Player safety and rule differences

Comparing CFL/NFL NCAA and CIS does the game rules or field size affect player safety? Example - does 1 yard off of the line of scrimmage help or hinder injuries. I wonder if the leagues have ever studied this. I would be interested to see a study on the differences relating to injuries. Is there anything out there published? NFL believes the CFL has fewer concussions and field size has some affect. NFL discussed the width of the field Feb 2013 increasing it to 60 yards but couldn't make it work in some stadiums. There are probably other things the CFL could do