The front row are the ones that face 'danger' from the initial impact, which has been lessened recently by the 'touch, bind, set' process, and the twisting of the neck while pushing and being pushed by man-mountains behind you.
Other injuries are usually caused by tackles at the breakdown and rucks where most contact occurs. All the players at senior level are aware, and junior players are taught at different stages as contact is gradually introduced over time.
My 16yr old grandson faces full contact, but my 9yr old grandson faces tackles but doesn't face scrums nor rucks, while his 7yr old friend doesn't face tackles as they play 'tag' rugby.
Every physical game has an element of risk associated with it, both physical and mental, but rugby, I feel, teaches the most about teamwork, character building and how to expend your energy in a positive way.
That's why the game of rugby is identified with players that are usually calm and collected off the pitch and fans that are reasonable and fair in their outlook, even to the opposition.