Fluoride Product Additives for Water Fluoridation
Frequently Asked Questions
- What additives are used to fluoridate water?
- Is fluorosilicic acid the residue of the production of pesticides, rodenticides
or the nuclear industry?
- Do these additives have to meet standards for quality and purity?
- Who establishes standards for the chemicals used to fluoridate water?
- What is the cost of installing fluoridation equipment for communities?
- How can I find out the fluoride concentration of my drinking water?
- My home gets its water from a well. Can I add fluoride to my well water?
- Will using a home water filtration system take the fluoride out of my home's water?
- Will boiling or freezing reduce the fluoride level in water?
- Will fluoride result in pipe corrosion or lead in water?
Fluorosilicic acid is the most commonly used additive for water fluoridation, followed by two dry additives—sodium fluorosilicate and sodium fluoride. Fluorosilicic acid is derived from production of phosphate fertilizers. The apatite ore (a type of limestone) is mixed and heated with sulfuric acid to form a phosphoric acid-gypsum slurry, the starting point to make pelletized phosphate fertilizers. The hydrogen fluoride and silicon tetrafluoride that would otherwise be released to the atmosphere or left in the gypsum slurry is deliberately recovered from the slurry by evaporators and condensed to fluorosilicic acid that can be used for the water fluoridation process. Both sodium fluorosilicate and sodium fluoride are created by neutralizing fluorosilicic acid with either sodium chloride (table salt) or caustic soda.
No. It is a valuable co-product derived from the production of fertilizer. It is not derived from pesticide, rodenticide or nuclear power production.
The American Water Works Association (AWWA) prepares standards for the manufacturing, quality, and verification of the fluoride additives. The National Sanitation Foundation (NSF) International prepares standards which covers impurities of drinking water treatment additives from their production and distribution to user and includes documentation of the purity of additives. Verification testing by independent certification entities including NSF International and Underwriters Laboratories (UL) documents that the actual purity exceeds the standards. The NSF/ANSI (National Sanitation Foundation/American National Standards Institute) standard 60 and 61 were developed by a consortium of associations, including NSF International, AWWA, the American National Standards Institute (ANSI), the Association of State Drinking Water Administrators, and the Conference of State Health and Environmental Managers.
Who establishes standards for the chemicals used to fluoridate water?
The American Water Works Association (AWWA) prepares standards for the manufacturing, quality, and verification of the fluoride additives. The NSF/ANSI (National Sanitation Foundation/American National Standards Institute) prepares standards which covers impurities of drinking water treatment additives from their production and distribution to user and includes documentation of the purity of additives. A key concept is that an additive should not add more than 10 percent of the MCL (Maximum Contaminant Level) of any regulated drinking water substance in order to ensure the protection of the public. independent certification entities including NSF International and Underwriters Laboratories (UL) documents that the actual purity exceeds the standards. The NSF/ANSI standard 60 and 61 were developed by a consortium of associations, including NSF International, AWWA, the American National Standards Institute (ANSI), the Association of State Drinking Water Administrators, and the Conference of State Health and Environmental Managers.
The cost of installing fluoridation addition equipment for a community water system varies from approximately $5 to $20 per person, depending on a number of factors. Each system would need to have an engineer review the requirements for an individual location to estimate its specific costs. Larger systems serving more customers are typically the most inexpensive and cost effective to manage. In fact, an economic analysis found that for larger communities of more than 20,000 people where it costs about 50 cents per person to fluoridate the water, every $1 invested in this preventive measure yields $38 savings in dental treatment costs.
All public water systems are required by the Environmental Protection Agency to publish an annual Consumer Confidence Report that will include numerous facts about your drinking water, including the fluoride level. If you are on a public water system, you can call the water utility company and request a copy of the utility's most recent Consumer Confidence Report. If you live in a state that participates in CDC's My Water's Fluoride, you can go online and find information on your water system's fluoridation status. If you have a home well, you will need to have a sample of your water analyzed by a laboratory. Your dentist, physician, or public health department should be able to help you get your water analyzed.
Whether on private well or public water supply, if you have water fluoride levels under 0.6 ppm, your child's dentist or pediatrician should evaluate whether your child can benefit from daily fluoride supplements. Their recommendation will depend on your child's risk of developing tooth decay and as well as exposure to other sources of fluoride (e.g., drinking water at school or daycare, toothpaste).
If the natural fluoride level of your well or community drinking water is greater than 2 ppm, you should consider an alternate source of drinking water for any child 8 years and younger. Their teeth are still developing and will be at risk for dental fluorosis.
Many groundwaters have naturally occurring fluoride content. If there is less than 0.6 ppm of fluoride in your well water, it is considered sub-optimal for preventing tooth decay. It is not feasible to add fluoride for an individual residence's well. You should have your home well water tested for its fluoride content by a laboratory. Check with your dentist, physician or public health department to learn how to have your home well water tested. Additional information on testing well water quality in private wells serving homes can be found on the U.S. Environmental Protection Agency Web site. See above question for more information.
Removal of fluoride from water is a difficult water treatment action. Most point-of-use treatment systems for homes that are installed for use by single faucets use activated carbon filtration, which will not remove the fluoride ion. The ability of other treatment systems such as reverse osmosis, ion exchange, or distillation systems to reduce fluoride levels vary in their effectiveness to reduce fluoride. Check with the manufacturer of the individual product.
Fluoride is not released from water when it is boiled or frozen. One exception would be a water distillation system. These systems heat water to the boiling point and then collect water vapor as it evaporates. Water distillation systems are typically used in laboratory installations. For home use these systems can be expensive and may present safety and maintenance concerns.
If you are concerned about the fluoride level in your home water (above the level of 2 parts per million), you should use water from a commercial bottler whose water has the level of fluoride you desire. The optimal level of fluoride in drinking water for the prevention of tooth decay is 0.7 ppm to 1.2 ppm.
Water fluoridation will not increase water corrosion or cause lead to leach (dissolve) from pipes and household plumbing fixtures. Although lead in public drinking water is typically found to be very low or is below laboratory detection, there are locations where old lead pipes, solder, or plumbing fixtures in old homes may experience leaching of lead into water. This is principally a problem in some older homes because newer homes have been constructed in accordance with new plumbing standards that prohibit the use of lead in plumbing pipes and fixtures. Ask your local water utility system if there have been problems with higher lead levels in water from older homes in your community. Claims by some that fluoride might result in increased lead leaching from pipes and fixtures has not been substantiated in the peer-reviewed literature.