A former NFL player is fighting for the league to change its harsh stance on marijuana

Former Baltimore Ravens offensive tackle Eugene Monroe didn't give up football last year because he got too old, or because he couldn't hack it in one of the most lucrative positions in football anymore — he left because of repeated head injuries.

And now, a year into his retirement, the 30-year-old has taken up a new cause: Convincing the NFL that players should be able to use medical marijuana.

In the piece, Monroe discussed how his 18-year love affair with the game left him foggy-headed and "terrified" of life-long brain injuries like chronic traumatic encephalopathy (CTE). Team doctors would prescribe him opioid-based painkillers and anti-inflammatory pills, which left him reeling from side effects.

"I just thought that for longevity purposes

A year later, he's devoted himself to cannabis activism, working with partners like Green Flower Media to educate others about how cannabis can be a much healthier alternative to opioids.

It all started in the locker room

Offensive tackle is one of the most demanding positions in football, fraught with big collisions and the injuries that follow. When Monroe was a player, team doctors prescribed him pills after games for each injury he sustained. That's where the trouble started.

A January study from the National Academies of Sciences, Engineering, and Medicine (NASEM) found "substantial evidence" that the main compounds in cannabis — THC and CBD — are effective at treating and relieving chronic pain.

Just like opioid painkillers bond to natural opioid receptors; cannabinoids like THC and CBD bond to the body’s natural cannabinoid receptors. Doctors think the cannabinoid system may play a crucial role in pain management, though the study notes that more research is needed to suss out the connection.

Further studies have shown promising results that CBD could have a "neuroprotective," effect and may reduce the risk of developing CTE. The disease is a major issue in professional sports — a 2015 study from Boston University's CTE Center found that 96% of the deceased NFL athletes they examined showed signs of CTE.

Monroe donated $80,000 of his personal money to researchers at Johns Hopkins and the University of Pennsylvania to study medical marijuana for brain injury treatment.

Doctors are still hesitant to recommend cannabis outright — pain management is a complicated — and there's still a ton of uncertainty around cannabis products. Cannabis's status as a Schedule 1 drug makes it difficult for doctors to obtain quality samples for research.

Despite Monroe and a number of other NFL players, including Nate Jackson and Ricky Williams, insisting that the NFL reevaluate its policy towards medical marijuana, NFL leadership has so far declined to do so.

Not so fast, says the NFL

Marijuana use has been a hot topic in the NFL in recent years. Perhaps the most high-profile case is that of Cleveland Browns wide receiver Josh Gordon, who was suspended for the entire 2015 season for smoking marijuana.

Though Gordon's 2015 suspension wasn't the first time he ran afoul of the NFL's substance abuse policies, he was arrested for driving under the influence in 2014, he recently completed a stint in rehab for his marijuana use. The

Roger Goodell, the NFL's commissioner, has not been positive about cannabis use, calling it "addictive" on an ESPN radio show in April.

Keeping up with the Joneses

Cannabis, however, is a collective bargaining issue, meaning that NFL players must make a concession in exchange for changes to the NFL's policy, according to NBC Sports.

Monroe called it "atrocious" for the NFL to "try to bargain something like this."

"The decision to simply no longer punish players for using marijuana — I don't think that needs to be negotiated," Monroe said. "That's something that can be added to the current language of the [Collective Bargaining Agreement]."

"Roger Goodell needs to put his big boy pants on and look