Yeah, the EPA is wading into it.
Government “Research”
I ran across an interesting paper this morning; “Chemistry and lung toxicity of particulate matter emitted from firearms.” It was published about a year ago, but I only just found it.
This came from the EPA, so I was expecting a real mess. But to my surprise the testing and analysis they did actually looks pretty good. The short version is that they captured “gun smoke” from the muzzle and breach, exposed mice to it, then did a fairly extensive chemical analysis of the particulate matter. They dissected the mice to see what effects occurred. All that was fine.