Posted on May 15, 2001 at 11:20 a.m.

BIRMINGHAM, AL — Older children who have outgrown booster seats but have not yet reached normal adult size may be at risk for severe injury in an automobile crash when restrained by some seat belt systems, according to a new study by researchers at UAB’s (University of Alabama at Birmingham) Injury Control Research Center (ICRC). The study indicates a gap in protection for adolescent passengers when placed in some 3-point belts with fixed shoulder belt anchorage points.

“Boys on average don’t reach the adult male seated height position on which seat belts are designed until age 15, and the average girl never reaches this height,” says Martha Bidez, Ph.D., senior scientist at the ICRC. “Size-appropriate restraint designs are needed in all positions where children may be seated.” In a recent report to the 2001 World Congress of the Society of Automotive Engineers, Bidez reported:

• Shoulder belts with fixed upper anchorage points, which are typical in the rear occupant space, may ride across a child’s torso in such a way to allow the child to roll out of the shoulder belt during some frontal collisions.
  
  
• Belt trajectory that passes across the neck of an older child may create an artificial fulcrum in the cervical spine resulting in quadriplegia.
  
  
• Long lengths of seat belt webbing, sized for large adult males, allow children too much space to move about during a crash, leading to violent rebound and the possibility of head injury from contact with dashboards or the rear of the front seat.
  
  

“There is a height and weight threshold that a person must reach before they can be safely positioned in a 3-point restraint system,” says Bidez. “But since children grow at different rates, there is a potentially dangerous gap between the age when children are deemed to have outgrown booster seats and before some reach that minimum threshold. We must design seats and seatbelts that can adapt to fit that ‘forgotten child’.”

The American Academy of Pediatrics recommends that a booster seat be used when the child has outgrown a convertible safety seat but is too small to fit properly in a vehicle safety belt. But a 1996 National Highway Traffic Safety Association report found that only 6.1 percent of booster seat weight children (40-60 pounds) were restrained in a booster seat.

Bidez says further injuries may be prevented through aggressive legislation at the state level and modification of car design, including seat belts, so that belts fit both adults and children.