Snus use in Sweden: another reply to Tomar.

I have previously discussed the role of snus in reducing smoking in Sweden, and criticized the IARC report’s coverage of this issue. Professor Scott Tomar (a member of the IARC committee) stated (as a comment to a posting criticising the new IARC monograph on smokeless tobacco):
“Using official Swedish data for smoking for 2004 (from the ULF survey conducted by Statistics Sweden), smoking quit rates (or what some call smoking quit ratios, defined as the proportion of ever smokers who are now former smokers), by age group and sex are:Age 16–24Men 13.2%Women 14.6%Age 25–44Men 37.8%Women 38.3%Age 45–64Men 54.5%Women 51.7% “

However, a colleague of mine based in Sweden (Lars Ramstrom), who is very familiar with Swedish surveys on tobacco use, has informed me that these figures on Swedish tobacco statistics are inaccurate in two ways:
1. They provide inaccurate numerical values for “the proportion of ever smokers who are now former smokers”
2. They inaccurately claim that the figures come from “the ULF survey conducted by Statistics Sweden”.

Statistics Sweden generally does not publish any figures on “the proportion of ever smokers who are now former smokers”. The main reason is that their ULF survey uses a questionnaire that does not include enough items to identify the subgroup “former occasional but never daily smokers who are now former smokers”. Since this subgroup must be part of both numerator and denominator of the calculation of such proportions, the ULF data are just unable to provide a basis for such calculations.

For this reason, we believe that the figures provided by Professor Tomar are likely to be inaccurate. However, the proportions in question can be calculated from other surveys that are performed by the Swedish research institute FSI, Research Group for Information and Societal Studies. These surveys are described in the literature (Ramström LM, Foulds J. Role of snus in initiation and cessation of tobacco smoking in Sweden. Tob. Control 2006;15;210-214). Using the same data base as the just mentioned article we get the following data:

Proportion of ever smokers (daily plus non-daily)
who are now former smokers
Age span Men Women
16-79 61% 54%
16-24 49% 42%
25-44 54% 53%
45-64 63% 55%
65-79 75% 68%

Professor Tomar made a point about the “similarity” between males and females quitting based on his original figures.
“Please explain why the quit rates in Sweden are so similar for men and women within each age stratum if snus had such a dramatic effect on cessation?”

In these figures we can see similarity in one age group only, 25-44. In this very age group a large proportion of women are planning or going through pregnancy and are thereby met the very forceful encouragement and treatment for quitting smoking that is very well established in the Swedish maternal health care system. This is a gender-specific condition that explains why this age group shows a different men/women comparison than the others.

The relevant question is rather opposite to the one asked by Professor Tomar:

Why are overall quit rates generally higher in men than in women in Sweden?

The answer is given by the following data picked up from the above mentioned article:
(These data refer to quit rate for daily smoking, while the data above refer to quit rate for all smoking. Therefore the numerical values differ a little)

Proportion of ever daily smokers
who are now former smokers
Men Women
Overall 59% 49%
With a history of daily snus use 72% 71%
Without history of daily snus use 51% 48%

These data illustrate that gender comparisons have to be made between truly comparable subgroups in order to yield meaningful conclusions.

In each one of the two lower lines there are comparisons between men and women who are comparable with respect to snus use. In each case there is no difference.

In each one of the gender columns the two lower lines give gender-specific comparisons indicating the influence of snus use. Both for men and women there are large differences in quit rate according to presence or absence of a history of snus use.

The above observations demonstrates that the overall difference between men and women does not stem from factors related to gender itself but to the fact that snus use, as a cessation promoting factor, is more prevalent among men than among women.

In summary, contrary to Professor Tomar’s thesis, the Swedish statistics on smoking cessation suggest that snus use is having a substantial effect in promoting cessation of smoking among men. Of course this is self evident from the simple fact that 24-30% of male Swedish ex-smokers used snus to quit smoking. My thanks to Lars Ramstrom for providing clarification on the pattern of tobacco use in Sweden.

Incidentally, the issue of snus for smoking cessation was recently debated in the British Medical Journal, at:
http://www.bmj.com/cgi/content/full/336/7640/358

For the record (again), I don’t believe that health professionals should recommend snus to their patients. I believe that we have medicines and counseling that can be effective treatments for addiction to cigarettes (or at least as efficacious as snus) and that these are what we should be recommending to patients. However, I do believe that the public should have accurate information about the relative risks of snus and cigarettes. Currently the public underestimates the risks from cigarettes, relative to snus or nicotine replacement therapy.

Labels: jonathan foulds, nicotine, nicotine nasal spray smoking cessation, smokeless, snus, tobacco

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New IARC monograph on smokeless tobacco

The latest report from the International Agency for Research on Cancer (IARC) was released at the end of 2007. (downloadable – though very large - at: http://monographs.iarc.fr/ ). This report is based on the opinions of an expert working group that met in Lyon, France in October, 2004. It is not clear why it took over 3 years for the report to become available, but one consequence of that delay is that some of its content (relating to Swedish snus) is already out of date and has been contradicted by subsequent evidence. However, the neutrality and balance of the report itself appears to have been undermined from the start, as indicated by some of the self-contradictory statements contained in it.

For example, on p35 in the intoductory remarks to the report it states:

“Some health scientists have suggested that smokeless tobacco should be used for smoking cessation, and claim that its use would reduce the smokers exposure to carcinogens and risk for cancer. They also attribute declines in smoking in Sweden to increased consumption of moist snuff in that country. However, as discussed in volume 1 of the monograph on smokeless tobacco, these claims are not supported by the available evidence.”

However, the section of the report that reviews the evidence (available in 2004) on snuff use in Sweden ends with the following sentence (p174):

“These findings suggest that snuff use may be associated with smoking cessation among Swedish men but not women.”

Later on in the monograph (p153) it gives another view of the relationship between snuff use and smoking in Sweden:

“ The exact role that snuff has played in reducing the prevalence of smoking in Sweden is unclear, but it has probably been overstated (Tomar et al. 2003).”
(Tomar was one of the IARC report authors).

But now that the report has been released in 2008, we have much more evidence on the relationship between snus use and non-smoking in Sweden, showing that it was unfortunately understated by the IARC expert group. Since 2003/4 (1) there have been subsequent publications that have confirmed that in Sweden, men who start using snus are less likely to become daily smokers, that men who smoke and then start using snus are more likely to stop smoking, and that a higher proportion of men than women in Sweden have quit smoking, with the difference largely attributable to snus use (2,3). It had previously been suggested that the men who quit smoking in Sweden are not the same ones who start using snus (and that snus use is therefore not involved in men quitting smoking) (4). However, studies have now verified that in fact a sizeable proportion (26-30%) of Swedish men who quit smoking use snus as a smoking cessation aid (2,5,6). The latest report found that 30.4% of Swedish men who quit smoking from 2000-2004 did so by switching to snus (compared to 14.8% who quit by using NRT) (6). In northern Sweden, where smokeless use is most prevalent, daily smoking prevalence among male 25-34 year-olds is down to 3%, while daily snus use is 34% (7).

It is now crystal clear (and was fairly clear in 2003) that their transfer of nicotine dependence onto snus has accelerated the rate of decline of smoking among Swedish men in substantial numbers. That transfer from an extremely harmful form of tobacco use (cigarette smoking) to a much less harmful form (snus) has contributed to a reduction in the rate of smoking-caused diseases in Swedish men. Of 100 geographic units (primarily countries) in Europe, Swedish men now have the single lowest rate of lung cancer, and less than a half of the rate of lung cancer in the rest of Europe (IARC).

1. Foulds J, Ramstrom L, Burke M, Fagerstrom K. The effect of smokeless tobacco (snus) on public health in Sweden. Tobacco Control 2003; 12:349-59.
Pdf available at: http://www.tobaccoprogram.org/staffarticles.htm

2. Ramström LM, Foulds J. The role of snus (smokeless tobacco) in initiation and cessation of tobacco smoking in Sweden. Tobacco Control 2006 Jun;15(3):210-4.
Pdf available at: http://www.tobaccoprogram.org/staffarticles.htm

3. Furberg Furberg H, Bulik C, Lerman C, et al. Is Swedish snus associated with smoking initiation or smoking cessation? Tob Control.2005; 14:422-424.

4. Tomar SL, Connolly GN, Wilkenfeld J, Henningfield JE. Declining smoking in Sweden: Is Swedish Match getting the credit for Swedish tobacco control’s efforts? Tobacco Control2003; 12:368-59

5. Gilljam H, Galanti MR. Role of snus (oral moist snuff) in smoking cessation and smoking reduction in Sweden. Addiction 2003;98:1183-9.

6. Lindström M. Nicotine replacement therapy, professional therapy, snuff use and tobacco smoking: a study of smoking cessation strategies in southern Sweden. Tob Control. 2007 Dec;16(6):410-6.

7. Stegmayr, B., M. Eliasson, and B. Rodu, The decline of smoking in northern Sweden. Scand J Public Health, 2005. 33(4): 321-4

For further information on smokeless tobacco check out:
Marlboro Snus: what is it? 6/10/07
http://www.healthline.com/blogs/smoking_cessation/2007/06/marlboro-snus-what-is-it.html

Why did Philip Morris’s new smokeless tobacco product (“Taboka”) deliver almost no nicotine? 6/12/07
http://www.healthline.com/blogs/smoking_cessation/2007/06/why-did-philip-morriss-new-smokeless.html

Carcinogens from smoking and smokeless tobacco use (1). 8/27/07 http://www.healthline.com/blogs/smoking_cessation/2007/08/carcinogens-from-smoking-and-smokeless.html

Smoking, smokeless tobacco and cancer (2). 8/28/07 http://www.healthline.com/blogs/smoking_cessation/2007/08/smoking-smokeless-tobacco-and-cancer-2.html

Labels: jonathan foulds, nicotine addiction, nicotine regulation, smokeless, smoking tobacco

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Snus use in Norway.

Snus is a form of smokeless tobacco that is widely used – primarily by men – in Sweden. It is characterized by being relatively low in toxins but delivers about as much nicotine as a cigarette. It is not harmless (causes gum erosion, and pancreatic cancer) but has been estimated to be about 90% less harmful than smoking cigarettes (no lung cancer, oral cancer, or chest diseases).

In Sweden more men now use snus on a daily basis than smoke, and about a quarter of Swedish men who quit smoking did so by switching to snus. Consequently Sweden is just about the only country in the world in which it is consistent that fewer men smoke than women. As I’ve previously discussed, multinational tobacco companies are now test-marketing their own snus products, including in then US. However, some doubt remains as to whether this product (which is banned in the European Union, Australia and New Zealand) could become popular in another country.

A report has just been published on tobacco use in Norway (which is not a member of the EU), which shows a fairly dramatic increase in snus use among young men.
http://www.shdir.no/publikasjoner/faktahefter/tall_om_tobakk_1973_2006_13509

This report found that in the period 2004-6 10% of men used snus on a daily basis and 7% on an occasional basis (compared to 7% and 6% in 2001-3). However, the proportion of users is much higher in young men, with 17% using daily and 17% occasionally in the 16-24 age group. Overall the proportion of daily snus users among men aged 16-44 has more than quadrupled from 1985 to 2006. It remains to be seen what the effects of this expansion of snus use is on smoking rates and health effects. Figure 24 in the report shows that of 631 men who successfully quit smoking during the period 1990-2006 and were surveyed in 2004-6, 17% quit smoking by using snus – a proportion equal to the number who quit by using the nicotine gum (10%), patch (4%) and Zyban (3%) added together. Most Norwegan male ex-smokers quit without any assistance, and 1% used the national telephone helpline. This suggests that a meaningful proportion of men are quitting smoking by switching to snus in Norway. Clearly no tobacco use is preferable to use of smokeless tobacco, and approved medicines are preferable as smoking cessation aids. But anything that gets people to quit smoking has the potential to reduce the harm to health in then population.

If you are interested in learning more about snus, and the effects it has had on smoking in Sweden, click on this link: http://www.tobaccoprogram.org/staffarticles.htm, scroll down to the papers by Foulds and colleages (2003) on “The Effect of smokeless tobacco (snus) on smoking and public health in Sweden” and the paper by Ramstrom & Foulds (2006). These are both available as pdfs for free from this site.

Labels: nicotine, smokeless, snus, tobacco

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Report on Tobacco Harm Reduction by Royal College of Physicians

The Royal College of Physicians of London (established in 1518) has a long history of producing influential, cutting edge reports on topics of critical importance to public health. For example, the RCP’s 1962 report “Smoking and Health” was the first major report to conclude that smoking causes lung cancer. The RCP has 12,500 fellows in over 90 countries and their reports have a similar status to the Surgeon General’s reports in the United States.

On Friday (October 5th) the Royal College of Physicians (London) released their latest report on tobacco and health, entitled, “Harm Reduction in Nicotine Addiction: Helping People Who Can’t Quit”. In the preface to the report, Professor John Britton, Chair of the RCP’s Tobacco Advisory Group, stated,

“Harm reduction is a fundamental component of many aspects of medicine and, indeed, everyday life, yet for some reason effective harm reduction principles have not been applied to tobacco smoking. This report makes the case for radical reform of the way nicotine products are regulated and used in society. The ideas we present are controversial, and challenge many current and entrenched views in medicine and public health. They also have the potential to save millions of lives. They deserve serious consideration.”

The 242-page report was written by a group of leading experts on tobacco from the UK, New Zealand, Canada and the United States. It reviews the history of tobacco use, the neurobiology of nicotine addiction, the health risks of various nicotine products and current regulation of nicotine delivery products, before making recommendations on future nicotine product regulation. Among the key conclusions and recommendations are the following:

- Most of the deaths and disease caused by smoking in the near and medium term future will occur in people who are smoking now.
- Current preventive approaches will be ineffective for the millions of smokers who, despite best efforts to persuade and help them to quit, will carry on smoking.
- Harm reduction in smoking can be achieved by providing smokers with safer sources of nicotine that are acceptable and effective nicotine substitutes.
- There is a moral and ethical duty to provide these products to addicted smokers.
- Current systems of regulation of nicotine products inhibit the development of innovative medicinal nicotine substitutes for cigarettes and perpetuate the use of the most dangerous nicotine products (cigarettes). This is unjust, irrational and immoral.
- The unprecedented and unjustifiable market freedoms enjoyed by manufacturers of cigarettes and other smoked tobacco products must end.
- Low nitrosamine smokeless tobacco products may have a positive role to play in a coordinated and regulated harm reduction strategy which maximizes public health benefit and protects against market exploitation.

The report provides numerous examples of the kinds of irrational regulation currently in place around the world and the effects it has on cigarette smoking for health. In the European Union, for example, Swedish snuff (snus) which has health risks around 90% lower than cigarettes, is banned in every country except Sweden, while cigarettes are available everywhere. Why restrict the public’s choice of tobacco products to only the most harmful ones? In the United States (and many other countries), medicinal nicotine products (e.g. nicotine gum) are sold in packs covered in lengthy warnings and contraindications, while cigarette packs have a very small, brief health warning on the side of the pack. The net result is that many smokers mistakenly believe that the medicinal nicotine products are about as harmful as smoking and so are less inclined to use them.

The new Royal College of Physicians report contains a wealth of information about tobacco, nicotine and health, as well as radical new proposals to reduce the number of smoking-caused deaths. The pdf of the report is available online at no cost at:
http://www.rcplondon.ac.uk/pubs/brochure.aspx?e=234

Labels: harm reduction, nicotine addiction cigarette smoking tobacco, nicotine regulation reduction smoking, quit smoking cessation tobacco advice cigarettes, smokeless

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Smoking, smokeless tobacco and cancer (2)

My previous post discussed toxin delivery from different tobacco products. Now what is the evidence relating use of these products to health problems? Unfortunately most studies don’t collect data on different brands or even categories of smokeless tobacco being used, and few compare directly the risks from smokeless with those from smoking. However, we can get a sense of the risks by examining studies based in different parts of the world where different types of tobacco are used. When we look at it this way we can find very clear evidence that the types of smokeless tobacco used in Sudan and India increase the risk of oral cancer. There is also toxicological evidence showing that Sudanese smokeless tobacco has very high concentrations of TSNAs (carcinogenic toxins), as do some forms of smokeless tobacco used in India. In Asia the picture is complicated by the tradition of adding other ingredients, especially areca nut which is highly carcinogenic on its own.

Then when we look at studies of smokeless tobacco use from the U.S. we see mixed results. One particular study published in the 1980s found very high risks of oral cancer. That study by Professor Deborah Winn and colleagues focused on women in southern United States and found that white never-smoking women (who tend to use oral dry snuff powder) had a relative risk of over 4.2 (2.6-6.7), for developing oral and pharyngeal cancer. Women who had used smokeless tobacco for 50 years had a 50-fold increase in risk for some oral cancers. It should be noted that only a tiny minority of smokeless users use the type of dry snuff tobacco that is commonly used by women in these rural parts of North Carolina. It should also be noted that the type of smokeless tobacco with the extremely high concentration of toxins mentioned in my previous post was also a type of dry snuff. So it begins to look like it’s the smokeless tobacco with very high toxin levels that has evidence of a causal effect on oral cancer. In fact, one of the largest studies on the effects of smokeless tobacco use in the United States (by the American Cancer Society) found no significant increase in the risk for oral cancer among smokeless tobacco users. One of these studies examined a population of 2488 smokeless tobacco users with a median age of 57 at enrolment (i.e. they'd used smokeless for decades) and followed them up 18 years later (i.e. mean age 75). This study found only one death from oral cancer in exclusive smokeless tobacco users, and none in former users, which was a slightly lower rate than occurred in people who had never used any tobacco in their life. These findings from the American Cancer Society suggest that any effect of commonly used brands of smokeless tobacco in the United States on oral cancer, if present, is relatively small.

Finally, we can examine the studies conducted in Sweden where the use of a form of low-toxin moist snuff (called snus) is more common than smoking in men. These studies consistently find no increased risk of oral cancer for snus users. One of the best of these studies was published in the Lancet recently and found that snus users have no increased risk of oral or lung cancer, but they have twice the risk of pancreatic cancer of never tobacco users. That same study found higher risks of all these cancers in smokers (e.g. smokers were about 10 times more likely to get lung cancer than either snus users or never tobacco users, who both had similar risks).

So now lets come back the recent report by Hecht and colleagues. It found similar concentrations of a specific carcinogen in smokeless users and smokers. But we have excellent data showing that smokers have much higher risks of lung cancer than smokeless users, and also higher risks of oral cancer than users of some forms of smokeless tobacco. The lung cancer pattern suggests that deposition of carcinogens directly into the lungs is relevant to the causal mechanism as smokeless tobacco has generally not been found to cause lung cancer in humans. But then we also have a higher risk of oral cancer for smokers. This causes one to consider whether the biomarker being measured in the urine in Hecht and colleague's study is very closely linked to the mechanism wherbye tobacco causes cancer in humans. Perhaps there are other toxins (e.g. benzo(a)pyrene) that are important in triggering cancer in smokers, but are found in lower levels in smokeless users? Whatever, the explanation, it seems that urine NNAL levels do not relate very closely to cancer risks in tobacco users.

But when discussing health risks from tobacco we need to be clear that these involve much more than lung or oral cancer, but also other cancers, and also other serious respiratory and cardiovascular diseases. For most of these, the health risks from smoking greatly outweigh the risks from smokeless tobacco. Chronic respiratory diseases are extremely common among smokers but there is neither good evidence nor a plausible rationale linking use of smokeless tobacco to these respiratory diseases.

So although it is clear that smokeless tobacco contains carcinogens and is not harmless, it is significantly less harmful than smoking cigarettes. I agree with Hecht and colleagues that we should not encourage anyone to use smokeless tobacco, when we have safe and effective medicines to help them quit smoking. However, I think we need to be able to give an honest answer to the question, “Are there forms of smokeless tobacco that are much less likely to kill me than smoking cigarettes?”. The honest answer is,”yes”. Similarly, of we are asked whether some types of smokeless tobacco may be less harmful than others, it seems prudent to suggest that some types of tobacco that have higher concentrations of toxins than others, and that the type of smokeless tobacco used in Sweden (snus) appears to be lower in toxins and health risks than much of the tobacco used in the rest of the world. It is far from risk-free (as are many things that people choose to do on a regular basis, like driving a car, eating donuts, drinking beer, mountain-climbing, or having sex), but experts agree that it is about 90% less harmful than smoking:
http://cebp.aacrjournals.org/cgi/content/full/13/12/2035
Similarly, given the relationship between toxin delivery and health effects from smokeless tobacco, it would seem to be sensible to regulate tobacco products in a manner that requires manufacturers to minimize the concentrations of toxins delivered as much as is technically possible.

In the mean time (and also after regulation is in place), manufacturers who produce and market products containing and delivering unnecessarily high quantities of toxins should be legally liable for the effects of their defective products.

Labels: cancer, smokeless, Smoking, tobacco

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Carcinogens from smoking and smokeless tobacco use (1)

This month an interesting study by Professor Stephen Hecht and colleagues at University of Minnesota was published in the journal, Cancer Epidemiology, Biomarkers & Prevention. The study compared cigarette smokers with smokeless tobacco users on their urine concentration of a biomarker of nicotine intake (cotinine, the main metabolite of nicotine), and a biomarker of exposure to a known carcinogen (NNAL, a biomarker of NNK exposure). The study found that the smokeless tobacco users had higher concentrations of the nicotine metabolite and higher concentrations of the carcinogen biomarker than smokers. The authors concluded that smokeless tobacco is not a safe substitute for smoking.

The authors are correct in this conclusion, as some forms of smokeless tobacco have been shown to be associated with oral cancer, other oral lesions, and may also increase some cardiovascular risks. The idea that smokeless tobacco is not safe is unlikely to be surprising to many people. But given that many of the major cigarette manufacturers are currently test-marketing smokeless tobacco products it may be worth examining the types and risks from smokeless tobacco in more detail, and also looking at how the epidemiological data relates to the recent findings from Hecht and colleagues.

The first thing that needs to be said about smokeless tobacco is that it is not just one thing. The extremely wide variety of different types of smokeless tobacco can be viewed on an excellent website produced by the U.S. National Cancer Institute and Centers for Disease Control, online at: www.cancercontrol.cancer.gov/tcrb/stfact_sheet_combined10-23-02.pdf.

Secondly, smokeless tobaccos vary enormously in the amount of toxins (including carcinogens) they deliver, and (not surprisingly) the ones containing higher concentrations of toxins (like carcinogenic tobacco-specific nitrosamines, or benzo(a)pyrene), appear to be more likely to have adverse health effects. To give an idea of the range of concentrations of toxins, Professor Brad Rodu at University of Louisville published data on the concentration of carcinogenic Tobacco-Specific Nitrosamines (TSNAs) in various smokeless tobacco products. Some examples are as follows (the units of measurement are parts per million based on dry weight):

Ariva (new powdered tobacco lozenge): <0.1 ppms
Ettan (Swedish snus): 2.0 ppms
Red Man (US chewing tobacco): 1.8 ppms
Copenhagen (leading US moist snuff): 12.1 ppms
Red Seal (US dry snuff): 1096 ppms

So we have here over a thousand-fold difference in the concentration of certain toxins in different types of smokeless tobacco! There are a few additional problems. Most of the smokeless tobacco products sold in the United States use fermentation in their production. This facilitates the development of carcinogenic compounds in the tobacco. In fact there is evidence to show that in these fermented products, they continue to ferment in the can, such that the concentration of carcinogens may increase in the can as it sits on the shelf. The method of production used for Swedish snus does not include fermentation, but rather uses a pasteurization-like process that treats the product with steam and appears to kill the microbes required for fermentation. This is thought to be the reason why Swedish snus has lower levels of carcinogens than US Smokeless tobacco. It may also be the reason that Swedish snus does not appear to cause oral cancer. However, the problem remains in the United States that the tobacco manufacturers can adjust the way they produce their products and the ingredients included in them without telling anyone. That is part of the reason why many experts support the pending legislation that would give the FDA the power to regulate tobacco products. This legislation appears to enable the FDA to require maximum permissible levels of harmful toxins in both smoked and smokeless tobacco products. With cigarettes the problem of what happens when you burn the product and inhale the smoke remains, but for smokeless there is a real prospect of offering a product that contains and delivers a known maximum level of toxins – and potentially a level that would be extremely unlikely to cause cancer. But for now, as demonstrated in Hecht and colleagues study, US smokeless tobacco delivers more toxins than necessary and there is little we can do about it.

In my next post I’ll discuss the relationship between the concentration of toxins in smokeless tobacco products and their harmfulness to health.

If you are interested in the views of tobacco and cancer experts on this topic you can learn more by reading the article linked below:
http://cebp.aacrjournals.org/cgi/content/full/13/12/2035

Labels: cancer, cigarette smoking, smokeless, tobacco

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