Water fluoridation programs in the United States and other countries which have them use either sodium fluoride (NaF), hydrofluorosilicic acid (HFSA) or the sodium salt of that acid (NaSF), all technical grade chemicals to adjust the fluoride level in drinking water to about 0.7–1 mg/L. In this paper we estimate the comparative overall cost for U.S. society between using cheaper industrial grade HFSA as the principal fluoridating agent versus using more costly pharmaceutical grade (U.S. Pharmacopeia – USP) NaF. USP NaF is used in toothpaste. HFSA, a liquid, contains significant amounts of arsenic (As). HFSA and NaSF have been shown to leach lead (Pb) from water delivery plumbing, while NaF has been shown not to do so. The U.S. Environmental Protection Agency’s (EPA) health-based drinking water standards for As and Pb are zero. Our focus was on comparing the social costs associated with the difference in numbers of cancer cases arising from As during use of HFSA as fluoridating agent versus substitution of USP grade NaF. We calculated the amount of As delivered to fluoridated water systems using each agent, and used EPA Unit Risk values for As to estimate the number of lung and bladder cancer cases associated with each. We used cost of cancer cases published by EPA to estimate cost of treating lung and bladder cancer cases. Commercial prices of HFSA and USP NaF were used to compare costs of using each to fluoridate. We then compared the total cost to our society for the use of HFSA versus USP NaF as fluoridating agent. The U.S. could save $1 billion to more than $5 billion/year by using USP NaF in place of HFSA while simultaneously mitigating the pain and suffering of citizens that result from use of the technical grade fluoridating agents. Other countries, such as Ireland, New Zealand, Canada and Australia that use technical grade fluoridating agents may realize similar benefits by making this change. Policy makers would have to confront the uneven distribution of costs and benefits across societies if this change were made.
Note from FAN: The authors of this study have issued a “corrigendum” to correct several errors in the above analysis. The corrigendum was published in the April 2014 issue of Environmental Science & Policy (volume 38, pages 282-284). The text of the corrigendum is as follows:
In this paper, the first author erroneously used life time exposure data to calculate number of cancer cases while using annual data on cost of fluoridation chemicals to calculate net social costs. Corrections are made by using annualized values for cancer cases and for chemical costs.
Section 3.4.2 of the paper is corrected by changing the title of that section to ‘‘Population life-time cancer risks: As concentration unit risk’’
Section 3.4.3 is corrected by changing the title and calculation results as follows: ‘‘Annual cancer cases: population life-time risk 1/70 life-time exposed population [3.1.3]
HFSA : 2:7 106 1=70 118 106 ¼ 4:6 cases
NaF : 2:9 108 1=70 118 106 ¼ 0:05 cases
The tables below correct the similar errors in numbers of cancer cases and associated treatment costs per year for the other three cases analyzed in the paper. In addition another case is analyzed, one that evaluates the impact of lowering the allowed amount of arsenic that may be added to the water supply by use of HFSA. In essence this case shows that changing the NSF/ANSI Standard 60 permitted level from 380 mg As/L in HFSA to 180 mg As/L would virtually equalize the cost of treating the cancers caused by this lower level of arsenic with the cost of preventing those cancers through substitution of USP sodium fluoride for HFSA.
Since these corrections lead to different Results and Conclusions, those sections are also updated to reflect annualized results.
Further, Table 1 has been simplified by eliminating the redundant column headed ‘‘Cancer cases per million,’’ because the intended exposition of cancer risk reduction factors is more clearly and simply expressed by comparing the number of cancers attributable to each of the fluoridating agents.
The additional cost of using pharmaceutical grade NaF over technical grade HFSA is about $97 million annually. Cancer risk reduction factors range from about 50 to about 1200 in favor of using NaF rather than HFSA and are exemplified in Table 1. The corresponding numbers of annual cancer cases along with the estimated treatment costs associated with each fluoridating agent are in Table 2. In Table 3 total annual social costs associated with use of the two fluoridating agents are presented. That Table shows that for typical HFSA and USP NaF, the total cost advantage lies with HFSA by a substantial amount. This comports with the U.S. Environmental Protection Agency’s stated policy that notes the use of HFSA, which would be an air pollutant or water pollutant if discharged directly into the environment from phosphate manufacturing plants, affords water authorities with a low-cost fluoridating agent.
The Table also shows, on the other hand, that the average As level in drinking water as reported in a letter from the National Fluoridation Engineer, Thomas Reeves (Supplemental Material Appendix C) results in a much smaller annual advantage for HFSA of $6.2 million. Table 3 shows that HFSA adding this much As to drinking water is expected to cause 26 cancers annually. If USP NaF were used instead of HFSA the cost of avoiding these cancers would be about $240,000 each, less than one-tenth the cost ($3,500,000) of treating a case of cancer.
Further, Table 3 shows that HFSA meeting the NSF/ANSI Standard 60 for As (380 mg As/L) would result in 59 cancers annually, and using USP NaF instead would save society over $100,000,000 annually. The lesson here is that as far as arsenic is concerned Standard 60 does nothing to protect public health or public wealth.
Finally, Table 3 includes calculations showing that a more stringent Standard 60, permitting only 180 mg As/L would restrict As-associated cancers to a level (28 annually), that would result in ‘‘break even’’ cost–benefit between USP NaF and HFSA based on cost of chemicals and cancer treatments.
Beyond arsenic-related cancers, additional social cost savings would be realized through avoidance of the consequences of elevated blood lead levels. We did not attempt to assess these additional social cost savings because of the complexities and uncertainties associated with the resulting effects, especially on lowering IQ of children exposed to higher lead levels. Nevertheless, based on two limited examples (Masters, 2003; Shapiro and Hassett, 2012), we recognize that there are potentially greater social cost savings attributable to avoiding this effect than from lowering cancer rates associated with arsenic exposure.
Our analysis shows that if local governments that currently add HFSA to their drinking water wish to continue delivering fluoride to their citizens and at the same time reduce the number of lung and bladder cancers among their citizens, they could do so by other means. For instance, assuming all 118,000,000 people considered in this paper chose to drink fluoridated water, and consumed 2 liters of it per day, making that drinking water available with 0.5 additional mg/L of fluoride (using USP NaF) would cost about $600,000 annually, nation-wide. This is surely an economically and socially feasible alternative to putting industrial grade HFSA into 100 gallons per day per capita and flushing more that 98 percent of that into municipal waste water treatment plants. Of course the phosphate industry would have to find some other means of dealing with 250,000 tons per year of HFSA than shipping it from their factories to drinking water treatment plants, passing it through households and into waste water treatment plants.
The last Congressional review of the national program of water fluoridation took place over thirty years ago, and a great deal of new knowledge has been developed during that time. What we have presented here is but a small, but we think important, portion of that new knowledge.