Long-term e-cigarette use could lead to chronic lung conditions, scientists have warned.

US researchers found e-cigarette vapour affects cells in the lungs in the same way as cigarettes smoke, even after just one hour.

Long-term exposure could lead to emphysema, which is also known as chronic obstructive pulmonary disease, or COPD.

Although these were preliminary results, experts have hailed the results as significant.

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Long term e-cigarette use could lead to chronic obstructive pulmonary disease (COPD), scientists warn

Dr Nicholas Hopkinson, medical adviser to the British Lung Foundation, told MailOnline: 'Most people are fairly confident that e-cigarettes are less harmful than cigarettes.

'The question now is whether they are harmless, and there is now evidence which shows there is some harm.

'A particular concern is people with lung disease who are smoking.'

COPD is an umbrella term used to describe chronic lung diseases that limit the air flow to the lungs and includes diseases like 'chronic bronchitis' and 'emphysema'.

The most common symptoms of COPD are breathlessness, or a 'need for air', and excessive production of mucus in the lower airways.

It is not just simply a 'smoker's cough', but an under-diagnosed, life threatening lung disease that may progressively lead to death, the World Health Organisation warns.

According to its latest estimates, currently 64 million people have COPD and 3 million people have died of COPD.

WHO predicts that COPD will become the third leading cause of death worldwide by 2030.

As part of the study, US researchers examined how e-cigarette vapour compares to tobacco smoke by testing how it affects cells.

SHOULD DOCTORS ADVISE PEOPLE TO GIVE UP E-CIGARETTES TOO? Dr Nicholas Hopkinson, medical adviser to the British Lung Foundation, said this study was small, but the results were significant. He told MailOnline: ‘Essentially, the normal healthy lung is made up of air sacs called alveoli, whose walls are made from protein. ‘There is a normal process where the protein is broken down and re-generated you have a stable structure as the walls of the alveoli. ‘In emphysema, this process is disrupted so when alveoli are damaged, they don’t re-generate. 'This means you then have less alveoli in the lungs, allowing exchange of oxygen.’ 'It is already known that there is an inflammation response in the body to things inhaled. And it is significant that vapour activates this pathway.' Dr Nicholas Hopkinson, medical adviser to the British Lung Foundation, says evidence e-cigarettes are not harmless could give doctors reason to encourage people to give up their use He added: 'Most people are fairly confident these e-cigarettes are less harmful than cigarettes. 'The question is whether they are harmless, and there is now evidence which shows there is some harm. 'A particular concern is people with lung disease who are smoking. 'It's good if people with COPD quit smoking and use e-cigarettes, as cigarettes are more harmful, so that's progress. 'But the next question is, are they harmless? And research showing, in fact, that they are not harmless, might give doctors reason to recommend people should quit using e-cigarettes too. 'If people start using e-cigarettes when they’re young they might use them for 40 years- and we don’t know what the long term effects. 'The risks associated with using e-cigarettes also seems to vary depending on the flavouring, and different devices. 'There’s quite a strong argument for regulation so the products work properly, so the most harmful flavours are taken out of the market.' Advertisement

They exposed human bronchial epithelial cells – cells from the lining of the bronchi, the network of tubes used to convey air to the lungs – and exposed them to e-cigarette vapour from one to six hours.

The team found even minimal exposure of e-cigarette vapor for one hour, disrupted the protein processes in cells 'significantly'.

This is the same path cigarette smoke and second-hand smoke takes in our bodies, they said.

Protein homeostasis or 'proteostasis' is the process that regulates proteins within cells in order to maintain the health of the cell and the organism itself.

In the lungs, the small air sacs, known as alveoli, have walls made of protein. So proteostatis is the normal process in which this protein is broken down and regenerated so they can function properly.

If proteostasis is disrupted, if the alveoli become damaged, they do not regenerate, meaning the lungs cannot carry out its function of oxygenating blood as well.

The World Health Organisatoin Warned COPD will be the third leading killer globally by 2030. Pictured is an X-ray of an elderly woman with the disease

The resarchers found e-cigarette vapour did disrupted protein processes, and it is this disruption which, in the long term, researchers said could lead to COPD.

The team confirmed its findings with tests on laboratory mice exposed to e-cigarette vapours, and found the same result.

Dr Neeraj Vij, an assistant professor at the Central Michigan University College of Medicine, said: 'COPD/emphysema is not a genetic disorder.

'We have described the role of overall protein processing in this and in previous research, which has been confirmed by studies from other groups.

'What we are talking about is how these proteins are made and how they are degraded. This process of proteostasis in our cells has to be very – in layman's terms – tightly regulated, because if it goes off-balance, it's a big problem.'

The findings were published in the Journal of the Federation of American Societies for Experimental Biology.