Props to dad4 for bringing more than opinion into this conversation.
Pure and simple, there isn't any well-done scientific evidence that I've seen which convincingly shows heading the ball is actually safe. And I do look at this primary literature. Talk to neurologists/neurosurgeons, they'll tell you the same thing.
It is a historically woefully understudied topic that thankfully is getting more attention and research dollars.
What is clear is that the more carefully people look with imaging and functional studies at heading, the more they find that heading the ball *isn't* good for the brain. And this risk probably extrapolates down to a situation where there isn't a "safe" or "ok" amount of heading. The same can be said of alcohol consumption and cancer risk.
There's not firm science behind the age threshold that US Soccer set in regards to heading (12 years), but I'm glad they did... something.
Interestingly, the EPL came out last year with guidance on heading in all players (
https://www.premierleague.com/heading-guidance)-- that includes adults and pros.
It is definitely clear from the science that girls' concussion risk is significantly higher than boys' in soccer, and the biomechanics behind this likely translate into headers being worse for female players than male players. The EPL link discusses that some.
I think the game should eliminate heading. We would all adapt. It would still be beautiful.
We can all talk about acceptable risk and where to set that threshold. But I think better information is needed for people to really understand the risks that they are inflicting on their kids (that many don't realize are there, especially from this conversation...).
To anyone who says you can't play at top levels without heading the ball, I say to you: Son Heung-min scored zero goals with his head last year. And, oh yeah, he tied for the golden boot in the EPL. Something like 2% or fewer of Messi's goals have come from heading the ball. I could go on. Yes, there are some very talented players in the air--- but it isn't critical for the game in all players.
I played the game for 30+ years and headed the ball many times (yes, with proper technique)-- occasionally seeing stars for a few seconds. That's not good. Do I wish I could eliminate that from my past? Absolutely. And I don't want my kids to be there either.