Changes in blood lead concentration and children's IQ between 7 and 11–13 years of age

Decline in blood lead concentrations, μmol/l (μg/dl)Change in IQ points, mean (95% CI)p Value*
*p value calculated using analysis of variance.
<0.11 (<2.3)−5.4 (−3.8 to −7.0)
0.11 to 0.24 (2.3 to 4.9)−5.0 (−3.2 to −6.8)0.45
>0.24 (>4.9)−3.8 (−2.3 to −5.3)