This was originally a comment from a visitor to the site (Janice Hicks), but it had so much information I put in this post.
Fluoridation can leach lead from pipes, even in non-acidic water (if they don’t take the fluoride out of Michigan’s/Flint’s city water, it will destroy the buffering agent that lines the pipes to prevent lead pipes from leaching lead into the water). The fluoride ion destroys the buffering agent and binds chemically and deposits more lead into the people who drink city water.
Even if fluoridation did not reduce the pH of Flint’s water, it could still have contributed to Flint’s lead crisis. As explained by scientists from the University of North Carolina, fluorosilicic acid (fluoride) “does not leach lead simply because it is an acid.” (Maas, et al. 2007). Fluorosilicic acid may also leach lead due to its “unique affinity for lead.”
In carefully controlled laboratory experiments, the North Carolina scientists found that fluorosilicic acid can increase the leaching of lead in non-acidic waters (pH 8), even from common brass fixtures, like faucets, that contain small quantities of lead. (Maas 2007)
The scientists found that combinations of fluorosilicic acid and chlorinated disinfectants can produce more severe effects than the chemicals by themselves, sometimes dramatically so.
In one experiment, the combination of fluorosilicic acid and chlorine caused lead levels to spike as high as 1,000 ppb, nearly 70 times higher than EPA’s action level, while, in another experiment, the joint action of fluorosilicic acid and chloramines produced lead levels to spike as high as 400 ppb, nearly 30 times the EPA action level.
To be clear, the North Carolina study used higher concentrations of fluorosilicic acid than are added to public tap water. The study used about 2 times more fluorosilicic acid than the level historically added to U.S. water supplies, and about 3 times more than the levels generally added today. As a result, the use of fluorosilicic acid for fluoridation programs may not produce as dramatic an effect as the North Carolina team observed.
The North Carolina study’s findings do demonstrate, however, that despite theoretical arguments to the contrary, highly diluted levels of fluorosilicic acid can leach lead from pipes and common brass fixtures, even in pH-adjusted water, and this effect can be unpredictably amplified in the presence of other common water treatment chemicals.
Fluorosilicic Acid Linked to Elevated Blood Lead Levels in Children
So, fluorosilicic acid can leach lead from pipes in laboratory experiments. This is now clear. But what about in real world conditions: can fluorosilicic acid contribute to measurable increases in our lead exposure?
The first two studies to investigate this issue analyzed the blood lead levels of almost 400,000 children living in areas with and without fluoridated water in New York and Massachusetts (Masters 1999, 2000). These studies found that children living in areas with fluorosilicic acid-treated water were at increased risk of having markedly elevated blood levels (>10 ug/dl).
These studies, conducted by Dartmouth professor Roger Masters and chemical engineer Myron Coplan, sent shock waves through the public health community. As Masters noted, “If further research confirms our findings, this may well be the worst environmental poison since leaded gasoline.”
Even the CDC has conceded that, if research confirms the link between fluoridation and elevated lead exposure, fluoridation would need to end, noting that “efforts to prevent dental caries via the use of fluoridated drinking water should continue unless a causal impact of certain fluoridation methods on PbB [blood lead] concentration is demonstrated by additional research.” (Macek 2006)
This brings us to CDC’s own study on the issue.
After criticizing the methodology of Masters and Coplan’s studies, the CDC published an analysis of a smaller sample of 10,000 children from across the country, whose blood was measured for lead during the 1988-1994 National Health and Nutrition Examination Survey. (Macek 2006).
The CDC study, which controlled for the key factors known to influence blood lead levels, including race/ethnicity, poverty status, and urbanicity, is sometimes touted as refuting the link between fluoridation and lead hazards, but a close look at its data shows that the study does little to dampen concern.
According to the CDC’s data, fluorosilicic acid was associated with an elevated risk for high blood lead (> 5 ug/dl) in every single category of children identified by the CDC, even after controlling for the other key risk factors. fluorosilicic acid was associated with
- a 20% increased risk (but not statistically significant) for high blood lead levels among children living in houses made prior to 1946;
- a 40% increased risk (but not statistically significant) for high blood lead levels among children living in houses made between 1946 and 1973;
- a 70% increased risk (but not statistically significant) for high blood lead levels among children living in houses made after 1974;
- a 530% increased risk (which was statistically significant) for high blood lead levels among children living in houses with unknown ages.
Since most of these elevated risks were not statistically significant, the CDC dismissed them as essentially a random fluke. However, the consistency in the direction of the risk, coupled with the statistically significant 530% increased risk for children in homes of unknown age, raises a serious red flag.