Expert: Sunflowers unlikely to leach lead
NEW ORLEANS (AP)--A project begun on Earth Day to study the results of growing sunflowers to reduce lead contamination in soil is not designed to produce a field of blooms.
It also seems doomed not to produce any evidence that sunflowers can make New Orleans contaminated soil any safer, according to scientists who have studied the subject.
"I'd like to be able to say planting sunflowers would protect the children of New Orleans," Dr. Howard Mielke, a research professor in the Department of Chemistry and Center for Bioenvironmental Research at Tulane University said on April 23. "But 25 years of research shows that it won't."
Students from Dillard University on April 22 measured the lead content of the soil before planting 10,000 sunflowers in six grids on a large corner lot. The plan is to harvest the plants three times between now and October--before they bloom--and check to see how much lead is in the roots.
Officials for the New Orleans Office of Recovery and Development Administration, which backed the sunflower project, did not return calls for comment on April 23.
Although lead contamination in all major cities is bad, New Orleans has a particular problem with lead paint used on houses, then sanded, which scattered the lead dust into the soil, Mielke said. Previous generations of leaded gasoline added to the problem, he said.
The use of plants to remove lead from soil does not work, according to Rufus L. Chaney, a senior research agronomist with the federal Agriculture Department, in Beltsville, Md., who has studied the subject for 25 years.
"Sunflowers do not take up lead," Chaney wrote in an e-mail. "No plant species takes up useful amounts of lead."
Plants have natural barriers to lead, Mielke said. Fruit trees planted in contaminated soil, for instance, will produce lead-free fruit.
In addition, Mielke said the planting site, where bare dirt would expose even more lead, should be fenced so children could not play in it.
Children are particularly vulnerable to toxic chemicals from the soil because they play outside and put their hands in their mouths. And New Orleans has particularly high lead levels, Mielke said.
"They range from five to 10 parts per million on the outskirts of town to 500 to 1000 per million on the interior," he said. "The EPA says below 400 parts per million is safe, but anywhere else in the world anything over 100 parts per million is unacceptable."
The need to reduce lead contamination in the city's soil is critical, Mielke said.
"In New Orleans' inner city 20 to 30 percent of the children have lead poisoning," Mielke said.
There are simple and relatively inexpensive ways to control the contaminated soil, Mielke said.
"If I could do one thing, I'd get people to just stop sanding the paint in old houses and scattering the leaded dust," he said. "That would be a major reduction in the danger to children."
The second thing he would like to see happen is for clean soil to be brought in to cover contaminated areas, especial in parks, around schools and in other areas children congregate or play.
"We're still rebuilding the city," he said. "Why don't we use this opportunity to build it back better."