Magnesium and Thermite Poisoning 

Updated: Aug 22, 2019
Author: Jayson Tappan, MD; Chief Editor: Zygmunt F Dembek, PhD, MPH, MS, LHD 

Overview

Practice Essentials

Two major types of metal incendiaries exist: those that are magnesium based and those of the thermite/thermate type. Incendiary metals are usually encountered in the military or industrial setting but can also be encountered in other applications due to common usage of magnesium shavings as a fire-starting technique such as for camping or in sparklers and fireworks.[1]

Magnesium, a silvery white metal of atomic weight 24.32, ignites at 632°C and burns at 1982°C, with magnesium oxide (MgO) as its combustion product. In an exothermic reaction, metallic magnesium can ignite to produce magnesium dihydroxide (ie, Mg(OH)2 and hydrogen. When combined with water while burning it releases hydrogen gas and oxygen. Magnesium is used in either powdered or solid form as an incendiary agent for both illumination and antipersonnel purposes.[2, 3]  Various alloys of magnesium (eg, aluminum/zinc/magnesium alloy found in US M126 round) are mechanically sturdier but also can be ignited easily. Militaries use magnesium in hand-held signal flares and in glowing “tracer rounds,” which are ammunition fired in series with traditional ammunition in automatic weapons to assist with aim (eg, US M856, M10, M17).[2]

Thermite is a mixture of powdered or granular aluminum and powdered iron oxide. When combined with other substances, such as binders, the material is termed a thermate. All such materials react vigorously when heated to the combustion temperature of aluminum. This reaction produces aluminum oxide, elemental iron, and sufficient heat to melt the iron. The reaction temperature is at least 2200°C. Due to its high temperature and creation of iron, the thermite is used industrially for welding such as welding together railroad track and other in place structural repairs. Thermite is also used to purify other metals through its high temperature.

The military uses thermite in grenades (US AN-M14) for the destruction of vehicles and equipment where their high heat renders vehicles and equipment inoperable. Possible thermite burns could be seen from a railroad employee opening the thermite crucible before the reaction had completed and being exposed to the still burning material or a military individual being exposed to the burning particles from the use or demonstration of one of these grenades.

Because the burning temperature of these chemicals is so high, standard hazardous-materials clothing (even level A self-contained and chemical-proof clothing) is not protective.[4]

For patient education information, see Chemical Warfare and Personal Protective Equipment.

Pathophysiology

Burning thermite or magnesium produces predominantly thermal injury that may be considered identical to deep partial- or full-thickness thermal burns (see Emergent Management of Thermal Burns). Thermite incendiaries may produce multiple small deep burns that contain scattered molten iron. These particles should be cooled immediately with water and removed. This may be possible with local anesthesia. Residual particles (especially of magnesium) may also produce chemical injury to the eyes, skin, and respiratory tract.

If exposure to incendiary metals takes place in a small, confined space such as in a military vehicle attacked by a thermite grenade, inhalation of hot gases can produce direct thermal injury to respiratory tissues. The magnesium particles can react with tissue fluid to create magnesium hydroxide, which is a strong base. This strong base can lead to alkali burns from the noncombusted magnesium particles. In a separate reaction, while the magnesium is burning, it can react with water to create hydrogen gas (H2), which is highly flammable. This is why water is not a recommended dousing agent for these magnesium burns.

Etiology

While exposure to incendiary metals can occur in many settings, serious burns are most likely to result from industrial or military incidents. Lung injury would most likely occur if a person were trapped in a confined space with one of these burning substances.[5]

Common sources of incendiary metal burns include the following:

  • Sparklers

  • Road/maritime flares

  • Campfire starters

Industrial sources of incendiary metal burns include the following:

See the list below:

  • Welding

  • Metal purification

Military sources of incendiary metal burns include the following:

  • Thermite grenades

  • Flares

  • Tracer rounds

In addition, terrorist explosives are a potential source of such injuries.

Epidemiology

No exhaustive study or series of incendiary injury exists. In a study of one burn center during a 51-year period, only one burn was attributed to magnesium and no burns were reported due to thermite. This seemingly low incidence likely stems from the fact that all thermal burns are managed similarly regardless of cause and often unique historical elements go unnoticed or unrecorded.

Incendiary burns show no predilection for race. Because incendiary metals are more commonly encountered in industrial and military settings, exposures are more common in males than in females. Because incendiary metals are more commonly encountered in industrial and military settings, exposures are more common in younger adults.

Prognosis

Prognosis depends on the extent of the burn injury, the underlying medical history of the victim, and the extent of care available. Outcomes and complications of incendiary metal burns are similar to other thermal injuries (see Emergent Management of Thermal Burns). 

 

Presentation

History

The history usually makes the nature of the exposure evident, as the patient or rescuer describes the circumstances leading to exposure to thermite or magnesium incendiaries. In the event that a patient presents with burn injury and is unable to give a history, consider exposure to magnesium, thermite, or other hazardous materials.

Determine if the injury occurred in a closed space. Gather information on other aspects of the incident.

Obtain the patient's relevant medical history. In decision-making, consider diseases (eg, diabetes mellitus, vascular disease) that may affect healing. Determine last meal and known drug allergies.

Physical Examination

Incendiary agents produce predominantly dermatologic and respiratory effects.

As with all resuscitations, first priority is to maintain and support airway, breathing, and circulation (ABC). Patients with airway burns or significant fume exposure may require endotracheal intubation and ventilatory support. Acute respiratory distress syndrome (ARDS) may develop.[6, 7]

Patients with significant dermal burns require aggressive fluid resuscitation, following a formula, such as the Parkland burn resuscitation guidelines, and require monitoring of urinary output and other vital signs.[6, 7]

Inhalation of magnesium dust or magnesium oxide smoke can produce respiratory irritation with the following potential signs and symptoms:

  • Nasal catarrh

  • Productive cough

  • Pneumonitis, including metal fume fever[8]

  • ARDS

  • Hypoxia and tachypnea

  • Airway burns (eg, edema, charring) or lung burns, with potential airway obstruction

  • Wheezes or crackles on lung examination

Unique features of incendiary metal burns are as follows:

  • Thermite burns can deposit molten iron in tissue resulting in very extensive localized tissue damage. Clinicians should assume that these burns are deep partial- or full-thickness until proven otherwise.

  • Magnesium particles can react with tissue fluid to produce magnesium dihydroxide, which produces an alkali chemical burn in addition to direct thermal effects.

  • Retained magnesium particles in skin may produce a lesion that mimics gas gangrene, with tissue necrosis and intratissue gas bubbles due to hydrogen gas formed from the same reaction.

Ocular examination

Incendiary metals emit intensely bright light in the infra-red, visible, and ultraviolet spectra. Tactical military uses include temporarily night blinding of adversaries. The intense light emitted by incendiary metals in military and industrial settings can cause ultraviolet (UV) keratitis. Staining with fluorescein and examination with a slit lamp will confirm such injuries. The fluorescein staining may reveal diffuse punctuate corneal lesions. These lesions generally have a discrete lower border where the lower lid protected the rest of the cornea. Patients may complain of photophobia, decreased visual acuity, and a foreign body sensation.[9]

The eyes must also be examined to determine whether any significant amount of magnesium dust was deposited on the corneas. This can also be seen with a slit lamp and will determine if any cleaning of the corneas or urgent ophthalmological referral is indicated.[9]

 

DDx

 

Workup

Laboratory Studies

Obtain laboratory studies as needed to manage thermal burns and associated lung injury. No specific studies are required for thermite or ignited magnesium exposure.

Imaging Studies

Perform chest radiography on patients with possible pulmonary involvement. Plain radiographs are indicated to evaluate for fractures and to evaluate for metallic wound contaminants.

Procedures

Bronchoscopy or laryngoscopy can be performed for possible airway injury. Slit lamp examination of the eyes for metallic particles, keratitis, burns, or other injuries can be performed.

 

 

Treatment

Prehospital Care

Remove patients from the burning environment, with appropriate attention to personal safety.

Flush thermite burns with copious amounts of water and brush or debride them to remove contaminating particles.

Initial care for magnesium burn wounds should include removal of all unburned particles by mechanical means, including wound debridement, if needed. If particles are present, do not flush with water until particles have been removed. If water irrigation is needed for burn treatment or other decontamination, use copious amounts to rapidly flush away residual magnesium before the resulting chemical reaction can cause harm. To stop burning particles that cannot be easily removed, the area can be submersed or coated in mineral oil to stop the oxidizing reaction.[10]

Treat burns with standard thermal burn treatment techniques. Undertake standard support of the ABCs, including intubation and fluid resuscitation if needed.[6, 7, 11]  Cover burned areas with dry, sterile dressings or burn-specific dressings. Avoid large areas of wet dressings due to the risk of hypothermia. Narcotic analgesia may be useful if the patient's hemodynamic status permits.

Emergency Department Care

Emergency department care comprises the following:

  • Institute airway support[12]

  • Start fluid resuscitation, guided by formulas for similar thermal burns[6, 7]

  • Perform wound debridement to remove residual particles of magnesium or iron if not already performed in prehospital setting

  • Aggressively seek and treat associated traumatic injuries (eg, from blast)

  • Assess and start initial treatment of any ocular injuries[9, 13]

  • Institute analgesia

  • Consider all incendiary burns tetanus prone and administer appropriate tetanus prophylaxis

Transfer patients with thermal burns to a burn center if they meet any of the following burn center criteria[11] :

  • Partial-thickness burns over 20% or more of body surface area

  • Full-thickness burns over 10% or more of body surface area

  • Burns involving hands, feet, eyes, ears, and/or perineum

  • Airway involvement

  • Significant underlying illness

  • Age younger than 1 year or older than 65 years

Inpatient care is identical to care for other thermal burns, and it usually involves topical antibiotics (eg, silver sulfadiazine) and surgical debridement. Skin grafting may be needed; institute life-support measures as necessary.

Consultations

A burn surgeon or other appropriate surgeon (eg, plastic, trauma) should be involved in care. Consult an ophthalmologist if eye injury has occurred. Continuing critical care expertise may be required if injury severity is high.

Prevention

Workplace and military instruction in the dangers and correct handling of incendiary metals are the mainstay of prevention for accidental exposure and injury. Similarly, public awareness campaigns targeting firework safety in particular can reduce accidental injury and exposure.

Long-Term Monitoring

Outpatient care is identical to care for other thermal burns. A physician experienced in burn management usually should provide follow-up care for patients. Treatment may include dressings, topical antibiotics, analgesia, and grafting.

Outpatient care for UV keratitis is cycloplegic drops to reduce ciliary muscle spasm and to reduce pain. Topical antibiotics, drops or ointments should be prescribed, to decrease the chance of secondary infection. Patients should also have close follow-up with an ophthalmologist within 24 hours.

 

Medication

Medication Summary

Major drugs of use are fluids for resuscitation, oxygen for respiratory support, tetanus prophylaxis, and analgesia. Follow standard therapeutic protocols for thermal burn injury. Antibiotic therapy, including topical agents (eg, silver sulfadiazine) and intravenous or oral agents, may be needed. Therapy for UV keratitis includes ophthalmological antibiotics and oral or intravenous pain medication.[10]

Gases

Class Summary

Oxygen is used to support respiration and metabolism.

Oxygen

Used to support respiration and metabolism.

Electrolytes

Class Summary

These agents are used to maintain hydration and salt balance.

Lactated Ringer with normal saline

Usually crystalloids such as normal saline or Ringer lactate; little indication for colloid use in acute burn management.

Topical burn treatment

Class Summary

This agent provides topical burn-healing and antimicrobial properties.

Silver sulfadiazine (Silvadene)

Contains both a sulfa antibiotic and a silver ion, which is an antibacterial; speeds burn healing and eases debridement.

Topical antibiotics

Class Summary

This agent is antibacterial and aids in burn healing.

Bacitracin topical (Baciguent)

Mild topical antibiotic, usually in an ointment base, for use on facial burns not deep enough to require grafting.

Immunizing agents

Class Summary

These agents are used to immunize patients against tetanus.

Tetanus toxoid adsorbed or fluid

Used to induce active immunity.

Immunizing agents of choice for most adults and children >7 y are tetanus and diphtheria toxoids. Necessary to administer booster doses to maintain tetanus immunity throughout life.

Pregnant patients should receive only tetanus toxoid, not a diphtheria antigen-containing product.

In children and adults, may administer into deltoid or midlateral thigh muscles. In infants, preferred site of administration is the mid thigh laterally.

Tetanus immune globulin (TIG)

Used for passive immunization of any person with a wound that may be contaminated with tetanus spores.

Analgesic nonsteroidal anti-inflammatory drug

Class Summary

These agents are used to decrease inflammation and for basic pain control.

Ibuprofen (Advil, Excedrin IB, Ibuprin, Motrin)

Usually the DOC for mild to moderate pain, if no contraindications exist; inhibits inflammatory reactions and pain, probably by decreasing cyclooxygenase activity, which results in the inhibition of prostaglandin synthesis.

Naproxen (Aleve, Anaprox, Naprelan, Naprosyn)

Used for relief of mild to moderate pain. Inhibits inflammatory reactions and pain by decreasing activity of enzyme cyclooxygenase, which results in prostaglandin synthesis.

Analgesic, narcotic

Class Summary

This agent is used for severe pain from burns or UV keratitis.

Acetaminophen and codeine (Tylenol #2, Tylenol #3, Tylenol #4)

Combines analgesic effects of a centrally acting opium-derived alkaloid (codeine) and a peripherally acting nonopioid analgesic (acetaminophen). Indicated for treatment of mild to moderate pain.

Antibiotic, Ophthalmic

Erythromycin ophthalmic (E-Mycin)

Inhibits bacterial growth, possibly by blocking dissociation of peptidyl tRNA from ribosomes, causing RNA-dependent protein synthesis to arrest.

Indicated for infections caused by susceptible strains of microorganisms and for prevention of corneal and conjunctival infections.

Moxifloxacin ophthalmic (Vigamox)

Indicated to treat bacterial conjunctivitis. Elicits antimicrobial effects. Inhibits topoisomerase II (DNA gyrase) and IV enzymes. DNA gyrase is essential in bacterial DNA replication, transcription, and repair. Topoisomerase IV plays a key role in chromosomal DNA portioning during bacterial cell division.