Trichothecenes
Dateline: 04/05/99
Fungi are noteworthy for their prominent roles in cheese-making,
antibiotic production, and infectious disease. Roquefort, cephalosporin,
and ringworm provide examples. They are also quite adept at synthesizing
lethal compounds used in chemical and biological warfare (CBW).
Fungi from the genus Fusarium, growing on barley, corn, oats,
rye, or wheat, produce dozens of derivatives of tetracyclic sesquiterpenes
called trichothecenes. The best known of these are nivalenol,
deoxynivalenol, diacetoxyscirpenol, and T-2 toxin. Bread inadvertently
made from Fusarium-infected wheat killed thousands of Russian
civilians after World War II, focusing attention on the chemistry of the
trichothecenes. Fungi apparently use trichothecenes to enhance their
infective attack on their plant hosts. These fungal virulence factors also
easily lend themselves to military applications.
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Nivalenol
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Deoxynivalenol
(Vomitoxin)
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Diacetoxyscirpenol
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T2
toxin
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Trichothecenes are an attractive warfare agent because they may enter
the body either by way of the skin, by inhalation, or by ingestion. If
used, trichothecenes would be deployed in an aerosol. (Military use of the
trichothecene-containing "yellow rain" in Laos and Kampuchea in the late
1970's has not been substantiated.) Preparation requires no great chemical
wizardry. Fusarium fungi growing on cereal grains perform the
complicated biosynthetic reactions involved in synthesizing the
trichothecenes; the chemist simply isolates these mycotoxins. The adult
LD50 (lethal dose to 50% of exposed individuals) of
trichothecenes is estimated to be only 35 milligrams.
Vomiting and bleeding – an effective means of incapacitating troops and
civilians – result from mild mycotoxicosis. Severe poisoning leads to a
protracted death. There are no antidotes; protective clothing and gas
masks offer the only defense. These heat- and ultraviolet light-stable
compounds, easily made and capable of long-term storage, are therefore
superb candidates for stockpiling. Not surprisingly, United Nations
Special Commission inspectors have established the presence of
trichothecenes (and other CBW agents) in Iraqi facilities.
Recommended Web resources for additional information:
Chronic
Sequelae of Foodborne Disease
Pathogens, their toxins, and their
long-term effects. From James A. Lindsay, University of Florida at
Gainesville.
Mycotoxins
and Mycotoxicoses
Economically important food-contaminating agents
produced by fungi. From Alabama A & M and Auburn Universities.
Reduced
Virulence of Trichothecene-Nonproducing Mutants of Gibberella
zeae in Wheat Field Tests
Role of trichothecenes in wheat head
scab. Abstract provided by the American Phytopathological Society.
Threat
of Deliberate Disease in the 21st Century
Details of chemical and
biological weapon stockpiling. From Graham S. Pearson, University of
Bradford.
Trichothecene
Mycotoxins
Information includes toxicology, symptoms, and first
aid. From Outbreak, an online service that follows emerging diseases.
Trichothecenes
Botanical
toxic products fact sheet from Yuan-Kuo Chen, Cornell University.
Use
of Chemical Weapons: Conducting an Investigation Using Survey
Epidemiology
Yellow rain in Laos and Kampuchea not due to a warfare
chemical. Reprint from the Journal of the American Medical
Association provided by Physicians for Human Rights.
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