Three meta-analyses on the relationship of low levels of lead to loss of IQ points in children, which included a total of 26 well-controlled studies, provided the raw materials for the analysis presented here. Despite some key limitations, results of lead–IQ studies have been instrumental in setting public policy. In this paper, five shortcomings in these studies are addressed, which, when taken together, suggest greater caution in the interpretation of the lead–IQ data. In addition, some other issues are addressed concerning the IQ loss attributed to low levels of lead.

Author notes

A preliminary draft of portions of this manuscript was partially funded by Ethyl, Richmond, VA. The author gratefully acknowledges Ethyl for access to their library of published scientific articles, and recognizes Jerry M. Roper, Ph. D., of the same firm, for his assistance with the scientific literature and for helpful support and input on this project.