nicotine delivered via the e-cigarette going to promote cancer in
already existing pre-cancerous cells?
likely and not in the next 10 years.
is not a known carcinogen
Nicotine, inhaled or by any route,
is not recognized by the state of California as a known cause of
cancer in humans or animals. Hundreds of other chemicals are so
recognized, and scores of them are in cigarette smoke. Second hand
tobacco smoke is recognized in this way.
follow up for 10 years - the
Lung Study in the USA has followed thousands of
ex-smokers for five years and then for 7.5 years after that,. Risk of cancer of the lung was increased in those
who continued to smoke, but not in those using nicotine alone compared
with those who quit entirely. That means 10
years of follow-up. If their cells were pre-cancerous to start with,
and nicotine was a cause of cancer, new cancers would have been
expected to appear within those 10 years.
use of nicotine for 25 years. Since 1984, nicotine has been given
to millions of smokers trying to quit smoking, to help them quit
smoking, with no reported increase in lung cancer. Over 40,000 were followed for at
least 6 months, and some have been followed for 20 years. Some 8% of nicotine gum users become long term
users,  but no increase in cancers has been reported in long term
users of nicotine gum or patch.
Pre-cancerous cervical cells are commoner
in smokers. Any smoker so affected, should obtain rigorous follow-up.
We have no reason, however, to believe e-cigarettes will increase the
risk of the cells becoming cancerous.
use reduces risk of cancer by supplanting the smoking of tobacco
Using e-cigarettes INSTEAD of smoking
tobacco cigarettes is bound to reduce the risks of lung cancer, because
the cancer-causing gases such as 1,3 butadiene found in the smoke of
all cigarette brands, are no longer inhaled.
Switching to e-cigarettes with nicotine
continued, can be expected to reduce lung cancer risk the same as
altogether quitting cigarettes without e-cigarettes.
quitting and complete switching required
100% altogether-quitting or 100% quitting
by 100% switching to e-cigarette is required.
Anyone continuing to smoke even one
cigarette per day along with e-cigarettes (dual smoking) increases risk
of premature death by about half.
If nicotine can cause
cancer in specially-bred susceptible mice, how can nicotine e-cigarettes
in humans lower cancer risk?
the nicotine inhaled per puff is much less than (about one tenth) in a
cigarette puff, and risk of cancer in mice from nicotine in their diet is
of great theoretical interest for researchers, but no proven effect for
Cancer risk has
been studied in a million Americans, and on follow-up the lung cancer
rates were 10-20 times higher for cigarette smokers, compared with
protect from cancer to the extent that e-cigarette users no longer
smoke tobacco cigarettes.