The fluoride chemicals used to fluoridate drinking water are: hydrofluorosilicic acid, sodium fluorosilicate, and sodium fluoride. Unlike the fluoride compounds found in toothpaste or supplements, fluoridation chemicals are not pharmaceutical grade quality. They are, instead, unpurified industrial by-products that are collected in the air pollution control systems of certain industries.
Due to the lack of processing, these chemicals are known to contain elevated levels of certain contaminants, particularly arsenic. In addition, recent research — including both epidemiological and laboratory investigations — have detected associations between the fluoridation of water with hydrofluorosilicic acid and elevated lead exposure, particularly those living in houses with old pipes.
1. The Industrial Sources of the Chemicals
Until recently, all fluoridation chemicals were obtained from the wet scrubbing systems of the phosphate fertilizer industry in central Florida. In recent years, however, an increasing number of water departments have begun purchasing their fluoride chemicals from China. Based on recent incidents, it appears that the quality control of the Chinese chemicals is even more lax, and variable, than the U.S.-produced chemicals.
Phosphate Fertilizer Industry (Florida, US)
In the process of converting phosphate rock into soluble fertilizer, two very toxic fluoride gases are released: hydrogen fluoride and silicon tetrafluoride. In the past, the phosphate industry used to let these two gases vent freely into the atmosphere. This, however, caused severe environmental damage among downwind communities, including widespread cattle poisonings, scorched vegetation, and various human health complaints.
Eventually, as a result of both litigation and regulation, the phosphate industry installed “wet scrubbers” to trap the fluoride gases. The collected liquid in these scrubbers (hydrofluoroslicic acid) is entered into storage tanks and shipped to water departments throughout the country. In 1983, an official at the Environmental Protection Agency stated the agency’s support for this process:
“In regard to the use of fluosilicic acid as the source of fluoride for fluoridation, this agency regards such use as an ideal solution to a long standing problem. By recovering by-product fluosilicic acid from fertilizer manufacturing, water and air pollution are minimized, and water authorities have a low-cost source of fluoride available to them.” [See letter]
Others at EPA, however, have voiced their objections to this process. In 2000, Dr. William Hirzy, the senior vice president of EPA’s Headquarters Union of Scientists and Professionals, stated:
‘”If this stuff gets out into the air, it’s a pollutant; if it gets into the river, it’s a pollutant; if it gets into the lake it’s a pollutant; but if it goes right into your drinking water system, it’s not a pollutant… There’s got to be a better way to manage this stuff.” [See interview]
It is becoming increasingly common for U.S. water departments to purchase their fluoride chemicals from China. While little appears to be known about the source of these chemicals, recent incidents indicate that the contents of these chemicals can vary quite dramatically. It was recently reported, for example, that a number of water plants using Chinese fluoridation chemicals were noticing a “mysterious residue” in the treated water. Although the CDC issued public assurances about the safety of these chemicals, it remains unclear exactly why, and how often, this problem occurs.
2. Arsenic Contamination
After being captured in the scrubbing system, the fluorosilicic acid is either shipped as is (an acidic liquid), or is converted into dry powders (sodium fluorosilicate and sodium fluoride). Whether shipped in its original liquid form, or converted into powder, the fluorosilicic acid does not undergo purification procedures. As a result, fluorosilicic acid has been found to contain various contaminants, particularly arsenic.
The level of arsenic found in fluoridation chemicals is not trivial. According to a review in the American Water Works Association’s publication Opflow, the amount of arsenic that fluoridation adds to finished water “is hardly a minimal amount.”
The arsenic problem is unique to fluoridation chemicals as no other water treatment chemical has a problem with arsenic contamination. As demonstrated in the Opflow review, “about 90 percent of the arsenic . . . contributed by treatment chemicals is attributable to fluoride addition.”
So, how much arsenic do fluoridation chemicals contain? It depends on who you ask, and when you ask them.
In 2000, the National Sanitation Foundation (NSF) released the results of its tests that showed fluoridation chemicals can add as much as 1.66 ppb arsenic to the finished water. NSF found that about 40% of the fluoridation chemicals it tested were contaminated with detectable levels of arsenic. Fluoridating water with these contaminated samples, the NSF stated, would add 0.43 ppb arsenic to the finished water.
To put these figures in perspective, 1 ppb arsenic is the maximum level of arsenic that water departments can add to the water under a standard known as the “Single Product Allowable Concentration” or SPAC. The premise of the SPAC is that water departments should not use any chemical that contributes more than 10% of the EPA’s “Maximum Contaminant Level” (MCL). Thus, since the EPA’s MCL for arsenic is 10 ppb, the addition of any fluoridation chemical that adds more than 1 ppb arsenic violates the SPAC and is deemed a “product failure.” In practice, however, there is no practical way for water departments to know if a batch of fluoridation chemical exceeds the SPAC. This is because very few batches (far less than 1%) of fluoridation chemicals are actually ever tested. It is almost certain, therefore, that “product failures” have been, and will continue to be, unknowingly added to drinking water.
There is, however, a twist.
When the NSF released its arsenic data in 2000, the MCL for arsenic was 50 ppb, and, hence, the SPAC was 5 ppb. Thus, when NSF stated that fluoridation chemicals were contributing up to 1.66 ppb, it was not conceding that some fluoridation chemicals were “product failures.” Today, however, the SPAC for arsenic is 1 ppb, and thus an admission today that fluoridation contributed up to 1.66 ppb would be an admission that a percentage of fluoridation chemicals were “product failures.”
Whether by coincidence or not, the NSF has been able to bypass this problem thanks to the results of new tests it has conducted in the wake of EPA’s enactment of the stricter arsenic MCL. According to these new tests, there is still detectable arsenic contamination in 43% of fluoridation chemicals. However, the highest arsenic level detected would contribute 0.6 ppb to finished water, and thus not exceed the 1 ppb “product failure” threshold.
Unfortunately, the veracity of the NSF’s new test data is virtually impossible to verify. Although the NSF is responsible for regulating the quality of water treatment chemicals, and although it acts, in many ways, like a government agency, it is a private organization and not subject to the same disclosure and accountability requirements of a government agency.
3. Silicofluorides and Lead
In addition to containing contaminants, such as arsenic, recent research suggests that fluoridation chemicals may also be leaching lead out of old pipes. Since lead exposure during childhood can cause a range of serious effects, including reduced IQ and asthma, the possibility that fluoridation may be increasing lead exposure among some children is a serious issue, which deserves very careful consideration (which it has not yet received).
Since the addition of fluorosilicic acid is known to increase the acidity of water, concerns that fluoridating water with fluorosilicic acid have been voiced for many years. The conventional wisdom, however, has been that if a buffering agent is added simultaneously with the fluorosilicic acid, the finished water would not have a corrosive effect. The issue, however, received renewed attention in 1999 and 2001 when several studies detected associations between fluoridation and elevated blood lead levels among children living in both New York State and Massachusetts. Although the methods used in these studies have been questioned, more recent research has tended to confirm that the fluoridation/lead link is real, not a mere statistical artifact.
Concern about this issue reached a new level in 2007, when the journal Neurotoxicology published two separate papers — one a controlled laboratory experiment and the other an analysis of geographic variations in childhood blood lead levels — that both found a fluoridation/lead connection.
In the laboratory study, a team of researchers submerged lead-containing brass pipes in water with various water treatment chemicals, including silicofluorides, under carefully controlled conditions. In so doing, the authors found that silicofluorides significantly increased the level of lead in the water, particularly when added in conjunction with chloramines (a disinfectant commonly used as an alternative to chlorine). As the authors noted:
“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.”
Consistent with these laboratory findings, an analysis of the CDC’s national data on blood leads levels found that children drinking water treated with silicofluorides had a significantly elevated risk of exceeding the estimated hazard threshold for lead in blood (5 ug/dL). According to the authors, the results indicate that an average of 2 out of every 100 children drinking “silicofluoridated” water will exceed the safe threshold of lead in their blood as a result of fluoridation.
Although the CDC’s Oral Health Division maintains that fluoridation does not pose a lead risk, its own analysis in 2006 found that water fluoridated with hydrofluorosilicic acid was significantly associated with higher blood lead levels in children living in houses built prior to 1946.
The current evidence, therefore, does suggest that fluoridating water supplies can increase the lead exposure of some children, particularly those living in old homes and in communities where both hydrofluorosilicic acid and chloramines are added to the water.
- EPA’s statement on using fluorosilicic acid for fluoridation (1983)
- EPA letter admitting lack of toxicological testing on silicofluorides (2000)
- AWWA’s Opflow review of arsenic in fluoridation chemicals
- NSF’s first test results (2000)
- NSF’s second test results (2012)
- Dartmouth press release discussing 2001 study on silicofluorides/lead
- FAN’s press release about the University of North Carolina-Asheville laboratory study
- Review of recent research on silicofluorides/lead
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