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)