I guess to keep in form with the title/subject of this thread - I would have to say that the most dangerous thing in the shop is called a Co-Worker. You may have a few in your shop. Heck - you might even BE the Co-Worker!
Co-Workers come in all sizes and levels of complexity. I have witnessed co-workers closing extension cords in doors leading into an operating Class1, Div1 (explosion proof) environnment.
I have seen Co-Workers use a cutting torch on empty acetone drums that were capped.
I have seen Co-Workers cut through the Oxy/Acet hose on a smoke wrench and then light the cut hose on fire and not know what to do to stop the fire.
I have seen Co-Workers fall asleep operating machines, fall into the machine and wake up with several compound fractures.
Co-Workers are dangerous. Keep your distance.
Scott