Interesting topic and less clear cut than it would seem on the surface as you look at all levels of the sport.
Doctor Uzma Samadani, who as an aside helped save my father's life or quality thereof in 2016, is at the center of much of the research locally and has a son who plays football.
I think some of her considerations are captured in this article by a student who worked in her Brain Injury Research Lab for a summer:
https://aansneurosurgeon.org/feature...-brain-injury/