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the blood are similar in magnitude in people using different forms of 

 tobacco. Once in the blood stream, nicotine is rapidly distributed 

 throughout the body. 



Nicotine is a powerful pharmacologic agent that acts in a variety 

 of ways at different sites in the body. After reaching the blood 

 stream, nicotine enters the brain, interacts with specific receptors in 

 brain tissue, and initiates metabolic and electrical activity in the 

 brain. In addition, nicotine causes skeletal muscle relaxation and 

 has cardiovascular and endocrine (i.e., hormonal) effects. 



Human and animal studies have shown that nicotine is the agent 

 in tobacco that leads to addiction. The diversity and strength of its 

 actions on the body are consistent with its role in causing addiction. 



Tobacco Use as an Addiction 



Standard definitions of drug addiction have been adopted by 

 various organizations including the World Health Organization and 

 the American Psychiatric Association. Although these definitions 

 are not identical, they have in common several criteria for establish- 

 ing a drug as addicting. 



The central element among all forms of drug addiction is that the 

 user's behavior is largely controlled by a psychoactive substance (i.e., 

 a substance that produces treuisient alterations in mood that are 

 primarily mediated by effects in the brain). There is often compul- 

 sive use of the drug despite damage to the individual or to society, 

 and drug-seeking behavior can take precedence over other important 

 priorities. The drug is "reinforcing"— that is, the pharmacologic 

 activity of the drug is sufficiently rewarding to maintain self- 

 administration. "Tolerance" is another aspect of drug addiction 

 whereby a given dose of a drug produces less effect or increasing 

 doses are required to achieve a specified intensity of response. 

 Physical dependence on the drug can also occur, and is characterized 

 by a withdrawal syndrome that usually accompanies drug absti- 

 nence. After cessation of drug use, there is a strong tendency to 

 relapse. 



This Report demonstrates in detail that tobacco use and nicotine 

 in particular meet all these criteria. The evidence for these findings 

 is derived from animal studies as well as human observations. 

 Leading national and international organizations, including the 

 World Health Organization and the American Psychiatric Associa- 

 tion, have recognized chronic tobacco use as a drug addiction. 



Some people may have difficulty in accepting the notion that 

 tobacco is addicting because it is a legal product. The word 

 "addiction" is strongly associated with illegal drugs such as cocaine 

 and heroin. However, as this Report shows, the processes that 



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