1-3.
Fifteen benefits of drinking water

By James McIntosh ｜ Last updated Mon 16 July 2018
Reviewed by Karen Cross, FNP, MSN

Fifteen benefits ｜ Kidney damage ｜ Sources ｜ Recommended intake ｜ Facts

Keeping hydrated is crucial for health and well-being, but many people do not consume enough fluids each day.

Around 60 percent of the body is made up of water, and around 71 percent of the planet's surface is covered by water.

Perhaps it is the ubiquitous nature of water that means drinking enough each day is not at the top of many people's lists of priorities.

Fast facts on drinking water

• Adult humans are 60 percent water, and our blood is 90 percent water.
• There is no universally agreed quantity of water that must be consumed daily.
• Water is essential for the kidneys and other bodily functions.
• When dehydrated, the skin can become more vulnerable to skin disorders and wrinkling.
• Drinking water instead of soda can help with weight loss.

Fifteen benefits of drinking water

Possible benefits of drinking water range from keeping the kidneys healthy to losing weight.

To function properly, all the cells and organs of the body need water.

Here are some reasons our body needs water:

1. It lubricates the joints

Cartilage, found in joints and the disks of the spine, contains around 80 percent water. Long-term dehydration can reduce the joints' shock-absorbing ability, leading to joint pain.

2. It forms saliva and mucus

Saliva helps us digest our food and keeps the mouth, nose, and eyes moist. This prevents friction and damage. Drinking water also keeps the mouth clean. Consumed instead of sweetened beverages, it can also reduce tooth decay.

3. It delivers oxygen throughout the body

Blood is more than 90 percent water, and blood carries oxygen to different parts of the body.

4. It boosts skin health and beauty

With dehydration, the skin can become more vulnerable to skin disorders and premature wrinkling.

5. It cushions the brain, spinal cord, and other sensitive tissues

Dehydration can affect brain structure and function. It is also involved in the production of hormones and neurotransmitters. Prolonged dehydration can lead to problems with thinking and reasoning.

6. It regulates body temperature

Water that is stored in the middle layers of the skin comes to the skin's surface as sweat when the body heats up. As it evaporates, it cools the body. In sport.

Some scientists have suggested that when there is too little water in the body, heat storage increases and the individual is less able to tolerate heat strain.

Having a lot of water in the body may reduce physical strain if heat stress occurs during exercise. However, more research is needed into these effects.

7, The digestive system depends on it

The bowel needs water to work properly. Dehydration can lead to digestive problems, constipation, and an overly acidic stomach. This increases the risk of heartburn and stomach ulcers.

8. It flushes body waste

Water is needed in the processes of sweating and removal of urine and feces.

9. It helps maintain blood pressure

A lack of water can cause blood to become thicker, increasing blood pressure.

10. The airways need it

When dehydrated, airways are restricted by the body in an effort to minimize water loss. This can make asthma and allergies worse.

11. It makes minerals and nutrients accessible

These dissolve in water, which makes it possible for them to reach different parts of the body.

12. It prevents kidney damage

The kidneys regulate fluid in the body. Insufficient water can lead to kidney stones and other problems.

13. It boosts performance during exercise

Dehydration during exercise may hinder performance.

Some scientists have proposed that consuming more water might enhance performance during strenuous activity.

More research is needed to confirm this, but one review found that dehydration reduces performance in activities lasting longer than 30 minutes.

14. Weight loss

Water may also help with weight loss, if it is consumed instead of sweetened juices and sodas. "Preloading" with water before meals can help prevent overeating by creating a sense of fullness.

15. It reduces the chance of a hangover

When partying, unsweetened soda water with ice and lemon alternated with alcoholic drinks can help prevent overconsumption of alcohol.

Kidney damage

Water helps dissolve minerals and nutrients, making them more accessible to the body. It also helps remove waste products.

The kidneys play a key role in balancing fluid levels.

These two functions make water vital to the kidneys.

Every day, the kidneys filter around 120-150 quarts of fluid.

Of these, approximately 1-2 quarts are removed from the body in the form of urine, and the rest is recovered by the bloodstream.

Water is essential for the kidneys to function.

If the kidneys do not function properly, waste products and excess fluid can build up inside the body.

Untreated, chronic kidney disease can lead to kidney failure. The organs stop working, and either dialysis or kidney transplantation is required.

Urinary tract infections (UTIs) are the second most common type of infection in the body. They account for around 8.1 million visits to health care providers in the U.S. every year.

If infections spread to the upper urinary tract, including the kidneys, permanent damage can result. Sudden, or acute, kidney infections can be life-threatening, particularly if septicemia occurs.

Drinking plenty of water is a simple way to reduce the risk of developing a UTI and to help treat an existing UTI.

Kidney stones interfere with how the kidneys work. When present, can complicate UTIs. These complicated UTIs tend to require longer periods of antibiotics to treat them, typically lasting 7 to 14 days.

The leading cause of kidney stones is a lack of water. People who report them often do not drink the recommended daily amount of water. Kidney stones may also increase the risk of chronic kidney disease.

In November 2014, the American College of Physicians issued new guidelines for people who have previously developed kidney stones. The guidelines state that increasing fluid intake to enable 2 liters of urination a day could decrease the risk of stone recurrence by at least half with no side effects.

Dehydration happens if we use and lose more water than the body takes in. It can lead to an imbalance in the body's electrolytes. Electrolytes, such as potassium, phosphate, and sodium, help carry electrical signals between cells. The kidneys keep the levels of electrolytes in the body stable when they function properly.

When the kidneys are unable to maintain a balance in the levels of electrolytes, these electrical signals become mixed up. This can lead to seizures, involving involuntary muscle movements and loss of consciousness.

In severe cases, dehydration can lead to kidney failure, which can be life-threatening. Possible complications of chronic kidney failure include anemia, damage to the central nervous system, heart failure, and a compromised immune system.

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Sources

Some of the water required by the body is obtained through foods with a high water content, such as soups, tomatoes, oranges, but most come through drinking water and other beverages.

During everyday functioning, water is lost by the body, and this needs to be replaced. We notice that we lose water through activities such as sweating and urination, but water is lost even when breathing.

Drinking water, whether from the tap or a bottle, is the best source of fluid for the body.

Milk and juices are also good sources of fluid, but beverages containing alcohol and caffeine, such as soft drinks, coffee, and beer, are not ideal because they often contain empty calories. Drinking water instead of soda can help with weight loss.

It was previously thought that caffeinated beverages had diuretic properties, meaning that they cause the body to release water. However, studies show that fluid loss because of caffeinated drinks is minimal.

Recommended intake

How much water we need to consume is influenced by the climate.

The amount of water needed each day varies from person to person, depending on how active they are, how much they sweat, and so on.

There is no fixed amount of water that must be consumed daily, but there is general agreement on what a healthy fluid intake is.

According to the U.S. National Academies of Sciences, Engineering, and Medicine, the average recommended daily intake of water from both food and drink is:

• For men: Around 3.7 liters or 125 ounces
• For women: Around 2.7 liters or 91 ounces

This would be around 15.5 cups for men and just over 11 cups for women. However, around 80 percent of this should come from drinks, including water, and the rest will be from food.

This means that:

• Men should drink around 100 ounces, or 12.5 cups of fluid
• Women should drink around 73 ounces, or just over 9 cups

Fresh fruits and vegetables and all non-alcoholic fluids count towards this recommendation.

Times when it is most important to drink plenty of water include:

• when you have a fever
• when the weather is hot
• if you have diarrhea and vomiting
• when you sweat a lot, for example, due to physical activity

Facts

Here are some facts about water:

• Babies and children have a higher percentage of water than adults. When babies are born, they are about 78 percent water, but this falls to 65 percent by the age of 1 year.
• Fatty tissue has less water than lean tissue.
• Men have more water than women, as a percentage.

Do we drink enough water?

A study carried out by the Centers for Disease Control and Prevention (CDC) in 2013 analyzed data from the National Cancer Institute's 2007 Food Attitudes and Behaviors Survey.

Out of a sample of 3,397 adults, the researchers found:

• 7 percent of adults reported no daily consumption of drinking water
• 36 percent of adults reported drinking 1-3 cups of drinking water a day
• 35 percent of adults reported drinking 4-7 cups of drinking water a day
• 22 percent of adults reported drinking 8 cups or more a day

People were more likely to drink less than 4 cups of drinking water daily if they consumed 1 cup or less of fruits or vegetables a day.

The study only measured the intake of drinking water. Fluid can be gained from other beverages, but water is best because it is calorie-free, caffeine-free, and alcohol-free.

Seven percent of respondents reported drinking no water at all daily, and those who drank a low volume of water also consumed less fruit and vegetables. This suggests that a certain number of people are risking their health by not getting enough fluid.

Even if the respondents reporting low levels of water intake were obtaining enough fluid, it is likely that they would be obtaining it from sources that could potentially compromise their health in other ways.

"The biologic requirement for water may be met with plain water or via foods and other beverages," write the study authors. "Results from previous epidemiologic studies indicate that water intake may be inversely related to volume of calorically sweetened beverages and other fluid intake."

1-4.
Water fluoridation 'does not lower IQ'

By David McNamee ｜ Published Saturday 24 May 2014

Drinking fluoridated water does not lower IQ, according to a new study by researchers from the University of Otago in New Zealand.

Many popular theories cast suspicion on the role of water fluoridation, with some people claiming that fluoridated water is associated with a range of adverse health outcomes.

Fluoride is routinely added to drinking water in the US and other countries as a supplement to safeguard against tooth decay. However, some people object to the compulsory nature of water fluoridation.

Also, some of the concern around water fluoridation stems from conspiracy theories relating to the end of World War II. These include suggestions that the Nazi regime secretly fluoridated water supplies in an attempt to damage the pineal gland of their citizens, which some people think promotes docility in humans.

The proximity of conspiracy theories to the issue has made the debate over health risks of water fluoridation contentious. However, in 2012, researchers from Harvard University in Cambridge, MA, cast doubts on the health benefits of fluoride in water supplies.

They conducted a review of studies looking at the effects of water fluoridation on children and found that children living in high-fluoride areas "had significantly lower IQs than those who lived in low-fluoride areas."

Fluoride, the researchers said, is a chemical "with substantial evidence of developmental neurotoxicity."

THowever, these findings are challenged by a new study published in the American Journal of Public Health.

The Dunedin Multidisciplinary Study and water fluoridation

Drawing data from a large study of 1,000 people born in Dunedin in New Zealand during 1972-1973 - the Dunedin Multidisciplinary Study - researchers from the University of Otago compared the IQs of study participants who grew up in suburbs with and without fluoridated water. They also took into account to what extent the participants were exposed to fluoride toothpaste or tablets while growing up.

Dr. Broadbent suggests that studies finding an association between water fluoridation and reduced IQ tend to have used poor research methodology with a high risk of bias.

The IQ scores for 992 participants were examined between the ages of 7-13. Of these people, 942 were tested again at age 38. The scores of tests assessing verbal comprehension, perceptual reasoning, working memory and processing speed were also available to the Otago researchers.

The team controlled the results for factors that are known to influence IQ variation in childhood, such as the socioeconomic status of the parents, birth weight and breastfeeding, as well as achievement in secondary and tertiary education, which are thought to influence adult IQ.

Lead author Dr. Jonathan Broadbent describes the team's findings:

"Our analysis showed no significant differences in IQ by fluoride exposure, even before controlling for the other factors that might influence scores. In line with other studies, we found breastfeeding was associated with higher child IQ, and this was regardless of whether children grew up in fluoridated or non-fluoridated areas."

Dr. Broadbent suggests that studies finding an association between water fluoridation and reduced IQ tend to have used poor research methodology with a high risk of bias. Speaking to Medical News Today, he said of the Harvard study: "The authors stated that each of the articles reviewed had deficiencies, in some cases rather serious. It is a meta-analysis based on poor quality research."

He adds that the Dunedin Multidisciplinary Study, by comparison, is world-renowned for the quality of its data and rigor of its analysis.

In conclusion, Dr. Broadbent says:

"Our findings will hopefully help to put another nail in the coffin of the complete canard that fluoridating water is somehow harmful to children's development. In reality, the total opposite is true, as it helps reduce the tooth decay blighting the childhood of far too many New Zealanders."

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Fluoride

From Wikipedia, the free encyclopedia

This article is about the fluoride ion. For a review of fluorine compounds, see Compounds of fluorine. For the fluoride additive used in toothpasete, see Fluoride therapy. For the 2015 French film, see Floreide (film).

Fluoride

Names IUPAC name Fluoride[1] Indentifiers CAS Number 16984-48-8 3D model (JSmol) Interactive image ChEBI CHEBI:17051 ChEMBL ChEMBL1362 ChemSpider 26214 Gmelin Reference 14905 KEGG C00742 MeSH Fluoride PubChem CID 28179 InChI　　　　　　　　　　[show] SMILES　　　　　　　　　[show] Properties Chemical formula F- Molar mass 19.00 g･mol-1 Conjugate acid Hydrogen fluoride Thermochemistry Std molar entropy(So298) 145.58 J/mol K (gaseous)[2] Std enthalpy of formation (ΔfHo298) -333 kJ mol-1 Related compounds Other anions Chloride Bromide Iodide Except where otherwise noted, data are giben for materials in their standard state (at 25 ﾟC[77 ﾟF], 100 kPa). Infobox references

Fluoride (/ˈflʊəraɪd, ˈflɔːr-/)^[3] is an inorganic, monatomic anion with the chemical formula F^- (also written [F]^-), whose salts are typically white or colorless. Fluoride salts typically have distinctive bitter tastes, and are odorless. Its salts and minerals are important chemical reagents and industrial chemicals, mainly used in the production of hydrogen fluoride for fluorocarbons. Fluoride is classified as a weak base since it only partially associates in solution, but concentrated fluoride is corrosive and can attack the skin.

Fluoride is the simplest fluorine anion. In terms of charge and size, the fluoride ion resembles the hydroxide ion. Fluoride ions occur on earth in several minerals, particularly fluorite, but are only present in trace quantities in bodies of water in nature.

Contents Nomenclature Occurrence Chemical propreties 3.1　Basicity 3.2　Structure of fluoride salts 3.3　Inorganic chemistry 3.4　Naked fluoride 3.5　Biochemistry Applications 4.1　Cavity prevention 4.2　Biochemical reagent Dietary recommendations Estimated daily intake Safety 7.1　Ingestion 7.1.1　Hazard maps for fluoride in groundwater 7.2　Topical Other dericatives See also References External links

Nomenclature

Fluorides include compounds that contain both ionic fluoride and those where fluoride does not dissociate. The nomenclature does not distinguish these situations. For example, sulfur hexafluoride and carbon tetrafluoride are not sources of fluoride ions under ordinary conditions.

The systematic name fluoride, the valid IUPAC name, is determined according to the additive nomenclature. However, the name fluoride is also used in compositional IUPAC nomenclature which does not take the nature of bonding involved into account. Fluoride is also used non-systematically, to describe compounds which release fluoride upon dissolving. Hydrogen fluoride is itself an example of a non-systematic name of this nature. However, it is also a trivial name, and the preferred IUPAC name for fluorane.^{[citation needed]}

Occurrence

Fluorite crystals

Fluorine is estimated to be the 13th most abundant element in the earth's crust and is widely dispersed in nature, almost entirely in the form of fluorides. Many minerals are known, but of paramount commercial importance is fluorite (CaF₂), which is roughly 49% fluoride by mass.^[4] The soft, colorful mineral is found worldwide.

In water

Fluoride is naturally present at low concentration in most fresh and saltwater sources and may also be present in rainwater. Seawater fluoride levels are usually in the range of 0.86 to 1.4 mg/L, and average 1.1 mg/L^[5] (milligrams per litre). For comparison, chloride concentration in seawater is about 19 g/L. The low concentration of fluoride reflects the insolubility of the alkaline earth fluorides, e.g., CaF₂.

Concentrations in fresh water vary more significantly. Surface water such as rivers or lakes generally contains between 0.01?0.3 ppm.^[6] Groundwater (well water) concentrations vary even more, depending on the presence of local fluoride-containing minerals. For example, natural levels of under 0.05 mg/L have been detected in parts of Canada but up to 8mg/L in parts of China; in general levels rarely exceed 10 mg/litre^[7]

• In some locations, such as Tanzania, the drinking water contains dangerously high levels of fluoride, leading to serious health problems.
• Worldwide 50 million people receive water from water supplies that naturally have close to the "optimal level".^[8]
• In other locations the level of fluoride is very low, sometimes leading to fluoridation of public water supplies to bring the level to around 0.7-1.2 ppm.

Fluoride can be present in rain, with its concentration increasing significantly upon exposure to volcanic activity or atmospheric pollution derived from burning fossil fuels or other sorts of industry.^[9][10]

In plants

All vegetation contains some fluoride, which is absorbed from soil and water.^[7] Some plants concentrate fluoride from their environment more than others. All tea leaves contain fluoride; however, mature leaves contain as much as 10 to 20 times the fluoride levels of young leaves from the same plant.^[11][12][13]

Chemical properties

Basicity

Fluoride can act as a base. It can combine with a proton ( H⁺):

　　F^- + H⁺ → HF　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　(1)

This neutralization reaction forms hydrogen fluoride (HF), the conjugate acid of fluoride.

In aqueous solution, fluoride has a pK_b value of 10.8. It is therefore a weak base, and tends to remain as the fluoride ion rather than generating a substantial amount of hydrogen fluoride. That is, the following equilibrium favours the left-hand side in water:

　　 F^- + H₂O ⇄ HF + HO^-　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　(2)

However, upon prolonged contact with moisture, soluble fluoride salts will decompose to their respective hydroxides or oxides, as the hydrogen fluoride escapes. Fluoride is distinct in this regard among the halides. The identity of the solvent can have a dramatic effect on the equilibrium shifting it to the right-hand side, greatly increasing the rate of decomposition.

Structure of fluoride salts

Salts containing fluoride are numerous and adopt myriad structures. Typically the fluoride anion is surrounded by four or six cations, as is typical for other halides. Sodium fluoride and sodium chloride adopt the same structure. For compounds containing more than one fluoride per cation, the structures often deviate from those of the chlorides, as illustrated by the main fluoride mineral fluorite (CaF₂) where the Ca²+ ions are surrounded by eight F^- centers. In CaCl₂, each Ca²+ ion is surrounded by six Cl^- centers. The difluorides of the transition metals often adopt the rutile structure whereas the dichlorides have cadmium chloride structures.

Inorganic chemistry

Upon treatment with a standard acid, fluoride salts convert to hydrogen fluoride and metal salts. With strong acids, it can be doubly protonated to give H₂F⁺. Oxidation of fluoride gives fluorine. Solutions of inorganic fluorides in water contain F^- and bifluoride HF^-₂.^[14] Few inorganic fluorides are soluble in water without undergoing significant hydrolysis. In terms of its reactivity, fluoride differs significantly from chloride and other halides, and is more strongly solvated in protic solvents due to its smaller radius/charge ratio. Its closest chemical relative is hydroxide, since both have similar geometries.

Naked fluoride

When relatively unsolvated, for example in nonprotic solvents, fluoride anions are called "naked". Naked fluoride is a very strong Lewis base,^[15] it is easily reacted with Lewis acids, forming strong adducts. Naked fluoride salts have been prepared as tetramethylammonium fluoride, tetramethylphosphonium fluoride, and tetrabutylammonium fluoride has been reported.^[16] Many so-called naked fluoride sources are in fact bifluoride salts.

Biochemistry

At physiological pHs, hydrogen fluoride is usually fully ionised to fluoride. In biochemistry, fluoride and hydrogen fluoride are equivalent. Fluorine, in the form of fluoride, is considered to be a micronutrient for human health, necessary to prevent dental cavities, and to promote healthy bone growth.^[17] The tea plant (Camellia sinensis L.) is a known accumulator of fluorine compounds, released upon forming infusions such as the common beverage. The fluorine compounds decompose into products including fluoride ions.
Fluoride is the most bioavailable form of fluorine, and as such, tea is potentially a vehicle for fluoride dosing.^[18] Approximately, 50% of absorbed fluoride is excreted renally with a twenty-four-hour period. The remainder can be retained in the oral cavity, and lower digestive tract. Fasting dramatically increases the rate of fluoride absorption to near 100%, from a 60% to 80% when taken with food.^[18] Per a 2013 study, it was found that consumption of one litre of tea a day, can potentially supply the daily recommended intake of 4 mg per day. Some lower quality brands can supply up to a 120% of this amount. Fasting can increase this to 150%. The study indicates that tea drinking communities are at an increased risk of dental and skeletal fluorosis, in the case where water fluoridation is in effect.^[18] Fluoride ion in low doses in the mouth reduces tooth decay.^[19] For this reason, it is used in toothpaste and water fluoridation. At much higher doses and frequent exposure, fluoride causes health complications and can be toxic.

Applications

　See also: Flurochemical industry, Biological aspects of fluorine, and Fluorine

Fluoride salts and hydrofluoric acid are the main fluorides of industrial value. Compounds with C-F bonds fall into the realm of organofluorine chemistry. The main uses of fluoride, in terms of volume, are in the production of cryolite, Na₃AlF₆. It is used in aluminium smelting. Formerly, it was mined, but now it is derived from hydrogen fluoride. Fluorite is used on a large scale to separate slag in steel-making. Mined fluorite (CaF2) is a commodity chemical used in steel-making.

Hydrofluoric acid and its anhydrous form, hydrogen fluoride, is also used in the production of fluorocarbons. Hydrofluoric acid has a variety of specialized applications, including its ability to dissolve glass.^[4]

Cavity prevention

　Main articles: Fluoride therapy and Water fluoridation

Fluoride is sold in tablets for cavity prevention.

Fluoride-containing compounds, such as sodium fluoride or sodium monofluorophosphate are used in topical and systemic fluoride therapy for preventing tooth decay. They are used for water fluoridation and in many products associated with oral hygiene.^[20] Originally, sodium fluoride was used to fluoridate water; hexafluorosilicic acid (H₂SiF₆) and its salt sodium hexafluorosilicate (Na₂SiF₆) are more commonly used additives, especially in the United States. The fluoridation of water is known to prevent tooth decay^[21][22] and is considered by the U.S. Centers for Disease Control and Prevention as "one of 10 great public health achievements of the 20th century".^[23][24] In some countries where large, centralized water systems are uncommon, fluoride is delivered to the populace by fluoridating table salt. For the method of action for cavity prevention, see Fluoride therapy. Fluoridation of water has its critics (see Water fluoridation controversy).^[25] Fluoridated toothpaste is in common use, but is only effective at concentrations above 1,000 ppm, as is common in North America and Europe. ^[26]

Biochemical reagent

Fluoride salts are commonly used in biological assay processing to inhibit the activity of phosphatases, such as serine/threonine phosphatases.^[27] Fluoride mimics the nucleophilic hydroxide ion in these enzymes' active sites.^[28] Beryllium fluoride and aluminium fluoride are also used as phosphatase inhibitors, since these compounds are structural mimics of the phosphate group and can act as analogues of the transition state of the reaction.^[29][30]

Dietary recommendations

The U.S. Institute of Medicine (IOM) updated Estimated Average Requirements (EARs) and Recommended Dietary Allowances (RDAs) for some minerals in 1997. Where there was not sufficient information to establish EARs and RDAs, an estimate designated Adequate Intake (AI) was used instead. AIs are typically matched to actual average consumption, with the assumption that there appears to be a need, and that need is met by what people consume. The current AI for women 19 years and older is 3.0 mg/day (includes pregnancy and lactation). The AI for men is 4.0 mg/day. The AI for children ages 1-18 increases from 0.7 to 3.0 mg/day. The major known risk of fluoride deficiency appears to be an increased risk of bacteria-caused tooth cavities. As for safety, the IOM sets Tolerable upper intake levels (ULs) for vitamins and minerals when evidence is sufficient. In the case of fluoride the UL is 10 mg/day. Collectively the EARs, RDAs, AIs and ULs are referred to as Dietary Reference Intakes (DRIs).^[31]

The European Food Safety Authority (EFSA) refers to the collective set of information as Dietary Reference Values, with Population Reference Intake (PRI) instead of RDA, and Average Requirement instead of EAR. AI and UL defined the same as in United States. For women ages 18 and older the AI is set at 2.9 mg/day (includes pregnancy and lactation). For men the value is 3.4 mg/day. For children ages 1-17 years the AIs increase with age from 0.6 to 3.2 mg/day. These AIs are comparable to the U.S. AIs.^[32] The EFSA reviewed safety evidence and set an adult UL at 7.0 mg/day (lower for children).^[33]

For U.S. food and dietary supplement labeling purposes the amount of a vitamin or mineral in a serving is expressed as a percent of Daily Value (%DV). Although there is information to set Adequate Intake, fluoride does not have a Daily Value and is not required to be shown on food labels.^[34]

Estimated daily intake

Daily intakes of fluoride can vary significantly according to the various sources of exposure. Values ranging from 0.46 to 3.6-5.4 mg/day have been reported in several studies (IPCS, 1984).^[17] In areas where water is fluoridated this can be expected to be a significant source of fluoride, however fluoride is also naturally present in virtually all foods and beverages at wide range of concentrations.^[35] The maximum safe daily consumption of fluoride is 10 mg/day for an adult (U.S.) or 7 mg/day (European Union).^[31][33]

The upper limit of fluoride intake from all sources (fluoridated water, food, beverages, fluoride dental products and dietary fluoride supplements) is set at 0.10 mg/kg/day for infants, toddlers, and children through to 8 years old. For older children and adults, who are no longer at risk for dental fluorosis, the upper limit of fluoride is set at 10 mg/day regardless of weight. ^[36]

Examples of fluoride content

Food/Drink Fluoride (mg per 1000g / ppm) Portion Fluoride (mg per portion) Black tea (brewed) 3.73 1 cup, 240 g (8 fl oz) 0.884 Raisins, seedless 2.34 small box, 43 g (1.5 oz) 0.101 Table wine 1.53 Bottle, 750 ml (26.4 fl oz) 1.150 Municipal tap-water, (Fluoridated) 0.81 Recommended daily intake, 3 litres (0.79 US gal) 2.433 Baked potatoes, Russet 0.45 Medium potato, 140 g (0.3 lb) 0.078 Lamb 0.32 Chop, 170 g (6 oz) 0.054 Carrots 0.03 1 large carrot, 72 g (2.5 oz) 0.002

Data taken from United States Department of Agriculture, National Nutrient Database

Safety

　Main article: Fluoride toxicity

Ingestion

According to the U.S. Department of Agriculture, the Dietary Reference Intakes, which is the "highest level of daily nutrient intake that is likely to pose no risk of adverse health effects" specify 10 mg/day for most people, corresponding to 10 L of fluoridated water with no risk. For infants and young children the values are smaller, ranging from 0.7 mg/d for infants to 2.2 mg/d.^[37] Water and food sources of fluoride include community water fluoridation, seafood, tea, and gelatin.^[38]

Soluble fluoride salts, of which sodium fluoride is the most common, are toxic, and have resulted in both accidental and self-inflicted deaths from acute poisoning.^[4] The lethal dose for most adult humans is estimated at 5 to 10 g (which is equivalent to 32 to 64 mg/kg elemental fluoride/kg body weight).^[39][40][41] A case of a fatal poisoning of an adult with 4 grams of sodium fluoride is documented,^[42] and a dose of 120 g sodium fluoride has been survived.^[43] For sodium fluorosilicate (Na₂SiF₆), the median lethal dose (LD₅₀) orally in rats is 0.125 g/kg, corresponding to 12.5 g for a 100 kg adult.^[44]

Treatment may involve oral administration of dilute calcium hydroxide or calcium chloride to prevent further absorption, and injection of calcium gluconate to increase the calcium levels in the blood.^[42] Hydrogen fluoride is more dangerous than salts such as NaF because it is corrosive and volatile, and can result in fatal exposure through inhalation or upon contact with the skin; calcium gluconate gel is the usual antidote.^[45]

In the higher doses used to treat osteoporosis, sodium fluoride can cause pain in the legs and incomplete stress fractures when the doses are too high; it also irritates the stomach, sometimes so severely as to cause ulcers. Slow-release and enteric-coated versions of sodium fluoride do not have gastric side effects in any significant way, and have milder and less frequent complications in the bones.^[46] In the lower doses used for water fluoridation, the only clear adverse effect is dental fluorosis, which can alter the appearance of children's teeth during tooth development; this is mostly mild and is unlikely to represent any real effect on aesthetic appearance or on public health.^[47] Fluoride was known to enhance the measurement of bone mineral density at the lumbar spine, but it was not effective for vertebral fractures and provoked more non vertebral fractures.^[48]

A popular urban myth claims that the Nazis used fluoride in concentration camps, but there is no historical evidence to prove this claim.^[49]

In areas that have naturally occurring high levels of fluoride in groundwater which is used for drinking water, both dental and skeletal fluorosis can be prevalent and severe.^[50]

Hazard maps for fluoride in groundwater

Around one-third of the human population drinks water from groundwater resources. Of this, about 10%, approximately three hundred million people, obtains water from groundwater resources that are heavily contaminated with arsenic or fluoride.^[51] These trace elements derive mainly from minerals.^[52] Maps are available of locations of potential problematic wells.^[53]

Topical

Concentrated fluoride solutions are corrosive.^[54] Gloves made of nitrile rubber are worn when handling fluoride compounds. The hazards of solutions of fluoride salts depend on the concentration. In the presence of strong acids, fluoride salts release hydrogen fluoride, which is corrosive, especially toward glass.^[4]

Other derivatives

Organic and inorganic anions are produced from fluoride, including:

• Bifluoride used as an etchant for glass.^[55]
• Tetrafluoroberyllate
• Hexafluoroplatinate
• Tetrafluoroborate used in organometallic synthesis.
• Hexafluorophosphate used as an electrolyte in commercial secondary batteries.
• Trifluoromethanesulfonate

See also

• Fluoride deficiency
• Fluoride selective electrode
• Fluoride therapy
• ¹⁹F NMR spectroscopy
• Sodium monofluorophosphate

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External links

• Fluoride in Drinking Water: A Review of Fluoridation and Regulation Issues Congressional Research Service
• U.S. government site for checking status of local water fluoridation