Monday, February 26, 2007

Flouride & Risk of Down Syndrome?

Someone posted a study on another list regarding flouride and the increased risk of DS. I decided to look at it a little further, since I thought it'd b interesting. It looks like there may be an association between flouride and an increased risk of DS, but there may also not be a significant link. So, basically they don't really know ;). But it's rather interesting.

Snip from the study, "Association of Down's syndrome and water fluoride level: a systematic review of the evidence."

Full text at:

"Four of the six studies provided a measure of the significance of the association of water fluoride level with Down's syndrome.[18, 14, 17, 16] Two of these studies found no significant difference in Down's syndrome incidence between high and lower water fluoride areas. [18, 14] The other two studies, by the same author, found an increased incidence of Down's syndrome in areas with higher water fluoride levels (p 16, 17] One of the other studies did not find any association between water fluoride level and Down's syndrome incidence, [13] depending on the control area selected, the crude relative risk ranged from 0.84 to 1.48. The remaining study [15] suggested a positive association between water fluoride level and Down's syndrome incidence (increased incidence with increased water fluoride concentration) when only the crude incidence rates were compared. To achieve some control for maternal age the analysis was limited to the 30 towns that initiated fluoridation. The rate of Down's syndrome among births in fluoridated areas was compared to the combined rate among births occurring before fluoridation and, for towns that stopped fluoridation, after fluoridation. Limiting the analysis in this way produced two groups comparable in maternal age, and produced similar estimates of the incidence of Down's syndrome in the two groups. Another factor thought to be confounding the association of Down's syndrome with water fluoride exposure was time. Time trend was controlled for and produced a maximum likelihood estimate for the relative risk was 0.95 (95% CI: 0.8, 1.2), suggesting no significant association between Down's syndrome and water fluoride level."



Takahashi K
Fluoride 31 (2), 1998, pp 61-73

SUMMARY: Down syndrome (DS) birth rates (BR) as a function of maternal age exhibit a relatively flat linear regression line for younger mothers and a fairly steep one for older mothers with the second line intersecting the first line a little above maternal age 30. Consequently, overall DS-BR for all maternal ages are not a very reliable parameter for detecting environmental influences, since they may be strongly affected by the ratio of the number of younger to older mothers. For this reason, data for mothers under age 30 were selected to detect an association between water fluoridation and DS for which the lower maternal age regression would be a much smaller contributing factor.
"The early research of I Rapaport indicating a link between fluoride in drinking water and Down syndrome was followed by studies claiming there was no such association. Application of sound methodology to the data in those later investigations shows that none of the criticisms against Rapaport's work are valid. For example, in the data of J D Erickson on maternal age-specific DS births in Metropolitan Atlanta, Georgia, when the three youngest maternal age subgroups are reasonably combined into single groups for areas with and without water fluoridation, a highly significant association (P < color="#660000">Full text for the above article can be seen at:

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