Smoking just one to four cigarettes a day almost triples a smoker'srisk of heart disease and lung cancer, reveals a large study in TobaccoControl.
The impact is stronger for women, the study shows, and quashes thecherished notion that "light" smokers escape the serious healthproblems faced by heavier smokers.
The researchers tracked the health and death rates of almost43,000 men and women from the mid 1970s up to 2002. All theparticipants were aged between 35 and 49 at the start of the study,when they were screened for cardiovascular disease and diabetes.
Although a significant proportion of the light smokersincreased their daily consumption, this had not exceeded 9 cigarettes aday. And almost as many had given up as had increased theirconsumption.
Taking account of risk factors likely to influence thefindings, the data nevertheless showed that light smoking endangeredhealth. The steepest risk occurred between nought and four cigarettes aday.
Compared with those who had never smoked, those who smokedbetween 1 and 5 cigarettes a day were almost three times as likely todie of coronary artery disease.
While there was little difference in the risk of dying from any type of cancer, this was not the case for lung cancer.
Men who were light smokers were almost three times as likely tobe killed by lung cancer. And women were almost five times as likely todie of the disease as their non-smoking peers.
Light smokers also had significantly higher death rates fromall causes - 1.5 times - than those who had never smoked, with thedeath rates corresponding to the number of cigarettes smoked every day.
As the light smokers had smoked for fewer years than the heavysmokers, the researchers analysed the projected impact of smoking atthis level for five years.
This indicated that the risk of death from coronary arterydisease would have been 7% higher, and the risk of lung cancer wouldhave been 47% higher in women.
[Health consequences of smoking 1-4 cigarettes per day Tobacco Control 20005; 14: 315-20]
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