The most toxic and dangerous poison on Earth

Bacteria are living organisms that synthesize the most violent ever known toxins. To date, botulinum toxin, Shiga toxin and tetanospasmin are three substances representing the most dangerous and powerful poisons ever observed: only a few tens of nanograms of one of these compounds, are sufficient to kill a human.

Botulinum toxin from the bacterium Clostridium botulinum, that causes botulism (but also one of the essential components of Botox!), seems to be the most violent of these substances, with an LD 50 (killing half of a given population) estimated between 1.2 and 0.4 ng/kg, so dangerous that only a pound of this toxin could cause the extinction of mankind

The Tetanospasmin, that causes tetanus, reaches a LD 50 of 1 ng/kg, and Shiga toxin from 1 to 20 ng/kg. As a comparison, strychnine or arsenic (considered more violent than the famous cyanide) have an LD 50 of 1 mg/kg : botulinum toxin is so around a million times more powerful. Most violent compounds of the animal kingdom, such as batrachotoxin from poison frogs, Fugu's tetrodotoxin, or venom of water snake Chitulhia belcheri, are by comparison, relatively small, since their LD 50 are assessed in micrograms (1000 times less powerful).