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4) Silicofluorides Linked (Again) to Lead Exposure Risk
Can water fluoridation increase the levels of lead circulating in a child’s blood? This is the question that has been asked ever since Dartmouth professor Roger Masters, and chemical engineer, Myron Coplan, published studies in 1999 and 2000 reporting that exposure to “silicofluoridated” water was associated with increased blood lead levels in children surveyed in Massachusetts and New York State. In 2007, two new studies have added yet further evidence to this issue.
One of the studies, a tightly controlled laboratory experiment conducted by scientists at the University of North Carolina, submerged lead-containing brass pipes in water with various water treatment chemicals, including silicofluorides (4a). The study found that silicofluorides increased the erosion of lead from the piping, particularly when added in conjunction with chloramines (a disinfectant commonly used as an alternative to chlorine). According to the authors:
“Prior to the present study, no one had looked at brass corrosion by combinations of either chlorine or chloramine with water fluoridating agents. Several factors applicable to such combinations can produce more corrosion than either of the disinfectants or fluoridating agents alone.”
One caveat to this laboratory study is that the researchers added silicofluorides at a concentration of 2 ppm, which is slightly higher than the levels commonly added to drinking water (0.7-1.2 ppm). A new analysis of national data from NHANES (Macek 2006), however, suggests that silicofluorides at 1 ppm may also enhance lead levels (4b).
The analysis -- conducted by Coplan and one of the lead authors of the North Carolina laboratory study — found that children drinking water with silicofluorides have an elevated, statistically-significant, risk of exceeding the hazard threshold for lead in blood (5 ug/dL) -– although the risk was not as great as previously estimated. According to this new data, the use of silicofluorides appeared to increase the lead risk in about 2 of every 100 children exposed -- a notable difference considering that over 100 million Americans consume "silicofluoridated" water.
NEXT: NRC Panelists Release Risk-Assessment on Fluoride
REFERENCES:
4a) Maas RP, et al. (2007). Effects of fluoridation and disinfection agent combinations on lead leaching from leaded-brass parts. Neurotoxicology 28(5):1023-31..
4b) Coplan MJ, et al. (2007). Confirmation of and explanations for elevated blood lead and other disorders in children exposed to water disinfection and fluoridation chemicals. Neurotoxicology 28(5):1032-42.
See also: Top 10 Scientific Developments of 2006 |
