Exposure to secondhand smoke can create symptoms of nicotine dependence in non-smoking preteens, according to a new study from Concordia University and the University of Montreal.

Published in the Oxford journal Nicotine & Tobacco Research, the study also found that tweens who repeatedly observe a parent, sibling, friend or neighbor consuming cigarettes are more likely to light up themselves as adolescents.

"Kids who see others smoking are more likely to take up the habit because they don't perceive cigarettes as unhealthy," says lead study author Simon Racicot, a PhD candidate in the Concordia University Department of Psychology and a member of its Pediatric Public Health Psychology Lab. "We found that kids who'd never smoked who were ex¬posed to tobacco use were more likely to hold positive beliefs about the killer habit. These are the kids who are more likely to start smoking as teenagers."

This new investigation builds on previous long-term studies examining the negative effects of being surrounded by smokers.

"To our knowledge, this is one of first studies to show how increased exposure to secondhand smoke leads to youth who've never smoked to report having symptoms of nicotine dependence, such as craving cigarettes and finding it hard to go without smoking," says Racicot.

Senior author Jennifer J. McGrath, a professor in the Concordia University Department of Psychology and director of its Pediatric Public Health Psychology Lab, says an estimated 60 per cent of children are exposed to secondhand smoke across North America.

"Greater exposure to smokers is largely associated with greater exposure to nicotine," she stresses. "Children exposed to the same amounts of secondhand smoke as adults absorb higher doses of nicotine. Early findings suggest that secondhand smoke exposure could possibly trigger addiction in the brain -- before kids actually start smoking themselves."

As part of the study, 327 sixth or seventh graders enrolled in French-language public schools were questioned about their smoking habits, the number of smokers in their entourage and the situations where they observed smoking. "Preteens who were surrounded by more smokers believed that there are greater advantages to smoking," says Racicot. "Therefore, smoking by parents, siblings, and friends increases risk factors for later smoking."

Participants also provided a spit sample to measure cotinine, a by-product of nicotine. Salivary cotinine provides an indicator of smoking over the previous one to three days. Because all the kids recruited to this study had never consumed cigarettes, negligible amounts of cotinine were found. In the next study, the researchers will measure nicotine samples from hair, which provides an indicator of smoking patterns over the last month.

The research team says new prevention efforts must be tailored to tweens who are highly exposed to secondhand smoke. The general public also needs to be educated on how smoking around youth normalizes a dangerous habit.

"When it comes to smoking around kids, the best thing a parent can do is to avoid exposing their kids to cigarettes and to secondhand smoke," says Racicot. "A parent should step outside of their home or car to smoke. And the addictive habit should remain out of sight, out of breath and out of mind."