A study of cellphone use by motorists suggests that they aren't any better off using a headset in the car than holding the phone to their ear: They're still four times more likely to end up in a crash and injured than if they weren't using the phone.
The survey, released Monday by the Insurance Institute for Highway Safety, said that using mobile phones while driving was just as dangerous whether they're chatting through a headset or holding on to the handset.
The statistical analysis, which compared phone records with the times of accidents, indicated that the risk was just as great across all age groups and in both sexes.
It's not just keying in phone numbers or calling up messages but the conversation itself that can be the most distracting, said Anne T. McCartt, the insurance institute's research executive overseeing the study.
"There's the possibility that some technology in the future would eliminate distractions from using the phone in the car, but it's hard to think of any way to eliminate the distraction from the conversation," she said. "Your brain can only perform so many tasks at once."
The American Insurance Assn., a Washington-based trade group for insurers, hailed the survey as a major advance in the emerging body of research on cellphone use by motorists.
"This study reinforces the fact that cellphone use is a major distraction and increases injury and death," said Julie Rochman, an executive with the group.
The research, to be published today in the British Medical Journal, drew on the experiences of about 500 drivers in Perth, Australia, who were treated in hospital emergency rooms after crashes from April 2002 to July 2004.
Using phone records, McCartt and researchers at the University of Sydney estimated the increased risk of injury by comparing the drivers' cellphone use as much as 10 minutes before their crashes occurred and at control intervals as much as a week earlier.
The institute had to go to Australia to conduct the survey because U.S. carriers would not permit a look at phone records to verify a driver's distraction at the time of a crash and to allow appropriate comparison periods.
McCartt said the city, with 1.3 million residents, was comparable to many U.S. cities. Western Australia also bans the use of cellphones while driving unless hands-free devices are used. Still, about a third of the crash victims interviewed, she said, had been holding phones to their ears.
The results could bolster the wireless industry's arguments against hands-free laws, or it could have the opposite effect of leading to bans on cellphone use altogether while driving.
"Based on our study, that would make some sense," McCartt said. "But it would be very hard to enforce a law like that."
The institute, a nonprofit research group funded by U.S. insurers, has not taken a position on any legislation.
A hands-free law, however, could at least help encourage drivers holding their cellphones to their ears to put them down, preventing some accidents, she said.
The proliferation of mobile phones -- the number of subscribers in the United States passed the number of land lines last fall -- has had profound effects on society. The prospect that air travelers may soon be able to call while flying, for instance, has many people upset because planes have been among the last bastions of freedom from cellphone chatter.
Cellphone customers spend more time talking on their phones while in their cars than anywhere else. Last year, they spent 40% of their time on mobile phones while driving, compared with 24% while in the home, according to an April survey of consumer habits by the Yankee Group, a Boston research firm.
The California Legislature is considering a law that would require motorists to use hands-free devices -- either headsets or new wireless technology that turns radios into temporary phones. A similar bill died in the Senate in the fall. And a bill to ban various driving distractions -- including smoking, eating and all cellphone use -- died in the Assembly.
"Clutching a cellphone to your ear means that in that split second in an emergency when you need both hands on the wheel, you won't have it. And that could be the difference between life and death," said state Sen. Joe Simitian (D-Palo Alto), the measure's sponsor.
Connecticut, New Jersey, New York and the District of Columbia have banned the use of hand-held cellphones while driving, mandating that motorists use headsets or other hands-free devices instead. So have Chicago and cities in five other states.
In New York, which passed the first such law in 2001, the insurance institute noted a 50% drop in motorists' use of cellphones, spokesman Russ Rader said. But over time, usage rose to nearly where it was before as drivers ignored the $100 fine.
Federal bills in 2001 and 2003 didn't make it out of committees.
Mobile phone carriers and the wireless industry, through the Cellular Telecommunications and Internet Assn., have opposed any laws singling out mobile phones.