There Is No Safe Dose of Prions: https://pmc.ncbi.nlm.nih.gov/articles/PMC3156228/

> substance itself is not what kills you - it's the dose

Doesn’t that apply to every single thing that exists?

Yes. IIRC Congress paid for a study in the early 20th century to try to nail a definition of the word "poison" by injecting mice with different quantities of bleach. The conclusion was that everything is a poison at the right dose. Most medicines are great at low doses, but then kill you when you take too much of them. Heck, even water is a poison.

The old toxicology proverb is: "The dose makes the poison"

I like to extend it to: "the portion makes the poison." Beyond getting the alliteration, it also includes food, which I think is important. A glass of water won't kill you, two gallons of water will. An ice cream cone once in a while is nothing; one every day will make the doctor's eyes go wide.

Jesus. I had a colonoscopy. Don't tell me about drinking 2 gallons of water. I won't even get started on an ice cream cone a day.