Smokeless tobacco

Smokeless tobacco differs depending on the type of product, the types of tobacco used, and the amount of each tobacco type used within a product. Each variable results in different level of nicotine. Furthermore, nicotine is absorbed by the body to different degrees depending on the pH level of the product, which is known as the free nicotine or unionized nicotine level.

Below are some measured nicotine levels of various smokeless tobacco products from 2006 and 2007 and their corresponding free nicotine levels as calculated by the Henderson–Hasselbalch equation.[12]

As of 2017, the World Health Organization states that "Smokeless tobacco use is a significant part of the overall world tobacco problem."[15] As of 2015, the American Cancer Society states that "Using any kind of spit or smokeless tobacco is a major health risk. It's less lethal than smoking tobacco, but less lethal is a far cry from safe."[17] As of 2010, the National Cancer Institute states that "because all tobacco products are harmful and cause cancer, the use of all of these products should be strongly discouraged. There is no safe level of tobacco use. People who use any type of tobacco product should be urged to quit".[18] A panel of experts convened by the National Institutes of Health (NIH) in 2006 stated that the "range of risks, including nicotine addiction, from smokeless tobacco products may vary extensively because of differing levels of nicotine, carcinogens, and other toxins in different products".[18] According to a 2002 report by the Royal College of Physicians, "As a way of using nicotine, the consumption of non-combustible tobacco is of the order of 10–1,000 times less hazardous than smoking, depending on the product".[19] As long ago as 1986, the advisory committee to the Surgeon General concluded that the use of smokeless tobacco "is not a safe substitute for smoking cigarettes. It can cause cancer and a number of noncancerous oral conditions and can lead to nicotine addiction and dependence".[18]

Quitting smokeless tobacco use is as challenging as smoking cessation.[6] There is no scientific evidence that using smokeless tobacco can help a person quit smoking.[18]

As of 2017, the World Health Organization states that "There is no evidence to recommend that any smokeless tobacco product should be used as part of a harm reduction strategy."[15] Tobacco companies that sell smokeless tobacco products promote them as harm reduction products and a less harmful substitute to cigarettes.[20]

Smokeless tobacco products vary extensively worldwide in both form and health hazards, with some evidently toxic forms such as from South Asia, and some forms with less hazards such as snus from Sweden.[21] It is correlated with a number of adverse effects such as dental disease, oral cancer, oesophagus cancer, and pancreatic cancer, cardiovascular disease, asthma, and deformities in the female reproductive system.[9] A correlation was identified between smokeless tobacco and risk of fatal coronary artery disease and fatal stroke.[5] Use of smokeless tobacco also seems to greatly raise the risk of non-fatal ischaemic heart disease among users in Asia, although not in Europe.[5]

It is estimated the safety risk of smokeless tobacco is similar to that of electronic cigarettes, which has about 1% of the mortality risk of traditional cigarettes.[8] Smokeless tobacco is not a healthy alternative to cigarette smoking.[6] There is no safe level of smokeless tobacco use.[6] The declines in smokeless tobacco initiation among adolescents and young adults is particularly relevant to improving the health of the nation because smokeless tobacco use is often linked to subsequent cigarette initiation.[6] Smokeless tobacco users can experience these negative health consequences at any age.[6] Smokeless tobacco accounts for an abundance of deaths globally with a significant proportion of them attributed to Southeast Asia.[10] Youth use of tobacco in any form is unsafe.[16]

Graphic from the 2016 Centers for Disease Control and Prevention report entitled Smokeless Tobacco: Health Effects.[14]

All tobacco products contain toxicants, and smokeless tobacco products contain cancer-causing chemicals.[6] The carcinogenic compounds occurring in smokeless tobacco vary widely, which rely upon the kind of product and how it was manufactured.[4] A 2017 review found "Overall, 28 carcinogens have been rigorously identified across a range of major smokeless tobacco products, primarily from 3 groups of compounds: nonvolatile, alkaloid-derived TSNAs; N-nitrosoamino acids; and volatile N-nitrosamines. Among these carcinogens, researchers identify TSNAs as the most abundant in smokeless tobacco and the most carcinogenic."[4] The amounts of nicotine in saliva from using smokeless tobacco could be at amounts that can cause cytotoxicity, according to in vitro studies.[22]

Other chemicals found in tobacco can also cause cancer.[14] These include: A radioactive element (polonium-210) found in tobacco fertilizer.[14] Chemicals formed when tobacco is cured with heat (polynuclear aromatic hydrocarbons—also known as polycyclic aromatic hydrocarbons).[14] Harmful metals (arsenic, beryllium, cadmium, chromium, cobalt, lead, nickel, mercury).[14] Products such as 3-(methylnitrosamino)-proprionitrile, nitrosamines, and nicotine initiate the production of reactive oxygen species in smokeless tobacco, eventually leading to fibroblast, DNA, and RNA damage with carcinogenic effects in the mouth of tobacco consumers.[9] The metabolic activation of nitrosamine in tobacco by cytochrome P450 enzymes may lead to the formation of N-nitrosonornicotine, a major carcinogen, and micronuclei, which are an indicator of genotoxicity. These effects lead to further DNA damage and, eventually, oral cancer.[9] Smokeless tobacco can cause white or gray patches inside the mouth (leukoplakia) that can lead to cancer.[14] The World Health Organization has classified smokeless tobacco products as human carcinogenic compounds, in particular tobacco-specific nitrosamines, which account for 76 to 91% of the total N-nitroso compound (NOC) burden.[9] A 2014 review found there is "a number of ethnically linked smokeless tobacco types that contain areca nut, a Group 1 carcinogen. Use of areca nut-containing smokeless tobacco is known to cause oral cancer, yet despite this, prevalence is increasing in the Western Pacific."[3] N-nitrosonornicotine and ketone are group 1 carcinogens to humans.[20] These two nitrosamines found in smokeless tobacco products are the main agents for the majority of cancers in smokeless tobacco users.[20]