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(blastomogens, cancerigens), chemical compounds capable of causing cancer and other malignant tumors, as well as benign neoplasms, when the body is exposed to them. Several hundred such substances, belonging to various classes of chemical compounds, are known. For example, certain polycy-clic hydrocarbons with a phenanthrene group in the molecule, azo dyes, aromatic amines, nitrosamines, and other alkylating compounds show marked carcinogenic activity. Carcinogens are found in certain industrial products, in air polluted by industrial waste, and in tobacco smoke.

The earliest notions of the existence of cancer-producing substances date from the 18th century, when cases of skin cancer in English chimney sweeps were connected with systematic contamination of the skin with coal tar and soot. In the early part of the 20th century skin cancer was induced in animals by smearing coal tar on their skin for a number of months. The carcinogens 3, 4-benzpyrene and other polycyclic hydrocarbons were subsequently isolated from the tar. Urinary bladder cancer frequently developed in workers in the aniline dye industry, who were exposed to the carcinogens β8-naphthylamine, benzidine, and 4-aminodiphenyl before the introduction of appropriate preventive measures. Lung cancer afflicts smokers more often than it does nonsmokers, and it afflicts those living in cities, where air pollution levels are high, more often than those living in rural areas.

The same carcinogen can give rise to tumors of different kinds and locations, depending on the site of application, and a given type of tumor can be caused by different substances. All carcinogens can be divided into three groups, according to the nature of their action: (1) locally active, (2) organotropic, that is, causing tumors not at the site of application but in certain organs, and (3) multiple, that is, producing different tumors in various organs.

The effect of carcinogens depends both on the amount of the substance and on the duration of its action; accumulation (deposition) in a tissue or organ intensifies the effect. Neoplasms do not develop immediately after exposure to a carcinogen. They do so only after a long period of time—one-fifth to one-seventh of the maximum lifetime of the given organism (this period might be 15–20 years for man and four to six months for mice). A neoplasm is preceded by precancerous changes.

The similarity of the chemical structure of carcinogenic hydrocarbons and many biologically active substances, such as sex hormones, biliary acids, and other steroids, suggested that the impairment of steroid metabolism could lead to carginogen formation in the body itself; this assumption was later confirmed experimentally. Such carcinogens, in addition to products of impaired steroid metabolism, include certain amino acid metabolites, such as tryptophan. Carcinogenic action is related to the chemical activity and electronic structure of the part of the carginogenic molecule responsible for the formation of complexes with certain cell components (apparently, nucleic acids and some proteins). It should be taken into account in considering the mechanisms of carcinogenesis that many carcinogens show pronounced mutagenic action.

Prevention of the action of carcinogens is based on a study of their distribution in man’s environment and on the use of prophylactic measures in occupational, public, and personal hygiene. It is important, therefore, to control pollution of the air, water, and soil by industrial wastes and to keep carcinogenic impurities out of food and drinking water. An effective way to prevent tumors is to discover which compounds have carcinogenic properties and remove them from the sphere of man’s activities.


Modeli i metody eksperimentarnoi onkologii. Edited by A. D. Timofeevskii. Moscow, 1960.
Neiman, I. M. Osnovy teoreticheskoi onkologii. Moscow, 1961.
Rukovodstvo po obshchei onkologii, 2nd ed. Edited by N. N. Petrov. Leningrad, 1961.
Shabad, L. M. Endogennye blastomogennye veschestva. Moscow, 1969.
Shabad, L. M. Metody izucheniia blastomogennosti khimicheskikh vesh-chestv. Moscow, 1970.


References in periodicals archive ?
Ortho-toluidine--used to make rubber chemicals, pesticides, and dyes --has been reevaluated and now is listed as a known human carcinogen.
The carcinogens have been shown to stunt brain neurons leading to developmental disorders in children as well as cause a number of cancers.
The people deserve to know if that water contains carcinogens so they can try and halt contamination, and exposure.
Washington, August 23 ( ANI ): Scientists have identified a substance in smokeless tobacco that is a strong oral carcinogen, a health risk for the 9 million users of chewing tobacco, snuff and related products.
We are of the view, however, that programs for control of chemical carcinogens must also encompass certain judiciously chosen class 2A or "probable" human carcinogens, such as diesel exhaust, indoor emissions produced by combustion of biomass fuels, and dimethylnitrosamine, for which there is already strong evidence of carcinogenicity in animal, cellular, or molecular models and limited human data (IARC 2011).
Aristolochic acids, a family of naturally occurring chemicals in plants grown in the United States and other countries, also were classified as known human carcinogens.
gov/go/roc12) 12th Report on Carcinogens now includes 240 listings.
Carcinogens are substances in the form of naturally or artificially produced chemicals, ultraviolet rays from the sun or radioactive materials, which change or mutate the cell structure, causing cells to grow uncontrollably and divide quickly.
Back in November of 2003 there was a myth circulating that a graduate student's thesis at the University of Idaho showed that DEHA, a plastics additive, was a human carcinogen that could be released from a PET container.
As a result, according to Susan Roll of the Massachusetts Breast Cancer Coalition, "one-third of personal-care products contain ingredients classified as possible human carcinogens.
To head off such reactions, the NTP's new Report on Carcinogens points out that many of the listed carcinogens, including some drugs, offer society substantial benefits and urges people not to eschew such agents without consulting a doctor or other expert.