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Community Water Fluoridation

Adjusting the fluoride content of water is a safe and healthy practice that 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.

How common are shortages or disruptions of fluoride products?

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 of short duration, 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, there may be sufficient fluoride products nationally, but 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, labor disputes involving the rail or truck transport industry, and other causes.

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Are fluoride shortages or disruptions seasonal in nature?

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 produce 30% to 50% more 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 would not be recommended, particularly for dry additives.

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Are shortages or disruptions industry-wide or supplier specific?

Fluoride additives are produced by several manufacturers, and it is not common for all the suppliers to be negatively impacted equally when production problems occur. Consequently, one group of water treatment facilities may have difficultly obtaining fluoride products from one supplier while other facilities in the same area may have a sufficient supply. Water treatment facilities often contract annually with the lowest bidder 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.

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Is there a difference between fluorosilicic acid and dry fluoride product markets?

All of 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. Roughly half of the dry additive sodium fluorosilicate is domestically produced in the United States by a single manufacturer and is dependent on the fluorosilicic acid market or conditions at the single location of production. The remainder is imported, principally from Asian sources, and supply is dependent on shipping and transportation factors. Most sodium fluoride is imported from Asia. Therefore, the availability of sodium fluoride is more dependent on shipping and transportation factors. If a surge in demand for dry additives occurs, several weeks may be required for logistical arrangements to increase imports and satisfy the greater demand. In spite of these constraints, historically, there are fewer reports of shortages of dry additives than of fluorosilicic acid.

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Has there been a shortage of fluoride additives in recent years?

Since 2009, the supply of fluoride products (i.e., additives) has been stable and reliable. There was a shortage from 2005 through 2009, however. This shortage resulted from termination of operations by two major producers of fluoride products, 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.)

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Can water treatment facilities minimize their vulnerability to shortages?

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. It is also beneficial to 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.

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Are there strategies for managing inventories if delivery of fresh product will be delayed?

Calibrate pumping rates and increase monitoring of fluoride additive feed rates to ensure that excess dosing 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 — better oral health and avoidance of tooth decay. However, if inventories are low or supplies uncertain, it is acceptable to feed fluoride at the lowest level (0.7 mg/L) recommended for U.S. climates for a short time during the shortage or disruption. Continued temporary operations at this lower feed rate will provide some continued protection for your community.

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What should I do if my inventory is exhausted and I must terminate fluoridation?

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, a short period without fluoride should not result in an immediate increase in tooth decay. Resumption of fluoridation at the earliest possible date is important to minimize the potential for tooth decay among residents of your community.

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Our utility has terminated fluoridation. Who should we notify?

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 customer base 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 the Water Fluoridation Additives fact sheet.

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