Tetrodotoxin

Tetrodotoxin is 1,200 times more lethal than cyanide. A pinhead-sized amount of tetrodotoxin is sufficient to kill approximately 30 people. Tetrodotoxin causes respiratory paralysis by blocking sodium channels in nerve cell membranes, preventing neurons from firing. Tetrodotoxin is not destroyed by cooking. Japanese chefs must complete specialized training and obtain a government-issued license to legally prepare fugu. Tetrodotoxin accumulates in the puffer fish's ovaries, intestines, and liver.