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Comment by sho | Hacker News Reader

> The lethal dose when consumed orally is around 30 billionths of a gram, which if you want a relatable comparison, is about the same as if you cut a single poppy seed into ten thousand equal pieces and ate one of them. It is an amount so tiny, it really doesn’t make sense.

That's right - it makes no sense. How could such a small amount of anything do enough damage to shut down your entire body? According to wikipedia, it works by "cleaving key proteins required for nerve activation". Unless there's some self-replication mechanism, how does that even work?

edit: I went and did the math. At an LD of 30 nanograms, that's about 1.2 billion actual molecules of this stuff to die. I guess that's enough to shut down a sufficient number of nerves that you just can't function anymore.

The math: lethal dose / per molecule weight (molar mass / avogadro)

(3.0e-10) / (149323.05 / 6.0221409e+23) = 1209888406.377984

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It's a protease which matches key neural proteins. The key to recognise is that it's reusable: one molecule can keep breaking proteins, and as soon as it does that faster than homeostatic processes can replace them you're in trouble.

Just how "rm -rf /" can destroy your whole system: it's a small character but it matches and destroys everything.

Its a simple spell but quite unbreakable

> According to wikipedia, it works by "cleaving key proteins required for nerve activation". Unless there's some self-replication mechanism, how does that even work?

The toxin is an enzyme and as such is not consumed during the cleavage reaction. A molecule of the botulinum toxin breaks down one protein molecule and then moves on to the next one until the toxin itself is degraded by the organism.

Wikipedia says "The estimated human lethal dose of type A toxin is 1.3–2.1 ng/kg intravenously or intramuscularly, 10–13 ng/kg when inhaled, or 1000 ng/kg when taken by mouth."

https://en.wikipedia.org/wiki/Botulinum_toxin

> 10–13 ng/kg when inhaled

Well, that answers the poor "how would Saddam have gotten us to eat it?" joke in the article - disperse it as a cloud instead

The thing that surprises me is: how does it get distributed widely enough? I would imagine that 30pg would lump together somewhere and damage a handful of neurons, not that it would spread and reach all essential parts of the nerve system.

Extracellular fluid is actively transported-- after all, it's where all gas exchange happens, and if you get a hypoxic spot in your body then those cells are going to die. The wikipedia article claims, without citation: "The extracellular fluid is constantly "stirred" by the circulatory system, which ensures that the watery environment which bathes the body's cells is virtually identical throughout the body. This means that nutrients can be secreted into the ECF in one place (e.g. the gut, liver, or fat cells) and will, within about a minute, be evenly distributed throughout the body."

I guess that we must therefore make a separate category for self replicating, otherwise prions would be probably the winners. It's like code golf but with chemistry. Great article BTW.

Terrifying, really

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