2009年02月23日 English, 奇闻轶事 暂无评论 阅读 1 次



Theyre touted as the cool new way to kick the habit, but are electronic cigarettes really risk-free? Helen Thomson lights up to find out

HAVE never been a smoker, so as I sit at the bar, chin resting on one hand, I try to remember how Audrey Hepburn did it. I take a gentle drag and exhale. A white mist wafts around my face as I wait for the rush of nicotine hitting my brain. People start to stare. Then the inevitable happens: “Hey, you can’t smoke that in here.” Only in this case I can, because I’m not really smoking.

I’ve just “lit up” an e-cigarette, a battery- powered electronic device that I bought for $60 from a UK website. It looks just like a real cigarette – the tip even glows red – and with every drag a few micrograms of nicotine from a disposable cartridge (I got six with my purchase) should reach my lungs. My e-cigarette even produces puffs of “smoke”, but it isn’t burning, and so it’s not banned. I’m not the only one smoking these sticks. In the growing number of public places worldwide where smoking has been banned, a new breed of smoker has appeared puffing on similar gadgets.

E-cigarettes may help smokers evade the ban, but do they also help them evade the health consequences of smoking or give the habit up altogether? In September 2008 the World Health Organization issued a statement warning smokers that there was no evidence to back up claims that e-cigarettes could help them quit. So what do we know about them and is there any evidence that inhaling the chemicals they contain may be harmful to your health? Could they genuinely help people to kick the habit?

E-cigarettes were invented by Hon Lik of electronics company Ruyan in Beijing, China. Ruyan sold its first electronic cigarette in May 2004, and e-cigarettes have been growing in popularity ever since. Accurate figures are hard to come by, but Ruyan – the world’s biggest manufacturer – claims to have sold over 300,000 in 2008. Smart Smokers, one company which sells Ruyan’s cigarettes in the UK, says sales are rising exponentially. In the US, hit TV show The Doctors featured the e- cigarette in the top 10 health trends of 2008. In a world where smoking is increasingly socially unacceptable, the e-cigarette looks like a success story in the making.

The device itself is pretty simple. It resembles a normal cigarette in shape and size but instead of containing cured tobacco it is mostly full of battery and an LED. The disposable filter holds a cartridge containing nicotine dissolved in propylene glycol, the liquid that is vaporised in nightclub smoke machines. When you take a drag, a pressure sensor switches on an electric heating coil that vaporises the PG and releases the “smoke” (see diagram, right). The strongest cartridge contains about the same amount of nicotine as a regular-strength cigarette, but lasts for about 300 puffs in comparison with a regular cigarette that lasts for about 15. The cartridges don’t “burn down” but deliver a puff whenever clip_image013you choose to take one. Cartridges come in high, medium, low and zero-nicotine strength and cost around $1.50 each.

However, on a per puff basis, the strongest cartridge only delivers around one-third the amount of nicotine delivered by a puff on a normal cigarette, says Murray Laugesen, a public health researcher who campaigned against tobacco smoking in New Zealand and is now studying the impact of smoking e-cigarettes.

”If the e-cigarettes are safe and acceptable to smokers the potential health benefits are huge”

Legal loophole

So far so good. But are e-cigarettes really less harmful than the real thing? Given they contain nicotine, an addictive drug, and are touted as an alternative for smokers, you might think an independent organisation would have tried to substantiate such claims. Far from it. In most countries e-cigarettes escape regulation. “If you make a health claim about a product, it becomes a drug and comes under drug regulation and approval,” says John Britton, a lung specialist at the University of Nottingham, UK, and chair of the Royal College of Physicians Tobacco Advisory Group. “If it’s a burnt tobacco product, it’s a cigarette.” The e-cigarette is not classed as either, giving manufacturers free rein to develop and distribute it with little more than an easily obtainable general hygiene certificate.

To complicate matters, some companies claiming that e-cigarettes can help you kick the smoking habit even went as far as to falsely cite the approval of the WHO. News of this led the WHO to recommend in September that all e-cigarettes be banned until proved safe.

So what precisely is the evidence for and against e-cigarettes? Laugesen is one of the few researchers tackling this question. In early 2007, his company – Health New Zealand – began a research programme to investigate what hazards e-cigarettes might pose. The research is funded by Ruyan but Laugesen insists it is independent, a view backed by the WHO. “Dr Laugesen is a respected tobacco control researcher,” emphasises Raman Minhas, technical officer of the WHO’s Tobacco Free Initiative.

Though Laugesen’s conclusions have yet to be published in a peer-reviewed journal, his preliminary results have been released and seem positive.

He found that each puff would release just a few micrograms of water, alcohol, nicotine, PG and flavourings. But what about the risk from carcinogens? Carcinogens such as tobacco- specific nitrosamines are found in regular cigarettes and are known to be the primary cause of many smoking-related cancers. While traces were found within the e-cigarette – most likely slipping in with the tobacco- derived nicotine used in the cartridges – Laugesen says that the concentration was no different from the amount present in nicotine patches. “If the levels are as low as in nicotine replacement therapy, I don’t think there will be much of a problem,” agrees Britton.

What my fellow patrons at the bar were most concerned about as I puffed away next to them was passive smoking. Although the e-cigarette does not produce carbon monoxide or the carcinogens that are the by-products of combustion, as Laugesen notes, its cartridge

contains acetaldehyde. The chemical is best known for its part in causing hangovers, and when allowed to build up in the body can be carcinogenic. “The small amounts found [in each cartridge – 5 parts per million] may be coming from the ethyl alcohol found in the cartridge liquid,” he says. If acetaldehyde is present in the mist, however, it is unlikely to cause harm as low levels can rapidly be broken down in the body.


Inhaled nicotine is over 98 per cent absorbed, and any exhaled PG mist dissipates within seconds, so Laugesen concluded that the mist is not harmful to bystanders. With no flame, nor products of combustion, the cigarette would be permitted under most current governmental smoking bans.

While some consider the e-cigarette something of a breakthrough, others have yet to be convinced that they actually help you give up smoking. “Wit

hout blood tests, it is difficult to confirm whether nicotine is reaching the bloodstream,” says David Burns, who researches tobacco-related disease at the University of California, San Diego. If it isn’t, then it’s unlikely to be an effective aid. Laugesen is now studying this issue and has submitted his results to the annual meeting of the Society for Research on Nicotine and Tobacco, which will meet in Dublin in April.

Safety concerns aside, what about the psychological element of smoking addiction? Numerous human studies suggest the sensory cues that accompany the ritual of smoking – the taste, aroma and handling of the cigarette – are important to smokers in terms of satisfying their cravings. Would a regular smoker accept an e-cigarette in lieu of the real thing? I decided to find out with a thoroughly unscientific experiment of my own. Not being a smoker myself, I gave an electronic cigarette to my 20-a-day dad.

Within a few days it became apparent that, for him, the e-cigarette has some major flaws. “Taking a drag requires quite a bit of effort, it’s heavier than a normal cigarette, there’s no nice smoke smell and the ‘filter’ is as hard as rock,” he complained. “It just doesn’t feel the same as a normal cigarette.” As far as my guinea pig was concerned it didn’t compare favourably with the real thing. In fairness, though, my dad is not keen to quit。

Marcus Munafo, a researcher on the influences of addictive behaviour at the University of Bristol, UK, suspects that part of the problem is down to the other chemicals present in real cigarettes. Although nicotine is the primary addictive component of tobacco, there are other components in the smoke that enhance nicotine’s addictive potential. The brain mechanisms behind this are unclear but animal studies suggest that chemicals in smoke other than nicotine inhibit up to 40 per cent of the activity of an enzyme called monoamine oxidase. Nicotine prompts the release of the neurotransmitter dopamine, whose action in the brain is linked to the pleasurable effects of smoking. It has been suggested that MOA inhibition might decrease the re-uptake of dopamine, giving genuine cigarettes a double-whammy effect.

The e-cigarette is not burning anything and so doesnt produce any of the toxic products of combustion

The WHO’s Study Group on Tobacco Product Regulation (TobReg) convened at the international conference on tobacco control in South Africa in November 2008 to consider the fate of e-cigarettes. Although their conclusions will not be published until September, New Scientist understands their advice to national departments of health will include proposing stricter regulations on their sale and manufacture: for example, that they should only be sold in pharmacies.

TobReg is also likely to recommend that it be made illegal to smoke the electronic cigarette indoors until there is evidence they are not harmful to passive “smokers” – a proposal that is a step too far for Laugesen. “This sounds like caution beyond common sense,” he says. Peter Hajek, a clinical psychologist and director of the Tobacco Dependence Research Unit at the Barts and London School of Medicine and Dentistry, UK, agrees. “Banning an alternative nicotine delivery device without any reason to believe that it has a potential for harm does not make much sense to me,” he says. “It could have a role in harm reduction and smoking cessation and thus be of public health benefit.”

“The problem is nobody knows anything about these devices,” says Britton. If it turns out that they deliver to the bloodstream an amount of nicotine comparable to a cigarette, are acceptable to smokers and are safe, then the potential health benefits to smokers trying to quit are huge, he adds.

“All pointers so far show the device is safe,” Laugesen claims. “Whether it will be a successful smoking cessation device in the future depends on whether governments wrap it in cotton-wool regulations or allow smokers to buy it with a modicum of reasonable safety checks.”

Back outside my local bar – where I’ve been sent to “prevent any trouble” – I realise that, ultimately, even if the e-cigarette and its ilk prove safe and are accepted by smokers, it will not necessarily be welcome in the increasingly smoke-intolerant world.

I take another drag. It makes me cough and feel a little light-headed. A sharp gust of winter wind later and my brief flirtation with nicotine is left, along with my fellow smokers, firmly out in the cold. ■

Helen Thomson is the editor of New Scientists

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