Chapter 6 
Xhe Changing Cigarette and Disease Risk: 
Current Status of the Evidence 
Jonathan M. Samet 
INTRODUCTION Since the early 1950's when filter tip cigarettes were first widely 
introduced, the cigarette has evolved continually through modifications 
intended to reduce yields of tar and nicotine (U.S. Department of Health and 
Human Services, 1991). Following the introduction of the filter tip cigarette, 
sales-weighted averages of tar and nicotine deliveries show a temporal trend 
of declining yield, which continues to the present (Figure 1). In the face 
of continued modifications of the cigarette and the seemingly associated 
changes in exposure of smokers to cigarette smoke components, questions 
have been raised concerning the implications of the changing cigarette for 
disease risks in smokers. 
Only epidemiologic studies can provide information on modification of 
the risks of smoking as the cigarette has evolved, and only epidemiologic data 
Figure 1 
Tar and nicotine content of U.S. cigarettes, sales-weighted average basis, 1957-1987 
1955 1960 1965 1970 1975 1980 1985 1990 
Year 
Source: U.S. Department of Health and Human Services, 1989. 
P 
77 
Sales-Weighted Nicotine (mg) 
