Electronic cigarettes (e-cigs) are once again the butt of some negative press following the publication of two new studies this week.

New research published in BMJ Open shows that e-cig use is more common among under 15s than tobacco.

The research, which was carried out by Cardiff University on behalf of the Welsh Government, used data from two national surveys undertaken in 2013-14 among primary and secondary school pupils.

It found that 6% of 10-11 year olds had tried an e-cig, compared to 2% who had tried tobacco.

Meanwhile, 5% of children who had never smoked tobacco said they had tried an e-cig – rising to 8% at age 15-16.

However, only 1.5% of those aged 11-16 said they used e-cigs regularly (defined as at least once a month) and the odds of regular e-cig use were 100 times higher among current weekly smokers than among non-smokers, and 50 times higher among those who had smoked cannabis.

The age limit for selling e-cigs will rise to 18 on October 1 this year.

Meanwhile, a second study published in the journal Tobacco Control claims that the levels of chemicals used to flavour some brands of e-cig fluid exceed recommended exposure limits and could be respiratory irritants.

Researchers tested a sample of 30 products including two single use disposable brands in five different flavours of tobacco, menthol, vanilla, cherry and coffee; the same flavours in refill bottles; and additional flavours of chocolate/cocoa, grape, apple, cotton candy and bubble gum in refill bottles.

Six of the 24 compounds revealed in the analyses were aldehydes, compounds recognised to be primary respiratory irritants, the study said.