The Cooper Institute
 

Founded in 1970 by the "Father of Aerobics"
Kenneth H. Cooper MD, MPH

 
 
 

How Does Smoking Just a Few Cigarettes a Day Affect Your Risk of Dying Prematurely?

Posted in

Monday, Oct 04, 2021

U.S. Surgeon General Luther Terry addressing press conference at the release of the 1964 Report on Smoking and Health
U.S. Surgeon General Luther Terry addressing a press conference at the release of the 1964 report on Smoking and Health

In 1964, the United States Surgeon General’s report on smoking and health was made public. At the time, just over 40% of U.S. adults were smokers. Over a half-century later, cigarette smoking remains the number-one health hazard worldwide, with an estimated 7 million deaths per year attributed to this deadly habit.


Here is some perspective: Lung cancer is the leading cause of cancer death in the United States; it is estimated that about 90% of these deaths occur as a direct result of smoking! While much progress has been made over the past few decades, about 15% of all American adults are still smoking. An increasing number of long-time smokers report that they smoke fewer than 10 cigarettes per day (CPD); this has been come to be known in health circles as ‘low intensity smoking.’ The health effects of long-term low intensity smoking have not been studied nearly as much as the effects of moderate and heavy smoking.


Research has shown that some low-intensity smokers, especially those who are younger, have the mindset that their level of tobacco use is 'safe'. In this blog, we will summarize findings from a study of long-term low intensity smokers who were enrolled in the National Institutes of Health-American Association of Retired Persons (AARP) study.

The objective of the study was to evaluate the relationships of long-term smoking an average of less than 1, or 1 to 10 CPD with various causes of death.


During 2004-2005, a questionnaire was mailed to 502,682 members of AARP with an average age of 71 years. A total of 290,215 individuals successfully completed and returned the questionnaire, which included several questions regarding lifetime cigarette smoking history, other lifestyle factors and medical history. Of these participants, 7.7% were current smokers, 53.9% were former smokers, and 38.4% were never smokers. Among the smokers, 6.5% reported smoking an average of less than 1 CPD and 30.4% reported smoking between 1 and 10 CPD at the time of the 2004-2005 questionnaire. Of note, most of these low-intensity smokers reported smoking substantially higher numbers of CPD earlier in their lives. However, 159 smokers reported less than 1 CPD throughout their smoking history, while 1493 smokers reported between 1 and 10 CPD throughout their smoking history. All study participants were followed for an average of 6.6 years, during which time, there were 37,331 deaths. The specific cause of death was determined by utilizing the National Death Index; this is a common procedure for these types of studies.

Now, let’s get back to the main question.

Among those who reported lifelong low intensity smoking, how did their risk of premature death compare to lifelong non-smokers? Let’s take a look at the results in the Figures below.


In Figure 1, we see that when compared to the group who never smoked, those who consistently smoked <1 CPD or 1-10 CPD had a 64% and 87% greater risk of all-cause mortality, respectively. 


In Figure 2, we see that when compared to the group who never smoked, those who consistently smoked <1 CPD or 1-10 CPD were 9.1 and 11.6 times more likely to die from lung cancer, respectively. 


This study was unique in that it was the first to report on the health effects of lifelong low intensity smoking. These findings offer substantial proof that there is no such thing as a safe level of smoking, as even those who reported smoking an average of <1 CPD had substantially greater risk of all-cause and lung cancer mortality when compared to participants who never smoked. The authors concluded that all smokers should be targeted for smoking cessation, regardless of how few cigarettes they smoke per day.  

Reference

Inoue-Choi, M., Liao, L., Reyes-Guzman, C., Hartge, P., Caporaso, N., Freedman, N. (2017). Association of long-term, low-intensity smoking with all-cause and cause-specific mortality in the NIH-AARP diet and health study. JAMA Internal Medicine, 177(1):87-95. Doi:10.1001/jamainternmed.2016.7511