Do low levels of lead produce IQ loss in children? A careful examination of the literature.

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.