There's always a continuity there ("the dose makes the poison"), there's no known substance that will reliably kill you if you're exposed to a single molecule of it.

The issue with potency is that the more potent a substance, the more precise equipment and quality control you need to stay on the safe side. With fentanyl, healthcare and pharmaceutical industry can handle the precision and QC demands (which includes guarantees and maintaining public trust). Criminal enterprises cannot.

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RajT88 17 minutes ago | parent | next [-]

Carfentanil has got to be closer to that. It is said to be up to 100x more powerful than fentanyl.

Micrograms (yes still many molecules) could be lethal

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throwdown7653 an hour ago | parent | prev [-]

prions perhaps?

	▲	prmph 29 minutes ago \| parent [-]
		Even with prions, there evidence that the body (and probably more so with some people than others) has some level of ability to resist, slow, or sometimes prevent a prion infection. See these: - The influence of PRNP polymorphisms on human prion disease susceptibility: an update [1] - A naturally occurring variant of the human prion protein completely prevents prion disease \| Nature [2] [1] https://pubmed.ncbi.nlm.nih.gov/26022925/ [2] https://www.nature.com/articles/nature14510?utm_source=chatg...