Re: Smoking and CMT: All forms of tobacco use or exposure are harmful

August 19, 2006

All forms of tobacco use or exposure are harmful

All forms of tobacco exposure - smoking, chewing or inhaling second

hand smoke - increase the risk of heart attack up to three times,

according to an Article in this week's issue of The Lancet.

Previous studies have shown that tobacco smoking increases the risk

of heart disease. However, to date most of these studies have been in

developed countries and few large studies have been done to examine

the effects of tobacco in other geographical regions.

In the INTERHEART study, Salim Yusuf and Koon Teo (McMaster

University, Ontario, Canada) and colleagues calculated the risk of

heart attack for various forms of active tobacco use (both smoking

and non-smoking) and second hand smoking (SHS) in all areas of the

world. The study included data from over 27 000 people in 52

countries. The investigators adjusted their calculations to exclude

the effect of other lifestyle factors that could affect heart attack

risk, such as diet and age.

They found that tobacco use in any form, including sheesha smoking

popular in the Middle East and beedie smoking common in South Asia,

was harmful. Compared to people who had never smoked, smokers had a

three-fold increased risk of a heart attack. Even those with

relatively low levels of exposure (8-10 cigarettes a day) doubled

their risk of heart attack. However, the researchers did find that

the risk of heart attack decreased with time after stopping smoking;

among light smokers (<10 cigarettes a day) there was no excess risk 3-

5 years after quitting. By contrast, moderate and heavy (20>

cigarettes a day) smokers still had an excess risk of around 22%, 20

years after quitting. The team also found that exposure to second

hand smoke increased the risk of heart attack in both former and non-

smokers. The findings suggest that individuals with the highest

levels of exposure to SHS (22 hours or more per week) may increase

their risk of heart attack by around 45%.

" Chewing tobacco also increased the risk of a heart attack two fold,

indicating that all forms of tobacco use or exposure are harmful, "

added Dr Koon Teo.

Professor Yusuf concludes: " Since the risks of heart attack

associated with smoking dissipate substantially after smoking

cessation, public-health efforts to prevent people from starting the

habit, and promote quitting in current smokers, will have a large

impact in prevention of heart attack worldwide. "

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