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In high concentrations, as with almost all substances, fluoride compounds are toxic. 5 grams of full strength sodium fluoride will kill most adult humans; a lethal dose is approximately 75 mg per kilogram of body mass. The acute toxic dose of fluoride is believed to be from 2 to 8 milligrams per kilogram of body mass.
Poisoning most commonly occurs following ingestion (accidental or intentional) of products that contain fluoride.
When ingested directly, fluoride compounds are readily absorbed by the intestines; over time, the compound is excreted through the urine, and the half-life for concentration of fluorine compounds is on an order of hours. Fluoride is taken out of circulation by the body and trace amounts bound in bone. Urine tests are a good indication of high exposure to fluoride compounds in the recent past.
Skin or eye contact with many fluoride compounds (in high concentrations) is dangerous.
The only generally accepted adverse effect of low concentration water fluoridation at this time is dental fluorosis. It is a condition caused by 'excessive' intake of fluorine compounds over an extended period of time, and can cause yellowing of teeth, hypothyroidism, or brittling of bones and teeth. The definition of 'excessive' in the context of fluorosis falls on the order of parts per million (ppm) and is generally accepted to mean significantly higher than the 0.7 to 1.2 ppm amounts recommended for fluoridated water.
Possible sources
The following is a list of possible sources of poisoning. Some of them have not been proven scientifically as the causes of poisoning, but they are still of interest because some people state they are. Historically, most cases of fluoride poisoning have been caused by accidental ingestion of insecticides or rodenticides.
Symptoms
Fluoride toxicity is characterized by a variety of signs and symptoms. Symptom onset usually occurs within minutes of exposure. Severity of symptoms can depend on the amount of fluoride compounds ingested.
Symptoms of fluoride poisoning point towards some kind of profound metabolic dysfunction, very similar to the symptoms of hypothyroidism.
When poisoned by fluoride, gastrointestinal signs predominate.
Method of action
Ingested fluoride initially acts locally on the intestinal mucosa. It can form hydrofluoric acid in the stomach, which leads to gastrointestinal irritation or corrosion. After ingestion, the gastrointestinal tract is the earliest and most commonly affected organ system.
Treatment
In case of accidental swallowing, give milk, calcium carbonate or milk of magnesia to slow absorption. Eye or skin contact should be treated by removing any contaminated clothing and flushing with water.
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