world cancer report - iarc
world cancer report - iarc
world cancer report - iarc
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users, that is, active smokers. The prevalence<br />
of smoking varies throughout the<br />
<strong>world</strong> and is subject to change (Fig. 2.8). The<br />
proportion of smokers is decreasing among<br />
men in industrialized countries. More than<br />
70% of men born in Europe and North<br />
America during the first decades of the 20th<br />
century smoked during some time of their<br />
life, but this proportion has decreased in<br />
more recent times. There is an increasing<br />
Production Import Export<br />
Location (tonnes/annum) (tonnes) (tonnes)<br />
USA 890,240 234,910 266,104<br />
Europe 760,086 772,675 319,568<br />
Russia 290,000 86,000 2,200<br />
Africa 274,624 85,989 187,208<br />
China 2,000,000 80,000 10,000<br />
India 525,000 100 104,862<br />
Global 6,660,000 1,512,638 1,484,144<br />
Table 2.1 Tobacco production, imports and exports. In some regions, such as Africa and India, the export<br />
of tobacco is a major source of income.<br />
Fig. 2.2 Magazine advertising in the1970s directed towards women in the USA.<br />
proportion of ex-smokers in many countries,<br />
particularly within older age groups.<br />
A different pattern is seen in women. In<br />
contrast to male smoking rates, smoking<br />
by women only became prevalent in the<br />
second half of the 20th century. While in<br />
some countries, such as the United<br />
Kingdom, the proportion of women who<br />
smoke has started to decrease in recent<br />
years, in most industrialized countries this<br />
proportion is still increasing [4].<br />
In developing countries, less comprehensive<br />
data are available. It is clear, however,<br />
that a great increase in smoking has taken<br />
place during the last decade in many countries.<br />
The increase is particularly dramatic<br />
in China, where more than 60% of adult<br />
men are estimated to smoke, representing<br />
almost one-third of the total number of<br />
smokers <strong>world</strong>wide. The prevalence of<br />
smoking among women in most developing<br />
countries is still low, although in many<br />
countries young women are taking up the<br />
habit. In India and its neighbouring countries,<br />
smokeless tobacco is widely used<br />
and “bidi” smoking is also common, this<br />
being the cheapest form of smoking available.<br />
Non-smokers are exposed to environmental<br />
tobacco smoke, the extent of exposure<br />
being determined primarily by whether<br />
family members smoke and by workplace<br />
conditions. The amount of tobacco smoke<br />
inhaled as a consequence of atmospheric<br />
pollution is much less than that inhaled by<br />
an active smokers [5].<br />
Cancer risk<br />
Tobacco smoking is the main known<br />
cause of human <strong>cancer</strong>-related death<br />
<strong>world</strong>wide. Smoking most commonly<br />
causes lung <strong>cancer</strong> [6]. For a smoker, lung<br />
<strong>cancer</strong> risk is related to the parameters of<br />
tobacco smoking in accordance with the<br />
basic principles of chemical carcinogenesis:<br />
risk is determined by the dose of carcinogen,<br />
the duration of administration<br />
and the intensity of exposure. In respect<br />
of these determinants of lung <strong>cancer</strong> risk,<br />
women are at least as susceptible as men.<br />
An increase in risk of lung <strong>cancer</strong> (relative<br />
to a non-smoker) is consistently evident at<br />
the lowest level of daily consumption, and<br />
is at least linearly related to increasing<br />
Tobacco 23