It’s a familiar sight at bus stops and in schools: students schlepping around, bent over by backpacks stuffed with textbooks, notebooks, lunches, musical instruments and other school supplies.

While students may consider heavy backpacks just a pain in the neck and part of the school day, medical experts view them as a health concern.

“Shoulder and back pain are common complaints, more so among middle and high school students,” said Marcia Statz, a South Whidbey School district nurse. “They seem to have more to carry and less passing time between classes.”

Some students in high school carry as much as 40 pounds on their backs in order to save time moving between classes. Students say there is not enough time to make it back to their lockers during the few minutes of passing time, forcing them to carry everything they need for the school with them.

“Passing time is an issue for me,” said Orson Ossman, a freshman at South Whidbey High School. “I carry at least three binders, three textbooks and all the other supplies I need with me all day.”

Students have eight minutes of passing time between first and second periods, three minutes between year-long daily courses, and six minutes between third and fourth periods.

“There just isn’t time to go to your locker between every class,” Ossman said.

Dr. Robert Sleight, a Langley chiropractor, is familiar with the health consequences of carrying heavy backpacks. He said students are vulnerable to injury during growth spurts. Carrying the heavy packs can cause undue stress on a child’s bone structure and may do permanent damage.

Sleight said he can see problems developing by observing how children stand and walk, and by checking for curves in the spine. Aberrant curves can develop through too much stress. Sleight said carrying a heavy backpack can even shorten a student’s leg.

“I see a lot of kids with problems associated with heavy backpacks.” he said. The problems can be corrected with treatment, chiropractic adjustment and muscle strengthening, Sleight said. But even with these precautions, parents need to keep an eye on their children’s growth.

“My advice to parents is measure your child on a door jamb for radical height changes one-half to two inches,” he said. “If they are using a heavy backpack at this time, they might be in trouble.”

Unfortunately, Sleight said, there is no rule of thumb about how much weight is appropriate for a student.

“A linebacker may be able to handle a 40-pound pack all day, but a 100-pound girl would suffer,” he said. “Parents should ask themselves if their student is in good enough condition to support the backpack they have.”

At school, nurses are also keeping an eye on students’ skeletal health. South Whidbey school district nurses do annual scoliosis screenings, which help detect problems.

“The screening helps us see if there is a problem beginning to develop,” Statz said.

Several factors appear to be at issue when it comes to overly heavy backpacks. One is the passing time between classes, while another is the shortage of lockers at some schools and just the hassle of getting a locker assigned at others.

Having a locker at high school is a choice for students, but there are still not enough for the number of students enrolled. High school Principal Mike Johnson said his building has 595 lockers to give out to 782 students.

Approximately 287 high school students have yet to sign up for a locker; 110 are still available. The school does “double up” students in lockers, Johnson said, if there is a need.

All Langley Middle School students were assigned lockers during home room meetings on the first day of school. All sixth graders have lockers in the sixth grade wing, while seventh- and eighth-grade students have their lockers in the school’s main hall. Passing time is four minutes between all classes, except for physical education classes, for which there are eight minutes.

Despite the risk of injury, South Whidbey school staff generally do not counsel students on backpack weight. And it is unlikely, according to school administrators, the schools will lengthen passing times: To do so would lengthen the school day and affect the district’s bus schedules.

The schools are not the only parties that probably will not make changes over the issue. Students are also resistant to a solution available to them — backpacks on wheels. Much like rolling luggage at the airport, these packs reduce back strain from books and school supplies but, according to student Ossman, they are definitely not cool.

For this reason and others, Sleight said there is little to be done about the loads students carry through the day. Backpacks are here to stay.

“They are part of our culture,” he said.