SMOKERS may huff about their rights to indulge their puffing habit, but they could be harming those around them even more than we thought. Inhaling passive smoke may physically prime some children to become smoking addicts later in life.
There is already growing evidence that second-hand smoke is not only harmful in itself, but that watching peers and parents light up teaches children to become smokers. Now Margaret Becklake, an epidemiologist at McGill University in Montreal, and her colleagues have found tantalising evidence of a more insidious effect.
They studied 191 boys and girls. On their first meeting, the children were an average age of 9.2 years. The researchers visited each child鈥檚 home and asked parents questions about how many people smoked in the household, and how many cigarettes they smoked, along with other questions such as income levels. They also measured the children鈥檚 lung capacity, took samples of their saliva to test for a breakdown product of nicotine called cotinine, and enquired whether the youngsters smoked.
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鈥淭he more nicotine a child had absorbed by around the age of 9, the more likely he or she was to become a smoker鈥�
Some years later, when the children were an average of 13 years old, the researchers contacted them again. By this time, 44 per cent had begun to smoke. Most had already gone through puberty, which is strongly linked to the uptake of smoking. But when physical development, income levels, and amount of smoke in the home were all accounted for, one final factor remained as the sole predictor of which children would start smoking as teenagers: the levels of cotinine found in their saliva when they were children (Canadian Medical Association Journal, vol 173, p 377).
That means the more nicotine a child had absorbed from passive smoking at around the age of 9, the more likely he or she was to become a smoker. Among pre-pubertal children surveyed a second time, high cotinine levels four years earlier doubled their chances of becoming a smoker. 鈥淗aving absorbed the nicotine is associated with wanting to take up cigarettes,鈥� says Becklake. She cautions that the study was small and not initially designed to explore this question, but is confident that the findings have revealed a real effect.
