Lethal dose of Fluoride

# The lethal dose of fluoride for a typical three-year-old child is approximately :

A. 100 mg

B. 200 mg

C. 350 mg

D. 500 mg

 

The correct answer is D. 500 mg.

The studies and surveys link fluorosis to three factors:

• Fluorosis is more common in geographic areas where the endemic levels of fluoride in the drinking water is higher than three parts per million

• Fluorosis is associated with fluoride supplementation at inappropriately high levels

• The use of fluoridated toothpaste has been implicated in fluorosis

In acute fluoride toxicity, the goal is to minimize the amount of fluoride absorbed. Therefore, syrup of ipecac is administered to induce vomiting. Calcium-binding products, such as milk or milk of magnesia, decrease the acidity of the stomach, forming insoluble complexes with the fluoride and thereby decrease its absorption. Note: Emergency Medical Service should be activated.

In acute fluoride toxicity, symptoms may appear within 30 minutes of ingestion and persist for up to 24 hours. Patients may experience some nausea, vomiting, diarrhea, and abdominal cramping. This may be due to the fact that 90-95% of ingested fluoride is absorbed through the stomach and small intestines. Fluorides are primarily eliminated from the body by way of the kidneys. However, the fluoride that does remain in the body is found mostly in skeletal tissue. In acute fluoride poisoning (which is rare), the most common causes of death are cardiac failure and respiratory paralysis. Fluoride toxicity shows up in the bones as osteosclerosis.

Important: The lethal dose of fluoride for a typical 3-year-old child is approximately 500 mg and would be proportionately less for a younger child and smaller child. To avoid the possibility of ingestion of large amounts of fluoride it is recommended that no more than 120 mg of supplemental fluoride be prescribed at any one time.

Note: If a six-year old child were receiving fluoridated water in the amount of 3 ppm, the result would most likely be fluorosis but not systemic toxicity. On the other hand, if a child in the same age range (6-7) were receiving 8 ppm of fluoridated water, there would be a good chance of systemic toxicity and moderate to severe fluorosis occurring.