Poisoning by an Illegally Imported Chinese Rodenticide Containing Tetramethylenedisulfotetramine - New York City, 2002

Morbidity and Mortality Weekly Report. 2003;52(10) 

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Editorial Note

TETS is a little-known, often unrecognized, and highly lethal neurotoxic rodenticide that once was used widely. An odorless, tasteless, and water-soluble white crystalline powder that acts as a -amino butyric acid (GABA) antagonist (China Center for Disease Control and Prevention [CDC], unpublished data, 2002), TETS, like picrotoxin, binds noncompetitively and irreversibly to the GABA receptor on the neuronal cell membrane and blocks chloride channels. The most common routes of exposures are through ingestion and inhalation (China CDC, unpublished data, 2002). TETS is not registered by the U.S. Environmental Protection Agency for use in the United States, and its importation, manufacture, and use in the United States are illegal.

TETS meets criteria for inclusion in the list of extremely hazardous pesticides maintained by the World Health Organization (WHO) and is more lethal than WHO's most toxic registered pesticide, sodium fluoroacetate.[2] Multiple large intentional and unintentional exposures in China have demonstrated the human toxicity of TETS.[1] The dose at which TETS kills 50% of mammals (LD50) is 0.1-0.3 mg/kg; a dose of 7.0-10.0 mg is considered lethal in humans. TETS is potentially 100 times more toxic to humans than potassium cyanide and might be a more powerful human convulsant than strychnine.[3]

The most recognizable clinical signs after a TETS exposure are refractory seizures. Other potentially serious signs include coma and possible electrocardiogram evidence of ischemia (China CDC, unpublished data, 2002). Symptoms typically begin within 30 minutes after exposure and can begin as long as 13 hours after exposure. Severe poisonings are usually fatal within 3 hours (Sun C, China NPCC, personal communication, 2002). TETS intoxication is determined rapidly from history and clinical suspicion. Laboratory identification, although not clinically useful in an acute presentation, is accomplished by several methods, including gas chromatography (GC) with nitrogen-phosphorous detection, GC with flame photometric detection, and GC-MS.[1,4,5] TETS is registered with the Chemical Abstract Service Division of the American Chemical Society as number 80-12-6, molecular weight 240, and chemical formula of C4H8N4O4 S2. Every attempt should be made to identify this chemical if it is suspected.

No proven antidote exists for TETS poisoning. Treatment should follow accepted modalities for a poisoned, altered, or seizing patient.[6] Universal precautions should be taken to prevent secondary exposure of health-care workers. If TETS is suspected, regional poison control centers can provide information and guidance. A small study of rodents conducted in China suggested that intravenous pyridoxine and dimercaptosuccinic acid might be effective treatments.[7] In China, charcoal hemoperfusion and hemodialysis are used to provide extracorporeal removal in patients poisoned with TETS[1,3] (Sun C, China NPCC, personal communication, 2002).

This is the first known case of TETS poisoning in the United States. The chemical's morbidity and lethality and the lack of a known antidote present a danger to human health in areas where TETS might be imported illegally, especially large urban areas with substantial immigrant populations. The appearance of a banned or illegal substance presents challenges to regulatory and enforcement agencies because of the increased risk for unintentional and intentional exposures. Poisoning caused by TETS exposure can be prevented with heightened public health education, increased awareness, and adequate enforcement by customs, border, and regulatory agencies.

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