Subsoil water is about 0.6% of the available water on Earth. However, it is the main drinking water supply.
Along with arsenic and nitrate, the fluoride ion (F-) is one of the major inorganic pollutants, with a mainly geogenic origin.
Fluoride in water is mainly due to the partial dissolution of minerals that contain this ion, present in the subsoil rocks in contact with water. High fluoride concentration is common in arid environments in which water flow is lower; consequently, contact time between water and rock is higher.
Fluoride is ingested by beverages and food, including medicines and cosmetics.
Traditionally it was considered that concentrations below 1.0 mg F/l are beneficial, particularly in growth stages, for calcification of teeth enamel, although this is disputed nowadays.
The World Health Organization and most countries in the world advise against water consumption when the concentration exceeds 1.5 mg F l, although many countries exceed this limit.
Several techniques for the removal of this anion have been proposed; however, the preferred methods, in terms of operating cost and ease, are based on adsorption, like HINDROP.
Fluoride in the world
Presence of fluoride in drinking water is limited in most countries of the world by 1.5 mg/L, as recommended by the World Health Organization (WHO).
Presence of fluoride in water is widespread worldwide, including several geographical areas in which its toxicity is a major health problem.
Continued ingestion of water by beverage or food causes dental fluorosis. When the exposure has been severe, skeletal fluorosis compromises mobility, sensory capacities and the nervous system. These diseases are the reason why the consumption of water with a higher fluoride concentration than 1.5 mg F/L is discouraged.
Latest data shows that fluorosis is endemic in at least 25 countries around the globe.
The total number of people affected worldwide is not known; by a conservative estimate, it is above 400 million people.
Percentage of population affected by fluoride in each continent
Effects of fluoride on the population
Fluoride is related to two serious health conditions: dental fluorosis and skeletal fluorosis. In addition to these health issues, fluoride may lead to other related problems that impact the quality of life of many people on Earth.
Dental fluorosis is a defect in the formation of the enamel, which is the outer hard layer of tooth crown.
Long-term exposure to fluoride concentrations above 1.5 mg / L, especially during the tooth formation stages (from gestation to 8 years of age) affect the teeth and lead to dental fluorosis.
During the tooth formation stages, the ameloblast or cell forming the enamel produces a matrix protein which is calcified; it is what we know as enamel. After its fulfillment, the ameloblast degenerates and disappears.
Severity will depend on the amount of fluoride ingested and the duration of exposure to the toxic agent.
In the case of low concentrations, it may appear in the form of whitish opaque spots distributed irregularly on the teeth surface.
Exposure to higher doses leads to enamel fragility, with brown stains and anomalies in the form of transverse striae, fissures and enamel loss that appears similar to abrasion.
In the most severe forms of dental fluorosis, the tooth erupts completely white as chalk, but its appearance may vary over time. This enamel, severely weakened due to hypomineralization, can be broken by masticatory force.
It causes more porous underlying enamel, with tendency to form diffuse brown spots.
Within the different levels of severity, the changes that we can appreciate in the teeth can be:
- White spots.
- Completely white enamel with chalky appearance
- Diffuse brown lesions
- Enamel loss
Skeletal fluorosis is a bone condition caused by excessive accumulation of fluoride in the bones. It may cause bone structure changes, making them extremely amorphous, fragile and brittle.
Early stages of skeletal fluorosis are characterized by an increase in bone mass, detectable by X-ray. If large amounts of fluoride are ingested for several years, skeletal changes cause stiffness and joint pain.
The most acute form of skeletal fluorosis is called “crippling fluorosis”. Its symptoms are ligament calcification, immobility, muscle mass loss and neurological issues due to spinal cord compression, bone embrittlement and neurological damage.
Scientific research has shown that most kidney diseases are strongly linked to fluoride toxicity. High doses of fluoride during a short-term exposure can affect renal function.
Several research studies prove that fluoride may interfere with the pineal gland and other brain functions.
Population exposed to high concentration of fluoride in drinking water has a greater propensity to be diagnosed with bladder cancer, osteoporosis, arthritis, bone embrittlement, infertility, brain damage, Alzheimer’s syndrome and thyroid disorder.