses" lead with calcium, a vital element for many bodily functions. For this reason, lead tends to get stored in bones and teeth, making it difficult to remove from the body (Worcester Roots). One body system reliant on calcium is the cardiovascular system. In 1985, an EPA study estimated that 5,000 Americans died each year from lead-related heart disease prior to the phaseout of leaded gasoline (Kitman).
Exposure to high levels of lead causes damage to organs, including the brain. Behavioral issues are one possible symptom of lead poisoning, particularly common in kids (Worcester Roots). A "significant body of research" links childhood lead exposure to violent crime (Eschner). It's likely that lead is one of many factors influencing gang violence, knowing that lead exposure is most prevalent in the inner city. When compared to poor white communities, children of color in the US are three times as likely to test high for blood lead levels (Nitti, 2015). In the city of Buffalo, children of color are twelve times as likely as white individuals to test high (McLeod).
Lead occurs naturally in soil, often within the range of 10 to 50 mg/kg. Due to lead from older buildings, formerly leaded gasoline, and industrial activity, soil lead levels may measure anywhere from 150 mg/kg to 10,000 mg/kg, such as at the base of a home painted with lead-containing paint. As a chemical element, lead does not biodegrade and can be found in soils for thousands of years (Stehouwer). However, we will learn in the next article how lead may be bound in less bioavailable forms in soil, plants, or fungi.
Though there are many possible sources of lead in and around the home, we'll focus on the three biggest contributors to soil contamination.
Lead from Older Buildings
For the home gardener, lead contamination is likely the highest close to buildings--particularly those built before 1978. This was the year the federal government banned lead-based paint for consumer use (US EPA, 2019). Check out the graphic below illustrating the national prevalence of lead-based paint.
Image Source: US EPA. www.epa.gov/lead/protect-your-family-exposures-lead
This issue hits close to home here in western New York. According to a 2004 article published in the journal Environmental Health Perspectives, New York State has the largest number (3.3 million) and largest proportion (43%) and of housing units built before 1950 of any state (Haley). Rates of children's blood lead levels above the Centers for Disease Control and Prevention action level of 10 μg/dL were higher in upstate NY cities than in New York City (Haley).
If you are unsure about the age of buildings near your garden, do a little research to find out. Worcester Roots, a Massachusetts non-profit offering support for lead-safe gardening, also suggests performing a visual assessment of paint degradation on a home. I like the free "Visual Assessment Form" offered on page 14 of their lead-safe gardening manual.
Worcester Roots has seen "a high correlation between visual assessments and soil test results" for lead, which means visual assessments can get us pretty far when paired with knowledge of the home's age. Still, the organization insists that a soil test is necessary when planting an in-ground garden, and when children are playing in an area.
According to Worcester Roots, the highest risk areas near historically lead-painted homes are "drip lines"--areas within two feet of a house or walkway, for example. I would create significantly more distance between my veggie and herb gardens and the home in question if possible.
Lead Contamination From Roads
Lead compounds were used in gasoline until they were finally banned in the US in 1986. (To understand my use of the word "finally," see Smithsonian Magazine article "Leaded Gas Was a Known Poison the Day it Was Invented.") Leaded gasoline was mostly phased out by the mid-1990s. An estimated 4.5 to 5.5 million tons of lead remain in US soil and dust from leaded gasoline (Stehauwer).
I wondered, "How wide is the area of concern on either side of the road when it comes to lead contamination?" I found a journal article by William H. Smith entitled "Lead Contamination of the Roadside Ecosystem" very helpful.
Soils close to older, high-traffic roads have the highest concentrations of gasoline-sourced lead. Since lead accumulates in soil, the age of the road is an important variable. Soil near an old road with little traffic may exceed the lead levels near a newer, busy road--especially if the road was built after the 1980s (Smith).
Smith reports that soil samples taken within a few meters of a heavily-used highway may contain more than 30 times the baseline levels of lead. At 33 feet from the roadway, however, lead levels are typically 5-15 times baseline levels. At around 66 feet from the road, several studies suggest that the influence of the roadway is lost in terms of lead levels (Smith, 6). However, many variables will affect lead levels near roadsides. Prevailing winds can result in much higher lead levels on the "lee" side of the road (Smith). Other influential variables include topography, soil type, vehicle types, and vegetation (Smith).
Image Source: Smith, 1976.
A similar trend in lead concentration can be noted when looking at soil depth. Within a few meters from the road, the top 2 inches of roadside soil may contain 30 times more lead than non-roadside soil. Since this is a highly biologically active layer, this is cause for concern (Smith). Often, lead content at 4-6 inches in depth is about 25% or less of that at 2 inches (Smith). However, making generalizations about roadside soil horizons is difficult since disturbance often occurs during road construction or maintenance (Smith).
Lead from Industrial Sources
Lastly, a number of current or historical industries are responsible for elevating soil and air lead levels in surrounding communities. This may include lead mining, smelting, and refining--but many other industries are responsible (Smith). They include coal plants, waste incinerators, metal and ore processing--including steel plants, a historic western NY industry--and more (EPA, 2017).
With its industrial history, western NY has housed many lead-contaminating companies. I will briefly share some info about the Michael Heyman Company, which operated a lead and zinc smelting and refining plant from 1917 to 1978 in the MLK Park area of Buffalo (Buffalo Chronicle, 2016).
Lead processing requires either the mining of new (primary) lead or the recycling of used (secondary) products and scrap metal. Both sources of the metal require "smelting," or a melting process, to obtain usable forms of lead (EnviroBlend).
Buffalo's Ferry Fields was used as a large dumping ground for toxic byproducts of the Michael Heyman Company's metal production and lead smelting. That property and land to its west have never been remediated "in part or in full" (Buffalo Chronicle, 2016). Many local children have played at the Ferry Fields. According to the Buffalo Chronicle, "Many even recalling eating apples, pears, and plums from trees there that would barely produce fruit; or playing in the brush along the railroad tracks where toxins are still present in alarming concentrations" (2016).
The Scajaquada drain runs underground along the property, and runoff flows towards Winchester and Fillmore Avenues (Buffalo Chronicle).
Today, this site is occupied by True Bethel Townhomes, an affordable housing development. This demonstrates the need for government regulation that prevents former industrial areas from being used in ways that put community members at risk, such as residences, parks, and playgrounds. See this post about the book Sites Unseen for more on this topic.
Researcher William P. Eckel's work revealed a list of 400+ former smelters in the US that were previously unknown to the federal government. I encourage you to visit this link and do a simple google search to find out if lead smelting has occurred in or near your community.
Creating Distance from Lead-Containing Soil
Since this article may read as doom and gloom, let's end by noting a few positive facts about lead contamination. First, knowing where we're most likely to encounter lead in our community's soils is hugely empowering as we cultivate and wild-harvest nourishing plants. Second, leaded gasoline has been banned, which means our exposure to lead in the air in the US has been drastically reduced. (These countries are still using leaded gasoline. If there are ways to support their citizens in banning it, may we do so.)
Because of this reduction in airborne lead, we can often get by with creating distance and/or barriers between our garden plants and contaminated soil. This is the easiest way to deal with lead contamination from older buildings or roads. This could mean distance in horizontal terms if we have the space. As noted above, roadside contamination has mostly dwindled at 66 feet from the road. According to Worcester Roots, the highest risk areas near historically lead-painted homes are "drip lines" close to a home.
Distance from lead contamination can also be created vertically by using containers or raised beds instead of planting in-ground. Check out this post with information about OMRI-certified soil products before investing in soil for raised beds. Page 12 of the Worcester Roots Lead-Safe Gardening Manual offers instructions for building one style of raised bed.
Stay tuned for fun facts about how lead, soil, and plants interact!
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Sources
Buffalo Chronicle. "Toxic legacy of lead smelting at the Ferry Fields."
Eckel, William P. "Supplemental Material 2016." Abandoned Secondary Lead Smelters. [List of 400+ former smelting sites not previously known by the US government.] www.researchgate.net/publication/308894740_Supplemental_Material_2016
EnviroBlend. "Industrial Applications: Primary and Secondary Smelting Operations." viewed Nov 2019. www.enviroblend.com/industrial-primary-secondary-smelting
Eschner, Kat. "Leaded Gas Was a Known Poison the Day it Was Invented." Smithsonian Magazine. Dec 9, 2016. www.smithsonianmag.com/smart-news/leaded-gas-poison-invented-180961368/#D1T7C6zEpUfMjIO0.99
Haley, Valerie B. and Thomas O. Talbot. "Geographic Analysis of Blood Lead Levels in New York State Children Born 1994-1997." Environ Health Perspectives. 2004 Nov; 112(15): 1577–1582. Published online 2004 Aug 18. www.ncbi.nlm.nih.gov/pmc/articles/PMC1247624/
Kitman, Jamie Lincoln. "The Secret History of Lead." The Nation. Mar 2, 2000. www.thenation.com/article/secret-history-lead/
McLeod, Marsha. "Buffalo Lags on Addressing Lead Poisoning." Investigative Post. May 1, 2019. www.investigativepost.org/2019/05/01/buffalo-lags-on-addressing-lead-poisoning/
Nitti, Lana. "Confronting Lead Poisoning Block By Block." TedxUtica talk. Sept 18, 2015. https://www.youtube.com/watch?v=N-7rJE_WpHM
Smith, William H. "Lead Contamination of the Roadside Ecosystem." Journal of the Air Pollution Control Association, 26:8, 753-766, DOI: 10.1080/00022470.1976.10470310. 1976. www.tandfonline.com/doi/pdf/10.1080/00022470.1976.10470310
Stehauwer, Richard. "Lead in Residential Soils: Sources, Testing, and Reducing Exposure." Penn State Extension. Viewed Nov 2019. https://extension.psu.edu/lead-in-residential-soils-sources-testing-and-reducing-exposure
US Environmental Protection Agency (EPA). www.epa.gov/lead-air-pollution/basic-information-about-lead-air-pollution
US Environmental Protection Agency (EPA). "Protect Your Family From Exposures to Lead." Updated March 26, 2019. www.epa.gov/lead/protect-your-family-exposures-lead
Worcester Roots. "Lead-Safe Yard Manual: A Do-It-Yourself Guide to Low-Cost Soil Remediation and Safe Gardening." viewed November 2019. www.worcesterroots.org/wp-content/uploads/2011/08/DIY_leadsafe_landscapingFinalDraft7-29-11sm.pdf
