Environmental lead and children's intelligence
BMJ 1995; 310 doi: https://doi.org/10.1136/bmj.310.6991.1408a (Published 27 May 1995) Cite this as: BMJ 1995;310:1408Studies included in the meta-analysis are not representative
- Herbert L Needleman
- Professor of psychiatry and paediatrics Western Psychiatric Institute and Clinic, University of Pittsburgh Medical Center, Pittsburgh, PA 15213-2593, USA
EDITOR,—Stuart J Pocock and colleagues' metanalysis of 26 studies of asymptomatic exposure to lead in children concludes that “the evidence strongly supports an inverse association between body lead burden and child IQ.”1 The authors then urge caution before the relation is accepted as causal. They do this on the basis of the following considerations: Are the studies representative? Is confounding adequately dealt with? Is selection bias at work? Is causality reversed: does low IQ cause ingestion of lead?
These questions have been asked and answered before. The criticism of non-representativeness could readily be applied to Pocock andcolleagues' analysis, which includes …
Log in
Log in using your username and password
Log in through your institution
Subscribe from £173 *
Subscribe and get access to all BMJ articles, and much more.
* For online subscription
Access this article for 1 day for:
£38 / $45 / €42 (excludes VAT)
You can download a PDF version for your personal record.