Lead Poisoning a Lingering Problem for Nation's Kids
May 9, 2001 -- A drug that effectively reduces blood lead levels in children does not prevent or minimize the brain damage caused by lead poisoning.
"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.