Low-level lead exposure and intelligence in children

Numerous prospective and cross-sectional studies of the relation between low-level lead exposure and cognitive functioning in children have suggested that intellectual and academic performance declines as lead burdens increase. Kaufman [Arch. Clin. Neuropsychol. (2001)] raises questions regarding interpretive issues along these lines, and therein challenges the wisdom of using the available lead/IQ data complex as an essential element of the decision-making process that leads to policy statements. In this article, we address some of the concerns expressed by Kaufman, and conclude that each of his five points are logically or statistically flawed, as is his overall strategy of critiquing individual studies after methodologically sound meta-analyses have been performed. Kaufman is perhaps correct that the findings from correlational research on low lead levels and IQ loss should be interpreted with caution, but the caution extends equally if not more greatly in the direction of previous research having underestimated the relationship between the two variables in question.