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. 2008 Jul 22;116(11):1443–1448. doi: 10.1289/ehp.11579

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Flow diagram of study selection process using PubMed. aUsing the “limits” feature in PubMed. bThe only exception is described in “Methods.” cThe relevant results from the Hamburg study were divided into two publications. dThese 509 references include replicates of articles cited in multiple publications.