Researchers analyzed and mapped soil lead concentrations along 25 miles of streets in Durham, North Carolina, a city of about 270,000 people. They found that while soil lead levels have generally decreased since the 1970s, they have decreased much less near residential foundations than along streets.

The researchers collected soil samples near foundations of houses built before 1978. Samples within a meter of the older homes averaged 649 milligrams (mg) of lead per kilogram (kg) of soil, more than three times the average level detected near streets, which was 150 mg/kg.

EPA guidelines say exposure to soil lead concentrations above 400 mg/kg is associated with potential long-term health risks to children, including possible damage to the brain and nervous system, slowed growth and development, learning and behavior problems, and hearing and speech problems.

“Urban soil processes are driving lead concentrations down over time, but it’s alarming that lead levels in some locations—typically older, poorer neighborhoods—still far exceed safe levels decades after leaded gasoline and lead paint were phased out,” says lead author Anna Wade, a postdoctoral researcher at the US Environmental Protection Agency and a 2020 PhD graduate of Duke’s Nicholas School of the Environment.

Read the full article about lead in soil by Tim Lucas at Futurity.