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Environmental Influences Resulting in Cancer

A carcinogen is anything that could possibly induce cancer in an organism. Some carcinogens directly mutate a cell's DNA, while other simply cause cells do divide at a faster rate. The list of suspected carcinogens is very long. While prolonged exposure to carcinogens should be limited, being exposed to a carcinogen does not guarantee one will develop cancer.

Carcinogens are determined through

  1. Information about chemical structure, etc.
  2. Laboratory tests in which animals are exposed to higher doses of the suspected carcinogen than humans normally are exposed to
  3. Epidemiological studies are conducted in which patterns in the human population are analyzed

The International Agency for Research on Cancer (IARC), a part of the World Health Organization (WHO), has set up a classification system for carcinogens:

  • Group 1: Carcinogenic to humans
  • Group 2A: Probably carcinogenic to humans
  • Group 2B: Possibly carcinogenic to humans
  • Group 3: Unclassifiable as to carcinogenicity in humans
  • Group 4: Probably not carcinogenic to humans
Out of 900 agents studied for carcinogenic qualities, only approximately 90 have been classified as a group 1.

The following list of human carcinogens in the Group 1 and Group 2A categories was compiled by the IARC.
"Carcinogenic to Humans" (Group 1)

  • Agents and Groups of Agents
    • Aflatoxins (naturally occurring mixtures of)
    • 4-Aminobiphenyl
    • Arsenic and arsenic compounds (Note: This evaluation applies to the group of compounds as a whole and not necessarily to all individual compounds within the group)
    • Asbestos
    • Azathioprine
    • Benzene
    • Benzidine
    • Beryllium and beryllium compounds
    • N,N-Bis(2-chloroethyl)-2-naphthylamine (Chlornaphazine)
    • Bis(chloromethyl)ether and chloromethyl methyl ether (technical-grade)
    • 1,4-Butanediol dimethanesulfonate (Busulphan; Myleran)
    • Cadmium and cadmium compounds
    • Chlorambucil
    • 1-(2-Chloroethyl)-3-(4-methylcyclohexyl)-1-nitrosourea (Methyl-CCNU; Semustine)
    • Chromium [VI] compounds
    • Cyclophosphamide
    • Cyclosporin
    • Diethylstilbestrol
    • Epstein-Barr virus
    • Erionite
    • Estrogen therapy, postmenopausal
    • Estrogens, nonsteroidal (Note: This evaluation applies to the group of compounds as a whole and not necessarily to all individual compounds within the group)
    • Estrogens, steroidal (Note: This evaluation applies to the group of compounds as a whole and not necessarily to all individual compounds within the group)
    • Ethylene oxide
    • Etoposide in combination with cisplatin and bleomycin
    • [Gamma Radiation: see X- and Gamma (g)-Radiation]
    • Helicobacter pylori (infection with)
    • Hepatitis B virus (chronic infection with)
    • Hepatitis C virus (chronic infection with)
    • Herbal remedies containing plant species of the genus Aristolochia
    • Human immunodeficiency virus type 1 (infection with)
    • Human papillomavirus type 16
    • Human papillomavirus type 18
    • Human T-cell lymphotropic virus type I
    • Melphalan
    • 8-Methoxypsoralen (Methoxsalen) plus ultraviolet A radiation
    • MOPP and other combined chemotherapy including alkylating agents
    • Mustard gas (Sulfur mustard)
    • 2-Naphthylamine
    • Neutrons
    • Nickel compounds
    • Opisthorchis viverrini (infection with)
    • Oral contraceptives, combined (Note: There is also conclusive evidence that these agents have a protective effect against cancers of the ovary and endometrium)
    • Oral contraceptives, sequential
    • Phosphorus-32, as phosphate
    • Plutonium-239 and its decay products (may contain plutonium-240 and other isotopes), as aerosols
    • Radioiodines, short-lived isotopes, including iodine-131, from atomic reactor accidents and nuclear weapons detonation (exposure during childhood)
    • Radionuclides, alpha-particle-emitting, internally deposited
    • (Note: Specific radionuclides for which there is sufficient evidence for carcinogenicity to humans are also listed individually as Group 1 agents)
    • Radionuclides, beta-particle-emitting, internally deposited
    • (Note: Specific radionuclides for which there is sufficient evidence for carcinogenicity to humans are also listed individually as Group 1 agents)
    • Radium-224 and its decay products
    • Radium-226 and its decay products
    • Radium-228 and its decay products
    • Radon-222 and its decay products
    • Schistosoma haematobium (infection with)
    • Silica, crystalline (inhaled in the form of quartz or cristobalite from occupational sources)
    • Solar radiation
    • Talc containing asbestiform fibers
    • Tamoxifen (Note: There is also conclusive evidence that this agent (tamoxifen) reduces the risk of contralateral breast cancer)
    • 2,3,7,8-Tetrachlorodibenzo-para-dioxin
    • Thiotepa
    • Thorium-232 and its decay products, administered intravenously as a colloidal dispersion of thorium-232 dioxide
    • Treosulfan
    • Vinyl chloride
    • X- and Gamma (g)-Radiation
  • Mixtures
    • Alcoholic beverages
    • Analgesic mixtures containing phenacetin
    • Betel quid with tobacco
    • Coal-tar pitches
    • Coal-tars
    • Mineral oils, untreated and mildly treated
    • Salted fish (Chinese-style)
    • Shale-oils
    • Soots
    • Tobacco products, smokeless
    • Tobacco smoke
    • Wood dust
  • Exposure Circumstances
    • Aluminum production
    • Auramine, manufacture of
    • Boot and shoe manufacture and repair
    • Coal gasification
    • Coke production
    • Furniture and cabinet making
    • Hematite mining (underground) with exposure to radon
    • Iron and steel founding
    • Isopropanol manufacture (strong-acid process)
    • Magenta, manufacture of
    • Painter (occupational exposure as a)
    • Rubber industry
    • Strong inorganic acid mists containing sulfuric acid (occupational exposure to)

"Probably Carcinogenic to Humans" (Group 2A)
  • Agents and Groups of Agents
    • Acrylamide
    • Adriamycin
    • Androgenic (anabolic) steroids
    • Aristolochic acids (naturally occurring mixtures of)
    • Azacitidine
    • Benz[a]anthracene
    • Benzidine-based dyes
    • Benzo[a]pyrene
    • Bischloroethyl nitrosourea (BCNU)
    • 1,3-Butadiene
    • Captafol
    • Chloramphenicol
    • a-Chlorinated toluenes (benzal chloride, benzotrichloride, benzyl chloride) and benzoyl chloride (combined exposures)
    • 1-(2-Chloroethyl)-3-cyclohexyl-1-nitrosourea (CCNU)
    • 4-Chloro-ortho-toluidine
    • Chlorozotocin
    • Cisplatin
    • Clonorchis sinensis (infection with)
    • Dibenz [a,h]anthracene
    • Diethyl sulfate
    • Dimethylcarbamoyl chloride
    • 1,2-Dimethylhydrazine
    • Dimethyl sulfate
    • Epichlorohydrin
    • Ethylene dibromide
    • N-Ethyl-N-nitrosourea
    • Etoposide
    • Formaldehyde
    • Glycidol
    • Human papillomavirus type 31
    • Human papillomavirus type 33
    • IQ (2-Amino-3-methylimidazo[4,5-f]quinoline)
    • Kaposi's sarcoma herpesvirus/human herpesvirus 8
    • 5-Methoxypsoralen
    • 4,4´-Methylene bis(2-chloroaniline) (MOCA)
    • Methyl methanesulfonate
    • N-Methyl-N´-nitro-N-nitrosoguanidine (MNNG)
    • N-Methyl-N-nitrosourea
    • Nitrogen mustard
    • N-Nitrosodiethylamine
    • N-Nitrosodimethylamine
    • Phenacetin
    • Procarbazine hydrochloride
    • Styrene-7,8-oxide
    • Teniposide
    • Tetrachloroethylene
    • ortho-Toluidine
    • Trichloroethylene
    • 1,2,3-Trichloropropane
    • Tris(2,3-dibromopropyl) phosphate
    • Ultraviolet radiation A
    • Ultraviolet radiation B
    • Ultraviolet radiation C
    • Vinyl bromide
    • Vinyl fluoride
  • Mixtures
    • Creosotes (from coal-tars)
    • Diesel engine exhaust
    • Hot mate
    • Non-arsenical insecticides (occupational exposures in spraying and application of)
    • Polychlorinated biphenyls
  • Exposure Circumstances
    • Art glass, glass containers and pressed ware (manufacture of)
    • Hairdresser or barber (occupational exposure as a)
    • Petroleum refining (occupational exposures in)
    • unlamps and sunbeds (use of)