BOSTON -- A major study of Boston children shows that removing lead from contaminated soil in back yards can reduce the level of the toxic substance in children's blood, but not as much as had been expected, according to federal officials.
A similar study was conducted in Baltimore, where children showed even less of an improvement in blood lead levels than those in Boston, officials said. The results of the Baltimore study have not been released.
The finding raises fundamental questions about how a key urban health problem should be addressed and about whether federal Superfund cleanup of lead-contaminated soil would help, say public health and government officials.
Lead concentrated in the soil is considered one of the top three sources of lead poisoning, behind paint and tap water drawn from lead pipes. Up to 4 million children nationwide are considered lead-poisoned, a condition that can cause brain damage.
The lead in the soil is the result of emissions that came from autos before restrictions were placed on the use of leaded gas, and from lead-based paint, which is still present in many older homes.
"There is a problem with soil, but soil removal as a strategy is certainly not the one you would want to use up the bulk of the resources for lead prevention activities," said Alonzo Plough, Boston's deputy commissioner for public health, who was involved with the Boston study released yesterday.
The $5.4 million, 5-year study, paid for by the federal Superfund, removed lead-contaminated soil around 152 homes and measured any improvements in the blood lead levels of children living in those homes. Soil removal cost between $5,000 to $10,000 per property, said David McIntyre, a U.S. Environmental Protection Agency official.
Instead of the expected average decrease, the study found only the soil removal decreased lead levels by half or less, Mr. McIntyre said.
The blood lead levels probably did not go down as much as expected because the children were exposed to lead through other routes, said EPA officials.
As a result of the Boston study, Julie Belaga, EPA regional administrator, yesterday announced a plan to treat the lead problem from a holistic perspective, looking not only at soil, but also at dust, paint and drinking water.