3-QND
3-QND was a hazardous chemical compound.
If 3-QND was detected in the atmosphere, Starfleet facilities would immediately erect a force field to isolate the source. Exposure to the compound immediately irritated humanoid respiratory systems and could potentially cause hallucinations down the line.
In 2259, Dr. Joseph M'Benga accidentally created the chemical while attempting to synthesize a treatment for his daughter Rukiya's cygnokemia. Shortly afterwards, he found the USS Enterprise transformed into a pastiche of the Kingdom of Elysian and the crew dressed as and largely behaving like characters from the namesake novel, leading him to speculate that he was hallucinating from exposure to the chemical, though this ultimately proved false. (SNW: "The Elysian Kingdom")