Saxitoxin has a large environmental and economic impact, as its presence in bivalve shellfish such as mussels, clams, oysters and scallops frequently leads to bans on commercial and recreational shellfish harvesting in many temperate coastal waters around the world including the Northeastern and Western United States, Western Europe, East Asia, Australia, New Zealand, and South Africa.

In the United States, paralytic shellfish poisoning has occurred in California, Oregon, Washington, Alaska, and New England.

Saxitoxin is a neurotoxin naturally produced by certain species of marine dinoflagellates (Alexandrium sp., Gymnodinium sp., Pyrodinium sp.)

[7] The concentrations in puffer fish from the United States are similar to those found in the Philippines, Thailand,[6] Japan,[6][8] and South American countries.

[11][12] Oxidation of saxitoxin generates a highly fluorescent purine derivative which has been utilized to detect its presence.

[17][18] One of the most potent known natural toxins, it acts on the voltage-gated sodium channels of neurons, preventing normal cellular function and leading to paralysis.

Without this ability, the nerve cell becomes unable to transmit signals and the region of the body that it enervates is cut off from the nervous system.

It binds directly in the pore of the channel protein, occluding the opening, and preventing the flow of sodium ions through the membrane.

The precise mechanism of how substrates bind to enzymes is still unknown, and genes involved in the biosynthesis of saxitoxin are either putative or have only recently been identified.

[1] The medical and environmental importance of saxitoxin derives from the consumption of contaminated shellfish and certain finfish which can concentrate the toxin from dinoflagellates or cyanobacteria.

The blocking of neuronal sodium channels which occurs in PSP produces a flaccid paralysis that leaves its victim calm and conscious through the progression of symptoms.

[29] In 1975, the CIA reported to Congress that it had kept a small amount of saxitoxin and cobra venom against Nixon's orders which was then destroyed or distributed to researchers.