The risks of distracted driving were greatest for newly licensed teen drivers, who were substantially more likely than adults to be involved in a crash or near miss while texting or engaging in tasks secondary to driving, according to the researchers from the National Institutes of Health and Virginia Tech Transportation Institute in the US.
"Anything that takes a driver's eyes off the road can be dangerous," said study co-author Bruce Simons-Morton, of the Eunice Kennedy Shriver National Institute of Child Health and Human Development, the NIH institute where the study was conducted.
"But our study shows these distracting practices are especially risky for novice drivers, who haven't developed sound safety judgement behind the wheel," Simons-Morton said.
The study analysed video from cameras installed in the cars of about 150 drivers in the Washington, DC, area and in southwestern Virginia.
About one-quarter of the drivers were novices, having had their license for no more than three weeks. The remaining drivers had, on average, 20 years of experience and ranged in age from 18 to 72.
Experienced adults were more than twice as likely to crash or have a near miss when dialling a cell phone as when they did not dial and drive, but did not have an increased risk while engaging in other tasks secondary to driving.
However, the researchers found that distracted driving substantially increased the risks for new drivers.
Compared to when they were not involved in secondary tasks, novice teen drivers were eight times more likely to crash or have a near miss when dialling, seven to eight times more likely when reaching for a phone or other object, almost four times more likely when texting, and three times more likely when eating.
Talking on a cell phone did not increase risk among the adult or teenage drivers.
However, because talking on a cell phone is preceded by reaching for the phone and answering or dialling - which increase risk greatly - the study authors concluded that their results provide support for licensing programmes that restrict electronic device use, particularly among novice drivers.
The study was published in the New England Journal of Medicine.