"The bottom line here is that once blood lead levels go up, we can't fix the damage," lead poisoning expert Walter J. Rogan, MD, tells WebMD. "So the main message is that we cannot let these levels go up in the first place. We have to prevent this damage from occurring."
Rogan headed a study to evaluate the effectiveness of a drug called succimer in children with moderately high levels of lead in their blood. Succimer helps the body get rid of lead by binding to it and eliminating it from the body in the urine. The study is available in the May 10 issue of The New England Journal of Medicine.
As many as one million U.S. children have blood lead levels high enough to impair their abilities to think, concentrate, and learn. Although on the decline, lead poisoning remains a significant hazard for the nation's roughly 24 million kids aged 6 and younger. These youngsters are particularly vulnerable to lead exposure because their nervous systems are still developing.
In the study, Rogan and his fellow researchers examined the thinking and learning skills of 780 toddlers aged 1-3 who had moderately high blood lead levels. Approximately half of the children were treated with succimer to reduce blood lead levels and the other half were given placebos.
Succimer significantly lowered lead levels in the blood of treated children. But 36 months after treatment, children given succimer performed no better on IQ tests than those who were not treated, and parents reported their behaviors as slightly worse than untreated peers.
The researchers concluded that succimer is not useful for children with moderate lead poisoning.
"We knew when we started this study that we could make the blood lead levels go down, but we didn't know whether we could prevent the long-term ... problems associated with lead poisoning," Rogan says. "These findings suggest that we can't, so public health efforts aimed at lowering the risk to children are critical." Rogan is a senior investigator with the National Institute of Environmental Health Sciences in Research Triangle Park, N.C.
These days, the most important source of childhood lead exposure is lead-based paint. Government figures suggest that one in four U.S. residences -- or 25 million homes -- have significant lead-based paint hazards that could pose a danger to young children. The risks are greatest for low-income children living in older housing. In fact, it is estimated that 16% of low-income kids under age 6 have some degree of lead poisoning, compared with around 4% of all children in this age group.
The federal government's goal is to eliminate childhood lead poisoning by the year 2010 through public awareness efforts and grant programs. Housing and Urban Development (HUD) has requested a total of $110 million next year for lead hazard reduction in publicly assisted housing.
But John F. Rosen, MD, who runs the lead program at New York's Children's Hospital at Montefiore in the Bronx, says this effort is just a "Band-Aid approach" to the problem. The only way to eliminate the risk of childhood lead poisoning, he says, is to remove all lead-based paint, not just repair or patch the problem.
"As a national priority, houses built before 1960, all of which contain lead-based paint, have to be de-leaded permanently and forever, so that no child entering any of these houses is at risk," Rosen says. "I consider it a national disgrace that this has not happened."
Rosen, who wrote an editorial to accompany the Rogan study, points to a 1991 cost analysis conducted by the CDC. That report suggested that $20 billion spent to remove lead paint from the nation's older houses would actually save billions in healthcare dollars.
"As long as lead paint exists, it is a ticking time bomb," Rosen says. "Sooner or later it is going to deteriorate, and it is going to poison young children. The current approach of the federal government is to put Band-Aids on those surfaces that are the worst. But if you have a disease, you want a total cure. This is only bringing your temperature down from 106( to 104( and saying you're cured."
In response, a HUD official who did not want to be identified, says it is unrealistic to call for total removal of all lead-based paint in this economic environment.
"In a perfect world that would be the goal," he tells WebMD. "But this is a more than 100-year-old problem. We have to reduce lead hazards now, and we are trying to do that."