You may underestimate how much you are putting your health at risk, even if you only smoke occasionally or in moderation.
People who consistently smoked an average of less than one cigarette per day over their lifetime had a 64 percent higher risk of earlier death than never smokers, according to a new study from researchers at the National Cancer Institute, part of the National Institutes of Health.
The study also found that those who smoked between one and 10 cigarettes a day had an 87 percent higher risk of earlier death than never smokers.
Risks were lower among former low-intensity smokers compared to those who were still smokers, and risk fell with earlier age at quitting. The results of the study were reported in “JAMA Internal Medicine.”
The researchers looked at risk of death from respiratory disease, such as emphysema, as well as the risk of death from cardiovascular disease. People who smoked between one and 10 cigarettes a day had over six times the risk of dying from respiratory diseases than never smokers and about one and half times the risk of dying of cardiovascular disease than never smokers.
Smoking has many harmful effects on health, which have been detailed in numerous studies since the U.S. Surgeon General’s 1964 report linking smoking to lung cancer. The health effects of consistent low-intensity smoking, however, have not been well studied and many smokers believe that low-intensity smoking does not affect their health.
To better understand the effects of low-intensity smoking on mortality from all causes and for specific causes of death, the scientists analyzed data on over 290,000 adults in the NIH-AARP Diet and Health Study. Low-intensity smoking was defined as 10 or fewer cigarettes per day. All participants were age 59 to age 82 at the start of the study.
Participants were asked about their smoking behaviors during nine periods across their lives, beginning with before they reached their 15th birthday until after they reached the age of 70 (for the older participants). Among current smokers, 159 reported smoking less than one cigarette per day consistently throughout the years that they smoked; nearly 1,500 reported smoking between one and 10 cigarettes per day.
The study had its limitations. For starters, it relied on people recalling their smoking history over many decades, which introduced a degree of uncertainty.
Another significant limitation was the lack of diversity in race and age among participants. Future studies among younger populations and other racial and ethnic groups are needed, particularly as low-intensity smoking has historically been more common among racial and ethnic minorities in the US.
The study also lacked detailed information about usage patterns among participants who reported smoking less than one cigarette per day. Hence, the researchers could not compare the effects of smoking every other day, every few days, or weekly, for example.
However, researchers say the study’s findings are valuable.
“The results of this study support health warnings that there is no safe level of exposure to tobacco smoke,” said Maki Inoue-Choi, Ph.D., NCI, Division of Cancer Epidemiology and Genetics, and lead author of the study. “Together, these findings indicate that smoking even a small number of cigarettes per day has substantial negative health effects and provide further evidence that smoking cessation benefits all smokers, regardless of how few cigarettes they smoke.”
For more information about smoking cessation and the impact of smoking on health, visit www.nih.gov.