By STU WOO, SARA GERMANO and JONATHAN CLEGG
In his 2012 book "Concussions and Our Kids," Boston University neurosurgeon Robert Cantu left little mystery about his tome's intended target: The photo on the cover shows a pack of little kids playing tackle football. Inside its pages, a section heading says: "No tackle football before fourteen."
As the Super Bowl approaches Sunday, this point of view has become an increasingly trendy one. The talk in New Orleans this week, even by some players, has revolved around whether this collision-centric sport can survive without drastic change. And a growing number of people inside and outside the sport are pushing the debate toward children. "If I had a son," President Barack Obama told the New Republic this week, "I'd have to think long and hard before I let him play football."
Recent studies performed on former longtime NFL players have left no doubt that playing professional football can be hazardous to one's brain—and one's future quality of life. But when it comes to the question of whether the sport is dangerous for kids, it's not that the evidence is inconclusive—there's no evidence whatsoever.
The Mayo Clinic has performed two studies on football and kids. In 2002, after examining 915 football players from elementary and middle schools, it concluded: "the risk of injury in youth football does not appear greater than other recreational or competitive sports." Last year, the Mayo Clinic studied 438 men who played high-school football between 1946 and 1956, when headgear was less advanced. That study found no increased risk of dementia, Parkinson's disease or Lou Gehrig's disease among these players compared with their non-football-playing male classmates.
The lack of data isn't a secret: In his book about kids and concussions, Cantu, the neurosurgeon, acknowledged that there aren't enough data to say anything about the long-term effects of football on "these little ones."
When Baltimore Ravens quarterback Joe Flacco was asked about the issue this week, he took a different view than many other experts and observers. "They're a bunch of 50-pound or 140-pound kids," he said. "I don't know how much damage they're actually doing to each other."
Kevin Guskiewicz, director of the University of North Carolina's Matthew Gfeller Sport-Related Traumatic Brain Injury Research Center, said the "vast majority" of kids playing in youth football leagues aren't going to have the type of exposure to injury NFL players have. "If you're looking at Junior Seau's situation," Guskiewicz said, referring to the NFL star who recently committed suicide, "he was off the charts in terms of exposure" to head injuries. "He shouldn't be used to compare to the average person."
At the elite levels of sport, head injuries have been a worry for many decades. Studies done on the donated brains of ex-boxers, football players and hockey players—many of whom suffered depression—have shown serious damage can be done by repeated blows to the head. But in the last three years, the debate about football has veered from the dangers facing the pros to the impact on kids.
In October, 2010, NFL commissioner Roger Goodell spoke at a "Keep Youth Sports Safe" conference. He said the league will support laws that bar young athletes from returning to play too soon after a concussion. "The NFL believes we can make sports safer than they are today," he said. The league also worked with the Centers for Disease Control and Prevention to create posters to educate kids on concussions.
That December, former NFL wide receiver and sportscaster Cris Collinsworth drew a lot of attention when he said publicly that he had doubts about whether his children should play football. Last year, former NFL quarterbacks Terry Bradshaw and Kurt Warner went further, saying they wouldn't want their kids to play. Also last year, Tom Brady Sr., the father of NFL star Tom Brady, caused a stir when he said he would be "very hesitant" to let his son play.
Researchers at Boston University's Center for the Study of Traumatic Encephalopathy, where Cantu is a co-director, performed a December 2012 study of 85 brain donors who had played football. It found that some people who never played above the college and high-school level also had signs of the disease. "You can have it at the high-school level, no question," Cantu said in an interview.
Stefan Duma, a Virginia Tech professor who is studying the issue, said it would be "incorrect" to rely too much on small pools of brain donors whose families may have suspected there was something amiss. "There is just so little data," to work with, he said.
There is some research in the works. Researchers are now putting sensors in the helmets of young players to analyze how many hits they take during football games and how forceful they are. Duma, along with researchers at both Virginia Tech and Wake Forest, is conducting a long-term study of how hits to the head affect 119 young football players. Still, Duma said, it may take as many as 20 years to reach a firm conclusion.
Meanwhile, Guskiewicz, the North Carolina expert, encourages children to continue playing contact sports to help them develop proper technique for later years. He worries that football concerns will outweigh those of issues like childhood obesity and diabetes. "If we flat-out begin to eliminate these sports, we're going to run the risk of taking steps backward," he said.
None of this seems to be reducing football's popularity. NFL games accounted for 31 of the 32 most-watched TV shows this past autumn, and the Super Bowl once again is expected be the year's most-watched program.
A spokesman for Pop Warner, the nation's largest youth-football organization, said it had 250,000 tackle-football players in 2011 and that participation hasn't had a year-over-year decline since 2003.
According to the National Federation of State High School Associations, more than 1.1 million high-school boys played contact football in the 2011-2012 school year, which makes the game nearly twice as popular as the No. 2 prep sport, outdoor track and field. Participation for high-school football was 1.1 million last year, a decline of 1.2% from 2007-08.
"You know that you have to tackle and you may get hit," says San Francisco 49ers linebacker NaVorro Bowman. "That's a choice I made as a child and I'll let my children make their choices."
A version of this article appeared February 2, 2013, on page A11 in the U.S. edition of The Wall Street Journal, with the headline: The Football Nanny State.