Smoking tobacco refers to tobacco that is heated and smoked. Some common examples of smoking tobacco include cigarettes, cigars, and hookahs. It is important to note that while e-cigarettes do not contain tobacco and are not burned during use, their rise in popularity as “smoking” devices has led the FDA to propose that e-cigarettes be regulated as tobacco products (1)(2). A section on e-cigarettes is included below.
Each cigarette typically contains less than 1 gram of tobacco. Cigarettes are made of hundreds of chemicals that react in the presence of heat to produce thousands of chemicals. Many of the chemicals that have been identified as cancer-causing agents (carcinogens) can be found in the sticky, partially burned residue known as “tar”. Some of the remaining thousands of chemicals have been identified as toxic substances that may damage a person’s health (3). Some examples of the chemicals found in tobacco smoke are arsenic (also found in rat poison), butane (also found in lighter fluid), cadmium (also found in battery acid), carbon monoxide (also found in car exhaust fumes), nicotine (also used as insecticide), and toluene (also found in paints) (4). Smoking tobacco produces several powerful cancer-causing chemicals, including nitrosamines and benzo(a)pyrene.
Each cigar can contain between 1-20 grams of tobacco, depending on the size of the cigar. Cigar smoke contains higher levels of toxins and carcinogens than cigarette smoke due to the type of tobacco and wrapping used. The tobaccos used in cigars are fermented, producing higher levels of carcinogenic nitrosamines, which are released into the air when a cigar is smoked. Furthermore, cigar wrappers are less porous than cigarette wrappers, so there is less complete burning of cigar tobacco than of cigarette tobacco, resulting in higher levels of toxins in cigar smoke. Although most cigar smokers do not deeply inhale cigar smoke while smoking, they are still exposed to the carcinogenic substances (5).
Hookahs are water pipes used to smoke flavored tobacco. Hookah smoking has similar health risks as cigarette smoking, and hookah smoke is comparable in toxicity to cigarette smoke. Depending on the length of a hookah smoking session, hookah smoking may be more detrimental to smokers’ health because hookah smokers may end up inhaling more toxic chemicals than if they were to quickly smoke a cigarette. On average, approximately 90,000mL (about the volume of 24 one-gallon milk jugs) of smoke is inhaled during a 1-hour hookah smoking session, while 500-600mL (about the volume of a 1-pint milk carton) of smoke is inhaled when smoking a cigarette (6)(7)(8). In addition, if the hookah mouthpiece is shared among several people, there is also the possibility of transmitting infectious diseases, such as herpes, hepatitis, tuberculosis, and others (9).
E-cigarettes are battery-powered devices that are typically designed to look like common objects, such as cigarettes, cigars, pens, pipes, and USB drives. These devices do not contain tobacco. Instead, they deliver nicotine in aerosol form for users to inhale (1). The FDA has found levels of carcinogenic nitrosamines and other toxic substances (ex: some chemicals also found in anti-freeze) in certain e-cigarette liquids. More research is needed to determine exactly what e-cigarettes contain, how they are used, and their effects on users. According to a study funded by the National Institutes of Health, researchers observed that rising high school students who had previously used e-cigarettes, but not combustible tobacco products, were more likely to start using combustible tobacco products over the following 12 months, compared to rising high school students who had never used e-cigarettes or combustible tobacco products (10). As of May 2014, the FDA has not yet approved e-cigarettes as devices that help people quit smoking (11). The FDA has, however, proposed that e-cigarettes be categorized as tobacco products. If the proposed rule passes, e-cigarettes will be regulated under FDA authority (2). Such regulations would involve minimum age restrictions, inclusion of health warning labels, and more (12)(2).
Electronic cigaretteSmokeless Tobacco
Smokeless tobacco refers to tobacco that is used in ways that do not involve burning the tobacco. Examples of smokeless tobacco include chewing tobacco and snuff. Smokeless tobacco contains over 30 known carcinogens. Examples include the nitrosamines, NNK (4-methylnitrosamino-1-3-pyridyl-1-butanone), and NNN (NL’;-nitrosonornicotine). There are approximately 1-5 μg of NNK and NNN present in every gram of smokeless tobacco. Smokeless tobacco users are exposed to 100-1000 times more carcinogenic nitrosamines than nonusers. The carcinogens listed above, along with their metabolites (metabolites are additional chemicals produced when the body processes something that has been taken in), can be detected in saliva and urine samples. Studies suggest that NNK and NNN that have been processed in the body may causeDNA changes in mouth tissues, which can lead to permanent DNA damage. DNA damage to important genes, such as RASand P53, can result in cancer. Additionally, the metabolism of carcinogens produces reactive chemicals that could lead to chronic inflammation and irritation in the body (13).
Chewing tobacco are loose tobacco leaves that are chewed and spat out. Chewing releases the nicotine present in tobacco, and the nicotine is absorbed through mouth tissues (14). Chewing tobacco was the most prevalent form of tobacco in the U.S. prior to the cigarette industry expansion in 1918 (13).
Snuff is found in 2 forms: dry snuff and moist snuff. Dry snuff is a form of powdered tobacco that is inhaled through the nose, while moist snuff, also known as dipping tobacco, is marketed as a discreet way of using tobacco. Moist snuff is placed in the mouth so that the nicotine is absorbed through the mouth tissues (14). Snuff is the most prevalent form of smokeless tobacco in some countries, including Sweden (13).