Monograph 13: Risks Associated with Smoking Cigarettes with Low Machine-Measured Yields of Tar and Nicotine: Questions and Answers
1. What is Monograph 13?Risks Associated with Smoking Cigarettes with Low Machine-Measured Yields of Tar and Nicotine is the 13th volume in the Smoking and Tobacco Control Monograph Series of the National Cancer Institute (NCI). The monograph series was established in 1991 as a way to communicate important information to the public about health issues regarding smoking and tobacco use. Former Secretary of Health and Human Services (HHS) Donna E. Shalala asked the NCI and other Department of HHS agencies in 1999 to review evidence of the relationship between machine-measured cigarette smoke and disease risk. In keeping with the secretary's request, the purpose of preparing Monograph 13 was to determine whether the scientific evidence, overall, shows that the changes in cigarette design over the last 50 years have reduced disease risks in smokers.
2. What is new about the monograph?This monograph thoroughly reviews epidemiologic and other scientific evidence from the past 50 years on the public health effects of low-tar cigarettes. New analyses of data sets from the American Cancer Society and the California Tobacco Survey were conducted to explore and clarify the differences between epidemiologic evaluations and the national trends in lung cancer death rates. The report also cites internal tobacco industry documents - made available to the public in 1998 by the state of Minnesota's settlement with the tobacco industry and by the Master Settlement Agreement - demonstrating tobacco companies' efforts to market "low-tar" cigarettes as a safer alternative to regular cigarettes. Additionally, the monograph extends and confirms earlier findings that the current Federal Trade Commission (FTC) method of testing the amount of tar and nicotine that smokers inhale does not provide meaningful information to consumers.
3. What were the conclusions of the monograph?The monograph concludes: - Scientific evidence does not show that changes in cigarette design and manufacturing over the last 50 years have benefited public health.
- When smokers switch to cigarettes that are called "low-tar", "light", "ultra-light" or "filtered", they change the way they smoke to compensate for the lower yield.
- The adoption of lower yield cigarettes in the United States has not prevented the continued increase in lung cancer among older smokers.
- Many smokers switch to lower-yield cigarettes out of concern for their health, believing that those cigarettes are less risky or are a step toward quitting.
- Measurements of tar and nicotine yields using the FTC method do not offer smokers meaningful information on the amount of tar and nicotine they will receive from a cigarette. The measurements also do not offer meaningful information on the relative amounts of tar and nicotine exposure likely to be received from smoking different cigarette brands.
4. Are low tar cigarettes safer than "regular" cigarettes? What do the conclusions in the monograph mean for the public?
There is no conclusive evidence of reduced risk from "low-tar" cigarettes. According to the monograph, cigarettes labeled "low-tar" do not typically deliver lower tar to smokers, and people who smoke low-tar cigarettes cannot expect to have fewer smoking-related health problems. There is no such thing as a safe cigarette. The only proven way to reduce the disease risks associated with smoking is to quit.
5. Should doctors recommend that their patients switch to lower-yield brands?
No. Data on disease risk do not support making a recommendation that smokers switch cigarette brands. Such a recommendation can cause harm if it misleads smokers to delay or prevent efforts to quit smoking. Evidence also suggests that switching to light or ultra-light cigarettes may reduce the likelihood of quitting.
6. How is it determined what cigarettes are "light"?Currently, the only information available to smokers on the levels of tar, nicotine, and carbon monoxide in cigarette smoke is obtained in the laboratory using the Federal Trade Commission (FTC) testing method. In this method, machines are programmed using specific settings to generate smoke for analysis of smoke components. According to current guidelines, cigarettes labeled "light" have up to 10 milligrams of tar and 0.8 milligrams of nicotine when measured by the FTC smoking machines. Studies have shown, however, that the current FTC method does not mimic real-life smoking behaviors because smokers compensate for the lower yields of nicotine by changing the way that they smoke, and therefore the testing does not provide meaningful information to consumers. The current FTC method - based on the general observations of smokers in the 1930s when there were no filtered cigarettes - has been in place, largely unchanged, since 1966.
7. What are the FTC and NCI doing to take steps towards a better testing method?
The FTC has asked the Department of Health and Human Services (DHHS) for guidance to improve its testing method for tar and nicotine. NCI and other DHHS agencies will convene a working group by the summer of 2002 to review and synthesize the science on this issue and to determine how the testing method can be improved to better reflect real-life exposures.
8. How have cigarettes changed over the years?
Major changes in the makeup of cigarettes were introduced between 1950 and 1975, leading to reductions in machine-measured tar and nicotine levels. According to the monograph, however, there have been few substantive changes since that time to further reduce the toxic and cancer-causing potential of cigarette smoke. Using the FTC method of measurement, the average yields of U.S. cigarettes decreased from about 37 milligrams of tar and 2.7 milligrams of nicotine in 1954 to 12 milligrams of tar and 0.88 milligrams of nicotine in 1998. During this time, changes in the agricultural, curing, and manufacturing processes of cigarettes have actually resulted in an increase in the amounts of some carcinogens (e.g., tobacco-specific nitrosamines) in cigarette smoke. These changes may have contributed to the increase in adenocarcinoma of the lung observed over the past several decades.
9. How have changes in cigarette design affected the amounts of nicotine and tar that are measured in cigarette smoke?
There are three main features of cigarettes that influence the levels of nicotine and tar measured by the FTC machines: length of tobacco column, nicotine content of tobacco, and filter ventilation. Length of Tobacco Column or Rod There is evidence that some cigarette companies have increased the length of the "overwrap" on their cigarettes (the paper wrap covering the outside of the filter) in order to decrease the number of puffs taken per cigarette in the machine testing. A longer "filter plus overwrap" leads to a longer cigarette butt remaining in the FTC smoking machine and, thus, fewer puffs per cigarette. However, tobacco exists under the overwrap that is still available to the human smoker. This additional tobacco would not be burned in the FTC test, resulting in a lower machine-measured yield, but a possibly higher yield for the smoker.Nicotine Content of Tobacco Different types of tobacco can contain different amounts of nicotine. Even different parts of the same tobacco plant can contain different nicotine levels depending on the nitrogen in the soil, the position of the stalk, and the curing process used. Tobacco blends, combined with the use of fillers, additives, and specially formulated sheets of tobacco in the tobacco column of the cigarettes, can lead to variations in nicotine contents among brands. Tobacco companies manipulate these formulations to achieve specific deliveries of select smoke components.Filter Ventilation Perhaps the most dramatic change in cigarette design since the 1950s has been the addition of a filter on the tobacco rod of some cigarette brands. In fact, 97 percent of cigarettes sold in the United States today are filtered. Filter vents, which usually are one or more rings of small holes or perforations, dilute the smoke with air, thus reducing measured levels of tar, nicotine, and carbon monoxide. The location of vents usually ranges from 11 millimeters to 15 millimeters from the mouth end of the filter. According to the monograph, a recent study found that the filter ventilation levels of 32 U.S. cigarette brands ranged from zero to 83 percent. A cigarette with zero percent filter ventilation would produce a puff of smoke undiluted by air from filters. A cigarette with 83 percent ventilation would produce a puff that is 83 percent air from vents and 17 percent smoke undiluted by air from vents.
10. Do these changes in cigarette design decrease the amount of tar and nicotine that smokers actually inhale?
These changes in cigarette design do not reliably decrease the amount of tar and nicotine that smokers inhale. The monograph finds that smokers compensate for lower yields of tar and nicotine in a number of easy and effective ways, leading the current testing method to not give meaningful information to smokers on either the amounts of tar and nicotine they will receive from a cigarette, nor the relative amounts of tar and nicotine that they would receive from smoking different brands of cigarettes. In addition to simply increasing the number of cigarettes that they smoke per day, smokers compensate for lower yields of tar and nicotine by: Increasing Puff Number Smokers can take more puffs per cigarette. A recent laboratory study found that smokers of low-yield cigarettes (cigarettes with less than or equal to 0.8 milligrams of nicotine by FTC measurement) waited a significantly shorter period of time between puffs than did smokers of high-yield brands (cigarettes with between 0.9 milligrams and 1.2 milligrams of nicotine by FTC measurement). Increasing Puff Volume Smokers can also increase the amount of smoke they inhale per puff. A 1988 Surgeon General report confirmed that puff volumes are often different from the FTC standard. The monograph cites numerous studies finding that smokers change their puff sizes in response to the type of cigarette they smoke, leading the FTC test to underestimate the volume of smoke taken from low-tar cigarettes. Tobacco industry studies also show that smokers take far more in total volume of smoke than is predicted by the FTC test, with puff volumes increasing as standard yields decrease.Blocking Filter Vents Another technique smokers can use to increase the amount of smoke they inhale is to block the filter vents on the cigarette. Filter vents are often not noticed by smokers and are placed just millimeters from lips and fingers. Studies have found that smokers can and do block the vents with either their lips or fingers, thereby decreasing or canceling out the air-dilution effect. According to the monograph, the cigarette industry has known for decades that smokers can easily and unknowingly compensate for low standard yields by interfering with the vents. Research has shown that a large portion of people who smoke filtered cigarettes - in one study as much as 58 percent - block the vents.
11. Who smokes "light" cigarettes?
Surveys have indicated that among the estimated 47 million adults who smoke in the United States, it is people who are most concerned about smoking risks, and who are most interested in quitting, who use brands labeled "light" or "ultra-light."
12. Has advertising for low-yield cigarettes been misleading?
Yes. Internal tobacco company documents in the monograph demonstrate that cigarette manufacturers recognized the inherent deception of advertising that offered cigarettes as "Light" or "Ultra-Light," or as having the lowest tar and nicotine yields.
13. Who wrote Monograph 13?
More than 10 public health experts from universities and organizations throughout the country contributed chapters to this monograph. Over 20 scientists, researchers, and others in universities, government, and the private sector provided comments and reviews. David Burns, M.D., of the University of California, San Diego School of Medicine is the senior scientific editor and Neal L. Benowitz, M.D., of the University of California, San Francisco, is the co-scientific editor. Donald R. Shopland, former coordinator of the NCI Smoking and Tobacco Control Program, was the general editor of the monograph. Stephen Marcus, Ph.D., assumed responsibility for the monograph series when Shopland retired from NCI in January 2001.
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