CASE STUDIES IN TOXICOLOGY When the Poisoned Risk Poisoning Others: Fatal Sodium Azide Overdose Marcin M. Ciesla; Diane P. Calello, MD; Lewis S. Nelson, MD A 24-year-old man arrived at the ED in cardiac arrest after intentionally ingesting sodium azide. Case What is sodium azide? A 24-year-old man in cardiac arrest was Sodium azide is a colorless, odorless crys- brought to the ED via emergency medical talline water-soluble solid that has a pK of services (EMS). Unfortunately, resuscita- 4.8.1 When sodium azide is dissolved in tion efforts were unsuccessful. Little was an acid, it liberates hydrazoic acid (HN3), known about the patient, but the emergen- which has a pungent odor, high vapor cy physician was informed that the patient pressure (484 mm Hg), and a relatively 2 had ingested sodium azide (NaN3), which low-boiling point of 37°C (98°F). he had ordered online. The patient col- The most common industrial use of so- lapsed shortly after ingesting the sodium dium azide is as a propellant in air bags. azide, approximately the same time police In this capacity, sodium azide rapidly de- officers arrived at the patient’s home. composes to nitrogen gas when it reaches a No specific details were known about the temperature of 300°C (572°F), causing rap- patient’s ingestion. Upon learning of the id expansion of the air bag. In addition to exposure to sodium azide, a member of the air bags, sodium azide is used in research ED staff contacted the local poison control laboratories as a preservative and in agri- center for information on the proper course culture as a pesticide. The main nontoxi- of action to ensure staff safety and limit ex- cological concern with all azide agents is posure. Shortly thereafter, several of emer- the potential for explosion when they react gency medical technicians and police offi- with metals, such as lead, copper, silver, cers, who had responded to the emergency and mercury, to form metal azides that are assistance call for this patient, presented to sensitive to shock.3 An example of the ex- the ED with concerns of exposure. plosive nature of these azides was demon- Mr Ciesla is a medical student, Rutgers New Jersey Medical School, Newark. Dr Calello is an associate professor of emergency medicine; and executive and medical director, New Jersey Poison Information and Education System, Rutgers New Jersey Medical School, Newark. Dr Nelson, editor of “Case Studies in Toxicology,” is professor and chair of the department of emergency medicine, Rutgers New Jersey Medical School; and a medical toxicologist, New Jersey Poison Information & Education System, both in Newark. He is also associate editor, toxicology, of the EMERGENCY MEDICINE editorial board. Authors’ Disclosure Statement: The authors report no actual or potential conflict of interest in relation to this article. DOI: 10.12788/emed.2018.0093 132 EMERGENCY MEDICINE I JUNE 2018 www.emed-journal.com CASE STUDIES IN TOXICOLOGY strated in a report wherein diluted sodium dote treatments are generally ineffective azide was poured down a drain, causing an in reducing azide-related death in animal explosion as a worker was fixing the pipe.4 models.3,8 Early aggressive supportive care In addition to industrial and commercial can improve survival rates.9 Some authors use, sodium azide is occasionally used in suggest that administration of oral acti- suicide attempts because it is rapidly fatal, vated charcoal, orogastric lavage, hemodi- has no specific antidote, and can be pur- alysis, and plasma exchange reduce azide chased online.3 concentrations, while others believe these treatments have little effect.3,9 More re- What is the toxicity of sodium azide? search is needed to identify effective thera- The lethal dose for both oral and dermal ex- peutic measures and to control for dose, posure to sodium azide is approximately 10 time, and patient population. to 20 mg/kg.3,5 Therefore, ingestion of 700 mg of sodium azide, a volume approximate- What are the safety concerns for emergency ly the size of a penny, is likely to be fatal.3 medical technicians and hospital staff Sodium azide is primarily a mitochondri- following exposure to sodium azide? al toxin, which binds the electron transport The most probable routes of exposure for chain, inhibiting oxidative phosphoryla- prehospital and hospital staff include der- tion. The resulting reduction in adenosine mal contact with sodium azide or inhala- triphosphate (ATP) production, even in the tion of gaseous hydrazoic acid; inhalation- presence of oxygen, results in metabolic al exposure is most concerning.1 In one failure.6 This mechanism of action is similar case, hospital-staff members developed to that of cyanide, although sodium azide headaches, light-headedness, and nausea causes more pronounced vasodilation due while treating a patient for azide poison- to the in vivo conversion of some azide to ing; however, staff exposure was not con- the vasodilator nitric oxide.7 Some reports firmed and no sequelae were evident.10 suggest that azide lethality is due to en- More objectively, workers at an azide hanced excitatory transmission from nitric plant exposed to azide concentrations oxide in the central nervous system.8 above the occupational exposure limit de- veloped headaches, hypotension, and pal- What are the clinical manifestations of azide pitations.11 Another study found no evi- poisoning, and what is the treatment? dence of kidney, heart, or liver damage after The early clinical findings of a patient patients were given sodium azide for more with azide poisoning include hypoten- than a year during a clinical trial.12 Not un- sion, dizziness, headache, nausea, vomit- expectedly, there is little risk of exposure ing, palpitations, tachycardia, dyspnea, and when proper safety precautions are taken. restlessness. Inhalation of hydrazoic acid Emergency response personnel should can also produce wheezing and coughing. carefully inspect the scene for the presence The most common effect is hypotension, of any sodium azide powder, and should also which can occur within 1 minute of expo- question bystanders and family members to sure. Following depletion of cellular ATP, determine if anyone performed mouth-to- anaerobic glycolysis generates lactate and mouth resuscitation on the patient. Standard produces acidemia. More severe findings universal precautions, along with attentive- of azide poisoning include seizures, cardiac ness to one’s surroundings, should be suf- arrhythmia, loss of consciousness, pulmo- ficient to prevent dermal exposure. If small nary edema, and cardiopulmonary failure.3 amounts of sodium azide residue are found Currently, there is no specific antidote on the patient, his or her clothes should be for azide poisoning, and treatment mainly cautiously removed and placed in a plastic consists of supportive care. Cyanide anti- bag to prevent dispersion of particles. If large www.emed-journal.com JUNE 2018 I EMERGENCY MEDICINE 133 CASE STUDIES IN TOXICOLOGY quantities of sodium azide are present on a urine, and vitreous humor out for analysis, patient, the hazardous materials response but did not conduct a full postmortem ex- team should be called, in accordance with amination. Notably, the stomach was not institutional and regional protocols. To opened, and its contents were not exposed. avoid explosion, every attempt should be made to prevent azide salt (eg, from emesis) References 1. Compound summary for CID 33557 (sodium azide). from contact with any metal surfaces (eg, National Center for Biotechnology Information. Pub- oxygen tanks, metal stretcher).13 Chem Compound Database. https://pubchem.ncbi. Vomit from patients who have ingested nlm.nih.gov/compound/sodium_azide. Accessed May 10, 2018. sodium azide can cause liberation of hy- 2. Compound summary for CID 24530 (hydrogen drazoic acid, which can escape through the azide). National Center for Biotechnology Informa- tion. PubChem Compound Database. https://pub- esophagus. A pungent ambient odor may chem.ncbi.nlm.nih.gov/compound/hydrazoic_acid. provide a warning, which is particularly Accessed May 10, 2018. 3. Chang S, Lamm SH. Human health effects of concerning in a confined space such as an sodium azide exposure: a literature review ambulance. As a precaution, EMS personnel and analysis. Int J Toxicol. 2003;22(3):175-186. doi:10.1080/10915810305109. should open windows and maximize venti- 4. Sodium azide explosion hazard. Washington State lation. After the call, EMS and hospital per- Department of Labor & Industries. Division of Occu- pational Safety and Health. https://www.lni.wa.gov/ sonnel should thoroughly wash their hands safety/hazardalerts/SodiumAzide.pdf. August 11, with soap and water, and change their uni- 2011. Accessed May 10, 2018. 5. Safety data sheet: sodium azide. ThermoFischer form if they believe it has been contami- Scientific. https://www.fishersci.com/store/msds?par nated. There is no risk of delayed exposure tNumber=S227I1&productDescription=SODIUM+AZ IDE+GRAN+PURIF+1+KG&vendorId=VN00033897& following exposure to hydrazoic acid. countryCode=US&language=en. Updated January 17, During autopsy, medical examiners 2018. Accessed May 10, 2018. 6. Bogucka K, Wojtczak L. Effect of sodium azide must exercise caution due to the potential on oxidation and phosphorylation processes for liberation of hydrazoic acids from the in rat-liver mitochondria. Biochim Biophys Acta. 1966;122(3):381-392. doi:10.1016/0926- 14 stomach. Unless it is absolutely necessary, 6593(66)90031-2. the medical examiner should avoid open- 7. Kruszyna H, Kruszyna R, Smith RP, Wilcox DE. Red blood cells generate nitric oxide from directly ing the stomach. If this is unavoidable, the acting, nitrogenous vasodilators. Toxicol Appl autopsy should occur in a well-ventilated Pharmacol. 1987;91(3):429-438. doi:10.1016/0041- 008x(87)90064-0. setting with the examiner wearing a sup- 8. Smith RP, Louis CA, Kruszyna R, Kruszyna H. Acute plied air respirator to limit exposure in a neurotoxicity of sodium azide and nitric oxide.