Finally, some good news for the folks of New Orleans. A new study from researchers at Colorado State University and Tulane University found that the flooding of New Orleans from Hurricanes Katrina and Rita may be responsible for declines in soil lead levels, and consequently, declines in children’s blood lead levels.
For the study, researchers collected 874 soil samples from 46 different neighborhoods before and after the hurricanes. They also measured blood lead levels from 13,306 children younger than six years old: 11,191 were measured before the hurricanes and 2,115 were measured after the hurricanes. Results were grouped by neighborhood.
They then examined changes in soil lead at the neighborhood level. They found that on average, soil lead levels declined 46 percent after the hurricane-related events. Sadly, before the hurricanes, 15 of 46 neighborhoods tested exceeded the U.S. Environmental Protection Agency's regulatory standard of 400 milligrams per kilogram (mg/kg) of lead. After the hurricanes, only six of the 46 neighborhoods were over the limit.
Declines in children's blood levels coincided with decreased lead levels in soil. The reduction was greatest in neighborhoods with more than 50 percent change in soil lead levels. When researchers compared average blood lead levels by neighborhood, they found that blood levels decreased 33 percent in the post-hurricane period to 3.45 µg/dL (measured in micrograms of lead per deciliter of blood) from 5.14 µg/dL.
Why the dramatic change? In 2005, Hurricanes Katrina and Rita struck and the subsequent catastrophic flooding caused the levees to break, which resulted in 80 percent of New Orleans being flooded. The resulting floodwater may have carried away top soil layers that were contaminated with lead, reducing soil lead levels and children's exposure to the toxin.
At least it's one positive note to come out of the series of hurricanes that wreaked havoc on a community still fighting to recover.