In this Oct. 24, 1993, file photo, New York Jets defensive lineman Marvin Washington (97) tackles Buffalo Bills’ Thurman Thomas (34) in the third quarter of a football game at Giants Stadium in East Rutherford, N.J. (AP Photo/Bill Kostroun, File)Marijuana is casting an ever-thickening haze across NFL locker rooms, and it’s not simply because more players are using it.As attitudes toward the drug soften, and science slowly teases out marijuana’s possible benefits for concussions and other injuries, the NFL is reaching a critical point in navigating its tenuous relationship with what is recognized as the analgesic of choice for many of its players.“It’s not, let’s go smoke a joint,” retired NFL defensive lineman Marvin Washington said. “It’s, what if you could take something that helps you heal faster from a concussion, that prevents your equilibrium from being off for two weeks and your eyesight for being off for four weeks?”One challenge the NFL faces is how to bring marijuana into the game as a pain reliever without condoning its use as a recreational drug. And facing a lawsuit filed on behalf of hundreds of former players complaining about the effects of prescription painkillers they say were pushed on them by team trainers and doctors, the NFL is looking for other ways to help players deal with the pain from a violent game.A Gallup poll last year found 58 percent of Americans believe marijuana should be legalized. That’s already happened in Colorado and Washington — the states that are home of last season’s Super Bowl teams.The World Anti-Doping Agency has said it does not need to catch out-of-competition marijuana users. And at least one high-profile coach, Pete Carroll of the champion Seahawks, publicly said he’d like to see the NFL study whether marijuana can help players.There are no hard numbers on how many NFL players are using marijuana, but anecdotal evidence, including the arrest or league discipline of no fewer than a dozen players for pot over the past 18 months, suggests use is becoming more common.Washington Redskins defensive back Ryan Clark didn’t want to pinpoint the number of current NFL players who smoke pot but said, “I know a lot of guys who don’t regularly smoke marijuana who would use it during the season.”Washington wouldn’t put a specific number on it but said he, too, knew his share of players who weren’t shy about lighting up when he was in the league, including one guy “who just hated the pain pills they were giving out at the time.” Another longtime defensive lineman, Marcellus Wiley, estimates half the players in the average NFL locker room were using it by the time he shut down his career in 2006.“They are leaning on it to cope with the pain,” said Wiley, who played defensive line in the league for 10 seasons. “They are leaning on it to cope with the anxiety of the game.”The NFL is fighting lawsuits on two fronts — concussions and painkillers — both of which, some argue, could be positively influenced if marijuana were better tolerated by the league.The science, however, is slow-moving and expensive and might not ever be conclusive, says behavioral psychologist Ryan Vandrey, who studies marijuana use at John Hopkins. Marijuana may work better for some people, while narcotics and other painkillers might be better for others.“Different medicines work differently from person to person,” Vandrey said. “There’s pretty good science that shows marijuana does have pain relieving properties. Whether it’s a better pain reliever than the other things available has never been evaluated.”Washington, who is part of the concussion lawsuit, is working with a bio-pharmaceutical and phyto-medical company called KannaLife Sciences that recently received licensing from the National Institutes of Health (NIH) to develop a drug to treat concussions using derivatives from medical marijuana.