BACKGROUND: According to the National Institute of Environmental Health Sciences, extreme lead exposure can cause a variety of neurological disorders such as lack of muscular coordination, convulsions and coma. Even lower levels of lead exposure have been associated with measurable changes in children's mental development and behavior.

Chronic lead exposure in adults can result in increased blood pressure, decreased fertility, cataracts, nerve disorders, muscle and joint pain, and memory or concentration problems.

DANGER IN THE GROUND: Lead is a highly toxic metal found in small amounts in the Earth's crust. Because of its abundance, low cost and physical properties, lead and lead compounds have been used in a wide variety of products including paint, ceramics, pipes, solders, gasoline, batteries and cosmetics.

Since 1980, federal and state regulatory standards have helped to minimize or eliminate the amount of lead in consumer products. However, a common source of lead exposure today is contaminated soil.

Lead in soil tends to bind tightly to surfaces of fine clay and organic particles. This means lead will not typically leach or move deeper into the soil.

Soil lead levels higher than 400 PPM are considered hazardous for contact by children.

WHERE DID IT COME FROM? One possible reason for lead levels in soil is residential home paint. Lead was not banned from residential paint until 1978, according to the Burlington Lead Program.

It is estimated that lead paint may exist on up to 75 percent of homes built before this date. Paint used prior to 1950 could contain up to 50 percent lead by weight. An older home with several layers of high lead content paint could contain as much as 250 pounds of lead in the painted surfaces.

Another problem that may contribute to lead accumulation in soil is lead gasoline. Gasoline contained lead additives until the mid 1980s. Until that time, as much as 5.5 million tons of lead was released into the environment from auto exhaust.

Soil near the busiest highways typically contains the highest amount of soil lead. More traffic usually means a higher contamination. Contamination tends to decrease as distance from traffic sources increase.

SOLUTIONS: According to the Burlington Lead Program, lead is a highly toxic, metallic element that will not biodegrade, breakdown or disappear over time. Soil contaminated with lead will remain contaminated forever without intervention.

One possible solution may be to use automatic watering systems to keep the soil from blowing when it's dry. Another step may be to use aggressive landscaping to cap over the lead-tainted soil with fabrics or mulch and then actively maintain some kind of ground cover to keep the lead-contaminated soils and dusts in place.

A more extreme measure in highly-contaminated areas is to completely remove the soil and replace it.

For More Information, Contact:
Anne Marie Chastain, Executive Director for Development and External Affairs
IUPUI School of Science
Indianapolis, IN
(317) 278-1051