Your is best more-than-random guess I've heard. (Ricin.. doesn't happen accidentally IIRC--and would have to be deliberate.)
But there's lots of stuff via n!/n-factorial accident which No One could cover, encyclopedically :-/
Would Chinese capitalists use awful xfmr oil to make a buck?
Did a Chinese "entrepreneur" put melanine in baby formula (to game the %protein test?)
He did--and lost his head/cleanly, I imagine.
We exported this deadly-system and China has Improved it beyond the merely unethical to the outright vicious.
Some pretty-Serious Cosmic Humor, worldwide now--if that's what it's about.
(Thus a pretty-sick Cosmos, to boot ?)