Sodium azide poisoning at a restaurant - Dallas County, Texas, 2010.

In April 2010, Dallas County Health and Human Services (DCHHS) staff members investigated reports of acute-onset dizziness among patrons in a local restaurant. Symptoms, which included fainting resulting from low blood pressure, occurred within minutes of consuming food from the restaurant and were consistent with chemical poisoning. Toxicologic and epidemiologic investigations were begun to determine the cause of the poisonings and identify potentially exposed persons. This report summarizes the results of those investigations, including a case-control study that identified iced tea as the likely contaminated food or drink (odds ratio [OR] = 65; 95% confidence interval [CI] = 2.4-3,292). Approximately 5 months after the incident, extensive laboratory testing identified sodium azide (NaN3) and hydrazoic acid (formed when sodium azide contacts water) as the toxic agents in the iced tea. All five ill restaurant patrons recovered from their symptoms. For rapid-onset foodborne illnesses, chemical poisons should be considered as a potential cause, regardless of negative initial toxicologic screening tests. Although unusual chemicals can be challenging to detect, a multidisciplinary approach involving public health officials and forensic and medical toxicologists can lead to appropriate testing. In the absence of an identified agent, epidemiologic tools are valuable for active case-finding and confirming suspected contaminated food vehicles.