Hall of Fame quarterback Brett Fave has a message for football parents: Don’t let your kids play tackle before they turn 14 years old.

The Super Bowl champion and 19-year NFL veteran makes that case in a PSA released with the Concussion Legacy Foundation. The ad seeks to explain how the chances of suffering chronic traumatic encephalopathy (CTE), a traumatic brain condition associated with football players, increases the longer someone plays tackle football.

For that reason, Favre believes kids shouldn’t play tackle football until they turn 14.

“A football player’s odds of developing CTE may be most determined by their parents, specifically what age the child is allowed to start playing tackle football,” Chris Nowinski, co-founder, and CEO of the Concussion Legacy Foundation said in a statement. “It’s time to accept that CTE is not just a risk for professional and college football players, but also for high school players, and the best way to prevent CTE among football players is to delay the introduction of tackle football.”

(AP Photo/Mark Schiefelbein)

Favre says he has no idea how many concussions he suffered in his nearly 30-year high school, college, and pro career.

“(There’s) no telling how many concussions I’ve had, and what are the repercussions of that, there’s no answer,” Favre told TODAY in an interview. “I wasn’t the best student, but I still can remember certain things that you would go, ‘Why would you even remember that?’ But I can’t remember someone that I played six years with in Green Bay … but the face looks familiar. Those type of issues that make me wonder.”

Favre, a 51-year-old grandfather with three grandsons aged 4, 7, and 11, says he will not encourage them to play football.

“If they choose to play, I will support them, but I’m not going to encourage them in any way to play. That surprises a lot of people, but I’m just fearful of what concussions can do,” Favre explained. “And it only takes one. Maybe I have had a thousand… It’s just too risky. I’m not going to encourage them to play until there’s a treatment.”

He added, “The best way to avoid concussions is not to play at all, and of course, that’s not going to happen.”

Concerns over CTE have led to several rule changes and a revolution in new helmet design at all levels of football. However, given that the disease is only detectable after death, it’s impossible to know how many players are afflicted with the condition.