Incendiary Chemical-Warfare Agents and Hydrogen Fluoride (HF)

Incendiary agents cause thermal burns. Some of them may be used in exploding projectiles which cause shrapnel that may lodge in tissue. White phosphorus may continue to burn on skin or clothing as long as it has access to air, and because magnesium will burn under water, both substances will continue to burn within tissue. White phosphorus is toxic and may also cause systemic effects, due to uncoupling of oxidative phosphorylation in hepatocytes, hyperphosphatemia, hypocalcemia (from binding of calcium to phosphorus), renal injury, and hyperkalemia (from hypocalcemia or from renal damage).

HF penetrates deeply and quickly into exposed tissue but generates hydronium ions relatively slowly. The fluoride released from the dissociation of hydrogen fluoride binds avidly to calcium and magnesium. This binding, particularly the binding to calcium, produces severe local pain and may produce systemic effects due to hypocalcemia, hypomagnesemia, and hyperkalemia; coagulopathy and fatal cardiac arrhythmias may occur.

Thermal burns due to incendiary agents have manifestations similar to those of other thermal burns, with important exceptions.

White phosphorus (WP) burns at extremely high temperatures and can cause immediate erythema and excruciating pain out of proportion to the visible erythema or burn damage. Vesicles and bullae may develop, and the skin may turn yellowish and become necrotic. Embedded fragments may luminesce, smoke, or reignite upon exposure to oxygen. Limb burns can become circumferential, leading to edema and potential compartment syndrome. The secondary generation of phosphoric acid can cause additional tissue damage. Systemic distribution of phosphorus from deceptively localized burns is possible and can lead to systemic toxicity characterized by nausea, vomiting, abdominal pain, and diarrhea; hypotension, metabolic acidosis, hyperkalemia, and acute kidney injury; and hypocalcemia (along with hyperphosphatemia and sometimes hypomagnesemia). ECG effects can include QT prolongation, ST-T changes, progressive bradycardia, and ventricular dysrhythmias with cardiovascular collapse and death.

Magnesium, like WP, can cause surface burns with a thermal component and thus is similar in clinical presentation to other burns. Also like WP, it can cause deep thermal and chemical injury from embedded particles. Magnesium on or in the skin can reignite upon contact with moisture, so water should not be used to try to extinguish magnesium burns on the skin, although the most expeditious method of removing particles from the eye may need to be copious flushing with saline.

The onset of pain after HF exposure depends on the concentration of HF; pain may appear within an hour but typically occurs after 2 or 3 hours. However, once pain occurs, it is often deep and intense. Affected skin is erythematous but does not appear to be as severely affected as the intense pain would suggest.

• History and physical examination

Most incendiary burns are readily apparent. However, burns due to low concentrations of HF may appear deceptively innocuous, and a high index of suspicion must be maintained for deep tissue injury and systemic toxicity. WP burns may glow or smoke when exposed to air.

• In general, treat as thermal burns

• For white phosphorus burns, avoid exposure to air

• For magnesium burns, avoid exposure to water or moisture

• For HF, topical and sometimes systemic calcium

See Burns for the general management of thermal burns.

For WP burns, the affected areas are flooded with water or smothered to avoid exposure to air (1). WP particles are removed mechanically (they often adhere tightly to skin) and placed in water. Smoking trails may be good indicators of the location of small particles. A bicarbonate solution may be used to flood the burns and to wet the burn dressings, but cupric sulfate (CuSO₄) is no longer recommended for these burns.

Magnesium reacts with water to generate highly flammable gas and with carbon dioxide to produce magnesium oxide and carbon. Burning magnesium can create severe partial- or full-thickness burns with the typical appearance of thermal burns but with two complications:

• Water added to magnesium burns in an attempt to extinguish them results in the formation of magnesium oxide and magnesium hydroxide, which can themselves create alkaline burns with their characteristic pain and potential deep penetration.

• Small embedded particles of magnesium can continue to damage the skin or underlying tissues even when surface burning is extinguished.

In addition, magnesium oxide volatized from magnesium in burns or in the immediate environment can cause respiratory irritation. Burning magnesium on the skin should be addressed by using a Class D dry fire extinguisher rather than water to extinguish the flames. Burning or smoking magnesium particles in the skin or subcutis should be removed as promptly as possible. If not all particles can be removed at once (eg, because of the number of wounds), oil can be used to cover wounds until removal can be accomplished. Eye injuries from magnesium are a true emergency, and immediate inspection and removal of any visible particles is a priority. Even though water is generally to be avoided with magnesium, copious flushing of the eye with saline or other fluid should be initiated and should continue until the measured ocular pH is between 7.0 and 7.2 (2).

Patients exposed to HF require prompt decontamination by copious flushing with water. However, because HF penetrates quickly, significant local and systemic effects may occur even after thorough decontamination. Calcium gluconate or calcium carbonate paste is applied to local burns. Sometimes local injection of 10% Ca gluconate is also given; some clinicians give Ca gluconate intra-arterially. Patients with significant exposure are hospitalized to undergo cardiac monitoring and treatment with CaCl or Ca gluconate (see table Symptoms and Treatment of Specific Poisons) (3).