Succimer Chelation Therapy is Ineffective in Improving Test Scores in Moderately Lead Poisoned Children

Walter Rogan, MD, NIEHS
Kim Dietrich, Ph.D., University of Cincinnati; R01ES08158
Robert L. Bornschein, DVM, Ph.D., University of Cincinnati; U01ES09720 and N01ES035364
James Ware, Ph.D., Harvard School of Public Health; N01ES35360
Frances Gill, Ph.D., Children's Hospital of Philadelphia; N01ES35361
Julian J. Chisolm, Jr., MD, Kennedy-Krieger Institute, Baltimore MD; N01ES35362
Richard Weeden, Ph.D., University of Medicine and Dentistry of New Jersey; N01ES035363

Background: Lead exposure in children continues to be a severe public health problem even though leaded gasoline and lead-based paint were removed from the market place years ago. Children continue to be exposed to lead through deteriorated urban housing containing lead-based paint and from soil and dusts contaminated with lead. Tens of thousands of of children in the United States each year have blood lead concentrations in the 10-20 µg per deciliter range. This level of lead exposure has been associated with cognitive and learning deficits. However, current chelation therapies have not been evaluated for their effectiveness in lowering blood lead levels and preventing cognitive impairment in children with blood lead concentrations in this range.

Advance: These investigators carried out a clinical trial in 780 children with blood lead levels in the 20-44 µg per deciliter range. The study tested the hypothesis that children with moderate blood lead levels who were given succimer, a lead chelating agent, would have lower blood lead levels and better scores than children given a placebo on a range of tests for learning, neuropsychological function, and behavior 3 years after treatment. Succimer treatment lowered blood lead levels over the course of the study but the test scores of the succimer treated children were not better than the placebo treated children.

Implication: This study used the recognized best chelation agent and dosing regimen for blood lead reduction. The lack of prevention of cognitive and learning deficits in the children in this study questions the value of public health programs that rely solely on treatment after lead poisoning has occurred. An accompanying editiorial by Drs. John Rosen and Paul Mushak, states that primary prevention "is the only satisfactory solution to this devastating problem." Removing the source of the lead exposure, namely lead-base paint in older housing, is the best method of prevention of lead poisoning in children.

Publication: Rogan WJ, Dietrich KN, Ware JH, Dockery DW, Salganik M, Radcliffe J, Jones RL, Ragan NB, Chisolm JJ Jr, Rhoads GG. The effect of chelation therapy with succimer on neuropsychological development in children exposed to lead. N Engl J Med. 2001 May 10;344(19):1421-6.