 for a prospective study of lead exposure and early development , we recruited pregnant women from a lead smelter town and from an unexposed town in yugoslavia and followed their children through 7 years of age . in this paper 
 we consider associations between lifetime lead exposure , estimated by the area under the blood lead ( bpb ) versus time curve ( auc7 ) , and intelligence , with particular concern for identifying lead 's behavioral signature . 
 the wechsler intelligence scales for children - version iii ( wisc - iii ) was administered to 309 7-year - old children , 261 of whom had complete data on intelligence , blood lead , and relevant sociodemographic covariates ( i.e. , home observation for the measurement of the environment ( home ) , birth weight , gender , sibship size , and maternal age , ethnicity , intelligence , and education ) . 
 these showed anticipated associations with 7-year intelligence , explaining 41 - 4% of the variance in full scale , performance , and verbal iq . before covariate adjustment , auc7 was unrelated to intelligence ; after adjustment , auc7 explained a significant 2.8%-4.2% of the variance in iq . 
 after adjustment , a change in lifetime bpb from 10 to 30 micro / dl related to an estimated decrease of 4.3 full scale iq points ; estimated decreases for verbal and performance iq were 3.4 and 4.5 points , respectively . 
 auc7 was significantly and negatively related to three wisc - iii factor scores : freedom from distractibility , perceptual organization , and verbal comprehension ; the association with perceptual organization was the strongest . 
 consistent with previous studies , the iq / lead association is small relative to more powerful social factors . 
 findings offer support for lead 's behavioral signature ; perceptual - motor skills are significantly more sensitive to lead exposure than are the language - related aspects of intelligence.imagesfigure 1 . 
 afigure 1 . 
 bfigure 1 . 
 cfigure 1 . 
 dfigure 2 . 
Images