The authors of the article proceeded from the hypothesis of the negative impact of low fluorine content on the occurrence of caries in children. The article provides a review of modern scientific data on the importance of fluorine in the formation of dental caries, on the classification of natural waters, including for drinking water supply. The material describes the probable mechanisms of fluorine conversion in the body.
Problem Status
The health of the population is directly dependent on the composition of natural waters in the sources from which the regular water supply of the territory is carried out. Every day a person consumes 1.5-2.5 liters of water, which should ideally not contain any harmful impurities that adversely affect human health. At the same time, drinking water should contain a sufficient amount of trace elements involved in metabolic processes person.
In nature, water is never found in the form of a chemically pure compound. Possessing the properties of a universal solvent, it constantly carries a large number of different elements and compounds, the composition and ratio of which is determined by the conditions of water formation, the composition of aquifers. Technogenic pollution has a great influence on the composition of natural waters, both surface and underground.
Water with increased mineralization affects the secretory activity of the stomach, disrupts the water-salt balance, resulting in a mismatch of many metabolic and biochemical processes in the body. The systematic use of distilled and low-mineralized water causes a violation of the water-salt balance, which is based on the reaction of the osmoreceptive field of the liver, which is expressed in an increased release of sodium into the blood. As a result, water is redistributed between the extracellular and intracellular fluids. In an experiment on laboratory animals and volunteers, it was found that the lower limit of mineralization, at which the body's homeostasis is maintained by adaptive reactions, is an empty residue of 100 mg/l, the optimal level of mineralization of drinking water is in the range of 200–400 mg/l, magnesium - 10 mg /l
Increased water hardness may be one of the etiological factors in the development of urolithiasis, too low a content of hardness salts contributes to the development of cardiovascular diseases. This is based on data from many studies. The content of fluorine in natural and drinking waters is a particular problem. Fluorine is widely distributed in nature. Its content in the earth's crust is 0.01%. Most often, fluorine occurs in the form of fluorides with metals. Many micas, lepidolite, tourmaline, phosphorite, fluorapatite, granite, etc., contain a lot of fluorine.
Fluorine is one of the substances capable of being isomorphically included (in low concentrations) in the composition of apatite, forming its more durable analogues. Fluorine replaces the hydroxyl group in the hydroxyapatite molecule, turning it into fluorapatite, which is more resistant to acids. Atmospheric precipitation, waters of melting snow, penetrating into the deep layers of the earth, wash out various layers. In those places where the soil is rich in fluorine compounds, it is enriched with salts. Therefore, more often The groundwater are richer in fluorine than the waters of rivers, lakes, wells.
1) Very low concentration - up to 0.3 mg/l, at which the incidence of dental caries in the population is 3-4 times higher than at the optimal concentration of fluorine; in children, there is a delay in ossification and defects in bone mineralization. Spotting of the first degree of tooth enamel can be observed in 1-3% of the population.
2) Low concentration of fluorine - 0.3-0.7 mg / l - fluorosis of the first degree in 3-5% of the population.
3) The optimal concentration of fluorine is 0.7−1.1 mg/l - the incidence of caries is close to the minimum.
4) Increased, but still acceptable concentration of fluorine - 1.1 - 1.5 mg / l 0 fluorosis in 2% of people.
5) Above the maximum allowable - 1.5 - 2 mg / l - fluorosis in 30% of the population.
6) High concentration of fluorine - 2−6 mg/l - up to 80% of the population suffers from fluorosis in the endemic area (Patrikeev V.K.).
7) A very high concentration of fluorine - 6-15 mg / l - the incidence of dental caries is much higher than the minimum. Up to 80−100% of the population is affected by fluorosis with a predominance of severe forms. Significantly increased abrasion and fragility of teeth. In children, disorders in the development and mineralization of bones are often observed, in adults - osteosclerosis of the bones.
So far, there are only a few assumptions regarding the mechanism of action of fluoride on teeth. Some authors believe that fluorine, being an enzymatic poison, reduces the activity of the phosphatase enzyme, binds calcium salts in the body, which are then excreted by the kidneys and sweat glands. As a result of the association of the body with calcium salts, a violation of the mineralization of tooth enamel occurs. According to other researchers (and this is a more reasonable idea), with an increased content of fluorine in drinking water changes in the tissues of the teeth occur as a result of the toxic effect of fluorine, as one of the most active elements, on enameloblasts during the development of enamel, as a result of which the processes of its formation and calcification are disrupted. With the optimal content, fluorine contributes to a more intensive inclusion of calcium in the calcified tissues of the body. Reacting with enamel hydroxyapatite crystals, fluorine forms compounds that are more resistant to acids, reduces the permeability of tooth enamel, strengthening the enamel microcrystalline lattice. Fluorine has a bactericidal effect, reducing the enzymatic activity (acid-forming) of microbes. The lack of fluoride in the diet contributes to the development of caries, because. the connection between organic (protein) and inorganic (calcareous elements of enamel and dentin of teeth is broken.
Numerous clinical observations indicate that caries in children develops most intensively in the first years after tooth eruption, which coincides with the period of immature enamel. Mineralization is provided a high degree enamel permeability of immature teeth (within a year after tooth eruption).
In the process of maturation, calcium and phosphorus ions enter the enamel, which accumulate in all layers of the enamel, especially in the surface. A highly polymerized layer up to three microns thick is formed, which is characterized by high resistance to acids. If enough fluorine enters the enamel at this time, the content of fluorapatites increases. The resistance of enamel to the development of dental caries increases. Before teething, fluoride enters the enamel from blood serum, and after teething, it also comes from saliva. the inclusion of fluoride in enamel from saliva has been scientifically proven. Fluorine regulates the absorption of calcium by the hard tissues of the tooth. The rate of mineralization in the presence of fluorine increases significantly. Even at such a low fluorine concentration as 1:1000, the rate of mineralization increases by 3–5 times.
For endogenous (internal) prevention and exogenous (external) prevention of caries, fluorine salts are used: sodium fluoride, fluorides of tin, lead, zinc, copper, silver, iron, zirconium, antimony-fluoride sodium and potassium, ammonium fluoride, titanium tetrafluoride, aminofluorides, sodium monofluorophosphate, fluorinated xylitol and sorbitol.
Own research
The city of Tchaikovsky is located in the south Perm Territory on the Kama River in the backwater zone of the Votkinsk reservoir. According to the data of the branch of the Center for Hygiene and Epidemiology in the city of Chaikovsky in 2005, in the Kassa River, when water is taken above the treatment facilities, the concentration of fluorine in the water corresponds to the optimal level, the pH is closer to neutral, and the hardness of the water is 3 times higher than in artesian wells. There is an excess of heavy metals (manganese, copper, zinc, iron and aluminum). Moreover, in previous years it was possible to take water for analysis only from the surface of the reservoir. Now the equipment of the laboratory of the Department of Ecology and Nature Management makes it possible to study the entire water column. The water pollution index is the lowest throughout the Perm region: water can be classified as class 3 (moderate pollution level). If over a number of years for heavy metals there were excesses of MPC up to 50–70 times (for example, for manganese), then in last years these indicators have decreased by a lot - up to 12-13, tk. tightening control over wastewater discharges.
For the Middle Urals, where the town of Chaikovsky, Perm Region, is located, the norm of fluorine in drinking water is 1.0−1.5 mg/l. In the wells of the city, the concentration of fluorine in the water is different. So in the wells of the Uralsky microdistrict (school No. 6) in 2005, the fluorine concentration is 0.15 mg / l, which, according to the classification, corresponds to low level. In the well near the bakery today, the concentration of fluorine in the water also does not correspond to the norm. In the wells of the city of Chaikovsky, which provide drinking water supply to the city, water has a reduced hardness: on average, from 0.15 to 0.9 mg-eq/l, maximum - 3.45 mg eq/l (in the well of the Zavokzalny district) at a rate of 7 mg-eq/l. Accordingly, as mentioned earlier, there is a risk of cardiovascular disease.
The hydrogen index (pH) of the city's water exceeds the permissible norm, and only in the well of the Zavokzalny district does the pH correspond to the norm.
Almost all wells in the city contain nitrogen-containing substances of organic origin in the water. One-time violations of hygienic standards for dry residue and fluorine levels are recorded.
Childhood It is best suited to use the ability to imitate and in a playful way to stimulate the care of the health of their teeth and gums. Through constant repetition and training, during the school years, it is possible to form in children an awareness of the need to constantly take care of their health.
IN early childhood the child is the most trainable, as it copies the behavior of parents and educators. IN school years the body is growing rapidly. At this age, the maturation of the enamel of permanent teeth is completed. From 11 to 15 years, the formation of bite is completed. Dentists consider adolescents to be at risk, requiring heightened attention when planning preventive measures: health lessons in schools.
Minerals are organic compounds essential for the healthy functioning of the human body. One of the most important minerals is fluorine. It is known that in human body contains about three grams of this trace element.
The biological significance of fluorine
Fluorine provides full-fledged formation and strengthening bone tissue as well as tooth enamel. Indeed, in the body, fluorine is mainly concentrated in the bones and teeth. In addition, fluorine is involved in many biochemical reactions and even in the process of hematopoiesis.
The daily requirement for the mineral is about 3.0-4.2 mg. The main source of trace elements, oddly enough, is drinking water. The trace element is also found in foods such as fish, beef, lamb, dairy products,. However, with food, a person receives only a small part of fluoride.
Approximately 70-85% daily allowance a person receives fluorine with water. Therefore, it is difficult to overestimate hygienic value this trace element in water. It is generally accepted that the optimal concentration of fluorine is 1.0-1.5 mg/dm 3 . Long-term use of water with insufficient or vice versa excessive fluorine content leads to certain disorders and diseases.
Reducing fluoride in water
Water in natural springs contains fluorine in various amounts. In some regions, the microelement is contained in water in a much larger amount, in others - in a smaller amount. Long-term use of water with high or vice versa low content This trace element inevitably affects health.
Thus, the use of water with a fluorine content below 0.5 mg / dm3 leads to a violation of the formed hydroxyapatites, from which tooth enamel is formed. Such metamorphoses lead to a decrease in the strength of the enamel, due to which it becomes unstable to the action of lactic acid, which is formed in the mouth from carbohydrates. The destruction of enamel and dentin begins, which is manifested by caries.
With insufficient intake of fluorine, the skeletal system suffers. The bone density gradually decreases, their fragility increases, which is fraught with the occurrence. Due to a violation of the metabolism of bone tissue develops.
Increasing fluoride in water
When the concentration of fluorine in drinking water is more than 1.5 mg / dm 3, it is said that its content is high. Prolonged use of such water leads to damage to tooth enamel and the formation of fluorosis. The disease is manifested by the appearance of chalky stripes, spots, erosions on the enamel, destruction of the tooth crown.
This is an endemic disease that occurs in certain geographic regions that are characterized by high levels of fluoride in the water. There is an obvious connection between the content of fluorine in water and the extent of human exposure to fluorine-dependent diseases. So, at the concentration of fluorine in water at the level of 1.1-1.5 mg/dm 3 signs of fluorosis are observed in approximately 20% of the population. With the content of fluorine in water at the level of 1.5-2 mg/dm3, mild forms of fluorosis are already registered in 40% of the population. A high concentration of fluorine (2-6 mg / dm 3) causes the development of fluorosis in more than 40% of people, and a trace element concentration of more than 6 mg / dm 3 - in 80-100% of the population, with predominantly severe forms of the disease.
With prolonged use of water with a very high fluorine content, even bone tissue can be affected with the development of skeletal fluorosis. This disease is manifested by osteosclerosis (hardening of bone structures), ossification of ligaments and cartilage. In large quantities, fluorine affects nervous system human, as well as the heart, kidneys, liver.
Methods for correcting the level of fluorine in water
In areas with a fluorine content in water below the permissible limit, tap water is fluoridated, that is, it is saturated with fluoride compounds. The method does not affect the organoleptic properties of water in any way, while the taste and smell are not distorted. For water fluoridation, special fluorination plants for centralized water supply are used.
The purpose of this intervention is to reduce the incidence of caries among the population by regulating the concentration of fluoride in tap water. To prevent the development of caries in settlements low in micronutrient local residents dentists also recommend the use of fluoride toothpastes.
What measures are taken in a situation where the permissible concentration of fluorine in water is exceeded? Perhaps the simplest, but ineffective method is mixing drinking water from separate sources with different concentrations of the microelement.
To more effectively reduce the fluorine content in water, defluorination methods are used. Utilities install defluorinators in the centralized water supply system. There are filtration and reagent methods of defluorination. Reagent methods are based on the binding and sorption of fluorine by hydroxides of aluminum and magnesium. As a result of the reaction, flakes of substances are formed and precipitated, which must then be removed by filtration. The filtration method consists in passing water through various filters (charcoal, ion exchange).
A special place in the study of the chemical composition of water is occupied by the content of fluorides in water. Fluorine is one of the trace elements with a pronounced biological effect. With its participation, mineralization processes are carried out in the tissues of teeth and bones. It has a particularly pronounced effect on the cells involved in the formation of enamel. Therefore, when drinking water with a low fluorine content, the processes of normal tooth mineralization are disrupted and, as a result, an increased incidence of dental caries is noted among the population. When drinking water with a high fluorine content, the processes of mineralization of teeth and bones are significantly enhanced, and another specific pathology occurs - fluorosis of teeth and bones. The hygienic significance of fluorine is not limited to the effect on teeth and bones - it takes part in interstitial metabolism, accelerating or inhibiting the activity of various enzyme systems. Biotic doses of fluoride have a positive effect on many body systems.
Surface (open) waters, which are the main sources of water supply for large water pipes, contain fluorine in larger quantities than atmospheric waters. However, in most surface waters, the fluorine content is also often low, usually not exceeding 0.5 mg/l.
Underground waters contain significantly higher amounts of fluorine than previous water sources. Small amounts of fluorine are found in interstratal waters, reaching in some cases on the territory of the Russian Federation 10-15 mg/l. IN groundwater the fluorine content reaches 1-1.5 mg/l, although in most it is up to 0.5 mg/l.
Hygienic standards for fluorine in drinking water. The maximum permissible concentration of fluorine in drinking water is set at 1.5 mg/l. Given that water consumption depends on the climatic and geographical conditions of the area, when organizing water fluoridation, the choice of fluorine dose is made depending on climatic regions (when water is fluoridated with the same fluorine concentration throughout the year) or seasonal conditions (when water is fluoridated with a seasonal concentration of trace elements) . According to the standards, when water is fluoridated with a constant dose, the content of fluorine in it should be 1.5 mg/l in climatic regions I and II, 1.2 mg/l in climatic region III and 0.7 mg/l in climatic region IV.
Indications for the organization of fluoridation. The expediency of water fluoridation in each specific settlement is established by the state sanitary and epidemiological supervision authorities (SSES). The main indication for water fluoridation is the low natural content of fluorine in the water of drinking water supply sources (less than 0.5 mg/l). An additional indication for the organization of fluoridation is the high incidence of dental caries in the population, for example, among children aged 12-14 years, more than 25-30% of persons are affected by caries in permanent teeth.
Fluoride has both positive and negative effects on human health. In terms of oral health, the incidence of dental disease is inversely related to the concentration of fluoride in drinking water; there is also a relationship between the concentration of fluoride in water and fluorosis. From a health standpoint in general, in regions where fluoride concentrations are high in both water and food, cases of skeletal fluorosis and bone fractures are common. However, there are other sources of fluoride. Demineralization and water treatment using membranes and anion exchange resins remove almost all fluorine from water. The use of such water for drinking purposes, the significance for the health of society is highly dependent on the specific circumstances. The main objective is to enhance the positive effect of the presence of fluoride in drinking water (protection against caries), while minimizing undesirable problems of the oral cavity and health in general.
The etiology of oral diseases involves the interaction of bacteria and simple sugars(e.g. sucrose) on the tooth surface. In the absence of such sugars in food and drinks, caries will cease to occur. significant problem. However, the problem will persist with high sugar intake until the right move is made to address it. Removing fluoride from drinking water has the potential to exacerbate an existing or emerging problem of oral disease.
The intake of fluoride in the human body
Fluorine is fairly widespread in the lithosphere; often occurs in the form of fluorspar, fluorapatite and cryolite and is the 13th most abundant on the globe. Fluorine is present in sea water at a concentration of 1.2-1.4 mg/l, in groundwater - up to 67 mg/l and in surface water - 0.1 mg/l. Fluorine is also found in food, in particular, in fish and tea.
While most foods contain trace amounts of fluoride, water and non-dairy beverages are the main sources of absorbed fluoride, accounting for 66 to 80% of intakes in US adults, depending on the fluoride content of drinking water.
Additional sources of fluoride are toothpaste(especially for small children, who swallow most of the pasta), tea - in those regions where tea drinking is an established tradition, coal (by inhalation) in some regions of China, where charcoal with a very high fluorine content is heated at home. Absorption of ingested fluoride occurs in the stomach and small intestine.
For the most part, fluorine, originally contained in water or added, is contained there in the form of free fluoride ion. Water hardness 0-500 mg/l (in terms of CaCO 3) affects ionic dissociation, which in turn slightly changes the bioavailability of fluorine. Absorption of a normal dose of fluoride varies from 100% (on an empty stomach) to 60% (calcium-rich breakfast).
The effect of fluoride from food and drink on the state of the oral cavity
The effect of fluoride, naturally present in drinking water, on oral health was considered in the 1930s and 1940s by Trendley Dean and colleagues at the US Public Health Service. A number of studies have been conducted throughout the US; studies have shown that with an increase in the content of natural fluorine in water, the likelihood of fluorosis diseases increased and decreased - caries. In addition, based on Dean's results, it could be assumed that at a concentration of 1 mg/l, the frequency, severity and cosmetic effect of fluorosis are not a socially significant problem, and caries resistance increases significantly.
When analyzing these facts, a natural question arises: will artificial fluoridation of drinking water allow the effect to be repeated? The first study on this topic was carried out in Grand Rapids under the direction of the USPHS in 1945. The results obtained over 6 years of water fluoridation were published in 1953. Additional studies were carried out in 1945-46. in Illinois (USA) and Ontario (Canada).
Also this problem was dealt with by scientists in the Netherlands, New Zealand, the United Kingdom (1955-1956) and East Germany. The results were similar: there was a decrease in the incidence of caries. After the publication of the results, water fluoridation has become a common health promotion measure at the community level. The optimal concentration of fluorine, depending on climatic conditions, is 0.5-1.0 mg/l. Approximately 355 million people around the world drink artificially fluoridated water. In addition, about 50 million people use water containing natural fluorine at a concentration of about 1 mg/l. In some countries, in particular in certain areas of India, Africa and China, water may contain natural fluorine in rather high concentrations, above 1.5 mg / l, the norm established by the WHO Guidelines for the Quality of Drinking Water.
Many countries that have introduced artificial enrichment of water with fluorine continue to monitor the incidence of caries and fluorosis using a cross-sectional random sample of children aged 5 to 15 years. An example of monitoring would be a report on children's oral health in Ireland (mostly fluoridated water) and the north of Ireland (non-fluoridated).
The number of affected, missing and healed teeth in children living in different regions Ireland with fluoridated and non-fluorinated water (NF), as well as in Northern Ireland(SI)
Fluoride intake and health
The effect of ingested fluoride on health was considered by Moulton in 1942, which preceded the study by Grand Rapids; since then, a number of organizations and individual scientists have been constantly occupied with the problem. The IPCS later conducted a detailed review of fluoride and its health effects. Research and reviews have focused on bone fractures, skeletal fluorosis, oncological diseases and abnormalities in newborns, but also affected other abnormalities, possibly caused or exacerbated by fluoridation. No evidence or adverse effects have been found with the use of water containing natural or added fluoride at concentrations of 0.5-1 mg/l, except for the cases of oral fluorosis described above. In addition, studies in areas of the United States where natural fluoride content reaches 8 mg/l have not shown any adverse effects of drinking such water. At the same time, there is evidence from India and China, where an increased risk of bone fractures is the result of long-term use a large number fluoride (total intake 14 mg/day) and the assumption that the risk of fractures already occurs at intakes above 6 mg/day.
The Institute of Medicine of the US National Academy of Sciences gives a recommended total dose of fluoride intake of 0.05 mg/kg of human body weight, arguing that taking this amount of fluoride minimizes the risk of caries in the population, while not provoking negative side effects (for example, fluorosis). ). protection agency environment The United States considers the maximum allowable concentration (not causing skeletal fluorosis) to be 4 mg / l, and the value of 2 mg / l - not causing oral fluorosis. The WHO Guidelines for Drinking Water Quality recommend 1.5 mg/l. WHO emphasizes that when developing national standards, it is necessary to take into account climatic conditions, the volume of consumption, the intake of fluorine from other sources (water, air). WHO notes that in regions with naturally high levels of fluoride, it is difficult to meet the recommended amount for the population to consume.
Fluorine is not an element bound in bone tissue irreversibly. During the growth of the skeleton, relatively most of fluorine entering the body accumulates in bone tissue. "Balance" of fluorine in the body, i.e. the difference between the incoming and outgoing amount can be positive or negative. With the intake of fluorine from mother's and cow's milk, its content in biological fluids is very low (0.005 mg / l), and excretion with urine exceeds intake into the body, while a negative balance is observed. Fluorine enters the body of infants in very small quantities, so it is excreted from bone tissue into extracellular fluids and leaves the body with urine, which leads to a negative balance. The situation with the adult population is opposite - about 50% of the fluorine entering the body is deposited in the bone tissue, the remaining amount leaves the body through the excretion system. Thus, fluorine can be released from bone tissue slowly, but over a long period. This ratio is possible due to the fact that the bone is not a frozen structure, but is constantly formed from the nutrients that enter the body.
The value of desalination
Desalting removes virtually all of the fluorine from sea water, therefore, if the outlet water is not subjected to remineralization, it will contain a clearly insufficient amount of fluorine and other minerals. Many natural drinking waters are initially poor in minerals, including fluorine. The significance of this fact for the health of society is determined by the balance of benefit and risk.
When comparing residents of different continents and within the continent, a significant difference in incidence is visible. WHO recommended the introduction of the DMFT index, which is determined in children of 12 years of age (this includes the number of affected, missing and healed teeth) as the most appropriate indicator; the WHO oral health database has extensive information. The etiology of caries includes the interaction of bacteria and simple sugars from food. In the absence of sugar in drinks and foods, this problem would be negligible. Under these circumstances, the goal of public health is to prevent the harmful effects of excessive concentrations of fluoride in water.
However, when the risk of caries is high, the effect of removing fluoride from centralized system drinking water supply will be comprehensive. IN Scandinavian countries where oral hygiene is at high level and alternative sources of fluoride are widely used (e.g. toothpaste), the practice of permanently removing fluoride from drinking water may have little impact. On the other hand, in some developing countries where oral hygiene is quite poor, water fluoridation in the amount of 0.5-1 mg/l remains an important task. public interest. There are also countries where there is a mixed situation. In particular, in the south of England, the incidence is under control and without artificial fluoridation of water; elsewhere, in the North West of England, the incidence is higher and water fluoridation is an important measure.
conclusions
The value of using demineralized water, not subsequently enriched with fluoride, depends on:
- concentrations of fluoride in drinking water from a specific source;
- climatic conditions and the volume of water consumed;
- risk of caries (for example, consumption of sugar);
- level of knowledge about oral problems in society and accessibility alternative sources fluorine for the population of a particular region.
However, it is necessary to address the issue of total intake from other sources and establish a reasonable lower limit of fluoride intake to prevent its loss from bone tissue.
Text quoted from World Health Organization report "Nutrient in Drinking Water".
