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E-Cigarettes represent the best method yet to reduce the smoking-related death and disease rate, because they are a clean nicotine delivery system and reproduce the smoking experience better than any other product. Swedish Snus is the best proven safe and effective replacement for smoking [1], but Snus is not seen as anywhere near as popular by comparison. The target markets for e-cigarettes are older smokers who have failed in several quit attempts, and parents who want to keep their health and not subject their children to smoke – but it is likely that most smokers can successfully switch to an e-cigarette given the correct motivation, resources and support.

The basic principal behind electronic cigarettes is Tobacco Harm Reduction: the replacement of a dangerous delivery system by a clean one. The harm is almost all caused by the smoke; remove the smoke and most of the potential for harm goes with it. For the vast majority of people, responsible consumption of nicotine poses no identifiable risk. There are no clinical trials or surveys that show responsible nicotine consumption over several decades has any elevated risk, and this can be clearly seen at population level from the Snus data.  Indeed, the Snus data shows the opposite: long-term ad lib nicotine consumption is all but harmless.

What evidence is there that this approach works?

Sweden reduced their smoking death rate by approaching 40%, due to smokers changing in large numbers to the special smokeless tobacco known locally as Snus. As a result they have the lowest smoking-related death rate in the developed world by a wide margin, understandable since they now have the lowest number of smokers: just 12% of the population. It’s known as ‘the Swedish Miracle’ in public health circles [2].

More than 150 clinical trials of Snus over more than 25 years with trials including tens of thousands of subjects show conclusively that ad lib consumption of nicotine over decades has no statistically significant risk. This is also confirmed by the smoking-related mortality figures from Sweden, which show an unprecedented reduction in the death rate (the lowest of any developed country by a wide margin and approaching a 40% reduction against comparable countries). From this it can be seen that (a) this approach is not new, indeed it has been exceptionally successful for many decades, and (b) the evidence base for advocating this approach is extremely strong – in fact irrefutable.

We fully expect the take-up of e-cigarettes to be even higher than that of Snus in Sweden. It has been estimated that the free availability of e-cigarettes and Snus in a country such as the UK would reduce the smoking-related death rate by more than 50% [3].

The number of smokers dropped quickly in the last two or three decades, due to education, high tobacco taxes, and an advertising blackout. Unfortunately that rapid fall has now stalled, and the current drop is around 0.4% annually in the US and UK. There are no measures left that will substantially reduce it further, and smoking prevalence is stuck around 21% to 22% (the average of the figure quoted by various organizations, which tends to vary between 19% and 24%, according to who is paying). There are even some reports that show the number of smokers has increased slightly in some areas (for example in Scotland).

However, smokers themselves have now found a better option, and have already taken action that considerably outperforms all official health initiatives: in the US and UK we know that, at Q1 2012, 5% of smokers have already switched to an e-cigarette. These ‘vapers’ now probably have the same expectation of risk as a Snus user – and a Snus user has the same risk as a non-smoker [2]. The smokers’ own action has already clearly outperformed official action, and that difference will increase.

Commentators generally state that the main reasons for the ongoing (though now extremely slow) reduction in smoking prevalence is due to such things as education, high cost of smoking (i.e. taxes), and social pressure (denormalization). Health interventions such as quit-smoking treatments never figure in these calculations as they are so minute in scale. The percentage of ex-smokers who report that they were assisted in their successful quit attempt is very small. Therefore, if the current rate of smoking prevalence reduction in a given country (such as the UK) is 0.4% per year, we could estimate that the effect of health service interventions would be less than 0.1%. This is not value for money when the UK cost of NHS quit smoking services (the national health service official programme including pharmaceutical interventions) approaches £200m. In effect it is money down the drain – especially when compared with e-cigarettes, which have already shown a 1% per year smoking prevalence reduction in the UK, about ten times (or greater) more effective than the official method – and at zero cost to the health service.

If e-cigarettes remain freely available and unobstructed, there is no reason why their effect should not equal and even overtake that of Snus in Sweden, which has reduced the number of smokers by 40%, with the number of smoking-related deaths falling toward the 40% reduction mark.

Do e-cigarettes work?

As a safer replacement for smoking, for long-term use, we know that e-cigarettes work. Several million people use them for that purpose (more than 2 million in the USA alone). Many people have successfully used them for several years. In the US, the annual market is worth over $100m, so we are not talking about a passing fad here – and the number of e-cigarette users grows by about 50% per year.

As regards their use for ‘quitting’, if that means total quitting of cigarettes, tobacco, nicotine, and all use of leisure products in this class – we don’t know the answer because nobody cares. Comparatively few people buy an e-cigarette for that purpose, there is no need. No doubt this works for some but it is not an application for which any community or industry members either support or are much interested in. Such persons would also be hard to track by the usual community methods such as forums in any case, as they would disappear from view.

It has been suggested that research be carried out on this aspect of their ‘efficacy’, but from the point of view of everyone involved currently, this would be the most pointless waste of money imaginable. Why quit drinking coffee?

We know that e-cigarettes work, because several million people use them, and have been using them for years; the number of people using them grows by about 50% per year; and because in addition to their unusual popularity, multiple user groups have grown up around their use and advocacy: online communities, local groups, national organisations, and trade associations. This in itself is a phenomenon and could not occur if e-cigarettes did not work.

We don’t know anything about their usefulness for total quitting because very few are interested in such an outcome – it is an application suited particularly to those with medical conditions that require nicotine cessation (cardiac issues?) and/or inhalation cessation (stage 3 or 4 COPD?), therefore it is up to the medical profession to investigate such a usage profile; it has no relevance to the bulk of the population. Swedish Snus is proven by huge amounts of data over almost 30 years to have a virtually zero health risk, and it has been argued by some that e-cigarettes will have an identical risk (or better). There is no medical reason that can be seen at present to quit using an e-cigarette. Ideally, no one would use consumer stimulants or stress relievers, but expecting total abstinence in the pressure-cooker environment of modern urban life is not reasonable.

At an individual level, it seems fairly certain some will prove intolerant to some of the ingredients inhaled, and may even find it difficult to locate an acceptable refill liquid. Such persons may need to find an alternative such as Snus, or quit. Since all the ingredients of e-cigarette refills with the exception of the flavorings are known to be harmless, and are used in medical applications for inhalation, we can be fairly sure there are no major surprises in store. It seems highly unlikely that chocolate flavor will cause thousands of deaths.

Therefore an e-cigarette can justifiably be seen as an acceptable replacement for smoking, and at this time it is hard to see a different outcome from that of Snus in the population-level proof of safety. There is no medical reason for quitting e-cigarettes, as a population-level measure. As always, individuals need specific solutions.

The safety of e-cigarettes

There have been more than fifty research papers, surveys and clinical trial results published on e-cigarettes. None show any evidence of potential for harm. Since the main ingredients are also used in inhalable medicines and disco fog machines, this is hardly surprising. Fog machines are licensed under employee health and safety regulations for long-term high-volume inhalation duty, and these regulations are both strict and impossible to pervert. There is 70 years of safety data on these materials in any case – we list around 40 references below [8].

Those trials paid for by commercial rivals, such as the pharmaceutical industry, tend to be published with admirable hyperbole – but the content of the press release is often at variance with the facts in the trial. A good example is the FDA’s famous press release and analysis of e-cigarette refills, where the hysterical text of the PR bore no relation to any facts discovered in the analysis.

Example 1 – FDA: “E-Cigarettes contain carcinogens.”
Full story: True – but at the same levels or less than are present in licensed NRTs. In the words of one professor of medicine, “These levels are millions of times lower than conceivably harmful to health” – a fact well-known to the FDA as they license the ‘carcinogenic’ NRTs.

Example 2 – FDA: “E-Cigarettes contain antifreeze.”
Full story: True – but so do the nebulizers used by lung-transplant patients. The ‘antifreeze’ in question, propylene glycol, is a non-toxic virtually inert material with an extremely low freezing point that is cheap to manufacture at industrial grade, and which possesses an extraordinary potency as a bactericide and virucide when dispersed as an aerosol. Since the pharmaceutical grade is injected into the bloodstream as the diluent for medicines such as diazepam, and breathed in by lung transplant patients, its potential for harm is presumably not too great. The use of industrial-grade PG as a specialist non-toxic antifreeze and virucide for use in applications such as air-conditioning plants in order to prevent Legionnaire’s Disease is hardly relevant – a fact well-known to the FDA as they license it for the medical uses.

The reliability and truthfulness of the FDA can be easily judged from these examples. At this point it may be prudent for sceptics to investigate the concept of Regulatory Capture. It might be questioned whether the FDA and similar groups work for the benefit of public health, or for the pharmaceutical industry.

Many professors of medicine and public health heads of departments have endorsed e-cigarettes. Their work is easily found by googling: profs. M Siegel, C Phillips, C Bergen, B Rodu and others [13]. Prof Siegel’s evidence was instrumental in obtaining the huge Master Settlement Agreement against the US tobacco industry, so it can be seen that such persons are not aligned with any smoking or facsimile-smoking agenda.

Doctor’s associations and groups have endorsed e-cigarettes:
AAPHP, the American Association of Public Health Physicians
ACSH, the American Council on Science and Health (whose physicians have been vociferous in denouncing the propaganda published against e-cigarettes)

The most well-known anti-smoking harm activist in the USA, William T Godshall of Smokefree Pennsylvania, whose evidence has contributed to the success of many actions against the tobacco industry, fully endorses e-cigarettes. He attended a State vaper’s meet in the US where hundreds of participants were available to inconvenience him with their exhaled vapor, and found no observed effect. He summarily dismissed a recent report paid for by the pharmaceutical industry that claims second-hand e-cigarette vapor causes throat constriction and dizziness [5], since he himself experienced no such effect.

This is a considerable statement when it comes from Bill Godshall, probably the most committed anti-smoking harm campaigner in the world. Perhaps we can also add the title of  ‘Most Honest’, as some colleagues do not seem to suffer from such an inconvenient attraction to the truth. Mr Godshall however is not funded by the pharmaceutical industry.

Nicotine

There is no research that shows responsible consumption of nicotine has any more health risk than drinking coffee. Nicotine does not cause the cancer and cardiovascular diseases caused by smoking.

However there are some individuals who would be wise to strictly limit their nicotine consumption – pregnant women and those with pre-existing heart disease for example.

It should be recognised that nicotine is a normal part of the diet and everyone tests positive for it either in the bloodstream or for metabolytes. This is why nicotine or cotinine tests for smokers have to have a minimum value delineated above which the person qualifies, since everyone tests positive at low levels (unless they eat no vegetables). The CDC in the US tested 800 people, all of whom tested positive, in order to validate the results of an earlier study in which 136 subjects all tested positive. It is possible however that if an individual avoids all vegetables, tea, ketchup and so on that they will be able to avoid nicotine, although this does not seem wise, since apart from other nutritional reasons, it is probable that nicotinic acid (vitamin B3 or niacin) would also be missing from the diet. This nutrient is co-located in vegetables and nutritional plants with nicotine, and can also be a nicotine metabolyte.

It therefore seems to be the case that ‘nicotine consumption’ as we refer to it in relation to tobacco use, in fact refers to ingestion of additional, larger amounts of a normal dietary constituent. Nicotine cannot be referred to in any way as an alien, toxic chemical or dangerous drug since it is part of the diet in small quantities – unlike caffeine or alcohol, which obviously qualify as more ‘alien’. Like many such materials it is toxic in high doses since one of the main differences between a nutrient or medicine and a poison is simply the dose (cf vitamin D).

The propaganda

All sorts of hysterical press releases, junk science and propaganda have been paid for by the pharmaceutical industry in their attempts to destroy what they see as a commercial rival. All these pseudo-scientific and quasi-medical efforts have been dismissed as junk science by professors of medicine who have actually carried out research into and investigations of e-cigarettes. In fact the authors of such propaganda have been dismissed as “crooks and liars” by one professor of medicine and public health expert.

There is not one shred of evidence that e-cigarettes can cause harm or pose any substantial risk to health. If there were, the FDA and MHRA would have found it. They have looked very hard for such evidence and most likely expended substantial resources on such searches. Nothing was found, which is why the FDA lost in their court action in the USA against e-cigarettes, the judge clearly stating they had provided no evidence to show any potential for harm, never mind any recorded incident. The fact they have been used globally by millions of people for many years without incident was found relevant. This can be easily be compared with the safety record of a certain quit-smoking drug introduced at the same time, which is widely reported to have killed hundreds and ruined thousands of lives.

Lung issues

Realistically, the only prospect e-cigarettes have for causing harm is in the area of minor lung issues. There will always be individuals who prove intolerant to one or other of the flavorings used. The other ingredients in an e-cigarette are used in asthma inhalers and the nebulisers used by lung transplant patients [10], so hardly pose a threat (glycerine and propylene glycol are the principal excipients).

There is some question about the inclusion of contaminants in e-liquids. In general it is not in the interests of a business to poison its customers, so responsible vendors buy good-quality materials and carry out testing. In the UK, all materials are tested by the Trading Standards agencies and no contamination has been found. The UK trade association, ECITA, own a GC-MS machine and have a professional chemist available for testing. It is in everyone’s interest if rogue traders are identified and shut down.

Some contaminants have occasionally been found in some samples elsewhere but these have all been shown to be insignificant or not relevant. For example one sample of liquid from 18 tested by the FDA showed very low level DEG contamination, but this was not detected in the vapor so is not of concern. Carcinogens are frequently detected but at the same level or lower than those in NRTs, which are assumed to be safe. If e-cigarettes are unsafe due to the carcinogens then all NRTs would presumably need to be withdrawn from the market immediately. Of course this argument is ridiculous, since the long-term Snus data shows no elevated risk for any kind of cancer, despite the levels in Snus being considerably higher. In fact a professor of medicine commented on the issue of carcinogens in e-cigarette refills, describing the hysterical press releases on this subject as laughable since the levels, “…are millions of times lower than conceivably harmful to health”.

The drawbacks of e-cigarettes

1. Tolerance issues
It is impossible that all ingredients in all brands of e-liquid will be well-tolerated by all individuals. The most likely problems that may be encountered are minor lung irritation issues that can be resolved by changing to a brand with a different ingredient profile. Some individuals may tolerate glycerine as the excipient better than propylene glycol, and some vice-versa. Some individuals may not tolerate some flavourings.

2. WTAs
Smoking dependence is a complex habit with multiple factors contributing to the dependence profile, which varies between individuals. As far as the active tobacco alkaloids are concerned, nicotine is the most likely to cause dependence but others are certainly involved for some individuals. If a smoker still experiences cravings even when consuming a high strength of nicotine when using an e-cigarette, with all factors therefore seemingly well-replicated, and a blood plasma nicotine test shows a sufficient level of nicotine, then clearly we are missing something. This occurs in a percentage of smokers during conversion. This missing component has been shown to be the other WTAs in tobacco, the whole tobacco alkaloids nornicotine, anabasine, anatabine, and myosmine. Adding Snus to the equation removes such cravings as Snus is a whole tobacco product. Another method is to use a liquid refill that contains such WTAs, of which there are two brands currently, and many more will become available.

Some smokers can convert immediately with no cravings, some take a week or two to get over the craving for the other WTAs, and some must employ Snus or WTA liquid refills, perhaps in the long term, in order to succeed. Opinions vary on the percentages of each group and there is no current agreement. One reason an e-cigarette may fail a particular individual is the lack of these WTAs, so it is something that can be resolved with a little application.

3. Minis
Many smokers who attempt to convert to an electronic cigarette will start with a ‘mini’ e-cigarette that resembles a regular cigarette: a small 1st-generation model, with a refill liquid that may not suit them, of a nicotine strength that may be too low to prevent cravings. It has been shown recently that higher levels of nicotine than are normally supplied with regular e-cigarette refills may be required in order to raise plasma nicotine levels sufficiently, for some individuals.While mini e-cigarettes may be sufficient for some smokers wishing to convert, it is clearly demonstrated that they are insufficient for a proportion of potential conerts as they have limited performance (half or less that of the larger 2nd-gen models called ‘mid-size’ ecigs, and a fraction of 3rd-gen models such as variable voltage APVs (advanced personal vaporizers).

Within the e-cigarette community we have clearly demonstrated a difference in individual tolerance to nicotine of a factor of 10, so this needs to be taken into account. We have demonstrated that what suits one person may be ten times too low or too high for another.

Mentoring is therefore quite important as the initial experience may not be optimal. There are hundreds of different equipment options and thousands of different refills, and the initial choice is not usually successful as a long-term solution – the equipment and refills must fit the individual, not the other way around [11]. We know that 92% of long-term users have upgraded their equipment, and it can be assumed that virtually all will have changed their refill choice. We cannot underestimate the value of mentoring, even if via remote methods such as effective forum support.

It can be admitted that although e-cigarettes are provably highly effective, they are not a simple ‘buy-and-go’ option. Their principal drawback may well be that they need to be tuned to the individual, for optimal results and/or long-term success. In many cases the subject will find the optimal solution by trial and error; in others, they may fail due to lack of support.

E-Cigarette medical license for NRT use

In Q3 2012 it is expected that the first pharmaceutical license for e-cigarette use as an NRT will be issued. The expected cost to the firm concerned is around £2.2m, which explains why there are few takers for this option. Subsequently, we expect there to be a considerable reduction in the untrue propaganda about e-cigarettes since the offenders may face legal action.

And, of course, the people who fund the propaganda will be wanting to get in on the action. Hardly surprising, as whatever purpose might be claimed for e-cigarettes, they work orders of magnitude better than any current NRT [12].

UK-specific information

At Q3 2011 the number of UK smokers who had switched to an e-cigarette was 4%, and by 2013 the proportion will be 6%. Already the action of smokers themselves has been several times more effective than NHS efforts in reducing the future death rate [9].

Given the considerable cost of the NHS Stop Smoking Services to the taxpayer, not to mention the fact that virtually all patients will return to smoking [4], many people feel that consumer Harm Reduction offers a far better deal. It would also help if elements within the Department of Health did not appear to be acting with the pharmaceutical industry to remove their commercial rivals; especially since the rivals in question will indisputably save a vast number more lives.

Conclusion

There is, naturally, opposition to the continued use of a tobacco product or a facsimile cigarette inhalation product. When such opposition can be shown to be baseless on health grounds, it must then be asked: is the desired result a reduction in smoking-related sickness and death – or is it, instead, the cessation of leisure use of mild stimulants and stress-relievers for some non-health related reason, such as idealogy or religious belief?

If the argument is strictly limited to the health issue, then there are no grounds whatsoever for restricting use of Snus (as has been proven) or e-cigarettes (as seems obvious). If the argument is about consumer products that may be stimulants or similar, and that are harmless with responsible consumption, then we are talking about also removing access to coffee, tea, chocolate, wine, beer, sherry and brandy. This does not seem likely to improve many people’s quality of life.

So, we can sum up with:

  • There is no medical reason to restrict the use of e-cigarettes
  • Restricting access to e-cigarettes will condemn many inveterate smokers to death
  • Restricting access to e-cigarettes will prevent the conversion of many smokers who might avoid sickness and death
  • It has been estimated that, eventually, e-cigarettes could reduce the smoking death rate by 50% or more in some countries (Snus has already achieved 40% so this is based on solid evidence)
  • An e-cigarette may not be the perfect choice for some individuals
  • Most of those responsible for opposition to e-cigarettes appear to be financially conflicted, since their employment or funding depends in some way on the pharmaceutical industry
  • A close examination of anti-ecigarette press releases and the clinical data they are supposed to depend on often reveals significant differences between the data and the PR
  • Anti-ecigarette ‘research’ qualifies as some of the worst junk science produced in any arena

 

 

Notes
[1] Snus is a special Swedish form of smokeless, oral tobacco that is usually sold in tins of very small packets that resemble tiny, flat teabags. It can be referred to as ‘spitless’ or ‘non-chewing’ tobacco because it is invisible in use, and no extra saliva is produced. A packet is inserted behind the upper lip (not lower), and disposed of after 10 minutes.

This THR alternative to smoking is very popular in Sweden, where they reduced the number of smokers by 40% by promoting its availability as a consumer Harm Reduction product. The smoking-related death rate also fell exactly in parallel, with the result that Sweden has the lowest smoking-related mortality rate of any developed country by a wide margin.

The tobacco is specially processed by steam in a method sometimes referred to as ‘pasteurising’. This steam-processing removes most of the carcinogens. Although some are left (c. 1,000 – 2,000ng/gm) the amounts remaining are not cancer-forming because the very large amount of clinical research data available clearly shows this. In addition, Swedish oral cancer rates have dropped sharply while Snus use has increased markedly. It is said that the most cancer-forming of all chewing tobaccos is still 4 times less likely to cause oral cancer than smoking, but Snus has no identifiable risk of oral cancer [1a].

[1a] Analysis by Profs. Phillips and Rodu:

http://www.tobaccoharmreduction.org/faq/healtheffectsofst.htm

[2] When pharmaceutical NRTs were licensed for long-term use in the UK recently, the only source of safety data that could be referenced was the Snus research from Sweden.There is no other data for long-term consumption of nicotine without smoke.

Because this huge amount of data (>150 trials over >25 years) proves that long-term nicotine use poses no significant risk, NRTs were successfully licensed as long-term treatments. It is reported that a smoker can expect a reduction in life expectancy of 8 years, a Snus user 15 days.

The Snus data has been collected over 25 years, includes more than 150 clinical trials and surveys, and has cohorts of tens of thousands of subjects. It provides data that can be accessed at the individual level and at population level. It proves beyond doubt that Snus use is not only safer than smoking but it is safe in absolute terms. The meta-analyses of 89 and 150 trials carried out by Lee and Hamling showed that a Snus user has no elevated risk for any type of cancer, heart disease or vascular disease. The difference between a Snus user and a non-smoker is not statistically significant for any type of disease in total (rr=1.1). A Snus user has virtually the same risk as a non-smoker (that is, a smoker who has totally quit). There are individual trials with contrary results (example: for cancer of the pancreas), but these must be weighed against 150 trials showing no identifiable risk [2a]. However, a slight elevation for risk of stroke cannot be ruled out, and Snus use appears to be associated with a reduction in life expectancy of 15 days.

[2a] Lee, Hamling: Smokeless tobacco US and SE, meta-analysis of 89 trials:

http://www.biomedcentral.com/1741-7015/7/36

[3] Snus is assumed to have been banned in the EU [6][7] because of the impact a safe form of tobacco use has on the income of the pharmaceutical industry, since the consumption of Snus is proven to have no health implications. Pharma loses in two ways:

  • Sales of NRTs and other quit-smoking drugs are hit very hard indeed. This is a billion-dollar market globally and one that pharma will fight hard to protect.
  • Sales of chemotherapy drugs, COPD drugs, cardiac drugs, vascular drugs and other therapies for sick and dying smokers are believed to value around 50 times the NRT market or more (($50bn +). Obviously, if the smoking death rate falls by 50%, the sales of these drugs are likely to fall in parallel.
  • Sales of NRTs and chemotherapy drugs (etc.) are particularly poor in Sweden, and the pharmaceutical industry is desperate to ensure this does not spread.

This is the most serious threat to pharmaceutical industry income that has ever been seen, and they have fought very hard to oppose e-cigarettes, even obtaining bans in some countries despite there not being a shred of evidence that e-cigarettes pose any risk.

[4] http://www.eccauk.org/index.php/nhs-quit-smoking-fail.html

[5] http://www.ecigarettedirect.co.uk/campaign/bill-godshall-report-on-e-cigarette.html

http://www.pasenategop.com/committees/finance/2009/021109/Godshall.pdf

[6] http://www.eccauk.org/index.php/uk-sitrep-2.html

[7] http://www.eccauk.org/index.php/ecca-library/21-why-is-snus-important.html

8] PG research stretches back to the 1940s, and no person has ever died from its use. It is the main excipient in some nebulisers given to lung transplant patients, and is regarded as inert. Note that it is also used as the diluent in injectable medicines that are immiscible, such as diazepam, and is therefore approved for direct injection into the bloodstream. Here are around 40 references:

http://www.e-cigarette-forum.com/forum/health-safety-e-smoking/959-propylene-glycol-inhaling-17.html#post948636

http://www.e-cigarette-forum.com/forum/pdf/novartis-pg.pdf

http://tsp.plasa.org/tsp/working_groups/FS/docs/cohen.pdf

The relevant characteristics of PG are:
1. It is generally regarded as inert or nearly inert for all forms of consumption including injection, inhalation and ingestion.
2. It has a powerful bactericidal and virucidal action when dispersed as an aerosol.
3. It has no implications for health except for some intolerance by individuals (>1, <10 ex 100).
4. The only likely effect of exposure to aerosols is the drying action on mucosa due to its humectant effect.
5. There are no recorded instances of death or severe harm.

[9] ref #2 @ http://www.eccauk.org/index.php/nhs-quit-smoking-fail.html

[10] Check British Pharmacopeia for full lists of ingredients including excipients and diluents, these are not usually included in MIMS. Search: propylene glycol BP and glycerine BP. Also see:

http://www.dow.com/safechem/optim/optim-advantage/applications.htm

[11] http://onlinelibrary.wiley.com/doi/10.1111/j.1742-1241.2011.02751.x/abstract

http://live.psu.edu/youtube/Ejcnzho95FA?mid=5295763

http://onlinelibrary.wiley.com/doi/10.1111/j.1360-0443.2011.03532.x/full

Vansickel A. R., Blank M., Cobb C., Kilgalen B., Austin J., Weaver M. et al. Clinical laboratory model for evaluating the effects of electronic ‘cigarettes’. February 2011; 17th Annual Meeting of the Society for Research on Nicotine and Tobacco. Toronto, Canada, 2011.

http://onlinelibrary.wiley.com/doi/10.1111/j.1360-0443.2011.03532.x/pdf

[12] http://onlinelibrary.wiley.com/doi/10.1111/j.1360-0443.2011.03505.x/abstract

http://www.ncbi.nlm.nih.gov/pubmed?term=The%20emerging%20phenomenon%20of%20electronic%20cigarettes

[13] Siegel: http://tobaccoanalysis.blogspot.com
Rodu: http://rodutobaccotruth.blogspot.com
Phillips, Rodu: http://www.tobaccoharmreduction.org
Rodu, Cole: http://smokersonly.org
Phillips: http://ep-ology.blogspot.com
Bergen: http://smokles.wordpress.com
Laugesen: http://www.healthnz.co.nz
Nitzkin: http://www.tobaccotoday.info/2009/05/05/electronic-cigarette-interview-with-dr-joel-nitzkin/

http://www.aaphp.org/Resources/Documents/20100402AAPHPEcigLegisStatemnt.pdf

http://www.tobaccoharmreduction.org/thr2010authors.htm

http://www.tobaccoharmreduction.org/interviews.htm