from a "Moms" point of view, its safe to have a smith machine.
But in reality you need the fredom of freeweights to strengthen you. Your body will learn how to control the weight.
If your worried about the weight falling on you, then there is more chance of you dropping the weight with a smitch machine, because you have to twist the bar, there is more chance of it sliping out your hand cos you have to pick it up and put it down useing un-natural wrist movements.
With a free bar bell, if it falls on you, you can tilt the weights off by letting go with one hand, it will hit the floor, then you can push it over. You cant do that with a smith, you have to push the bar up to the next peg.
I have been lifting with a barbell for 2 years, some of the guys have been lifting for many many years, I doubt any of them hav been damaged by a barbell.