A Senate committee led by California Sen. Barbara Boxer plans to look into government funding of studies that put fertilizer made from treated human and industrial waste on the lawns of East Baltimore rowhouses and a vacant lot near a school in East St. Louis, Ill.
Additionally, the president of the Maryland NAACP said yesterday that he is asking federal and state officials to launch a criminal investigation.
The sludge was used to see if it could be a cheap way to clean up lead-contaminated soil - and ultimately to see whether cleaner soil would protect children from lead poisoning.
"Someone putting human waste and industrial waste in someone's yard as a test? That sounds like Tuskegee all over again," said Gerald Stansbury, president of Maryland State Conference of NAACP Branches. The Tuskegee Experiment began in the 1930s and continued for 40 years, during which time researchers allowed syphilis in black men in Alabama to go untreated.
Stansbury was responding to an Associated Press article about the sludge study. The study was begun in 2000 and resulted in a paper written in 2005.
Also in reaction to the article, Boxer said the Senate Environment and Public Works Committee would hold hearings before summer's end on risks associated with using sludge as fertilizer.
But several waste-management specialists and researchers said the same material used in the study - done by researchers with the Johns Hopkins Bloomberg School of Public Health - is used in residential gardens throughout the country and even in a park in front of the White House.
"Believe me, it's all over suburbia," said Robin Davidov, executive director of the Northeast Maryland Waste Disposal Authority, a government agency that helps turn sewage into composted sludge. The process is similar to pasteurization. The material is heated to a high temperature to kill pathogens, she said.
About 6 million tons of this fertilizer are sold a year. The Maryland Department of the Environment has approved its use for nearly three decades, as has the U.S. Environmental Protection Agency.
There have been some questions raised about the safety of composted sludge, which is also used in a slightly different form on farmland throughout the U.S. A report by the National Academy of Sciences in 2002 found fault with how the EPA developed its regulations on sludge but found no risk to public health.
The yards were chosen because of the high concentration of lead found in poor, African-American neighborhoods of Baltimore, places where families couldn't afford to rip up their yards, officials said. The families all volunteered to be part of the study and were fully informed of every aspect of the research, said Dr. Rufus L. Chaney, a research agronomist with the U.S. Department of Agriculture.
The idea was to have the sludge bind to the lead in the soil and make it less likely to be absorbed if consumed. The study found that it worked, Chaney said. He said other studies - which included feeding treated soil to rats, pigs and humans, showed a 69 percent reduction in lead absorption. The Hopkins study was not designed to check the possible impact on the health of children who lived in the houses, he said.
The Associated Press contributed to this article.