(CNN) The NFL and the NFL Players Association have a staunch policy prohibiting marijuana use , but some players are asking them to reconsider it, saying pot can be used for pain relief, and possibly as concussion prevention.

If you play professional football, "your job automatically gives you the symptom of chronic pain," said Baltimore Ravens offensive tackle Eugene Monroe , who has played in the NFL since 2009. "You're hitting each other as hard as possible every single day in practice. Your body is in pain a lot of time."

More and more players are looking to marijuana for pain relief, he said, despite risking punishment from the NFL.

There are existing ways to manage pain: opioids and noninflammatory medications. But Monroe and other players are concerned about addiction and the potential for overdoses

"All over our country people are addicted, and that's happening in our locker rooms," Monroe said.

Last year, a class action lawsuit was filed against the 32 NFL teams by former players who alleged that team coaches, staff members and doctors pushed painkillers onto players to get them back on the field. The case has been transferred to the federal court in the northern district of California. A similar suit was filed in 2014, but was dismissed.

During Super Bowl week, NFL Commissioner Roger Goodell said of the current marijuana policy, "It's an NFL policy and we believe it's the correct policy, for now, in the best interest of our players and the long-term health of our players."

Goodell acknowledged that there have been some scientific developments about the uses of marijuana, but not enough.

"I agree there has been changes, but not significant enough changes that our medical personnel have changed their view," he said. "Until they do, then I don't expect that we will change our view."

The NFL Players Association said, "Marijuana is currently a banned substance under the collectively bargained Substances of Abuse Policy. Both parties to the Policy (NFL and NFLPA) seek guidance from the independent medical professionals who administer the policy, and no change to marijuana's status as a banned substance has been recommended by those medical professionals."

But Monroe said it is time for more research to look at the possible benefits of medical marijuana, especially as he sees players turning to it. He's the first current NFL player to publicly take this stance.

"The NFL will need to have legitimate information before they remove marijuana from the banned substance list and ultimately not hurt their product in the field," Monroe said. "But there's opportunity in that space also, for the NFL to get involved and maybe lead efforts."

Marijuana use in the NFL

Some retired players admitted to using marijuana while in the NFL, and active players, such as Monroe, have said it's common. All the numbers regarding marijuana use in the NFL -- whether for pain relief, concussion prevention or recreation -- are anecdotal. Admitting to marijuana use could be career ending.

Nate Jackson , who retired after six seasons with the Denver Broncos, said he started using pot recreationally in high school, but began using it to manage pain on the field. Last year, he called on the NFL to reconsider its marijuana ban.

Former Denver Broncos player Nate Jackson said he medicated himself with cannabis.

"Cannabis has been part of my football experience since I started," said Jackson, who played from 2003 to 2008. "I never liked the pills and medicated with cannabis."

Heather Jackson, one founder of the nonprofit Realm of Caring Foundation , said she knows of 19 current and former players who are using oil derived from the cannabis plant to lessen the impact of potential brain injuries when they are out on the field, and as a therapy after being hit with a concussion.

To get a better grasp of just how many players are using marijuana and why, Realm of Caring is raising money to help launch a study with Johns Hopkins University. Realm of Caring provides education and support about cannabis to adults and children suffering from a host of diseases, including epilepsy, cancer, multiple sclerosis and Parkinson's.

"We want to go in and learn as much about the players. Who's using? What kind of benefit? How does it benefit (players) versus traditional treatments? Are there other associated effects?" said Ryan Vandrey , an associate professor of psychiatry and behavioral sciences at Johns Hopkins Medicine.

Vandrey has been involved in cannabis research for 16 years. He also plans to do biological testing for "inflammatory biomarkers that have been associated with head trauma and pain."

With a large assessment of the players, Vandrey hopes that better studies can help researchers understand marijuana's impact on players.

Research on marijuana

The marijuana plant is composed of some 500 chemicals that work together to create its impact on the brain. It's known as " the entourage effect " -- the chemicals work best together, instead of in isolation. Two particular chemicals of interest are THC and cannabadiol, known as CBD.

Photos: 7 uses for medical marijuana Photos: 7 uses for medical marijuana Between its outlaw image, controversial legal status and complex makeup -- the cannabis plant contains more than 400 individual chemicals -- marijuana's action in the brain and body is in many ways a mystery. The vast majority of studies on the drug have examined potential harm, as opposed to potential benefits. Even so, some medical uses are widely accepted and others are the subject of serious research. Here's a look at some potential uses of marijuana as medicine. Hide Caption 1 of 8 Photos: 7 uses for medical marijuana Pain – In the United States, pain is the most common condition for which medical cannabis is taken. Studies show the drug is especially effective against neuropathic pain, a type of pain involving nerve damage. Marijuana is less habit-forming than opiate drugs and carries virtually no risk of a fatal overdose. Hide Caption 2 of 8 Photos: 7 uses for medical marijuana Multiple sclerosis – Sativex, a pharmaceutical version of cannabis, is approved in 25 countries as a treatment for painful muscle spasms arising from multiple sclerosis. Hide Caption 3 of 8 Photos: 7 uses for medical marijuana Nausea – The munchies are no joke. Marijuana is sometimes prescribed to stop nausea or induce appetite in people who have trouble eating, including patients suffering from AIDS or going through chemotherapy for cancer. Hide Caption 4 of 8 Photos: 7 uses for medical marijuana Epilepsy – More than 100 families have moved to Colorado to access "Charlotte's Web," a cannabis strain that in some epileptic children seems to dramatically reduce seizures . Taken as an oil, the medicine is high in a chemical called CBD and low in THC, the component that makes people "high." Hide Caption 5 of 8 Photos: 7 uses for medical marijuana Concussion – NFL commissioner Roger Goodell said the league is following the work of Israeli researchers who are exploring cannabis as a potential treatment for traumatic brain injury. In 2003, along with two colleagues, Nobel laureate Julius Axelrod, an American, obtained a patent on the drug for its anti-inflammatory and neuroprotective properties. Hide Caption 6 of 8 Photos: 7 uses for medical marijuana Alzheimer's disease – In studies of rats, marijuana helps stave off memory problems and Alzheimer's-like brain changes. A leading researcher said the drug's iffy legal status has held up further research. Hide Caption 7 of 8 Photos: 7 uses for medical marijuana Bipolar disorder – A small study at Harvard found that marijuana seems to stabilize the brains of people who suffer from bipolar disorder. Some studies show the drug actually raises the risk of developing mental illness, but those findings are controversial. Hide Caption 8 of 8

When it comes to pain relief, marijuana has a scientific track record . THC is the chemical ingredient that makes people feel high. However, it can also provide relief from pain. For patients undergoing chemotherapy, it can help them regain their appetite. It has been found to reduce pain for patients with arthritis , and has anti-inflammatory qualities. Marijuana was widely used for pain relief in the 1800s.

on brain cells. When CBD was administered to Mice who were administered CBD had There's not much research about marijuana's impact on brain injuries. Animal studies have found that CBD has a neuroprotective effecton brain cells. When CBD was administered to pigs with brain injuries, CBD brought electircal activity close to normal levels and reduced amounts of stress on the brain.Mice who were administered CBD had fewer brain cells die from brain injury, when compared to mice that didn't have CBD.

Research on marijuana is difficult because the U.S. Drug Enforcement Administration continues to categorize it as a drug with no currently accepted medical use

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But the U.S. government holds a patent on marijuana as a neuroprotectant. In the patent, it says "The cannabinoids are found to have particular application as neuroprotectants, for example in limiting neurological damage following ischemic insults, such as stroke and trauma, or in the treatment of neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease and HIV dementia."

Art Caplan, dean of research for New York University's Sports and Society program, said it's too early to start using pot to help relieve concussions.

"I think the science on concussion is nonexistent. I hear it said. I think it's just talk," Caplan said.

"There isn't data yet, but there should be, and the government shouldn't be holding back on doing research," she said.

Policy changes ahead?

As more states legalize marijuana use, Caplan said, the NFL will have to catch up.

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"(The NFL has) to bring their policies in line," Caplan said. "It's absurd to work in the Nancy Reagan 'just say no' frame when we have acceptance of use sweeping through the U.S. at a rapid rate."

For players on the field, Eugene Monroe said, marijuana isn't just a tool to be pain free, but to live life beyond the football field.

"When the season is over," Monroe said, "players can play with their kids, see their families and not have their bodies ache."