Indianapolis and Lead Soils
IMAGIS ADAR Multispectral Imagery of Marion County. This map was developed from research by Dr. Gabe Filippelli (Department of Earth Sciences, IUPUI). You can listen to Dr. Filippelli discuss his research at this link.
The third case study on soil pollution occurs right here in Indianapolis. Indianapolis, like many urban areas, has areas of elevated soil lead levels. This is mainly due to the use of lead paints up until the 1950s and leaded gasoline up until the 1996. While the lead paint was banned in 1978 and the EPAs first reductions in leaded gasoline were made in 1973, the legacy of lead paint in urban homes and use of leaded gasoline until its 1996 ban has left urban areas like, Indianapolis, with highly elevated levels of lead in the soil. As we learned in our example from Ryland Homes, once lead is in soil, it cannot be removed. The soil must be removed either by natural processes (i.e., erosion or mass wasting) or mechanically removed by human activity.
The effect of this lead in soils is the high incidence of elevated lead levels in children. Children are prone to lead poisoning because they often accidentally ingest lead dust and/or soils. (How many children do you know of who wash their hands every time after touching dirt?) The Centers for Disease Control and Prevention estimates that approximately 250,000 US children aged 1-5 have blood lead levels higher than 10 micrograms per deciliter of blood. Every blue dot on the map of Indianapolis shows the address of a child in Indianapolis whose blood level equals or exceeds this 10 microgram per deciliter threshold. This work is being done by Dr. Gabe Filippelli, Department of Earth Sciences, IUPUI.
What does this threshold represent? Lead poisoning can cause many symptoms from lethargy and anemia to seizures, coma, and death. At low levels such as 10 micrograms per deciliter, children start to have neurological problems, which can be measured by a reduction in IQ. Some studies have shown that children exposed to lead also have a higher tendency for aggressive behavior.
While the color coded areas show that lead levels in Indianapolis are lower than the government’s acceptable limit of 400 ppm, the exposure of children to lead is evident by their blood lead levels. While telling children not to play outside is not feasible, since there are many benefits to physical activity, many groups are working to find ways to encapsulate the soil either by paving over it or by doing something as simple as placing new sod over the contaminated soil.