World Rugby must do more to protect players long term from the game's increased physicality, says former Scotland number eight Johnnie Beattie.
A group of ex-internationals, including English World Cup winner Steve Thompson, claim the sport has left them with permanent brain damage and are to sue rugby authorities for negligence.
Beattie, 35, is "relieved" to have retired in January.
"I'm very lucky to have scraped through without too many head knocks," he said.
"But I'm worried for my friends and colleagues. My fear is that pre-2014-15 we haven't had the education around it and coaches didn't take it seriously or understand.
"I genuinely feel a little bit heartbroken for Steve and probably the hundreds of other players both in amateur and professional sides of the game that will now come forward over the next few weeks."
Beattie, who earned 38 caps from 2006 to 2015 and says rugby has given him "everything", says the sport's safety protocols are now "as good as they've ever been".
But he highlighted the comparison of American football in claiming more improvements need to be made.
Speaking to BBC Good Morning Scotland, Beattie added: "I can remember a coach in Scotland referring to Chris Cusiter as Chris Concusiter and laughing. That shows how far Scotland has come.
"Now we have HIAs [head injury assessments] that are fantastic with independent doctors at games looking for head knocks, we have zero tolerance for connections with heads in the tackle area.
"There are things that World Rugby are going to have to look at to change the game to protect people, because it can't keep getting more aggressive and harder physically.
"They've taken steps to try to protect people but more are needed to make rugby safer. Around 80-90% of impacts come in training, so there has to be more control across the board.
"You can look at NFL and think World Rugby has to sit up and take note. The NFL caps collisions per year and does other things such as brain scans every year. I did that off my own back in France just to be sure."
Speaking on Tuesday, World Rugby told BBC Sport they were not prepared to comment on "speculation" but added they they take player safety "very seriously and implement injury-prevention strategies based on the latest available knowledge, research and evidence".