injuries poisoning
Toxins as Mass Casualty Weapons
Botulinum Toxin
Botulinum toxin, or botulinum neurotoxin, refers to any of 8 known types of neurotoxins produced byClostridium botulinum, of which 5 affect humans. It is one of the most concentrated poisons, with an LD50 (the dose that would cause death in half of an exposed group) of from 1000 ng/kg orally to as little as 10 ng/kg via inhalation and 1 ng/kg IM or IV. Even the oral toxicity is far greater than that of most poisons commonly encountered. is not required. Food-borne, wound, and infant botulism are described elsewhere (see Botulism ). Mass casualties from botulinum toxin could occur from widespread contamination of food or water or from inhalation of aerosolized botulinum toxin. Botulinum toxin blocks the action of acetylcholine at muscarinic receptors in smooth muscle and exocrine glands but does not penetrate the blood-brain barrier to gain entry to the central nervous system. As with wound botulism, neurologic symptoms (typically bilaterally symmetrical descending paralysis with mydriasis) without nausea, vomiting, cramping, or diarrhea would be expected 12 to 36 hours (range 2 hours to 8 days) after exposure. Sensation and mentation are not affected. Clinical diagnosis is sufficient to make the decision to administer antitoxin, which becomes progressively less effective as symptoms and signs develop. One vial of equine heptavalent botulism antitoxin diluted 1:10 in 0.9% saline solution is given slowly IV. The antitoxin binds only to circulating toxin and thus does not alleviate existing manifestations caused by toxin already attached to receptors. 