smoking 'is not enough'
Smoking causes cancer
The only way for smokers to avoid exposure to significant levels
of cancer-causing substances is to quit completely, research
A team from the University of Minnesota found that smokers who
cut their cigarette consumption are exposed to lower amount
of a potent carcinogen. However, the drop is not proportional
to the reduction in the number of cigarettes smoked.
The study is published in the Journal of the National Cancer
There is no safe level of smoking.
Cigarette smoking is the cause of 90% of the world's lung cancer
cases - but it is not known whether smokers who reduce the number
of cigarettes smoked per day also decrease their risk of lung
The Minnesota team set out to answer this question by measuring
the metabolites of a specific tobacco carcinogen in the urine
of smokers who were taking part in a programme to cut their
The carcinogen, NNK, has been heavily linked with lung cancer.
The volunteers cut their cigarette consumption in stages, and
provided urine samples at regular intervals. Overall, their
urine contained lower levels of NNK metabolites by the time
they had significantly cut back on their habit.
However, the magnitude of the reduction was generally less than
the reduction in cigarettes smoked per day.
Even when smokers reduced their cigarettes per day from a mean
of 24.7 at the beginning of the study to 2.60 at week 12 (a
reduction of 90%), the average level of metabolite concentration
in their urine was only reduced by 46%. The researchers, led
by Dr Stephen Hecht, suggest that the most likely explanation
for the results is that people who are trying to cut back by
smoking fewer cigarettes per day alter their smoking behavior
by inhaling longer and deeper.
They said: "The results indicate that some smokers may
benefit from reduced smoking, but for most the effects are modest,
probably due to compensation."
Amanda Sandford, the charity Action on Smoking and Health, told
BBC News Online: "The message is quite clear: there is
still no substitute for quitting smoking all together.
"There is no safe level of smoking. Even one a day can
potentially put you at risk."