The short (7 weeks) and long (6 months) term effects of lowered blood lead levels on cognitive performance were measured in 154 previously untreated lead-poisoned children, aged 13 to 87 months, examined at the Department of Pediatrics, Albert Einstein College of Medicine, Montefiore Medical Center, Bronx, NY. Pre-treatment blood lead levels were 25-55 mcg/dL, and erythrocyte protoporphyrin levels were >0.65 mcmol/L, in children enrolled. Housing inspections and abatement procedures were performed as necessary, and an iron supplement (6 mg/kg day) was prescribed for children (39% of group) with ferritin levels <16 mcg/L. Those with positive lead mobilization tests (40% of group) were administered a 5 day course of EDTA. Cognitive development was measured by the Bayley and Stanford-Binet 1) before treatment, 2) at 7 weeks, and 3) 6 months after enrollment. The Stanford cognitive index (CI) increased 1 point for every decrease of 3 mcg/dL in blood lead level after 6 months but not at 7 weeks after treatment. A moderate correlation of test performance with ferritin levels was the only significant change at short term: every increase of 3 mcg/L in serum ferritin was associated with an increase of 1 point on the CI. 
COMMENT. The results suggest an association between decreases in blood lead level and cognitive improvements in lead-poisoned children. The authors remain cautious in making causal correlations, and they admit a possible contribution of iron supplements or other factors in the cognitive improvements observed.
A study of lead-contaminated soil abatement in Boston and blood lead levels of 152 urban children less than 4 years of age showed that soil abatement around homes results in only a modest decline in blood lead levels (2.44 mcg/dL after an 11 month interval). The median surface soil lead levels were 2075 ppm before abatement and 105 ppm after abatement. Urban children with low-level lead exposure are not appreciably benefited by soil abatement programs . An estimated 3 million children in the United States and 69% of children, 6 months to 5 years of age, in Boston have blood lead levels >10 mcg/dL, sufficient to impair intelligence and development.