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Table of Contents

Magill’s Medical Guide, 9th Edition

Carcinogens

by Alvin K. Benson

Category: Disease/Disorder

Anatomy or system affected: All

Specialties and related fields: All

Definition: A substance or agent that causes or precipitates cancer.

TYPES AND EFFECTS

Carcinogens include chemicals, radiation, or viruses that can alter the DNA (deoxyribonucleic acid) in a normal human cell and eventually mutate it into a cancer cell. Some carcinogens change DNA structure directly, while others make DNA more susceptible to damage from other sources or increase the possibility of DNA changes by causing cells to divide faster than normal. This means that the mechanism for how to regulate their growth stops working properly. This is known as the inhibiting of cell regulation division.

Susceptibility to different carcinogens varies widely from person to person and is highly dependent upon genetic makeup, physiology, exposure time, dose of the carcinogen, and nutrition available to the cells affected.

The Report on Carcinogens (RoC) released by the U.S. government in 2011 identifies over 50 known carcinogens. The government also made available a list, last updated in 2010, that identifies reasonably suspected carcinogens, which have not yet been proven to be carcinogenic (cancer-causing). There are currently known viral carcinogens present on the list, including hepatitis B virus (HBV), hepatitis C virus (HVC), and human papillomaviruses (HPVs). Lately, vaccines have been used to prevent infection and subsequent cancer formation from such etiologies. A list of carcinogens is also published by the International Agency for Research on Cancer (IARC).

CLASSIFICATION AND REDUCING RISK

Identification and classification of carcinogens is made from human observation and from laboratory studies that include animal experimentation and cell cultures. The RoC data include information about the ability of each substance to cause cancer, its ability to damage genes, and the biological changes that it can produce in the body. It reports the potential for human exposure to the listed substances and the federal regulations that are imposed to limit exposure. The RoC also gives updates on current efforts to investigate potential public health concerns. For example, they explain a current effort by the National Toxicology Program to investigate any potential health hazards from exposure to cell phone radiation.

A number of important measures can lower the risk of exposure to carcinogens. Avoiding cigarette smoking, excessive alcohol consumption, and abnormal exposure to ultraviolet (UV) radiation from sunlight reduces the risk of many cancers. Another way to protect against exposure to carcinogens is to be informed about the carcinogenic (cancer-causing) substances that may be present at home or in the workplace. Exercising the necessary precautions can be beneficial in avoiding exposure and risk. It is very important to follow the directions on any chemical containers.

PERSPECTIVE AND PROSPECTS

The identification of cancer-causing agents, or carcinogens, dates back to the 1930s when dozens of substances, including industrial pollution and tobacco smoke, were classified as carcinogens. U.S. federal law requires that the secretary of Health and Human Services publish the RoC through the National Toxicology Program (NTP) every two years. In addition to listing carcinogens, the IARC report also lists substances that have been studied and determined not to be carcinogens.

But even potential carcinogens can be a cause of concern. For example, RoC and IARC reports indicated that acrylamide, a chemical in French fries and potato chips, is a possible carcinogen, as well as the charred residue on barbecued meats. The Food and Drug Administration (FDA) reported that in a test of 124 cosmetics, over half of them contained the carcinogens triethanolamine (TEA) and diethanolamine (DEA). To complicate matters even more, beneficial drugs can also have carcinogenic side effects. Perhaps the best example is the drug tamoxifen, which, while used effectively in the treatment of breast cancer, increases the risk of some types of uterine cancer.

See also Asbestos exposure; Cancer; Environmental diseases; Environmental health; Hepatitis; Human papillomaviruses (HPV); Mutation; Smoking.

For Further Information:

1 

Adami, Hans-Olov, David Hunter, and Dimitrios Trichopoulos. Textbook of Cancer Epidemiology. 2nd ed. New York: Oxford University Press, 2008.

2 

Benigni, Romualdo, ed. Quantitative Structure-Activity Relationship (QSAR) Models of Mutagens and Carcinogens. Boca Raton, FL: CRC Press, 2003.

3 

McKinnell, Robert Gilmore, ed. The Biological Basis of Cancer. 2nd ed. New York: Cambridge University Press, 2006.

4 

Milman, Harry A., and Elizabeth K. Weisburger, eds. Handbook of Carcinogen Testing. 2nd ed. Park Ridge, NJ: Noyes, 2001.

5 

Pohanish, Richard P., ed. Sittig’s Handbook of Toxic and Hazardous Chemicals and Carcinogens. Vols. 1 and 2. 5th ed. Norwich, NY: William Andrew, 2008.

6 

Weinberg, Robert. The Biology of Cancer. New York: Garland Science, 2007.

Citation Types

Type
Format
MLA 9th
Benson, Alvin K. "Carcinogens." Magill’s Medical Guide, 9th Edition, edited by Anubhav Agarwal,, Salem Press, 2022. Salem Online, online.salempress.com/articleDetails.do?articleName=MMG2022_0223.
APA 7th
Benson, A. K. (2022). Carcinogens. In A. Agarwal, (Ed.), Magill’s Medical Guide, 9th Edition. Salem Press. online.salempress.com.
CMOS 17th
Benson, Alvin K. "Carcinogens." Edited by Anubhav Agarwal,. Magill’s Medical Guide, 9th Edition. Hackensack: Salem Press, 2022. Accessed October 22, 2025. online.salempress.com.