Smallest thing that can kill you?

This question came to mind as I watched the distressed look on my 300+ pound friend hold a tiny little shot of Patron. I know he hates shots - they make him vomit - but someone bought an unannounced round. The only excuse my friend could come up with was that he could potentially die from that shot. The sheer absurdity of a tiny little shot potentially killing this gargantuan human caused an outburst of laughter from those who heard. But I digress…

So what’s the smallest individual thing that can kill an average-sized adult human being? I know radiation and viruses are tiny, but it would take many of these particles to kill someone. Bonus points for the smallest thing known to have actually killed someone.

Apparently 50 nanograms of Polonium 210 is a ‘Median lethal dose.’ wiki cite.

1 cosmic ray hitting the right cell and causing cancer. In the end, most radiation-induced cancers probably start with that one chance encounter/mutation/'toma.

So does your friend really have some lethal allergy or was it an excuse not to drink? (Your post isn’t quite clear.)

Frankly, I would have said (accurately), “Well, I’ll toss this down to be sociable if you insist, but I hate even the smell of tequila so much I will likely projectile-vomit all over y’all. Bottoms up…”

A few micrograms of peanut dust (provided you’re severely allergic).

Barring allergies, there are some small but lethally venomous animals out there.

A single cone snail sting can cause death in five minutes.

Just a bad excuse, although there would be about a 50% chance of vomiting shortly thereafter. He told everyone he was on a medication that could create a life-death issue if he did the shot. Of course, he drank plenty of beer already which is why no one believed him.

The cosmic ray thing is a bit of a reach, IMO. While one could trigger a cancer you are subject to gazillions of them per day with little or no problem. So they are only very rarely a real problem.

the Polonium 210 is the probable winner I guess. 50 nano grams is about as close to nothing as you can get yet it’s fatal half the time.
As far as quasi-living things go I’d suggest any of a number of viruses.

Botulinum toxin is pretty close to polonium, with an LD[sub]50[/sub] of 1-2 nanograms per kilogram. For that matter, a single bacterial spore surviving the sterilization process will grow into a colony and poison your canned food. Unlike polonium, acute botulinum intoxication is relatively easy to treat and reverse if diagnosed, but it’s still not pleasant.

Also unlike polonium, it’s intentionally injected into people’s faces to make them look prettier.

A single virus could kill you, if it got lucky. Ditto for a single photon.

Just to be a bit different the 2mm Kolibri round only weights 0.2 g and it could kill from close enough in the right spot.

In the animal world - specifically the ocean in this case - not counting the tendrils, which are about 3 meters, the box jellyfish’s body is a mere ten inches across.

You DO NOT want to encounter one of them. EVER.

I’m sure one of you can come up with something equally lethal and even smaller on land.

A single virus can’t kill a human on its on, not without reproducing. Can it?

However, isn’t there a species of amoeba that can kill a human by eating its way up a sinus nerve path and into the brain? Can’t find a link at the moment, but I thought a single amoeba could kill a host this way, if it got access to the right nerve.

50 nanograms is pretty small - but here’sa short Heinlein story where someone died of something that weighed even less.

Based on a real-life incident.

Prions come to mind. Good luck trying to get rid of them!

For one of the smallest, deadliest things you can grow in your back yard, I nominate the castor bean. Two to four seeds (beans) can kill a child. We’re keeping this in mind for the apocalypse, should things get completely untenable. :slight_smile:

Say “Hi” to the Irukandji jellyfish. :eek:


What about a blood clot?

And you don’t even need to be in the water …

Man stung by irukandji jellyfish while fishing from bulk carrier

I’d concede that thoughts could kill, but the mechanism of death is something else biological or biochemical.

And no, a single virus can’t kill, but it can start an infection that’s lethal. Not sure if it counts on that basis.

I’ll maintain that a single radioactive particle/ray damaging a cell could be the singlehanded start of a lethal cancer. It’s all in the odds, which is why vastly greater numbers of actual cell damage are needed to be statistically significant.

What, no Lilly of the Valley?

Dr. Ruth is really small, and she trained as a sniper.