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Illegally imported foreign products can result in domestic exposures
to unusual toxic chemicals, and health-care providers might not be able to
provide appropriate therapy because the chemical ingredients might not be
listed or recognized even after translation of the product label. This report
describes the first known case in the United States of exposure to a Chinese
rodenticide containing the toxin tetramethylenedisulfotetramine (TETS), a
convulsant poison. The report of this investigation highlights the need to
prevent such poisonings through increased public education, awareness, and
enforcement of laws banning the importation of illegal toxic chemicals.
On May 15, 2002, a previously healthy female infant aged 15 months living
with her family in New York City was found by her parents to be playing with
a white rodenticide powder that they had brought from China and applied in
the corner of their kitchen. After 15 minutes, the child had generalized seizures
and was taken to an emergency department. Her initial blood glucose level
was 108 mg/dL (normal range: 80-120 mg/dL). Despite aggressive therapy with
lorazepam, phenobarbital, and pyridoxine, she had intermittent generalized
seizure activity for 4 hours and required intubation.
After 3 days, the infant was extubated successfully but appeared to
have multiple neurologic deficits, including absence seizures and possibly
cortical blindness. Continuous electroencephalogram monitoring, performed
during the initial hospitalization, revealed multiple epileptogenic foci.
The infant was discharged in June; as of November 5, the infant remained severely
developmentally delayed and was on valproic acid therapy for seizure control.
Translation of the rodenticide package labeling from Chinese to English
did not clarify its contents. A search of the China National Poison Control
Center's (NPCC) web-site for rodenticides suggested that the ingredients might
have included sodium monofluoroacetate, fluoroacetamide, tetramethylenedinitrosotetramine,
or strychnine. However, an initial laboratory analysis was negative for sodium
fluoroacetate, fluoroacetamide, bromethalin, strychnine, 1,3-difluoro, 2-propanol,
and carbamate insecticides.
On September 14, a snack shop owner in China poisoned food in a competitor's
snack shop with a rodenticide identified as Dushuqiang, resulting in 38 deaths.
Although Dushuqiang, which contains TETS, has been banned for sale since the
mid-1980s, it is still widely available in China. Following news reports of
this incident, the New York City Poison Control Center conducted additional
laboratory testing of the product associated with the poisoning in New York
City and confirmed TETS in the product by gas chromatography-mass spectrometry
(GC-MS).1 TETS concentration was 6.4% weight/weight [w/w] in one
rodenticide packet and 13.8% w/w in another.
F Barrueto Jr, MD, LS Nelson, MD, RS Hoffman, MD, New York City Poison
Control Center; MB Heller, PhD, Public Health Laboratory, General Toxicology
and Environmental Science Laboratory, New York City Dept of Health and Mental
Hygiene; PM Furdyna, New York State Div of Environmental Conservation; RJ
Hoffman, MD, Div of Toxicology, Maimonides Medical Center, New York, New York.
KS Whitlow, DO, MG Belson, MD, AK Henderson, PhD, Div of Environmental Hazards
and Health Effects, National Center for Environmental Health, CDC.
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 g-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 TETS1,3 (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.
This report is based on data provided by N Besbelli, MD, World Health
Organization, Geneva, Switzerland. J Blondell, PhD, U.S. Environmental Protection
Agency, Washington, DC. A Buchwald, MD, D McNutt, MD, County of Santa Cruz
Health Svcs Agency, Santa Cruz, California. M Mostin, MD, Centre Antipoisons-Antigifcentrum,
Brussels, Belgium. D Rise, U.S. Environmental Protection Agency, Helena, Montana.
D Sudakin, MD, National Pesticide Medical Monitoring Program, Oregon State
Univ, Corvallis, Oregon. W Temple, MD, National Poisons Centre, New Zealand.
R Imtiaz, MD, Div of International Health, Epidemiology Program Office, CDC.
References: 7 available
Poisoning by an Illegally Imported Chinese Rodenticide Containing Tetramethylenedisulfotetramine—New York City, 2002. JAMA. 2003;289(20):2640–2642. doi:10.1001/jama.289.20.2640