Liz Hook loved her L.L. Bean backpack so much that she carried it to high school every day, filled to the brim with books and school supplies.

But although she was at the forefront of fashion at her high school, the Weinberg sophomore may have been sacrificing her health.

“I had a sore back for four years,” she said. “My backpack often weighed up to 15 pounds, and I usually wore it on one shoulder.”

The U.S. Consumer Product Safety Commission reports that about 12,700 injuries between 1999 and 2000 were caused by backpacks. And a study published in the January 2003 issue of Pediatrics magazine said many backpack-related injuries affect areas other than the back.

A Cincinatti Children’s Hospital’s study examined 247 children and teens, aged 6 to 18, who were taken to the emergency room with backpack-related injuries. Only 11 percent of those injuries were to the back, while 22 percent were cuts to the head and face and 27 percent to the hand, wrist and elbow.

The study reported that only 13 percent of the cases had anything to do with wearing the backpacks. In 29 percent of the injuries, kids or teens tripped over their backpacks, and 13 percent were caused by kids being hit by backpacks.

Some chiropractors argue the Cincinatti study is inaccurate because it only looked at emergency room cases and did not take into account less serious injuries, like Hook’s situation.

“The study is a lack of education,” said Jerome McAndrews, the national spokesman for the American Chiropractic Association. “It’s a lack of education of the dynamics of the musculoskeletal system.”

McAndrews said many backpack carriers experience back pain and discomfort but only report it to their local doctors, or not at all.

“Lower-back pain is the second most common reason people see a general medical practitioner, and the third most common reason for surgery,” McAndrews said.

He said backpack misuse is a cause of lower back pain for many, especially students. According to the U.S. Consumer Product Safety Commission, a backpack should be worn with both straps.

“Wearing a backpack improperly over a continuous period could disrupt the natural alignment of the spine,” McAndrews said.

A backpack’s weight also can contribute to discomfort, he said. If it exceeds 10 to 15 percent of its wearer’s total body weight, it will cause stress on the musculoskeletal system, he said.

Various studies have shown that 30 to 50 percent of teens suffer from back pain or discomfort.

“A lot of it comes from postural issues,” said Evanston chiropractor Teel Miller. “But backpacks, larger purses, laptops and suitcases tend to cause lower-back injuries also.”

With new safety precautions in schools, some students don’t even have to worry about carrying a heavy backpack.

“In my high school, we weren’t allowed to take backpacks from class to class,” said Rodrigo Lopez, a Communication sophomore. “We carried our books, so I never had to worry about lugging around those 20-pound weights.”

Miller said backpacks are safe when used properly. A backpack should never exceed 20 percent of one’s body weight or be wider than a person’s torso, she said.

“If your body’s bent forward, the backpack is too heavy,” Miller said. “It’s as simple as that.”