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Sheppard PR, Bierman BJ, Rhodes K, Ridenour G, Witten ML.Sheppard PR, et al. Among authors: ridenour g.J Environ Public Health. 2012;2012:509458. doi: 10.1155/2012/509458. Epub 2012 Mar 14.J Environ Public Health. 2012.PMID: 22523506Free PMC article.