I once bought some pure botulinum toxin for an experiment (it blocks the release of acetyl choline at neuromuscular junctions). I want to say it was a milligram, but I don’t remember (that would have been 1000 times the lethal dose by inhalation). We had to get special export permission from the US government.

When the tiny vial arrived in a very large multilayered package, I sat down and read the Materials Safety Datasheet and contemplated the implications. I then decided never to open the package. We stored it under a big hollow block of concrete until the hazardous waste disposal people could figure out what to do with it.