In medical discussions, “tar” refers not to the substance used in road construction, but to the complex particulate matter found in smoke, predominantly tobacco smoke. While both are sticky residues, their chemical compositions and effects on human biology are vastly different. This medical tar contains numerous compounds harmful when inhaled.
What Tar Is and Where It’s Found
Medical tar is a complex, sticky, brownish-black substance that forms when organic materials, such as tobacco, are burned. It is not a single chemical but a mixture containing thousands of chemical compounds, many of which are toxic, irritant, and carcinogenic. For example, known carcinogens found in tobacco tar include polycyclic aromatic hydrocarbons (PAHs), benzene, acrylamide, and acrylonitrile.
The primary source of medical tar exposure is tobacco smoke, specifically from cigarettes, cigars, and pipe tobacco. When tobacco burns, it produces both a gas phase and a particulate phase; tar is a component of this particulate phase. While tobacco smoke is the most common source, other forms of smoke, such as from environmental pollutants or burning other plant materials, can also produce similar harmful particulate matter. The term “tar” in cigarettes often represents the total weight of solid and liquid residue in cigarette smoke after nicotine and water have been removed.
How Tar Impacts the Body’s Systems
Tar damages the body through various mechanisms, affecting the respiratory and cardiovascular systems and possessing genotoxic properties. Upon inhalation, tar directly irritates the lining of the airways and lungs. This irritation can lead to inflammation and increased mucus production, contributing to a smoker’s cough.
The sticky nature of tar coats the cilia, tiny, hair-like structures lining the airways responsible for sweeping out foreign particles and mucus. Tar paralyzes and eventually destroys these cilia, impairing the lungs’ natural cleaning mechanism. When cilia are damaged, harmful substances and mucus accumulate in the lungs, increasing susceptibility to infections and further irritation. In the cardiovascular system, components of tar can affect the elasticity of blood vessels and contribute to plaque formation within arteries, hindering blood flow.
Beyond physical irritation, tar contains compounds with genotoxic properties, meaning they can damage DNA. These chemicals can induce mutations in cells, disrupting normal cell growth and division. This DNA damage can occur throughout the genome, increasing the likelihood that mutations will arise in genes linked to cancer. The combination of DNA damage and chronic inflammation, which tar also promotes, creates an environment conducive to cancerous cell development.
Major Health Conditions Linked to Tar
Exposure to tar is directly linked to a range of serious health conditions, affecting the respiratory and cardiovascular systems. One of the most common health risks is various forms of cancer. Tar contains numerous carcinogens that can lead to lung cancer, which is the leading cause of cancer death, as well as cancers of the throat, mouth, larynx, esophagus, and bladder. The risk of lung cancer increases with cumulative tar exposure, even from “low-tar” cigarettes.
In addition to cancers, tar contributes to chronic respiratory diseases. These include Chronic Obstructive Pulmonary Disease (COPD), which encompasses conditions like emphysema and chronic bronchitis. Emphysema involves irreversible damage to the air sacs in the lungs, reducing their ability to exchange oxygen and making breathing difficult. Chronic bronchitis, characterized by persistent inflammation and narrowing of the airways and excessive mucus production, is also associated with tar exposure.
Cardiovascular issues also arise from tar exposure. Components in tar can contribute to heart disease, stroke, and peripheral artery disease by damaging blood vessels and promoting plaque buildup. This can lead to reduced oxygen delivery to organs and tissues, forcing the heart to work harder. The combined effects of tar on these systems underscore its impact on overall health.