Letter

Environmental lead and children's intelligence

BMJ 1995; 310 doi: 10.1136/bmj.310.6991.1408a (Published 27 May 1995)
Cite this as: BMJ 1995;310:1408.2

Access to the full text of this article requires a subscription or payment. Please log in or subscribe below.

Studies included in the meta-analysis are not representative

  1. Herbert L Needleman
  1. 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 …

    Access to the full text of this article requires a subscription or payment

    Subscribe

    Article access

    Article access for 1 day

    Purchase this article for £20 $30 €32*

    The PDF version can be downloaded as your personal record

    * Prices do not include VAT

    Rapid responses

    THIS WEEK'S POLL

    BMJ most popular