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Fluoride Toxicity

Fluoride Toxicity

Fluorides

Fluoride toxicity may present as acute or chronic toxicity.

  • Acute toxicity involves rapid intake of excessive dose of fluoride over a short period time.
  • Chronic toxicity refers to long term ingestion of fluoride in amounts exceeding the approved therapeutic level. It can manifest as dental and skeletal fluorosis.

Concentration of fluoride in drinking water and its effects

Fluoride concentration (mg/L) Effect
Less than 0.5 Dental caries.
0.5 - 1.5 Promotes dental health, prevents tooth decay.
1.5 - 4.0 Dental fluorosis (mottling & pitting of teeth).
4.0 - 10.0 Dental fluorosis, Skeletal fluorosis (pain in neck bones & back).
More than 10.0 Crippling fluorosis.

Factors Influencing Toxicity

  • Solubility of the compound.
  • Cation content of the compound.
  • Route of administration.
  • Age.
  • Rate of absorption.
  • Acid-base status.

Acute Fluoride Toxicity

It occurs due to intake of a single dose of fluoride above the Certainly Lethal Dose (CLD) i.e., 32-64 mg/kg body weight.

  • Certainly Lethal Dose (CLD): It is the amount of fluoride that is likely to cause death if timely intervention is not initiated.
  • Safely Tolerated Dose (STD): It is the amount of fluoride that can be ingested without causing symptoms of serious acute toxicity. It is usually 1/4th of the CLD i.e., 8-16 mgF/kg.

Clinical Manifestations

  • GI symptoms: Excessive salivation, Nausea and vomiting, Abdominal pain, diarrhea and cramps.
  • Neurologic effects: Headache, tremors, muscle spasm, tetanic contractions, hyperactive reflexes, seizures, muscle weakness.
  • Electrolyte abnormalities: Hypocalcemia, hypomagnesemia, hyperkalemia, hypoglycemia.
  • Cardiovascular effects: Widening of the QRS complex, corrected QT interval (QTc) prolongation, arrhythmias, shock, cardiac arrest.

Management

Initial Emergency Response

  1. If the patient is conscious and gag reflex is intact, vomiting should be induced using an emetic agent.
  2. Administer 1% Calcium chloride or Calcium gluconate orally to bind to fluoride. If these are not available, milk should be ingested.
  3. Monitor vital signs, call for medical assistance and shift the patient to an emergency care facility.

Definitive Management

  1. The patient should be placed on a cardiac monitor and an electrocardiogram should be obtained. Airway and intravenous line should be established.

  2. Gastric aspiration & lavage: Small-bore nasogastric tube aspiration followed by lavage is recommended.

    • Lavage is done with 1-5% calcium chloride solution or activated charcoal (to bind fluoride in the stomach).
    • Gastric aspiration and lavage are most effective when instituted within 1 hour of ingestion.

  3. Manage electrolyte abnormalities, esp. hyperkalemia, hypocalcemia, and hypomagnesemia.

    • IV calcium chloride or calcium gluconate should be administered to correct calcium deficiency.
    • Cardiac arrhythmias from fluoride toxicity are difficult to treat because they do not respond to lidocaine, cardioversion, or defibrillation.

  4. Maintain cardiovascular circulation.

  5. Supportive therapy:

    • Fluid replacement to reverse effects of vomiting and diarrhea, and to maintain urine flow,
    • Glucose administration,
    • Oxygen,
    • Artificial respiration, and other supportive measures.

  6. If the patient responds favorably, continue supportive therapy until mental status, vital signs and blood profile returns to normal.

References

  • C. M. Marya - A Textbook of Public Health Dentistry, Jaypee Brothers Medical Publishers (P) Ltd (2011). https://amzn.to/3SHP36G
  • S. S. Hiremath - Textbook of Public Health Dentistry, Elsevier India (2016). https://amzn.to/49mh2jw

*This article is an excerpt from the above mentioned books and Medical Sutras does not make any ownership and affiliation claims.