Nicotine is the chemical in cigarettes that makes them addictive. Higher levels of nicotine in a cigarette can make it harder to quit smoking. A report by the Massachusetts Department of Health found that the amount of nicotine in cigarettes has steadily increased over the last 6 years. (Massachusetts is one of several states that require tobacco manufacturers to submit yearly reports regarding cigarettes.) Higher nicotine levels were found in all cigarette categories, including "light" brands.
Some researchers feel nicotine is as addictive as heroin. In fact, nicotine has actions similar to heroin and cocaine, and the chemical affects the same area of the brain.
Depending on the amount taken in, nicotine can act as either a stimulant or a sedative. Cigarette smoking has definite immediate positive effects. For example, it can:
Most smokers have a special fondness for the first cigarette of the day because of the way brain cells respond to the day's first nicotine rush. Nicotine, particularly taken in the first few cigarettes of the day, increases the activity of dopamine, a chemical in the brain that elicits pleasurable sensations, a feeling similar to getting a reward.
Over the course of a day, however, the nerve cells become desensitized to nicotine. Smoking becomes less pleasurable, and smokers may be likely to increase their intake to get their "reward." A smoker develops tolerance to these effects very quickly and requires increasingly higher levels of nicotine.
Smokeless tobacco, also called spit tobacco, includes chewing tobacco (dip and chew), tobacco powder (snuff), as well as flavored tobacco lozenges. These products also contain nicotine.
Smokeless tobacco products allow tobacco to be absorbed by the digestive system or through mucous membranes. Smokeless tobacco contains at least 28 cancer-causing substances, and is not a safe substitute for smoking cigarettes or cigars. According to the National Institutes of Health, chewing on an average-size piece of chewing tobacco for 30 minutes can deliver as much nicotine as smoking three cigarettes.
Although research is inconsistent, some evidence suggests that smokeless tobacco produces an increase in the risk of oral cancer, gingivitis, and tooth loss. A recent review of existing literature found that while the risk of cancer in people using smokeless tobacco is lower than that of smokers, it is still higher than that of people who do not use tobacco at all.
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