Teens may underestimate their risk of dying in a car collision because they not only see themselves as invincible but also make faulty assumptions, Canadian researchers say.

Teenage drivers have the highest crash and fatality rates of any age group, despite injury prevention programs.

"Students need to comprehend that it is lack of judgment, not only lack of skill, that increases the risk of injury to oneself and others," said Dr. Najma Ahmed, assistant trauma director at St. Michael's Hospital in Toronto.

In the August issue of the Journal of the American College of Surgeons, Ahmed and her colleagues said they found teenagers consistently underestimated risks of driving, because they mistakenly assumed that:

• Vehicle and highway design were more likely to cause crashes than human error.
• Age and agility would allow them to overcome the effects of poor driving conditions or intoxication compared with more experienced drivers.
• Doctors would be able to save their lives and leave them unscathed.

Injury prevention programs at accredited hospital trauma centres are required to stress the risks of not buckling up regularly, speeding and drunk driving. But the researchers said these programs often fail to counter the flawed beliefs of teens, a gap they recommend filling.

To test what teens gained from injury prevention programs, the team evaluated 262 high school students who went to a one-day workshop.

Participants toured an intensive care unit and met a young person who had suffered a mild traumatic or spinal cord injury. All of them completed questionnaires before the program, and some were tested eight days afterward and 30 days later.

While those who attended were better able to identify safer options and were better at perceiving risks, the knowledge didn't seem to stick for a month, the researchers found.

Smoking bans at home effective for teens

As for other strategies for keeping teens healthy, a second study found that young people were less likely to experiment with cigarettes when their parents enforced smoking bans at home.

In the October issue of the American Journal of Public Health, Alison Abers of Boston University's School of Public Health and her colleagues said they came to the conclusion after interviewing more than 2,200 teens aged 12 to 17 in Massachusetts. The teens were followed for four years.

"These bans send a strong message to teens that it's not OK to smoke, and in the face of so many other external factors that may influence teens to smoke — peers, advertising — a home smoking policy is one thing that parents can control to some extent," said Mary Hrywna, manager of the tobacco surveillance & evaluation research program at the University of Medicine and Dentistry of New Jersey in Newark, commenting on the study.