eLetters to:

EXPERIENCE AND REASON: Jessica L. VanArsdale, Richard D. Leiker, Mel Kohn, T. Allen Merritt, and B. Zane Horowitz Lead Poisoning From a Toy Necklace Pediatrics 2004; 114: 1096-1099 [Abstract] [Full text] [PDF]

eLetters: Submit a response to this article

eLetters published:

cause vs association

josephq scheller   (14 October 2004)

Re: cause vs association

Jessica L. VanArsdale   (10 November 2004)

cause vs association 14 October 2004
josephq scheller, physician children's national medical center Send letter to journal: Re: cause vs association jschelle{at}cnmc.org josephq scheller	the author in footnote 13 misquotes the study of Drs Lanphear et al from the New England Journal. that study shows an association between lead levels <10 and IQ loss, but does not show that lead levels in that range causes IQ loss.
Re: cause vs association 10 November 2004
Jessica L. VanArsdale, physician United Indian Health Services Send letter to journal: Re: Re: cause vs association drjva{at}earthlink.net Jessica L. VanArsdale	Thank you for raising this important point. Showing an association does not necessarily mean that the relationship is causal. There are several criteria that should be met in order to conclude that a causal relationship exists. These criteria include; finding a statistically significant association, making sure that the findings can’t be explained by reverse causality, bias, or confounding, having internal and external validity, showing a strong association, and having biologic plausibility. The study by Lanphear et al. was well designed and met most of the criteria for causality. Perhaps we need more studies looking at low level lead exposure in order to increase the external validity and then we can determine if there is true causality.