NEW YORK (Reuters Health) - For small- and large-stature adults, automobile airbags may do more harm than good, new research indicates.

A detailed look at crash data spanning 11 years for over 65,000 front seat passengers found that while airbags are "modestly" protective for people of medium stature (5 foot 3 inches to 5 foot 11 inches), they appear to increase the risk of injury to people smaller than 4 foot 11 inches and taller than 6 foot 3 inches.

Dr. Craig Newgard of Oregon Health and Science University, Portland, reported the findings Wednesday at the Society for Academic Emergency Medicine meeting in Chicago.

"There's been a lot of interest in airbags for the last 10 to 15 years," Newgard noted in a pre-meeting interview with Reuters Health. "Airbags are designed to be a protective mechanism for automobiles but as the years have gone on and we've gained more insight we know that certain groups of people are at risk of injury rather than have a benefit from them."

"That's pretty well established in kids and there have been some small case reports to suggest that maybe small stature adults are also at risk but it's never really been demonstrated conclusively," Newgard said.

He and colleagues took a more rigorous look at this issue in their study, asking the question: "Among adult occupants in the front seat (both drivers and passengers), does body size (both height and weight) seem to correlate with risk of injury from an airbag as opposed to having a protective benefit?"

Among 52,552 drivers and 14,732 front-seat passengers involved in motor vehicle crashes over the 11-year study period, 2.5 percent of drivers and 2.6 percent of passengers were seriously injured

The data suggest, Newgard said, that "both small-stature and large-stature occupants look to be at increased risk of injury from the airbag rather than having a benefit."

Body weight was not a contributing factor to injury rates. This is a potentially important observation, given that many "smart" airbags use body weight to determine how the airbag deploys.

Based on the study findings, Newgard offers the following advice: "For passengers, if you happen to be tall or small stature and you have a choice, riding in the back is probably a smarter choice not only from the airbag issue but there is a lot of other research that suggests that the backseat is a safer place.

For drivers, there are fewer options. "For those either small or tall drivers, the current recommendations are to try to sit as far away from the airbag -- at least 12 inches," Newgard said. "But probably what needs to happen is to allow people fitting those statures to have an airbag on/off switch installed in the vehicle.