Talking on a cellular telephone while driving quadruples the risk of having an accident, making it as dangerous as driving while legally drunk, Canadian scientists reported today.
The first large study of the wireless phones, which number 34 million in the United States, also found, to the authors’ surprise, that so-called hands-free phones are no safer to use in a car than conventional handheld phones.
“This may indicate that the main factor … is a driver’s limitations in attention rather than dexterity,” said Dr. Donald A. Redelmeier of the University of Toronto.
But the good news, he added, is that if you do have an accident, the cell phone makes it much easier to get help.
Surprisingly, the authors of the report, which appears today in the New England Journal of Medicine, are not recommending bans on using the phones while driving.
“Our study is not about the role of regulation but about the role of individual responsibility,” Redelmeier said. “Our role is to inform the debate (over cell phone safety), not to dominate the discussion.”
An editorial in the same journal by Dr. Malcolm Maclure of the Harvard University School of Public Health and Dr. Murray Mittelman of Beth Israel Deaconess Medical Center said the research is “the first direct evidence that the use of cellular telephones in cars contributes to roadway collisions.”
“No insurance company would be surprised by (the findings),” said Steven Goldstein, director of public relations for the Insurance Information Institute, which represents several large insurance companies. “Handheld cell phones should not be used while you are driving anymore than you should turn around while you are on the interstate to reprimand your child in the back seat,” he said.
However, a spokesman for the Cellular Telecommunications Industry Association cautioned that the study shows only an association between talking on the phone and accidents, not that talking on the phone actually causes accidents. But even the association cautioned against using the phones while driving.
“When you are behind the wheel, your most important responsibility is safe driving. Period,” said the association’s Tim Ayers. “It is not using a phone or drinking coffee or reading a map or combing your hair.”
Redelmeier and statistician Robert J. Tibshirani studied 699 accidents in Toronto over a 14-month period in 1994 and 1995. None of the accidents involved serious injuries. In each case, they used telephone company records to determine whether the driver was using a cellular phone during or immediately before the accident.
For controls, they used the same drivers, examining their phone records from the day preceding the accident. This type of “crossover study” is the scientific way of asking: “Did anything unusual happen to you immediately before the event being studied?” in this case, the collision.
Overall, the researchers found that people using a cellular phone were 4.3 times as likely to have an accident as other drivers. Those using handsfree phones were 5.9 times as likely to have an accident, but the number of such drivers was too small for the difference between accident rates using hands-free and hand-held phones to be statistically significant. The researchers did not examine other potential causes of inattention.
For comparison, Redelmeier noted that driving with a blood alcohol level at the legal limit also causes a four-fold increase in risk. But a blood alcohol level 50 percent above the legal limit gives a tenfold increase.
The use of phones while driving has been controversial ever since they were introduced. Both simulations and real driving experiments have shown that such calls slow reaction times by a half-second or more.
Placing a call was found to be no more distracting than tuning a car radio or engaging in an intense conversation, early studies found, but it made steering more imprecise, especially in city traffic.
As a result of earlier studies, Brazil, Israel, Switzerland and two states in Australia have banned the use of hand-held phones while driving. Some other countries, such as Germany, are considering such action.
But few in the United States are arguing for such a law.
The insurance industry also doesn’t support a ban. “What we support is responsible driving,” Goldstein said. Cellular phones “serve an important purpose,” he added. “If they are used for safety, they can make the difference between life and death.” An estimated 18 million emergency and 911 calls are made from cellular phones each year in the United States.