E-cigarette devices could be releasing higher amounts of two toxic chemicals when they get warm, experts have warned.
Dangerous levels of 31 harmful chemicals can be inhaled from the devices – including two carcinogens that were previously unknown to scientists.
New research has found propylene oxide and glycidol are both emitted during every puff of an e-cigarette.
And older gadgets could be more damaging to someone’s health than newer ones in terms of their emissions.
Dangerous levels of 31 harmful chemicals can be inhaled from e-cigarettes – including two carcinogens previously unknown to scientists
It follows a rapid rise in the use of e-cigarettes in recent years, especially among smokers trying to cut down or quit.
The gadgets deliver a nicotine hit by heating a nicotine-containing propylene glycol (e-liquid) to create an aerosol (usually called ‘vapour’), which is inhaled.
Chemicals such as acrolein and formaldehyde are released when e-liquids inside the devices are heated up.
But researchers estimated e-cigarettes emit up to six times less of acrolein – which can severely affects the lungs and eyes – than ordinary cigarettes.
And scientists warn the heat of the device could be a factor in determining how many chemicals the body consumes during each puff.
They also found emission levels of aldehyde – a chemical linked to some forms of cancer and heart disease – increased by 60 per cent in a device that had been used more frequently.
But experts from the Lawrence Berkeley National Laboratory warn the results don’t mean e-cigarettes are safe to use at lower temperatures.
Study author Hugo Destaillats said: ‘Advocates of e-cigarettes say emissions are much lower than from conventional cigarettes, so you’re better off using e-cigarettes.
‘I would say, that may be true for certain users – for example, long time smokers that cannot quit – but the problem is, it doesn’t mean that they’re healthy.
‘Regular cigarettes are super unhealthy. E-cigarettes are just unhealthy.’
And he said their findings could be valuable to manufacturers and regulators seeking to minimize the health impacts of the increasingly popular devices.
But researchers estimated e-cigarettes emit up to six times less of acrolein – which can severely affects the lungs and eyes – than ordinary cigarettes
He added: ‘Understanding how these compounds are formed is very important.
‘One reason is for regulatory purposes, and the second is, if you want to manufacture a less harmful e-cigarette, you have to understand what the main sources of these carcinogens are.’
The study, which was published in Environmental Science & Technology, decided to test the safety of heating on inhaling two common chemicals found in e-cigarettes.
The health benefits of e-cigarettes have been dealt a blow by a study which warned they are a ‘gateway’ to tobacco and cigarettes.
Manufacturers and health experts have suggested vaping can cut smoking by persuading people to switch from cigarettes.
But evidence indicates many people who had never smoked are experimenting with e-cigarettes.
Researchers said around 1.5 per cent of secondary school pupils reported vaping in the past 30 days in 2011, four years after the devices first went on sale.
By last year this had soared to 16 per cent – or one in six pupils.
Just under a fifth – 19 per cent – of 17-18-year-olds admitted smoking in the past 30 days in 1995, dropping to nine per cent by 2004.
In 2014 the figure had only fallen to just eight per cent.
But the data also showed when cigarettes and e-cigs were combined, 14 per cent of pupils had used one or the other in the previous month.
Dr Jessica Barrington-Trimis, a research associate at the University of South California and lead author of the US study, warned vaping was ‘eroding the progress made over the last several decades in tobacco control’.
Experts simulated vaping using three types of e-liquids in two different devices operated at different battery power settings.
One device was considered cheap and had one heating coil, while the other was slightly more expensive and had two coils.
They used gas and liquid chromatography to determine what was in the vapour, looking at the first few puffs as well as later ones when the device had heated up and reached a ‘steady state’.
Researchers took five-second puffs on the e-cigarette every 30 seconds.
They found vapour temperature rose quickly in the first 10 minutes before reaching a ‘steady state’ temperature.
The single-coil e-cigarette emitted 0.46 micrograms in the first five puffs, but at a steady state it emitted 8.7 micrograms.
Researchers estimate e-cigarettes to emit up to 100 micrograms of acrolein. In comparison, ordinary cigarettes give off 400 to 650 micrograms per cigarette.
Correspondingly, emissions levels between the first few puffs and the steady state increased up to 10 times in some cases, depending on the device, the battery voltage and the emitted compound.
To test the affects of ageing, researchers used a device over nine consecutive 50-puff cycles without cleaning it.
They found emissions of formaldehyde, acetaldehyde and acrolein all increased with usage.
And researchers found as the voltage increased, both the amount of e-liquid consumed per puff and the vapour temperature were higher.
In the case of acrolein and formaldehyde, the amount formed at the highest voltage of 4.8V was significantly higher than the amount at the lowest voltage of 3.3V.