Researchers at the Karolinska Institute presented a report on health effects from Swedish oral smokeless tobacco (in Swedish), Stockholm 2005-12-05:
Men constitute the overwhelming majority of snuff users in Sweden, but the use of snuff has increased in both sexes during the last 20 years. The ban on tobacco smoking in restaurants and bars, which was introduced recently, may increase the consumption even more. In 2004 22% of Swedish men used snuff daily and 3% of the women. The use of snuff decreases with age and is now highest in the aged group 18-29 years. The strongest increase in snuff use has occurred among well educated men and women. Daily use of snuff is rarely combined with daily smoking, but often with occasional smoking. Snuff use among teenagers follows the same pattern as among adults, with an increase among both boys and girls during the 1990s. In 2004 21% of the boys and 8% of the girls at the age of 15 used snuff daily or occasionally. There are major regional differences in the use of snuff, which is more common in northern Sweden. This is particularly evident for snuff use during pregnancy. Snuff consists of grinded tobacco and salts as well as moisturising and flavouring agents. Nicotine is the primary addictive component of snuff. Many carcinogens have been detected in snuff, e.g., nitrosamines, polycyclic hydrocarbons, aldehydes, heavy metals and polonium-210. The tobacco-specific nitrosamines appear most important for the cancer risk. The content of nitrosamines in snuff has decreased steadily during recent decades. Experimental studies show that snuff extract can stimulate cell growth, but also induce cytotoxic and genotoxic damage. Reactive chemicals in snuff can produce oxidative stress, affect thiol and ionic balance, damage DNA and inhibit enzymatic function, which influences gene expression and adversely affect biologic functions. Snuff also contains protective agents, such as antioxidants, which partly counteract such effects. Effects of snuff can in many instances be related to the content of nicotine and tobacco- specific nitrosamines. The most common adverse effect of snuff is the snuff lesion in the oral cavity. Daily use, use of loose snuff, snuff with high pH and nicotine content produce more damage. The lesions are mostly reversible when snuff use is stopped and Swedish studies have not indicated malignant transformation of these lesions. A gingival recession is common where snuff is placed in the mouth. This lesion is irreversible. A Swedish study has shown an association between snuff use and gingivitis and another suggests that the risk of parodontitis is increased in snuff users, especially among users of both cigarettes and snuff. The carcinogenicity of snuff has been evaluated twice by the International Agency for Research on Cancer, 1985 and 2005. On both occasions it was concluded that oral use of snuff is carcinogenic. No particular assessment was made of Swedish snuff. Animal experiments indicate that snuff can induce cancer, for example in the oral cavity. Effects in American studies tend to be stronger than in Swedish studies, which might be explained by a higher content of tobacco specific nitrosamines. These agents increase the risk of cancer of many sites in animal experiments. Results of epidemiological studies on snuff use and cancer are not fully consistent. Certain studies of Swedish snuff show increased risks of cancer of the pancreas and oral cavity, while others did not confirm these associations. Similar results have been obtained in studies of other types of snuff. In some studies the associations were more evident for those who never smoked, which may be because important sources of bias are less prominent in this group. An overall assessment of the experimental and epidemiological evidence indicates that Swedish snuff is carcinogenic. Both studies in experimental animals and epidemiological studies show that snuff affect the cardiovascular system, for example by inducing effects on blood pressure and pulse rate. The evidence regarding long term use of snuff and hypertension is not consistent. Snuff use does not appear to increase the risk of myocardial infarction, but there seems to be an increased risk of mortality from cardiovascular disease, including myocardial infarction. This is consistent with the results of animal experiments which show that nicotine increases the risk of cardiac arrhythmias and the size of myocardial infarction. The evidence regarding stroke and diabetes in relation to snuff use is too limited to allow firm conclusions. The evidence regarding snuff use during pregnancy is limited. The results of one Swedish study showed an increased risk of preterm delivery and preeclampsia, and probably also reduced foetal growth, in the offspring of mothers who used snuff during pregnancy.
(Summary given by Paul Nordgren, Public Health Planning Manager, National Institute of Public Health)