Depends what kind of Output you mean. If you mean the Output force of an Arduino board orbiting Earth striking a space station, than yeah that would be dangerous for the crew living on the spaceship.
If you calculate: The mass of an Arduino board is about 25grams and various objects orbit Earth at a speed of 2000 m/s. Now we could find the momentum with this formula. p=m*v.
p=2000*0.025=50 kg/s
I think that is enough to treat a life.
If you are talking about the electric current from the Arduino being dangerous for you, then that is too boring to answer. But considering that you are a Newbie and this is your first post, I'm not going to say anything else.