Toxicology – Hydrofluoric Acid (HF) Exposure

Sources

Hydrofluoric acid is used in several industrial and commercial processes, including:

• Glass etching
• Semiconductor and computer-chip manufacturing
• Oil refining
• Chemical production
• Metallurgy
• Some rust removers and wheel-cleaning products

Typical Presentation

A worker exposed to HF develops severe, deep pain several hours after skin contact, despite relatively minor-looking surface burns.

Pain that seems out of proportion to the visible injury is an important clue.

Clinical Features

Skin exposure may cause:

• Severe burning or throbbing pain
• Tissue destruction that can extend deeply beneath the skin
• Delayed symptoms, particularly with more dilute solutions

Significant exposure can produce systemic electrolyte abnormalities, especially:

• Hypocalcemia
• Hypomagnesemia

These may cause:

• Muscle cramps or spasms
• Tetany
• Chvostek or Trousseau signs
• QT prolongation
• Ventricular dysrhythmias
• Cardiovascular collapse in severe poisoning

Inhalational exposure can also cause significant respiratory tract and pulmonary injury.

Mechanism of Action

HF toxicity is unusual because both components contribute to injury.

The hydrogen ion produces local corrosive damage, while absorbed fluoride ions penetrate deeply and bind calcium and magnesium.

This sequestration can cause profound electrolyte disturbances and disrupt cardiac electrical activity.

Management

HF exposure is a medical emergency. Initial treatment includes:

• Immediate removal from the source
• Prompt removal of contaminated clothing
• Copious water irrigation of exposed skin
• Early cardiac monitoring for significant exposures
• Serial monitoring of calcium, magnesium, potassium, and ECG findings

After initial decontamination, calcium gluconate is used to bind fluoride and limit ongoing tissue injury. The route of calcium treatment depends on the location and severity of exposure and should be directed by experienced clinicians or a poison center.

Severe exposures may require intensive treatment of electrolyte abnormalities, dysrhythmias, and respiratory complications.

Key Points

• Severe pain out of proportion to the visible burn is characteristic of HF exposure.
• HF can penetrate deeply even when the surface injury initially appears mild.
• Fluoride binds calcium and magnesium, potentially causing life-threatening electrolyte disturbances.
• Significant exposure can produce QT prolongation and dangerous ventricular dysrhythmias.
• Rapid decontamination and calcium-based treatment are central to management.
• Because deterioration can be delayed, significant HF exposure requires urgent medical evaluation and toxicology guidance.