The case of the poisoned ice tea

June 29, 2012, 1:49 pm

★★★★½

Sodium Azide Poisoning at a Restaurant — Dallas County, Texas, 2010. MMWR June 29, 2012;61:457-460.

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This fascinating report describes clinical details of five cases of sodium azide exposure, as well as the multi-agency investigation into the exposure.

In April 2010, five persons in Dallas County, Texas, presented to hospitals with acute dizziness. Other initial signs and symptoms were vomiting (5 patients), diaphoresis (5), fainting (4), sense of impending doom (3), headache (2), and tachycardia >; 100 bpm (2). Investigation revealed that all patients had consumed iced tea from the same self-serve urn at a local restaurant. All patients recovered.

Samples of tea initially tested negative for nearly 100 chemicals and drugs (except for caffeine). Additional samples were sent to the FBI for further analysis. Five months after the incident, hydrazoic acid — a chemical formed when sodium azide comes into contact with water — was identified.

The article notes that the iced tea urn was accessible to customers and not always visible to employees. It was never determined exactly how the tea became contaminated, and the police investigation has been closed.

Sodium azide is a metabolic inhibitor with a toxic mechanism similar to that of cyanide. It inhibits cytochrome oxidase and interferes with cellular respiration. sodium azide is a profound vasodilator, and can cause hypotension, headache, dyspnea, nausea, vomiting coma, metabolic acidosis, and death. Since there is no well-established antidote, supportive care is the key to clinical management.

To read my 2010 Emergency Medicine News column on sodium azide and “The Case of the Poisoned Coffee Pot”, click here.

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