Fluoride is an ionic form of fluorine which is naturally found in the water, oceans, soil, and air. It is an essential mineral with remineralizing properties that helps to strengthen the bones and teeth. It is well known for its cavity-fighting properties, which help to reduce the incidence of caries. While inadequate intake of fluoride may lead to the development of caries, excess intake of fluoride can cause serious health problems. In this situation, it resembles a double-edged sword.
We all are familiar with the benefits of fluoride. However, fluoride toxicity is an area of concern which is not well known among the people of the community. Fluoride toxicity is a condition which is caused by elevated levels of fluoride in the body. A high increase in the fluoride level can lead to a severe health problem like bone deformity, fluorosis, and in extreme cases, sudden death.
There are palliative treatments available to treat fluoride toxicity. However, it is essential always to stay aware of the daily dietary intake. Today’s article will highlight the consequences of fluoride toxicity. Furthermore, we will also discuss some of the treatments available for curing fluoride toxicity.
What is fluoride toxicity?
Although low concentrations of fluoride are considered safe for dental health, continued consumption of large amounts of fluoride can pose a threat to the health and welfare of an individual. (1)
Fluoride toxicity is a health condition that is characterized by elevated levels of fluoride in the body. Taking sodium fluoride as an example, the lethal dose of fluoride is listed as follows –
- 5-10 gm of fluoride is potentially life-threatening for most adults with a bodyweight of 50 kg.
- Ingestion of fluoride at least 15-20 times lower than the dose mentioned above, which sums up to 10-15 mg, can cause gastrointestinal discomfort. (2)
Additionally, intake of large amounts of fluoride can interfere with tooth and bone formation leading to fluorosis and skeletal bone deformity.
A note on the history of fluoride toxicity
During the early 19th and 20th centuries, sodium fluoride, one of the popular compounds of fluoride family, was used as a pesticide. This is because of its bacteria-killing properties. However, the resemblance of fluoride pesticide to powdered milk led to reported cases of accidental or intentional fluoride poisoning. Fluoride pesticides were after that banned worldwide. (3)
In the 1960s, fluoride came into the limelight with its cavity-fighting properties. The World Health Organization recommended optimal levels of fluoride in drinking water to range from 0.5 – 1.0 ppm. It is essential to keep track of the daily intake of fluoride to prevent toxicity.
What are the dietary recommendations of fluoride?
The average daily intake of fluoride from any source such as water, milk, salt, or dietary supplements is recommended to be between 2.0 – 2.2 mg for adults. Children between the age of five and fourteen years can ideally take 1.02 mg of fluoride daily. Additionally, the lethal and tolerable doses of fluoride are listed below –
- Certainly, lethal dose (CLD) – the amount of drug that can cause death – 32-64 mg /kg body weight at one time. (4)
- Safety tolerated dose – the maximum dose that can be ingested without toxicity – 8-16 g /kg body weight.
What are the types of fluoride toxicity?
Typically, fluoride toxicity is categorized into two types –
Acute fluoride toxicity
Acute fluoride toxicity occurs when large amounts of fluoride are ingested over a short time. Usually, acute fluoride toxicity occurs after 2-4 hours of fluoride ingestion fatality. (5) The fluoride ions block the healthy cellular metabolism of the body leading to cardiac failure and respiratory paralysis. Lack of medical attention or first aid can lead to sudden death within a few hours.
To prevent such an incident, it is essential to keep track of daily fluoride intake in the form of toothpaste or any fluoride-containing the product. (6)
Chronic fluoride toxicity
Excessive ingestion of fluoride over a long period leads to chronic fluoride toxicity. One of the most common types of fluoride toxicity is fluorosis. It is a condition that develops due to the deposition of excessive fluoride in the hard and soft tissue of the body. Typically, fluorosis can be divided into two types –
- Dental fluorosis – It is characterized as hypomineralization of tooth enamel caused by excessive fluoride ingestion over a long period when the teeth are in their developing stage. The teeth appear chalky and flaky with white striations or brown pitted discolorations. (7)
Dental fluorosis mainly occurs in young children up to five years of age when they ingest twice the optimal daily intake of fluoride.
- Skeletal fluorosis – It is a health condition that leads to an increase in bone density and joint stiffness. Patients with skeletal fluorosis may experience severe pain in the backbones, joints, hips, and spine. Additionally, the legs and hands may bend, leading to Knock-knee syndrome. (8)
Pregnant mothers with skeletal fluorosis may risk the life of the fetus. In severe cases, the spine may become rigid and stiff, leading to immobilization of the patient. Skeletal fluorosis typically occurs in children and young adults between the age of 10-20 years when the daily fluoride intake is around 10-25 mg/day.
What is the treatment for fluoride toxicity?
Treatment of fluoride toxicity depends on the type and severity of the symptoms. Typically, it can be categorized as follows –
Treatment for acute fluoride toxicity
The main aim of this treatment is to reduce the amount of fluoride available for absorption from the gastrointestinal tract. It can be done in the following ways –
- Induce vomiting by administering an emetic drug
- Calcium containing products such as milk must be given as it binds with the fluoride ions and neutralizes the free ionic form of fluoride in the body (9)
- Transport the patient immediately to the nearest hospital at the earliest time possible
Treatment for chronic fluoride toxicity
- Conservative treatments can treat mild dental fluorosis like bleaching and enamel micro-abrasion. Advanced cases of dental fluorosis may require masking of discolored areas with the help of tooth-colored filling such as a composite and resin-modified glass ionomer or esthetic veneers and prosthetic crowns. (10)
- Skeletal fluorosis requires prompt medical management with calcium, magnesium, aluminum salts to neutralize the free ionic form of fluoride. Medications like magnesium metasilicate and hydroxide have proven to be useful in mobilizing excess fluoride from the bones.
In the case of a neurological manifestation, a surgical approach like decompression of the spine may be required.
Take away message
Fluoride is one of the essential minerals that is required to maintain the strength of the teeth and bones. Moreover, fluoride is beneficial for promoting good oral health and protects the teeth from tooth decay. However, such benefits can only be fruitful if fluoride is taken within the daily recommended level. Excess intake of fluoride can have fatal effects on the oral and overall health of an individual. Such an incident is termed as fluoride toxicity.
Fluoride toxicity can be categorized into acute and chronic based on the duration of ingestion. Acute toxicity is usually fatal and can lead to sudden death. On the other hand, chronic toxicity may lead to debilitating conditions such as dental and skeletal fluorosis.
Some of the symptoms of chronic fluoride toxicity include hypomineralization and discoloration of teeth, bone deformity, spine, and neurological disorders. Treatment of fluoride toxicity depends upon the type and severity of the condition. It is essential to keep track of the daily fluoride intake to prevent the occurrence of fluoride toxicity.