system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How is the lethality of a substance determined in an ethical way?

I recently saw a documentary and learned that the most venomous snake on earth (the Inland Taipan) can kill over 100 grown humans with its venom.

How is that figure determined? I know that it is not likely that some scientist tried to try and kill as many people as possible. So how is it done? How do we tell if something is lethal? And how do we tell how many people it can kill?

What about a completely foreign substance? The effects of which on humans is relatively undocumented?
gpt
> How is that figure determined?

Apply carefully measured doses to a series of rats until half of your sample dies. Consult prior research where lethality in rats was compared to more analogous animals such as pigs. From this you determine the LD50, the lethal dose for half of a given population. Then it is just a matter of comparing how much venom the animal typically injects vs the LD50 amount.