If you are being coerced into doing something unethical or illegal, or something wrong that may follow you in your career.
If you are being verbally abused by a coworker, be it a manager or a subordinate.
Beyond that I’m not sure what else might cause you to feel “unsafe.” A tech company is one of the softest and least demanding jobs in all of human history.
So innocent old moi comes down the hall, wonders what's up with the box, and fiddles with it, never dreaming it has that kind of weight in it. Once it started coming over, it was beyond my strength to stop. It landed on my foot.
By luck and/or the grace of God, they also left this low cart/dolly thing in the hallway. It caught the last inch of the box - enough to stop the cardboard, but not enough to catch any of the steel. The steel then slowly tore through the box. But it was enough that the weight slowly landed on my foot, rather than slamming it. It was the difference between a fair amount of pain, and crushing all the bones in the arch of my foot (or so I suspect - I haven't done the experiment).
So, yeah. Falling mass can cause crush damage, even in a cubicle farm.
Wasn't this an invitation to brag?
Psychological leading to physical: Anything that pushes people over the edge causing them to act out in harm to themselves and/or others especially when they might not see the alternate options available to them and/or may already be suffering an unstable state of mind from external pressures.