Smoking: no small risk for light smokers

Smoking one to four cigarettes a day is enough to triple or even quintuple for women, the risk of death from cardiovascular disease or lung cancer, according to a Norwegian study presented on the website of the journal "Tobacco Control"

Numerous epidemiological studies have suggested that the severity of disease caused by smoking is associated with the number of cigarettes, but in most of them, the minimum consumption evaluated ranged from one to nine or fifteen cigarettes per day, the authors explain .

Given that only few prospective studies have evaluated the health consequences of less than five cigarettes daily consumption, Dr. Kjell Bjartveit, National Screening Service in Oslo, and Aage Tverdal and the Norwegian Institute of Public Health in Oslo , conducted a study in four Norwegian cities (including the capital) to determine the risk of death associated with consumption of one to four cigarettes per day.

In total, their survey included 23,524 men and 19,201 women. Aged 35 to 49 between 1972 and 1978, these people then participated in a screening program for cardiovascular risk held in four cities chosen. In this study, were notably recorded deaths from ischemic heart disease, lung cancer, all cancers and all causes.

Analysis of these data allowed the authors found that people who smoke one to four cigarettes per day are at risk of dying from ischemic heart disease almost tripled compared to people who have never smoked (multiplied by 2.74 for men and 2.94 for women).

The risk of death from lung cancer shows also clearly influenced by low tobacco consumption: it is tripled among light smokers, but especially for small fivefold smokers.

The risk of death from all causes, it is multiplied by 1.57 for men and 1.47 for women, while the results for the death by cancer of all types do not prove significant.

The authors note that for all diseases and levels of smoking assessed the risk of death proves to be lower for women than for men, except for cardiovascular disease (regardless of the number of cigarettes smoked per day) for lung cancer (especially for low power consumption).

If some similar results have been reported in rare previous studies, the researchers acknowledge that their analysis could be biased by changes in smoking habits over time. Indeed, some light smokers may be former heavy smokers and non-smokers at baseline may become smokers.

Consumption of five cigarettes per day was considered a threshold beyond which appear serious health problems, but it is now essential that health authorities and health professionals insist more strongly on the risks faced by young smokers.