The nature of the show I think precludes being entirely safe. After all, watching a controlled explosion is okay, but watching an explosion that is supposed to controlled but might not be is much more interesting.
In tonight’s show (about car bumpers exploding off burning cars) I noted that Adam, despite his lovely silver suit, almost got caught in the flames when they lit the first car up. Because he wasn’t injured it gave all of us watching a bit of a thrill and then a good laugh.
And then there was the casual evacuation of the room when the bumper mount began to emit a noxious-smelling white smoke unexpectedly. They joked about it, but they did leave and took the camera man with them.
I do note that in the past few shows, including this one, most of the personnel were huddled behind some sort of transparent safety shield, so they are thinking about safety. I also note that they all seem to have all their fingers, and everyone is accounted for on each episode, so apparently serious injuries are successfully being avoided.
I suspect that Mike Rowe (Dirty Jobs) has had more frequent injuries than any of the Mythbusters cast have. At least, he shows every bump, scrape and bite on camera.