Chiefs spokesman Ted Crews and NFL spokesman Greg Aiello both declined to comment on the suit.
Ken McClain, an Independence attorney, said the lawsuit is allowed in Missouri after a state workers' compensation statute was amended in 2005 to exclude cases of occupational injury that occur over an extended time.
That exception more commonly applies in workplaces where smoking is allowed and workers suffer lung problems because of it. McClain also represented workers at a Jasper popcorn plant who were awarded millions of dollars in lawsuits claiming they got cancer because of a chemical in butter flavoring used at the plant.
The lawsuit says the Chiefs ignored decades of research indicating that concussions cause long-term brain damage, instead referring to the injuries as "getting your bell rung" or a "ding." It accuses the team of lying to players in saying concussions are not serious injuries.
In recent years, a string of former NFL players and other athletes who suffered concussions have been diagnosed after their deaths with CTE, including Junior Seau and Ray Easterling, who both committed suicide.
In August, the NFL agreed to pay approximately $765 million to settle lawsuits filed by more than 4,500 former players who developed dementia or other concussion-related health problems they say were caused by playing football. The settlement, subject to approval by a federal judge Philadelphia, would apply to all past NFL players and spouses of those who are deceased.
Plaintiff's attorneys say individual payouts would be capped at $5 million for men with Alzheimer's disease; $4 million for those diagnosed after their deaths with a brain condition called chronic traumatic encephalopathy; and $3 million for players with dementia.
About 19,000 retired players would be eligible to seek awards or medical testing, but current players are not part of the deal. The settlement does not include an admission from the NFL that it hid information from players about head injuries.
At the time, the settlement announcement appeared to remove a major legal and financial threat hanging over the NFL. But if too many former players opt out, the deal could fall apart.