SANTA CLARA -- Brent Jones played 11 seasons for the 49ers, won three Super Bowls and at age 34 might have had a few good years left in his career. But the tight end decided to retire because he worried about the effect of eight diagnosed concussions on his life after football.

He still worries nearly 16 years later.

"The thing that scared me the most: Is there a point that pushes you over the gray line?" said Jones, now 50, about when concussions can lead to brain damage. "They didn't know what that was then, and remarkably we still don't know."

Finding those answers is why Jones and former teammate Ronnie Lott will join some of the country's leading brain-injury experts Thursday at a Santa Clara University symposium that will examine the crisis of head trauma in sport. Santa Clara's Institute of Sports Law and Ethics assembled a powerhouse group of speakers to address arguably the biggest issue in sport today.

The conference comes just weeks after the NFL settled a lawsuit with thousands of former players and at the start of a new football season when fans are gaining an acute awareness that the bone-crunching hits they enjoy watching also can leave devastating, long-term brain impairment.

"People are starting to look at the game differently because we're seeing the damage," said UC Berkeley's Dr. Cindy Chang, one of the featured panelists. After celebrating a big hit, she added, fans are "then realizing 'Hey, maybe I shouldn't be cheering.' "

The conference will focus on what can be done to make a range of sports safer -- from football to soccer and hockey, and from the youth leagues to the pros.

"People are asking themselves now, 'Am I a bad parent for letting my kid play peewee football?' " added Chang, the U.S. team's chief medical officer at the 2012 Summer Olympics.

Even so, it's clear that football's popularity -- from youth leagues to the NFL -- has not been hurt by a growing body of research that links concussions to brain damage. The Wall Street Journal recently reported that the league will break the $10 billion mark in revenues this year, and the NFL's network partners are bragging about the huge ratings from last weekend's opening of the season.

The growing question is the cost for the modern-day gladiators on the field.

In late August, the NFL agreed to pay $765 million to settle with 4,500 retired players who said they had developed dementia and other brain disorders caused by the game's inherent violence. But the agreement included no admission from the league that it had concealed the risks of head injuries, which the players had claimed.

Despite the settlement and media spotlight on head injuries, many football fans believe the issue has been overblown. And the conference organizers see that resistance as both a challenge and opportunity.

"I would love it if people come who think (this) is the global warming of athletics, a contrived thing to get people grant money," said Mike Gilleran, executive director of the Santa Clara University Institute of Sports Law and Ethics, which is hosting the conference. "In our case, the more sunshine, the better. We live not knowing what the NFL knew and when they knew it."

Pro football is bracing for the upcoming book, "League of Denial: The NFL, Concussions and the Battle for Truth," written by ESPN reporters Mark Fainaru-Wada and Steve Fainaru, who are scheduled to speak at the conference. Already the book has triggered some controversy as ESPN has withdrawn from its collaboration with PBS' Frontline for a two-part program in early October, timed to the publication. The league has denied charges that Commissioner Roger Goodell pressured the network to drop out of the project.

Meanwhile, many former players such as ex-49er George Visger are upset with the settlement terms.

"No one I've spoken to is happy," said Visger, a member of the 49ers' 1982 Super Bowl team. "It's PR. Just crunch the numbers and it comes out to something like $730 a month (per person). They didn't even accept responsibility. It's all about the love of money and not the human carnage."

When the settlement was announced last month, Goodell described it as the best outcome for both parties.

Visger, a former defensive lineman, has to write everything he does in notebooks because he quickly will forget it. He has lost his house, his environmental consulting business and is 100 percent disabled with frontal lobe dementia.

Visger, 54, recently moved to Southern California for treatment while his wife and their two younger children stay with family in Sacramento.

"My wife is so angry," he said. "She was saying the other day, 'I hate the NFL. I hate what it's done to my family.' You know, I expected to be injured. I expected to have knee, ankle and shoulder problems. But I never expected to not be able to remember the last 20 years of my life."

While concussion talk has centered on the NFL, the issue trickles down to every level of sport. Gilleran, a former West Coast Conference commissioner and NCAA investigator, discovered that when he and his wife pulled their son from football after he suffered from a concussion.

"But then what?" Gilleran asked. "The fallback is soccer and as we learn more, soccer is not a safe haven. The media have focused on football and not so much other sports. We need to learn more about that."

Dr. Robert Cantu, another conference panelist, said parents need to be aware of the dangers of all collision sports. Research shows how repetitive, "sub-concussive" blows can have a cumulative effect on the brain even when no concussion ever is diagnosed.

"Adults can do what they want to do if they understand the risk, but youngsters really don't have informed consent," said Cantu, author of "Concussions and Our Kids." "I want our youth to play sports, but I don't want them banging heads. I want to take heading out of soccer, full-body checking out of hockey and tackle-football away until you're in high school."

But just how much contact is relatively safe remains subject to debate even among experts.

"No, you're not a bad parent," Chang said of those who choose to let their kids play football, "but only if you are educated, your child is educated and your coach is educated."

Contact Mark Emmons at memmons@mercurynews.com and Elliott Almond at ealmond@mercurynews.com.

Sports concussions: Problems and Proposed solutions
What: Fourth Annual Sports Law and Ethics Symposium
Where: Locatelli Center, Santa Clara University
When: Thursday from 9 a.m. to 6 p.m.
Featured speakers and panelists include: Former 49ers stars Ronnie Lott and Brent Jones, soccer standout Brandi Chastain, Dr. Robert Cantu of Boston University's Center for the Study of Traumatic Encephalopathy, former head physician for UC Berkeley athletic teams Dr. Cindy Chang, University of Missouri law professor and youth sports expert Doug Abrams, New York Times writer Alan Schwarz, and the reporting team of Steve Fainaru and Mark Fainaru-Wada, authors of the upcoming book "League of Denial: The NFL, Concussions and the Battle for Truth."
If you want to attend: A limited number of walk-in registrations will be available at a cost of $175. Santa Clara University students can attend for free with valid ID. For more information, http://law.scu.edu/ai1ec_event/third-annual-sports-law-and-ethics-symposium.


Concussion Education Program
What: The California Concussion Coalition will hold free concussion training.
When: Tuesday from 7 p.m. to 8:30 p.m.
Where: Oakland's Skyline High School
Who: The program, sponsored by Kaiser Permanente, will be presented by Dr. Cindy Chang, Dr. Jean Hayward, neuropsychologist Eric Freitag and former 49er Ben Lynch. The California Concussion Coalition was founded by the Sports Legacy Institute, a Boston-based nonprofit organization founded to advance the study, treatment, and prevention of brain trauma in athletes.


Concussions by the Numbers
173,285: Number of sports-related traumatic brain injuries, including concussions, treated at U.S emergency rooms each year for youth 19 and under. The two leading sports are football and girls' soccer.
15: The percentage of concussions in all sports-related injuries suffered by high school athletes.
4,447: Number of former NFL players who have sued the league over head injuries.
35 million: Number of kids between ages 5 and 18 who participate in youth sports.
2.8 million: Number of kids between ages 6 and 14 who play in tackle football leagues.
Sources: The Centers for Disease Control and Prevention, the Washington Times, USA Football, National Alliance for Youth Sports, The American Journal of Sports Medicine
For more information about concussions, go to www.cdc.gov/concussion.