On Thursday, May 20, 2021 at 12:40:03 PM UTC-4, Commander Kinsey wrote:
It was caused by severe negligence - unsanitary conditions in wet meat markets. If a company accidentally outputs a load of nuclear waste and kills millions of people, they would be held accountable.

No such determination has been made. Scientists and investigators so far say they don't know how it originated. We may never know, because China isn't allowing a full, open, investigation by the world.