Recall of a lead-contaminated vitamin and mineral supplement in a clinicaltrial

Purpose - The Treatment of Lead-exposed Children (TLC) trial tested whether developmental outcome differed between children treated for lead poisoning with succimer or placebo. On 7 July 1997, TLC was informed that the vitami n and mineral supplements it gave to ail children were contaminated with ab out 35 mu g of lead per tablet. Methods - TLC recalled the contaminated supplements and measured the childr en's exposure. Results - The families of 96% of the children were contacted with 30 days. Among the 571 children to whom the contaminated supplements were dispensed, the mean increase in blood lead was 0.06 +/- 0.01 mu mol/L (1.2 +/- 0.2 mu g/dL); among 78 children to whom they were not, it was 0.09 +/- 0.03 mu mo l/L (1.8 +/- 0.7 mu g/dL). There was no evidence of a dose-response relatio n between estimated supplement consumption and increase in blood lead conce ntration. Conclusions-The children's blood lead concentrations were not detectably af fected by the contamination. Since the association of cognitive delay with lead exposure is best described for blood lead, we believe that the trial's inference about the effect of drug therapy on lead induced cognitive delay should be unaffected. Copyright (C) 1999 John Wiley & Sons, Ltd.