A carcinogen is a substance that is capable of causing cancer in humans or animals. If a substance is known to promote or aggravate cancer, but not necessarily cause cancer, it may also be called a carcinogen. Though there are many things that are believed to cause cancer, a substance is only considered carcinogenic if there is significant evidence of its carcinogenicity.

A carcinogen may act on deoxyribonucleic acid (DNA), causing dangerous changes, or it may work to increase the rate of cell division. This change in cell division may work to increase the probability of DNA changes. Some carcinogens promote the development of cancer in other ways as well.

It is important to note that carcinogens don’t lead to cancer after every exposure. Some cause cancerous changes following high-level, prolonged exposure, while others may cause damage at lower levels and shorter exposure periods. Furthermore, an individual’s unique genetic makeup may influence the body’s response to a carcinogen.

Testing human subjects for carcinogenic behavior and properties is considered unethical, not to mention hazardous to the health of the test subjects. As such, animals are often used for carcinogen testing. Additionally, cell cultures from both humans and animals are used in testing. Scientists also consider the effects of substances at the molecular level in determining whether or not they are carcinogenic. Evidence of links between exposure to substances and the development of cancer is also considered.

Many substances have been identified as carcinogenic. Some commonly known carcinogens include asbestos, radon, certain pesticides, arsenic, and tobacco smoke. Smokeless tobacco is a known carcinogen as well.

One major carcinogen originates from something vital to life. The sun emits ultraviolet rays that are carcinogenic. Ultraviolet radiation is known to lead to a variety of cancers affecting the skin.

Sadly, carcinogens can be found in everything from snack foods and drinks to certain types of plastic and everyday objects. All too often, a substance isn’t identified as carcinogenic until it has been used or consumed by humans for many years. Furthermore, so many substances are rumored to be possible carcinogens that it can be hard to figure out just what is safe to consume, breathe, or use, and what is not.

In some cases, substances that are helpful to man are also carcinogenic. Chlorine is one such carcinogen. Chlorine is helpful for disinfecting water for bathing, drinking, and swimming. At the same time, its byproducts are capable of causing a range of illnesses, including lung cancer.