Fluoride poisoning
In high concentrations, as with almost all substances, fluoride compounds are toxic. 5 grams of pure sodium fluoride will kill most adult humans; a lethal dose is approximately 70 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 weight with lethal doses reported with levels of 16mg/kg in children and 32-64mg/kg in adults.
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 during tooth development (before teeth erupt into the mouth), 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. Fluoride in small amount is beneficial to teeth see Fluoride therapy.
One of the side effects of fluoride poisoning is gastro-intestinal inflammation as fluoride toxicity has a corrosive effect on the mucous membrane which line the gut.  Among the potential metabolic disturbances reported caused by fluoride toxicity is the increased impact of the natural plant toxin, salicylate,which may have particular significance in subgroups who already have high incidence of salicylate intolerance such as the ADHD and autism populations (see Autism therapies).

# 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. As such, the accuracy of the following list is doubtful at best. 
Historically, most cases of fluoride poisoning have been caused by accidental ingestion of insecticides or rodenticides.
- Air pollution
- Anesthetics
- Antibiotics
- Automobile wheel-cleaning products
- Contaminated beverages and food products
- Dietary supplements that contain sodium fluoride
- Fluoridated milk
- Fluoridated salt
- Fluoridation of public water supplies
- Fluoride tablets
- Glass-etching or Chrome-cleaning agents like ammonium bifluoride
- Groundwater pollution
- Household products
- Industrial exposure to fluxes used to lower melting points of metals.
- Insecticides containing sodium fluoride
- Mattresses emitting fluoride gases
- Scotchgard
- Soy products
- Rodenticides containing sodium fluoride
- Tea
- Teflon
- Toothpaste or other oral dental products containing sodium monofluorophosphate
- Vaccine contamination

# Chronic Toxicity
This article is focused on acute toxicity: the results of ingesting a large amount of fluoride in a short period of time. Chronic toxicity, the result of ingesting small amounts of fluoride over a long period of time, results in dental fluorosis and skeletal fluorosis. These conditions are seen in areas where there is natural fluoride in the drinking water at levels above that added in public water supplies in the United States.

# Symptoms of Acute Toxicity
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.

## Gastrointestinal
When poisoned by fluoride, gastrointestinal signs predominate.
- Abdominal pain
- Diarrhea
- Dysphagia
- Hypersalivation
- Mucosal injury
- Nausea
- Vomiting

## Electrolyte abnormalities
- Hyperkalemia
- Hypocalcemia
- Hypoglycemia
- Hypomagnesemia

## Neurologic effects
- Headache
- Hyperactive reflexes
- Muscle weakness
- Muscular spasm
- Paresthesia
- Seizures
- Tetanic contractions
- Tremor

## Cardiovascular
- Cardiac arrest
- Shock
- Widening of QRS
- Various arrhythmias

# 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.