|
Chemical Warfare
Toxins derived from from genera of fungi being proposed as
mycoherbicides against drug crops.
This
page is under construction
Trichothecene
mycotoxins
We include here some references to
chemicals extracted from Fusarium species which have had a history
of proposed or alleged use as chemical warfare toxins. We present
this evidence here to
illustrate the inextricable link between Fusaria mycotoxins and a series of
known chemical warfare agents.
The chemicals extracted from Fusaria
for proposed chemical warfare investigation or use all belong to the
trichothecene group, the most notorious being "Mycotoxin
Trichothecene 2", "T-2 Toxin", or "Fusariotoxin":
Other compounds in this series share similar
characteristics, as can be seen with the examples of Nivalenol and
Vomitoxin below.
The Trichothecenes are easily
chemically distinguished from the other major group of Fusarium toxins,
the Fumonisins,
in that they do not posses an amine function (there
is no nitrogen in these compounds), and the trichothecenes are generally less soluble in
water and therefore would tend to contaminate the area in which they were
produced for a longer period than the Fumonisins and other more polar
Fusaria compounds. For a discussion of potential effect of all of these
Fusaria toxins on
soil, please go to our soil
page.
The reason that these Fusaria
compounds were considered for use as chemical warfare agents is because of
the effects they have on living cells (human, plant, and other
organisms). A simple glance at the Merck Index's description
of Fusariotoxin
(Mycotoxin T-2) shows that it kills 50% of experimental animals
(female rats, in this case) at a dose of 4 mg/kg, and "Caution: May be
highly irritating to skin and mucous nembranes. Direct contact may cause
extensive inflammation and tissue necrosis (Marasas). Topical exposure has
lead to systemic toxicity and death in experimental animals (Scheiffer,
Hancock)." Indeed, during the early 1980's there was concern
that these compounds were used in chemical warfare by Russian troops under
the name "Yellow Rain", a claim that has been highly contested
by experts. The debate rages on after twenty years and indeed
deserves more than a cursory review. See William
Kucewicz, The Wall Street Journal. See
also: www.about.com
review See below:
Yellow Rain or no yellow rain,
Fusarium mycotoxins have been heavily studied by several governments,
including the US. A recent FOIA to XX produced several thousands
hits for papers. UNDER CONSTRUCTION.
Of special
interest is the surveillance of Iraq by the U.N.
and the U.S. for its reported mycotoxin extraction program, and at the
same time the U.N.'s push to use such toxins in the form of mycoherbicides
against drug-crop-producing countries such as Colombia and Afghanistan.
Fusarium:
Trichethene
mycotoxins (from "http://www.about.com"):
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.
 |
 |
Nivalenol
|
Deoxynivalenol
(Vomitoxin)
|
 |
 |
Diacetoxyscirpenol
|
T2 toxin
|
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.
|
|
|
