world cancer report - iarc

Substances Tobacco smoke Smokeless tobacco
(per cigarette) (ng/g)
Volatile aldehydes
Formaldehyde 20-105 µg 2,200-7,400
Acetaldehyde 18-1,400 µg 1,400-27,400
Crotonaldehyde 10-20 µg 200-2,400
N-Nitrosamines
N-Nitrosodimethylamine 0.1-180 ng 0-220
N-Nitrosodiethylamine 0-36 ng 40-6,800
N-Nitropyrolidine 1.5-110 ng 0-337
Tobacco-specific nitrosamines
N '-Nitrosonornicotine (NNN) 3-3,700 ng 400-154,000
4-(Methylnitrosamino)-1-(3-pyridyl)- 0-770 ng 0-13,600
1-butanone (NNK)
4-(Methylnitrosamino)-1-(3-pyridyl)- + +
1-butanol (NNAL)
N '-Nitrosoanabasine (NAB) 14-46 ng 0-560
Metals
Nickel 0-600 ng 180-2,700
Cadmium 41-62 ng 700-790
Polonium 210 1-10 mBq 0.3-0.64 pci/g
Uranium 235 and 238 - 2.4-19.1 pci/g
Arsenic 40-120 ng
Polycyclic aromatic hydrocarbons
Benzo[a]pyrene 20-40 ng >0.1-90
Benzo[a]anthracene 20-70 ng -
Benzo[b]fluoranthene 4-22 ng -
Chrysene 40-60 ng -
Dibenzo[a,l]pyrene 1.7-3.2 ng -
Dibenzo[a,h]anthracene + -
Table 2.2 Carcinogenic agents in tobacco smoke and smokeless tobacco. + = present, - = absent
ing male smokers, risk of developing cancer
of the oral cavity is about double that
for non-drinking non-smokers. Elevations of
ten-fold or more are evident for cancer of
the larynx and five-fold or more for
oesophageal cancer. The proportion of
these cancers attributable to smoking
varies with the tumour site and across communities,
but is consistently high (80% or
more) for laryngeal cancer specifically.
A common feature of lung and other smoking-induced
cancers is the pattern of
decreased risk which follows smoking cessation
(“quitting”) relative to continuing
smoking [2]. The relative risk of cancer at
most sites is markedly lower than that of
current smokers after five years’ cessation,
although risks for bladder cancer and adenocarcinoma
of the kidney appear to persist
for longer before falling. Despite the
clearly established benefit of cessation, the
risk for ex-smokers does not decrease to
that for “never smokers”. Overall,
decreased risk of lung and other cancers
consequent upon quitting is further evidence
(if any were needed) that smoking is
causes the diseases in question (Tobacco
control, p128).
Other cancer types may be a consequence
of smoking [9]. These include cancer
of the stomach, liver, nose and
myeloid leukaemia. In contrast, some of
Fig. 2.6 Risk of lung cancer is determined by number
of cigarettes smoked.
the increased incidence of bowel and cervical
cancer in smokers may be due to
confounding. Exposure to environmental
tobacco smoke causes lung cancer and
possibly laryngeal cancer, although the
burden of disease is much less than in
active smokers; the relative risk has been
estimated at about 1.15-1.2. Association
of increased risk of breast cancer with
exposure to environmental tobacco
smoke is controversial [5].
Tobacco smoking has been estimated to
cause approximately 25% of all cancers in
men and 4% in women, and, in both genders,
approximately 16% of cancer in more
developed countries and 10% in less developed
countries [11], although some estimates
are as high as 30% [12]. The low
attributable risk in women (and, to a lesser
extent, in developing countries) is due to
the low consumption of tobacco in past
decades. A recent upward trend in smoking
prevalence among women in many
developing countries will result in a much
greater number of attributable cancers in
the future. Use of smokeless tobacco
products has been associated with
increased risk of head and neck cancer
[10]. Since chewing of tobacco-containing
products is particularly prevalent in
Southern Asia, it represents a major carcinogenic
hazard in that region.
Tobacco 25