Tobacco-specific nitrosamines (TSNAs) are a group of chemicals widely recognized for their carcinogenic properties. These harmful substances are primarily formed during the curing, fermentation, and combustion of tobacco, and they are some of the most potent cancer-causing agents found in tobacco products. In this article, we’ll explore where TSNAs are found, the varying levels of TSNAs in different products, and the health risks associated with exposure to these chemicals.
What Are TSNAs?
TSNAs are a subset of nitrosamines, which are chemical compounds found in a variety of products. However, the “tobacco-specific” part of TSNAs means they are primarily linked to tobacco products. The most common TSNAs include:
- N’-nitrosonornicotine (NNN)
- 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK)
- N’-nitrosoanatabine (NAT)
- N’-nitrosoanabasine (NAB)
These TSNAs are known to be formed during the drying and aging processes of tobacco and are also generated during the combustion of tobacco products. Their presence in tobacco smoke is a significant factor in the increased cancer risk for smokers.
Where Are TSNAs Found?
TSNAs can be found in a wide range of tobacco-related products. Here are some of the most common places they occur:
1. Traditional Cigarettes
Cigarettes are the primary source of TSNAs for most smokers. When tobacco burns, it creates a chemical reaction that significantly increases the levels of TSNAs in the smoke that the smoker inhales. Studies show that traditional cigarettes contain the highest levels of TSNAs compared to other nicotine products. The level of TSNAs in cigarette smoke can range from 100 to 200 nanograms per cigarette, making it one of the most dangerous sources of nitrosamine exposure.
2. Heat-Not-Burn (HNB) Products
Heat-Not-Burn products, such as Philip Morris International’s IQOS or British American Tobacco’s glo, heat tobacco at lower temperatures than cigarettes. Because there is no combustion, the levels of TSNAs are lower than in traditional cigarettes but still present. For example, HNB products can contain 20-40% lower levels of TSNAs compared to regular cigarettes, though the exact percentage can vary depending on the brand and product design. While they may reduce exposure, the health risks are still significant, as even small amounts of TSNAs pose a carcinogenic risk.
3. Smokeless Tobacco
Smokeless tobacco products, like chewing tobacco and snuff, also contain TSNAs. Because these products do not involve burning, the levels of TSNAs are lower than in cigarette smoke, but they can still be dangerous. The level of TSNAs in smokeless tobacco can range from 1 to 10 micrograms per gram of tobacco, depending on the product. Although users are not inhaling the toxins directly into their lungs, oral exposure to these chemicals has been linked to cancers of the mouth, throat, and esophagus.
4. Vaping Products (E-cigarettes)
E-cigarettes and vaping products do not contain tobacco, and as a result, they have significantly lower levels of TSNAs compared to cigarettes or HNB products. However, trace amounts of TSNAs have been detected in some vaping liquids. These levels are extremely low, usually in the range of 0.1 to 0.2 nanograms per milliliter of e-liquid, which is far below the concentrations found in tobacco products. The reduction in TSNAs in vaping products is one of the reasons public health agencies like Public Health England consider vaping a safer alternative to smoking.
5. Nicotine Replacement Therapy (NRT) Products
Nicotine Replacement Therapy (NRT) products such as nicotine patches, gums, and lozenges are designed to help smokers quit by delivering nicotine without the harmful chemicals found in tobacco. While NRTs are free from tobacco combustion, trace amounts of TSNAs have been detected in some products due to the nicotine extraction process. These levels are extremely low and not considered to pose significant health risks. For example, TSNA levels in NRT products have been found to be up to 97% lower than those in traditional cigarettes.
Health Risks of Absorbing TSNAs
The presence of TSNAs in tobacco products poses a significant risk to human health. These chemicals are classified as Group 1 carcinogens by the International Agency for Research on Cancer (IARC), meaning they are confirmed to cause cancer in humans. Here are some of the health risks associated with TSNA exposure:
1. Cancer
TSNAs are most strongly linked to various forms of cancer. NNN and NNK are particularly associated with:
- Lung cancer: TSNAs are among the key carcinogens in cigarette smoke that cause lung cancer. Smokers are at much higher risk, but even smokeless tobacco users have elevated risks due to TSNA absorption through the mouth.
- Oral cancers: Users of smokeless tobacco are at a higher risk of developing cancers of the mouth, throat, and esophagus due to direct exposure to TSNAs.
- Pancreatic cancer: NNK is associated with an increased risk of pancreatic cancer, one of the deadliest forms of cancer with low survival rates.
2. Cardiovascular Disease
Although cancer is the most prominent risk, TSNAs also contribute to other serious health issues, including cardiovascular disease. By contributing to systemic inflammation and oxidative stress, TSNAs can damage blood vessels and increase the likelihood of heart attacks and strokes, particularly in smokers.
3. Respiratory Issues
Long-term exposure to TSNAs, particularly through smoking or HNB products, can lead to chronic respiratory problems such as emphysema, chronic bronchitis, and COPD. These diseases result from the toxic effects of both TSNAs and other harmful substances found in tobacco smoke.
Conclusion
Tobacco-specific nitrosamines (TSNAs) are highly carcinogenic chemicals found in various tobacco products, including traditional cigarettes, HNB products, and smokeless tobacco. While products like e-cigarettes and NRTs contain significantly lower levels of TSNAs, the potential health risks from exposure to these chemicals remain a serious concern. Whether through inhalation, ingestion, or skin contact, TSNAs increase the risk of cancer, cardiovascular disease, and respiratory issues. The safest way to avoid TSNA exposure is to quit tobacco and nicotine products altogether, but for those unable to quit, switching to regulated alternatives like vaping or NRT products can significantly reduce the harm associated with smoking.