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Principles of Ecology

Carcinogens

by Oluseyi A. Vanderpuye

Fields of Study

Air Quality Monitoring; Biology; Ecology; Environment; Environmental Microbiology; Medicine; Oncology

Summary

The effects of human exposure to carcinogens in the environment may include the development of different types of illness, deaths, and economic obligations on a national and global scale.

Principal Terms

  • aflatoxins: poisonous carcinogens that are produced by certain molds, which grow in soil, decaying vegetation, hay, and grains

  • asbestos: a fibrous mineral, either amphibole or chrysotile, formerly used for making incombustible or fireproof articles

  • benzene: a colorless, volatile, flammable, toxic, slightly water-soluble, liquid aromatic compound, obtained chiefly from coal tar

  • beryllium: a toxic divalent metallic element, steel-gray in color, light and strong but brittle, used chiefly as a hardening agent in alloys

  • carcinogens: substances or physical agents that cause or worsen cancer

  • dioxins: any of several persistent toxic heterocyclic hydrocarbons occurring especially as by-products of industrial processes, such as pesticide manufacture and papermaking, and waste incineration

  • formaldehyde: a colorless, toxic, potentially carcinogenic, water-soluble gas with a suffocating odor, usually derived from methyl alcohol and used chiefly in aqueous solutions, as disinfectants and preservatives, and in the manufacture of various resins and plastics.

  • vinyl chloride: a colorless, easily liquefied, flammable, slightly water-soluble gas, with a pleasant, etherlike odor, used in the manufacture of plastics, as a refrigerant, and in the synthesis of polyvinyl chloride and other organic compounds

Cancer is a leading cause of death throughout the world. Environmentalists and others have raised concerns regarding the cancer-causing (carcinogenic) potential of exposure to a constantly growing number of both newly developed and long-existing chemicals in the environment. In addition, humans seem to be increasingly exposed to various sources of electromagnetic waves, such as microwaves, and some groups and individuals are concerned about the possible carcinogenicity of these physical phenomena.

Carcinogens can be categorized based on their origin as chemicals (naturally occurring or synthetic), physical agents, or infectious agents. Chemical carcinogens can be classed as compounds that occur naturally, such as aflatoxins, chromium 6 compounds, and arsenic compounds; and others that are largely synthetic in origin, such as benzene, formaldehyde, vinyl chloride, and dioxins. In addition, there are carcinogenic minerals, such as asbestos. Other carcinogenic chemicals are elements or substances such as radon (a radioactive gas), beryllium, and cadmium. Some carcinogens—such as tobacco smoke and alcoholic beverages—are mixtures of compounds. Physical agents that are carcinogens include solar radiation (primarily ultraviolet radiation), gamma rays, and x-rays.

Fusarium ear rot, caused by the fungi Fusarium verticillioides and F. proliferatum, is a type of aflatoxin. By UIUC

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Infectious disease agents that have been implicated as carcinogens include human papilloma virus (HPV), which can cause cervical cancer; Helicobacter pylori (H. pylori), a bacterium causally associated with stomach cancer; the hepatitis C and hepatitis B viruses, which can cause liver cancer; Epstein-Barr virus, which is associated with Burkitt’s lymphoma; and human T-lymphotrophic virus type 1 (HTLV-1), which has been linked to leukemia in adults. The human immunodeficiency virus (HIV), which causes acquired immunodeficiency syndrome (AIDS), has been associated with Kaposi’s sarcoma. Viruses have also been shown definitively to cause tumors in animals such as mice (mammary tumor virus), chickens (Rous sarcoma virus), and Tasmanian devils.

Exposure to carcinogens can be related to work environments, such as in the case of workers in the nuclear power and medical radioisotope industries. Sometimes carcinogenic agents happen to be concentrated in particular geographic regions; for example, widespread exposure to the carcinogen arsenic occurred in Bangladesh as the result of contaminated drinking water from a large number of wells that accessed groundwater in which arsenic was uncommonly abundant. Exposure to H. pylori is believed to occur through contaminated water supplies and thus is considered to be environmental in origin. Tobacco smoke, a major cause of lung cancer, is an environmental carcinogen to which people are widely exposed.

Carcinogens may lead to cancer by directly damaging deoxyribonucleic acid (DNA), as in the case of radiation; through conversion through metabolism; or through effects on metabolism. In the case of viruses, viral genetic material may be incorporated into host DNA at sites of oncogenes, which are genes whose altered function or disruption leads to cancer. Different carcinogens often lead to effects on different organs, thus H. pylori is associated mainly with stomach cancer, whereas tobacco smoking or use is associated with lung, oral, and laryngeal cancers (and also bladder, colon, and kidney cancers, among others), and asbestos is primarily linked to lung cancer. The time period and frequency of exposure to carcinogens as well as a person’s genetic background can also influence the likelihood that a carcinogen causes cancer.

Further Reading

1 

Hill, Marquita K. “Chemical Exposures and Risk Assessment.” Understanding Environmental Pollution. 3rd ed. New York: Cambridge UP, 2010. Print.

2 

“Known and Probable Human Carcinogens.” Cancer.org . American Cancer Society, 12 Dec. 2014. Web. 29 Jan. 2015.

3 

McKinnell, Robert. G., et al. The Biological Basis of Cancer. 2nd ed. New York: Cambridge UP, 2006.

4 

National Institute of Environmental Health Sciences. “Report on Carcinogens.” 12th ed. Research Triangle Park: US Dept. of Health and Human Services, Public Health Service, National Toxicology Program, 2011.

5 

Ward, Elizabeth M. “Cancer.” Occupational and Environmental Health: Recognizing and Preventing Disease and Injury. Ed. Barry S. Levy, et al. 6th ed. Philadelphia: Lippincott, 2011.

Citation Types

Type
Format
MLA 9th
Vanderpuye, Oluseyi A. "Carcinogens." Principles of Ecology, edited by Jennifer Heath, Salem Press, 2019. Salem Online, online.salempress.com/articleDetails.do?articleName=PREcology_0034.
APA 7th
Vanderpuye, O. A. (2019). Carcinogens. In J. Heath (Ed.), Principles of Ecology. Salem Press. online.salempress.com.
CMOS 17th
Vanderpuye, Oluseyi A. "Carcinogens." Edited by Jennifer Heath. Principles of Ecology. Hackensack: Salem Press, 2019. Accessed December 14, 2025. online.salempress.com.