This issue of The Journal contains a very important and likely controversial article by Lozoff et al from the University of Michigan. The study examines data from three separate studies of lead levels in infants for which data on breast feeding duration was available. The three studies (performed at very different times and in very different areas) all suggested a relationship between infant lead levels and duration of breast feeding.
As a stand-alone observation, this study would be somewhat interesting but certainly not convincing. It must be read, however, with the knowledge that there is a plausible biologic mechanism for increased levels of lead in the milk of mothers in areas of elevated environmental lead; lactation may mobilize skeletal lead and permit its transfer into milk.
The study is put into perspective in an accompanying editorial by Weitzman and Kursmark, which provides further background on the problem. The editorialists agree with the authors that these observations should not be considered as an indictment of breast milk, but should stimulate studies to identify women at particular risk of having elevated body lead burdens and developing evidence based guidelines for them.
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