The findings of a joint study from nine Canadian institutions suggest that exposure to second-hand smoke may be associated with an increased risk of children experiencing nicotine dependence symptoms, even though they had never smoked. The study is published in the September edition of the journal Addictive Behaviours.

Highlighting the importance of public health programs that promote non-smoking in the presence of children, the researchers said their findings confirm the results of previous studies, which said that exposure to second-hand smoke might lead to several nicotine withdrawal symptoms, including trouble sleeping, anxiety, depression and trouble concentrating.

It is known that in families where at least one parent smokes, children have a level of cotinine (a toxic metabolite of nicotine) five times higher than normal. The level of cotinine in the blood is proportionate to the amount of exposure to tobacco smoke, so it is a valuable indicator of tobacco smoke exposure, including secondary smoke.

The researchers looked at students age 10 and 11 from 29 Quebec schools. Participants were asked to complete questionnaires on their health and behaviour, including questions about symptoms of nicotine dependence and exposure to second-hand smoke.

The researchers were surprised to see evidence of in children as young as 10, even though they had never smoked. The dependence was related to second-hand smoke. “Our study found that 5 percent of children who had never smoked a cigarette, but who were exposed to secondhand smoke in cars or their homes, reported symptoms of nicotine dependence,” said Mathieu Bélanger, the study’s lead author. Children are at significant risk to develop many acute and chronic diseases as a result of second-hand smoke exposure.

According to recent statistics, 53,800 people die every year from second-hand smoke exposure.

“These findings support the need for public health interventions that promote non-smoking in the presence of children, and uphold policies to restrict smoking in vehicles when children are present,” the researchers concluded.