Napalm Toxicity

Article Author:
Gregory Guldner
Article Editor:
Curtis Knight
Updated:
3/23/2019 1:35:59 AM
PubMed Link:
Napalm Toxicity

Introduction

Napalm is a weaponized mixture of chemicals designed to create a highly flammable and gelatinous liquid.  The initial thickening agent was a combination of naphthenic and palmitic acids leading to the trade name “na-palm” but more generically known as firebomb fuel-gel mixture. Many variations of the chemicals used in napalm exist.  The most common current composition includes aluminum salts, polystyrene, and benzene. Detonation then occurs by various explosive compounds that ignite phosphorous which burns at a temperature adequate to ignite the fuel mixture.

The consistency of napalm results in its tendency to adhere to exposed surfaces, increasing its lethality and destructive capability.  Additionally, the increased viscosity allows the ignited liquid to maintain a directable stream when dispersed under pressure allowing for its use in military flamethrowers.

The toxicity of napalm comes from multiple etiologies.  Burns are the most obvious harm, but the delivery of napalm may come from explosive delivery devices leading to blast-burn injuries. Burning napalm rapidly de-oxygenates the surrounding environment causing asphyxiation. Byproducts of flaming napalm include high levels of carbon monoxide and carbon dioxide that can lead to toxicity.  Some types of napalm use polystyrene chemicals that convert to styrene which is a neurotoxin and likely carcinogen.

Etiology

Napalm toxicity occurs almost exclusively as a result of military action. Military uses include dropping napalm containing bombs from aircraft, napalm use in flamethrowers (handheld or vehicle-borne), and napalm use in ground explosive devices.  

Non-military related exposure may arise from improvised hand-held fire bombs or "Molotov cocktails." Home-made firebombs may employ fuel thickening agents to create a weapon with an effect similar to military grade napalm. Individuals or groups utilizing these weapons may not necessarily have affiliations with a uniformed military. 

Epidemiology

Chemists developed napalm in 1942, and its first documented military use was in 1944.  Allied bombers used napalm in incendiary bombs throughout the European and Pacific theaters during World War II. Handheld or vehicle-borne flamethrowers deployed napalm primarily against dug-in positions given its ability to kill or displace defenders where other weapon systems would fail.  Militaries have deployed napalm in multiple other conflicts including the Korean War and Vietnam War and numerous smaller engagements. Civilian exposures to napalm are rare outside of military conflicts.  Although the United Nations banned the use of napalm on civilian targets in 1980, numerous reports suggest its use in several modern conflicts. Homemade mixtures approximating napalm have exploded during manufacture or improvised use causing injuries outside of armed conflicts.

Pathophysiology

Napalm burns at the same temperature as the flammable liquid used in its composition, typically gasoline, kerosene, diesel fuel, or benzene.  Direct contact with flaming napalm results in full-thickness burns. Large surface area contact results in rapid loss of blood pressure, loss of consciousness, and death.[1]  Napalm also can produce localized areas of high carbon dioxide concentration due to incomplete combustion. Carbon dioxide levels of 0.4% can cause death in approximately one hour while burning napalm creates concentrations near 20%.[2]  Contained areas near burning napalm can rapidly de-oxygenate resulting in loss of consciousness and death in minutes due to asphyxiation. Surface exposure to non-ignited napalm may cause mild skin irritation similar to gasoline exposure. No reports exist of ingestion of napalm, but treatment would be as ingestion of the individual components such as benzene and polystyrene.

Toxicokinetics

Ignited napalm burns for a duration determined by the underlying material fueling the combustion, but frequently burns for several hours.  The hypoxia caused by burst ignition resolves relatively rapidly (seconds to minutes) in open areas but can take much longer in closed environments.  High carbon dioxide levels may remain for hours in enclosed environments especially given that its density causes it to settle into the lowest levels of terrain where cross currents may not disperse the gas for some time. Carbon monoxide is roughly equivalent to the density of ambient air and will disperse at a rate dependent on the degree of cross current ventilation.

History and Physical

Militarized use of napalm typically results in a clear exposure history either by the victims themselves or by general situational awareness.  Homemade napalm combustion might not be obvious.

The physical exam of survivors of ignited napalm exposure will vary depending on the exposure type. Direct contact exposure will cause full-thickness burns, occasionally with ongoing active combustion if first responders arrive rapidly.  The intense heat from a napalm blast may burn off all clothing. Those with second-degree burns will have severe pain while some with third-degree burns will appear potentially pain-free.  Napalm dropped by aircraft, as opposed to flamethrower deployed, will include a blast component which may cause typical blast injuries. A thorough physical exam may find blunt and penetrating injuries due to blast effect that may cause life-threatening internal or external hemorrhage, cardiac tamponade, tension pneumothorax, or open pneumothorax requiring immediate treatment. The impressive nature of the burns may distract clinicians from traumatic injuries requiring more immediate interventions and clinicians should use a structured trauma approach to blast-burn injuries.  

Initial assessment of the airway consists of evaluation for mucosal burn injuries such as charred facial and nasal hair and soot or fire debris in the oropharynx or nasopharynx.  Careful repeated assessment of the appearance of the uvula, tongue, lips, and palate for signs of edema that portends impending airway compromise is vital.

Some patients not exposed to direct contact of flaming napalm may present with altered mental status from blast effect induced head trauma or from hypoxia, carbon monoxide, or carbon dioxide toxicity.

Evaluation

Initial evaluation of napalm exposed patients includes immediate efforts to stop any ongoing burning generally by smothering or chemical fire extinguisher.  In patients exposed to napalm via a blast dispersal, typical trauma evaluation should be undertaken looking systematically for blunt and penetrating injury requiring immediate treatment.  Except for minor exposures clinicians should consider intubation and early airway control to prevent late recognition of airway edema resulting in a difficult or failed intubation.  Many more severely injured patients will require high doses of opioids to control pain which may impair their respiratory drive when already under physiologic distress. Patients not intubated early must be re-evaluated at short intervals to determine the status of the airway.  Drooling, change in voice, swelling of the uvula, palate, tongue or lips are signs of worsening airway and should prompt consideration of intubation before the development of an airway crisis.

After decontamination and airway control clinicians should assess breathing and oxygenation; impaired ventilation and oxygenation may result from head injury, carbon dioxide exposure, carbon monoxide exposure, exposure to other toxins burning in the environment, or restricted chest movement due to burns.  Blast victims could have pneumothoraces or sucking chest wounds requiring decompression and chest seals. Rapid evaluation by auscultation, visualization of chest rise, oxygen saturation, and evaluation of respiratory rate may prompt interventions unrelated to burns. Torso burns may require early chest escharotomy to allow ventilation.  

A circulatory evaluation includes measurement of blood pressure, peripheral pulses, and assessment of shock.  Hypotensive patients may have internal injuries from blast effect and clinicians should evaluate for the need for surgical intervention. Clinicians must evaluate for external bleeding, cardiac tamponade, tension pneumothorax, hemothorax, intraabdominal and retroperitoneal bleeding apart from the visible external burns.  Inhalation of cyanide from nearby combustibles may cause shock and highly elevated serum lactate.

Once initial stabilization of the airway, breathing, and circulation is complete additional evaluation depends on the clinical situation.  Some patients will require extensive trauma evaluation including CT scanning of the brain, cervical spine, chest, abdomen, and pelvis for internal injuries.  Altered patients may require an arterial blood gas and co-oximetry for carbon monoxide. In more severely ill patients highly elevated serum lactate may suggest cyanide inhalation.

Determination of the total body surface area (BSA) burned aids in the determination of fluid resuscitation and the necessity for transfer to a burn center.

Treatment / Management

Treat victims of blast-burn napalm using a standard trauma evaluation paying careful attention not to over-focus on burns before the management of other life-threatening injuries.  Frequently early airway control and mechanical ventilation are required. Unstable patients may require chest thoracostomy, chest wound seals, escharotomy, blood transfusion, and prompt exploratory laparotomy or thoracotomy.  Unstable patients with high lactate levels and an enclosed space burn history may benefit from treatments aimed at cyanide toxicity. Carbon monoxide and carbon dioxide exposure treatment is with supplemental oxygen.

Clinicians can achieve pain control with opioids, though the doses required may result in a drop in blood pressure or respiratory drive.  Alternatively, some military and civilian providers may use ketamine in either a low-dose or dissociative dose protocol to achieve initial control of pain.[3]

While fluid resuscitation protocols for burns are well described,[4] resuscitation in burn-blast victims may be complicated by blast injuries causing hemorrhage.  Some hypotensive patients will require blood transfusion in addition to crystalloids. The volume of crystalloids infused for burn patients typically follows an algorithm such as the Parkland formula which predicts fluid requirements over the first 24 hours from the time of the burn.  Four milliliters crystalloid per percent body surface area burned per kilogram of patient weight estimates the total volume for 24 hours with half given in the first 8 hours from the time of the burn and the second half given for the remaining 16 hours.

Clinicians generally should transfer patients with napalm burns to a burn center given the unusual nature of these burns and the tendency for complications such as keloids.

Differential Diagnosis

The diagnosis of napalm burns is typically clear by history.  However, in the rare situation where a history of exposure is unknown patients exposed to napalm effects, but not burned, may present with altered mental status, hypoxia, respiratory collapse, or shock.  The area surrounding the patient’s initial location would show clear signs of combustion. Clinicians should consider carbon monoxide toxicity, carbon dioxide toxicity, cyanide inhalation, and blunt head injury in such patients.  

Prognosis

The prognosis of napalm exposure varies markedly.  Most patients who die from exposure do so immediately by immolation, blast effect, or respiratory failure.  Those with a large surface area burn risk death by infection and multi-organ system failure in hours to days.  Patients with less severe burns will likely survive with treatment from burn centers and burn specialists.

Complications

Napalm burns result in severe skin damage that can cause multiorgan system failure and death.  Severe disfigurement and loss of function are common requiring skin grafting and specialized care. Keloid formation may occur in some individuals.  The psychological effect of exposure to napalm may be severe.

Postoperative and Rehabilitation Care

Many patients exposed to napalm will require rehabilitative care from specialists in burn management including plastic surgeons.[5]  Some will require specialized care from physical and occupational therapists to recover function. Mental health counseling may prove helpful.

Consultations

The initial and ongoing management of napalm injuries may require consultation with trauma surgeons, pulmonologists, burn specialists, plastic surgeons, intensivists, physical medicine and rehabilitation physicians, physical and occupational therapists, psychiatrists and psychologists. Early toxicologist input may be helpful in those more seriously injured or those with altered mental status and concern for carbon monoxide or cyanide exposure.

Deterrence and Patient Education

The United Nations banned napalm usage against civilian targets in 1980, but this has not stopped its use in many conflicts around the world.  Although the use of traditional napalm has generally ceased modern variants are deployed allowing some countries to assert that they do not use “napalm.”  

Online instructions for homemade napalm exist and entice some individuals to attempt to make their own napalm for both routine uses (destroying insect colonies or burning tree stumps) and nefarious purposes; this generally requires heating a flammable substance such as gasoline or kerosene and then slowly mixing in various gelatinizing agents such as soap. When performing this operation over an open flame, the entire mixture may inadvertently ignite and cause extensive burns.  

Enhancing Healthcare Team Outcomes

The care of an injured patient exposed to napalm must follow carefully developed algorithms such as the American College of Surgeons’ Advanced Trauma Life Support approach.[6]  Patient care teams can become easily focused on the extensive burns while missing other traumatic injuries in these patients. Simulations using high fidelity simulation technology with manikins can assist in detecting and mitigating common errors in these complex patients.[7]  Care coordination of these patients requires multiple specialties and disciplines. Systems designed to care for napalm victims can improve performance and decrease error by developing care pathways before the arrival of their first patients.


References

[1] Hu Q,Chai J,Hu S,Fan J,Wang HW,Ma L,Duan HJ,Liu L,Yang H,Li BL,Wang YH, Development of an Animal Model for Burn-Blast Combined Injury and Cardiopulmonary System Changes in the Early Shock Stage. The Indian journal of surgery. 2015 Dec     [PubMed PMID: 27011494]
[2] Guais A,Brand G,Jacquot L,Karrer M,Dukan S,Grévillot G,Molina TJ,Bonte J,Regnier M,Schwartz L, Toxicity of carbon dioxide: a review. Chemical research in toxicology. 2011 Dec 19     [PubMed PMID: 21732636]
[3] Guldner GT,Petinaux B,Clemens P,Foster S,Antoine S, Ketamine for procedural sedation and analgesia by nonanesthesiologists in the field: a review for military health care providers. Military medicine. 2006 Jun     [PubMed PMID: 16808125]
[4] Guilabert P,Usúa G,Martín N,Abarca L,Barret JP,Colomina MJ, Fluid resuscitation management in patients with burns: update. British journal of anaesthesia. 2016 Sep     [PubMed PMID: 27543523]
[5] Waibel JS,Phuc Phan Thi K,Hoenig LJ, Laser Treatment Performed More Than 4 Decades After Napalm Burns: Healing the Scars of the     [PubMed PMID: 30193374]
[6] Navarro S,Montmany S,Rebasa P,Colilles C,Pallisera A, Impact of ATLS training on preventable and potentially preventable deaths. World journal of surgery. 2014 Sep     [PubMed PMID: 24770906]
[7] D'Asta F,Homsi J,Sforzi I,Wilson D,de Luca M,     [PubMed PMID: 30268630]