Tobacco and Public Health - TCSC Indonesia

Cotinine (ng/ml)
750
500
250
OXCHECK Smokers
0
0 10 20 30 40 50 60
Cigarettes/day
MICHAEL MURPHY ET AL.
Fig. 35.1 Plasma cotinines measured in those reporting particular levels of cigarette
consumption per days
pharmacology, and biology of the actions of nicotine which underlie human use of the
drug, but also help to demonstrate the amount of genetic variation that exists in the
way nicotine achieves its effects. The work of Collins and Marks in particular has
demonstrated that inbred strains of animals (who therefore became increasingly
homozygotic and invariant for, albeit anonymous, alleles) differ markedly between
strains (in the relevant but unknown genes) contributing to:
*nicotine sensitivity
*nicotine receptor density
*tolerance development
*cross tolerance
*nicotine self administration
Even more telling is the evidence from human studies (mostly of twins, but some
singleton adoption studies) which estimate the likely size of the contributions of
genotype and environment, defined in the broadest sense, to determining smoking
behaviour (Sullivan and Kendler 1999; Hall et al. 2002). Many of the twin panels
whose results contribute to these estimates were established to answer the questions
posed originally by Fisher’s hypothesis that the same genes may determine not only
that a smoker does so but their risk of disease also. The evidence from these studies
unequivocally supported the alternative idea that smoking delivers toxic and
carcinogenic products that determine disease risk directly. They have however
also provided reliable evidence about the balance of contributions to smoking
behaviour.
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