Maybe of interest here?
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"Three times as many children have tried e-cigarettes as have smoked tobacco, according to official figures.
It has reinforced concerns that using the devices could become a "gateway" to smoking cigarettes.
The study found 6% of 10 to 11-year-olds in Wales said they had used e-cigarettes, compared to 2% who had smoked tobacco."
There's plenty more in the news article, including a link to the full Childhood Exposure to Tobacco Smoke (CHETS) report.