CHICAGO — Eric Field was on his skateboard last August, holding onto the back of a friend's car, when the wheels on his board gave out and he flipped over.

Without a helmet, Field, 15, suffered a subdural hematoma, four skull fractures and a bruised brain. He was unconscious for two weeks but suffered no brain damage. He quit skateboarding.

"Whenever we would buy him the knee pads or elbow pads, they'd last for a day or two and then he'd put them away because he wouldn't see anyone else wearing them," his mother, Sharon Field, said.

More than 65,000 children younger than 15 received treatment in an emergency room for skateboarding-related injuries in 2006, according to estimates presented Wednesday by the U.S. Consumer Product Safety Commission. In an effort to promote safety, the agency released data on sports-related injuries incurred by kids younger than 15.

The authors, extrapolating from a sample of 100 hospitals across the nation, estimate nearly 240,000 kids 14 and younger were treated for bike-related accidents, the highest number for any sport.

Football resulted in about 221,000 injuries for that age group, baseball almost 85,000 and operating unpowered scooters just over 37,500.

"We wanted to make the point that with any outdoor activity, parents need to be thinking about safety as well as the activity itself," said Nancy Nord, acting chairman of the commission. "Parents should not send their kids out to bike, roller blade or scooter without helmets, wrist guards, elbow pads or whatever is appropriate for their sport."

The data are significant not only because of the risks for kids, but the costs to society, experts say.

"Injury is arguably the most compelling public health problem facing youth in this country because it is the leading cause of death and acquired disability from ages 1 through 44 years," said Gary Smith, director of the center for injury research and policy at Nationwide Children's Hospital in Columbus, Ohio. "For the age group they presented, sports and recreation is a very important piece of the injury picture."

Experts estimate that more than 30 million children participate in sports each year in the U.S. About 3 million children ages 14 and younger get hurt annually participating in recreational activities, according to the American Academy of Orthopedic Surgeons.

Seventy percent of the kids involved in bicycle accidents are male. Injuries to the face and head are typically the most serious, and a frequent result of bike accidents. Wearing a helmet while cycling can reduce the risk of serious head injury by 85 percent, according to a study in the New England Journal of Medicine.

The new commission report also documents 77 deaths related to bicycles in children younger than 15 in 2004, compared with 149 who died in accidents involving all-terrain vehicles, the data show.

Skateboards were involved in four deaths, and unpowered scooters and football resulted in two deaths each for the same age group.

Experts are quick to note, however, that the risk of keeping children indoors and discouraging them from participating in sports outweighs the risks of sport-related injury.

"It's so important for our children to be active rather than sitting in front of a flat screen TV or video game that some relatively minor risk is worth taking," said Dr. Angela Davis, an orthopedic surgeon at the Children's Hospital of Philadelphia. "The minor risk of a broken wrist is worth (avoiding) the later risk of diabetes."

Parents can reduce risks by encouraging proper sporting techniques and making sure children use safety equipment such as bike helmets, Davis said.

Still, one challenge is the culture of certain sports in which helmets and protective gear are ridiculed.

While the CPSC data has bicycling ranked as the sport requiring the most emergency rooms treatments, researchers say the data can be misleading.

Football is seasonal, while people can bike year-round. Furthermore, more people ride bikes than play football.

Other experts said that because some patients opt not to visit the emergency room or seek medical attention at all, the figures could be skewed.

Lanier Johnson, executive director of the American Sports Medicine Institute, said that on game nights his hospital sets up Friday night football clinics, where athletes can go straight to the sports medicine facility instead of the emergency room.

"That's not unusual, where you have very well organized sports medicine facilities," he said. "I'm guessing those injuries could be underreported."