I'll get the ball rolling with some of the safety lapses I have observed:
- One of my students thought you turned off a Bunsen burner by yanking the hose off of the gas. To make a long story short, he left the gas on in a lab overnight. That could have ended badly...
- Back when I was a grad student at ORNL one of my associates left his watch on when we were working on a vacuum evaporator. The power was on and it was surprisingly easy to accidentally locate the live connection. He could fly! I guess that is better than being rooted to the spot, right?
- Really, he could fly. He proved it a second time when we were doing something with the power source for a class IV laser. Electrons make people fly.
- One student pushed a glass pipette through his hand when trying to force it through a hole in a stopper. He's actually the only person I have seen do that, though I have been told it's a common accident.
- This isn't an accident or safety violation, but it relates to one. A student splashed a chemical in her eye and went to use the eye wash station. The water in the eye wash station didn't have a drain since it was for emergencies, so it was only turned on when it was tested. The water from the eye wash station ran white for a couple of minutes. We later tested it for lead (very old building). Let's just say the girl would have been better off running to the bathroom and sticking her face in the toilet than using the eye wash.