Shortages of Fluoridation Additives
Adjusting the fluoride content of water is a safe and healthy practice that prevents tooth decay and provides significant oral health benefits for a community. For the greatest benefits to occur, it is important to consistently maintain optimum fluoride levels. The three fluoride additives used for water fluoridation are derived principally from phosphate fertilizer production. Although shortages of fluoride additives for water fluoridation are infrequent, they do sometimes occur.
Shortages or disruptions of fluoride product deliveries are not common. However, there have been periods of shortages and disruptions resulting in difficulties obtaining fluoride additives for water fluoridation. Most shortages and disruptions tend to be for a short period, on the order of several weeks. Shortages or disruptions are usually regional. Fluoride products are produced in only a few areas of the country, and then must be transported to regional depots, typically by rail tanker car. Therefore, while there may be sufficient fluoride products nationally, a particular region may have shortages or disruptions. Shortages or disruptions can also result from inclement weather in fluoride-producing areas. Florida is the largest producer of fluoride products, and hurricanes or other severe weather events can cause phosphate fertilizer manufacturers to suspend operations for several weeks at a time. Seasonal disruptions, such as manufacturing plant maintenance periods, also may delay operations in entire production facilities for weeks to months at a time. Because the supply of fluoride products is related to phosphate fertilizer production, fluoride product production can also fluctuate depending on factors such as unfavorable foreign exchange rates and export sales of fertilizer. Other causes of fluoride shortages have been phosphorite rock ore quality with lower fluoride yields and labor disputes involving the rail or truck transport industry.
Although shortages or disruptions can occur at any time of year, the most common season for shortages is summer. In the summer months, irrigation often results in the greatest demand for water, and water plants can commonly provide 30% to 50% more water in summer months than in winter months. Many water treatment facilities have a 2 to 3-month storage capacity. Planning for summer demand by storing inventory to the maximum capacity at water treatment facilities at the beginning of the summer or by scheduling a delivery in mid-summer can minimize the potential for supply shortages. Storage of fluoride inventories longer than 6 months is not recommended, particularly for dry additives.
Fluoride additives are produced by several manufacturers, and it is not common for all the suppliers to be equally affected by production problems. Consequently, one group of water treatment facilities may have difficulty obtaining fluoride products from one supplier while other facilities in the same area may have a sufficient supply. Water treatment facilities often contract annually for chemicals and supplies. Some larger systems will negotiate multiple contracts with two or more suppliers, agreeing to purchase some minimum quantity of fluoride even at a higher cost so that if shortages or disruptions with one supplier occur, some fluoride can still be obtained from another source. If you are contracting with a local supplier of chemical additives, identify the national distributor furnishing the fluoride for that supplier—it may be possible to contract with different regional suppliers or different national distributors.
The liquid fluorosilicic acid used for water fluoridation is produced in North America, so shortages and disruptions of fluorosilicic acid are limited to U.S. influences. About half of the dry additive sodium fluorosilicate is produced in the United States by a single manufacturer and depends on the fluorosilicic acid market or conditions at the single production location. The rest is imported, principally from Asian sources, and supply is dependent on shipping and transportation factors. Because most sodium fluoride is imported from Asia and Europe, its availability is dependent on shipping and transportation factors. If there is a surge in demand for dry additives, it may take several weeks to increase imports and satisfy the greater demand. In spite of these constraints, there have been fewer reports of shortages of dry additives than of fluorosilicic acid.
Since 2009, the supply of fluoride products (i.e., additives) has been stable and reliable. However, from 2005 through 2009 there was a shortage of additives. This shortage was the result of two major producers of fluoride products ceasing operations, realignment of other producers, and factors associated with the globalization of the chemical industry. (Source: Supply of Critical Drinking Water and Wastewater Treatment Chemicals—A White Paper for Understanding Recent Chemical Price Increases and Shortages, 2009, available from the Water Research Foundation.)
Since the supply of fluoridation products can be subject to occasional periods of shortages, water treatment facilities should have at least 3 months of inventory on hand. Water treatment facilities should monitor their inventories, order supplemental deliveries with sufficient lead time, and arrange for alternate suppliers who have different national distributors. Water systems should also verify pump delivery calibration and increase confirmatory testing. Regular and careful calibration of metering pumps can ensure that optimal fluoridation is provided with minimal waste.
Calibrate pumping rates and increase monitoring of fluoride additive feed rates to ensure that excess feeding of additive is minimized. It is important to maintain feed rates as close to the target within the optimal range for your community to ensure the benefits of fluoridation—prevention of tooth decay and better oral health.
Although exhaustion of fluoride products at a water treatment facility is rare, it does occur. If imminent exhaustion is anticipated, call your supplier and appeal for a small delivery to satisfy the immediate need. If fluoridation must be terminated, however, short periods (1 to 2 months) without fluoridation should not present problems for a community. Although consistent and constant fluoride levels in the optimum range provides the greatest benefit to a community, if fluoridation has been maintained in the period before the shortage, a short time without fluoride should not result in an immediate increase in tooth decay in the community. Resuming fluoridation at the earliest possible time is important to minimize the potential for tooth decay among community residents.
If a utility must terminate fluoridation, it is important to notify the state drinking water administrator and dental director. Most utilities try to actively communicate with their customers about water quality issues, so notifying public health professionals and the public through newspaper announcements or press releases may be appropriate if the utility has used those media outlets in the past. It is important to give the public a sense of when fluoridation will resume, for example, “We expect to have delivery of fluoride in 2 weeks and will resume fluoridation at that time.”
For more information on additives, see Water Fluoridation Additives.