The N.F.L. also remains immensely influential, despite a recent decline in television ratings and mounting worries about the long-term health of players subjected to years of head hits. It is the largest sports league in the country, with $14 billion in revenue, and its games draw more viewers than nearly everything else on broadcast television.
The reintroduction of the New York bill comes as research increasingly shows a correlation between long-term brain disease and the age at which children begin playing tackle football. Last week, a study published in the journal, Brain, showed evidence of the degenerative brain disease, chronic traumatic encephalopathy, or C.T.E., in teenage athletes who sustained head impact injuries.
Doctors note that head hits absorbed by young players are more damaging because their brains are not fully developed, and are less capable of fully repairing themselves. Younger players also have weaker neck muscles, and therefore are less capable of bracing for impact and supporting the weight of a football helmet.
“Some of my colleagues quibble that the science has not determined which age is the right age, but they don’t seem to realize that health experts set age minimums for all sorts of activities like drinking, smoking and driving, and the science is never purely black and white,” said Dr. Robert Cantu, the co-founder and medical director of the Concussion Legacy Foundation, who has studied head trauma in children for years.
Cantu and a growing number of other experts recommend that children play flag football, and take up the tackle version of the game only when they reach 14. Some former N.F.L. players have endorsed this approach.
Nick Buoniconti, a Pro Football Hall of Fame linebacker with the New England Patriots and Miami Dolphins, estimates that he absorbed more than half a million hits during his playing days, which began on sandlot football fields when he was nine, and ended when he left the N.F.L., in 1976, when he was 36 years old.
“I made a mistake by starting my career at nine years of age, with an ill equipped helmet,” Buoniconti, who now suffers from dementia, said last week. “I beg all parents to please don’t let your children play football until high school. “That is my message.”
Stung by a decline in number of children playing youth tackle football, the N.F.L., USA Football and other organizations have also begun promoting flag football as a safer alternative for children interested in the game. Flag football participation rates have risen sharply.
In recent years, youth sports organizations have introduced safety initiatives to address the dangers of head hits, but the responses have been far from uniform. In 2015, the United States Soccer Federation banned players age 10 and younger from heading the ball, and will reduce headers in practice for those from ages 11 to 13. But the regulations only address U.S. Soccer youth national teams and academies, including Major League soccer youth teams.
National organizations governing youth hockey and lacrosse have also made rule changes to minimize potential head trauma.
Pop Warner, one of the largest youth football leagues in the country, has also changed rules to prevent concussions and potential long-term cognitive problems. In 2016, the organization eliminated kickoffs in its three youngest divisions, which includes players between 5 and 10 years old. It also further reduced the amount of contact time in practice in all age groups, to 25 percent from 33 percent.
Benedetto’s bill would ban the sport entirely for preteens, which would effectively shut down Pop Warner and other youth organizations in New York state. Lawmakers in other states, he said, are looking to introduce similar legislation.
Benedetto named his amended bill the John Mackey Youth Football Protection Act, after the New York-born N.F.L. star tight end who developed severe dementia and died in 2011. After pressure from Mackey’s widow, Sylvia, the N.F.L. started a benefits program, the 88 Plan, for families caring for former players with dementia. Mackey wore the number 88 on the Baltimore Colts.