Tobacco and Public Health - TCSC Indonesia

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ADOLESCENT SMOKING
We use three age-specific indices to identify where a community or population is on
this uptake continuum. The first is the proportion of the group who are committed
never smokers. In the United States, the main movement out of the committed neversmoking
group occurs between the ages of 10 and 14 years. The second marker is the
proportion of adolescents who have experimented with smoking, even a few puffs. The
modal age of experimentation in the United States is between 12 and 14 years. There is
thought to be an important age window for completing experimentation during the
teenage years that influences the probability of later daily smoking. The marker used to
indicate completion of the experimentation phase is having smoked at least 100 cigarettes
in one’s lifetime, which is the accepted definition of an adult smoker in the
United States. It has been estimated that 50 per cent of adolescents who reach at least
100 cigarettes will still be smoking at age 35 years (Pierce and Gilpin 1996).
Interestingly, previously secret tobacco industry documents obtained through the US
lawsuits have indicated that the tobacco industry felt that brand loyalty occurred generally
after smoking as little as 200 cigarettes of the same brand. Despite this research
and concerns relating to recall bias, the traditional measure of adolescent smoking is a
period prevalence measure, the proportion who have smoked in the previous 30 days.
How strong is genetics in determining who will become a
smoker?
In 1958, the famous statistician, Sir Ronald Fisher, argued that it was possible that
people who were genetically at risk to develop cancer were the same people who
were genetically at risk to start smoking (Fisher 1958). Given the overwhelming evidence
supporting a causal association between smoking and lung cancer, this argument
was not at all persuasive in the public policy debate of the time. However, it did
raise the issue that there is probably a genetic component to smoking initiation. There
has now been considerable research on identical twins, some who have been raised
apart. These studies allow the separation of the social environmental influences from
genetic influences, and have generally found that there is an important genetic influence
on who becomes a smoker. However, the genetic influence is not related to the development
of a susceptibility to smoking. Instead, people respond differently to exposure
to nicotine, with some appearing to be genetically predisposed to become dependent.
In a series of different studies, it appears that a relatively constant 30–50 per cent of
experimenters go on to become addicted smokers. As there is a lot of research in this
area at the present time, we can expect the knowledge base in this area to expand
rapidly in the next decade.
How do friends who smoke effect initiation?
One of the most consistent findings in research on adolescent smoking is that nonsmokers
who have friends who smoke soon become smokers themselves (USDHHS 1994).