"Toxin" is often loosely used to refer to any poison but technically refers only to a poisonous chemical produced by an organism (although some toxins can now also be produced synthetically). Because toxins used as mass-casualty weapons Overview of Incidents Involving Mass-Casualty Weapons Mass-casualty weapons are weapons that can produce a mass-casualty incident. Mass-casualty incidents overwhelm available medical resources because they involve so many injured people (casualties)... read more do not include the infectious agents from which they are derived, they are not transmissible from person to person. Thus, toxins are more like chemical agents Overview of Chemical-Warfare Agents Chemical weapons are developed by governments for wartime use and include Toxic agents (intended to cause serious injury or death) Incapacitating agents (intended to cause only temporary, non–life-threatening... read more than biological agents Biological Weapons Biological warfare is the use of microbiological agents as weapons. Such use is contrary to international law and has rarely taken place during formal warfare in modern history, despite the... read more because they cause poisoning rather than infection.
Hundreds of toxins are known. However, it is difficult to make large quantities of most toxins and hard to distribute toxins widely enough to affect many people. Thus, most toxins are more suited to assassination than to creating mass casualties. Only four toxins are considered high-threat agents by the U.S. Centers for Disease Control and Prevention (CDC):
Botulinum toxin
Epsilon toxin from Clostridium perfringens
Ricin toxin
Staphylococcal enterotoxin B
Of these, only botulinum toxin is classified among the highest-priority agents. Epsilon toxin from C. perfringens is mainly of historical interest as an agent reportedly developed by Iraq in the 1980s.
Botulinum Toxin
Botulinum toxin Botulism Botulism is a rare, life-threatening poisoning caused by toxins produced by the anaerobic bacteria Clostridium botulinum. Botulism toxins, usually consumed in food, can weaken or paralyze... read more , or botulinum neurotoxin, refers to any of eight known types of neurotoxins produced by the bacterium Clostridium botulinum. (Only five of these types affect humans.) Food-borne botulism Foodborne botulism Botulism is a rare, life-threatening poisoning caused by toxins produced by the anaerobic bacteria Clostridium botulinum. Botulism toxins, usually consumed in food, can weaken or paralyze... read more , wound botulism Wound botulism Botulism is a rare, life-threatening poisoning caused by toxins produced by the anaerobic bacteria Clostridium botulinum. Botulism toxins, usually consumed in food, can weaken or paralyze... read more , and infant botulism Infant Botulism Infant botulism is a potentially life-threatening infection that causes muscle weakness. It develops in infants who eat food containing spores of Clostridium botulinum bacteria. (See... read more are described elsewhere. Mass casualties from botulinum neurotoxin could occur from widespread contamination of food or water or from inhalation of an aerosol form.
Botulinum neurotoxin blocks one of the types of chemicals that nerve cells use to send signals to other nerve cells and to muscles (neurotransmitters). Because the particular signaling chemical, acetylcholine, does not work properly, people become weak or paralyzed. Typically the paralysis starts at the top of the body about 12 to 36 hours (range 2 hours to 8 days) after exposure to botulinum neurotoxin and extends downward. The toxin does not enter the brain, so thinking is not affected.
Diagnosis is made based on the person's symptoms.
Doctors give an antitoxin by vein. The antitoxin acts only against toxin circulating in the blood and not against toxin already attached to nerve cells. Thus, antitoxin prevents worsening of symptoms and signs but does not help relieve them and becomes progressively less effective as symptoms and signs develop.
Ricin and Abrin
Ricin comes from beans of the castor plant, and abrin comes from jequirity, or rosary pea (see Plant and Shrub Poisoning: Castor and jequirity beans Castor and jequirity beans Only a few commonly grown plants are very poisonous, but many others have less serious toxic effects. Generally, poisoning is unlikely unless a plant is highly toxic or large quantities are... read more ). Although ricin has been injected in assassination attempts, mass casualties would probably involve inhalation of an aerosol form of the toxin.
Symptoms of ricin and abrin poisoning vary by route of exposure. Within 4 to 8 hours of inhalation exposure, people develop cough, respiratory distress, and fever. Many organs are progressively affected over the next 12 to 24 hours, culminating in respiratory failure and often death.
Diagnosis is made based on the person's symptoms.
No specific antidote or antitoxin is available, and treatment focuses on supporting the person's breathing.
Staphylococcal Enterotoxin B
Staphylococcal enterotoxin B is one of seven enterotoxins (toxins acting in the intestine) produced by the bacteria called Staphylococcus aureus. Staphylococcal enterotoxin B Staphylococcal Food Poisoning Staphylococcal food poisoning results from eating food contaminated with toxins produced by certain types of staphylococci, resulting in diarrhea and vomiting. This disorder can be caused by... read more 
is responsible for staphylococcal food poisoning when ingested. Mass casualties could result from deliberate contamination of food but also from inhalation of an aerosol form of the toxin.
Symptoms typically occur 1 to 12 hours after ingestion and 2 to 12 hours (with a range of 1.5 to 24 hours) after inhalation. After initial flu-like symptoms of fever, chills, headache, and muscle aches, subsequent symptoms depend on the route of exposure. Ingestion causes nausea, vomiting, and diarrhea for 1 to 2 days. Inhalation causes cough, chest pain, and often nasal irritation and congestion. Eye inflammation (conjunctivitis) can result from contact of the aerosol with the eyes. Inhalation can rarely cause death. In survivors, fever may persist up to 5 days and cough for 4 weeks.
Special laboratory tests may help doctors confirm the diagnosis.
Doctors aim treatment efforts at relieving the person's symptoms. No specific antidote or antitoxin is available.
The views expressed in this article are those of the author and do not reflect the official policy of the Department of Army, Department of Defense, or the U.S. Government.
