By Lindsey Tanner
The Associated Press

CHICAGO - Instructions for installing child safety seats in cars are written in language too difficult for many adults to understand, researchers say.

Such manuals are written at a tenth-grade reading level on average, according to a new study, while data suggest that nearly a quarter of U.S. adults read at or below a fifth-grade level, and at least 25 percent read at about an eighth-grade level.

The findings are cause for concern because motor vehicle collisions are a leading cause of death and injury for infants and children. About 80 percent of car safety seats are improperly installed or misused, the study found. The study, appearing todayin the March issue of Pediatrics, was conducted by Dr. Mark Wegner and Deborah Girasek at the Uniformed Services University of the Health Sciences in Bethesda, Md.

The Juvenile Products Manufacturers Association, which represents car-seat makers, disputed the findings. But Joe Colella of the National Safe Kids Campaign, an advocacy group that works with manufacturers on child-safety issues, said most are aware of the problem.

For liability reasons, lawyers usually are involved in writing installation instructions, and legal jargon might make instructions sound confusing, Colella said.

Car-seat makers "have made us aware they're going to rewrite most of their instructions" to make them more readable, he said.

Girasek said manufacturers could help by writing installation instructions at a fifth-grade level, which literacy experts say is optimal for understanding health-related information.

Simplifying car-seat design and installation also might be beneficial, but that would be more costly, Girasek said.

Reading difficulty was tied to the number of words with three or more syllables appearing in 10-sentence samples.