San Francisco 49ers linebacker Chris Borland .

After just one season in the NFL, San Francisco 49ers linebacker Chris Borland retired, saying he wants to avoid sustaining serious concussion-related injuries in the future.

Borland, 24, made his announcement on ESPN’s “Outside the Lines” on March 16. Boland said he retired because of concerns about the long-term impact of football-related head trauma.

“I can relate from the outside looking in that it wouldn’t make sense to a lot of people, and I’ve had close friends who have said, ‘Well, why don’t you just play one more year, it’s a lot more money, you probably won’t get hurt,’” Borland told ESPN.  “I just don’t want to get in a situation where I’m negotiating my health for money. Who knows how many hits is too many?”

Borland may have to return three-quarters of his $617,436 signing bonus, and could lose most of a four-year contract worth about $3 million.

A week before Borland made his decision, 49ers seven-time All-Pro linebacker Patrick Willis announced he was retiring at age 30 due to the long-term effects the NFL has on players

In his first season as a professional player, Borland made a huge impact, with 108 tackles and two interceptions.

Former Miami Dolphins cornerback Cortland Finnegan, 31, Tennessee Titans quarterback Jake Locker, 26, and Pittsburgh Steelers linebacker Jason Worilds, 27, also retired during this year’s offseason for various reasons.