Avoid These Human Carcinogens For Breast Health

Carcinogens are cancer-causing substances found in our environment, both natural and man-made. Exposure to these substances can increase your risk of cancer, including breast cancer. Some carcinogens, for example sunlight, are not possible to avoid entirely, but extended exposure should be avoided.

The International Agency for Research on Cancer (IARC), part of the World Health Organization (WHO), classifies substances into 5 groups, depending on their likelihood of causing cancer in humans:

  • 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

Group 1: Carcinogenic to Humans

These substances have been proven to cause cancer, though dosages and exposure length vary between substance.

Tobacco smoke, both direct and second-hand, as well as oral tobacco is listed in Group 1 as being carcinogenic to humans. Photo by: Fried Dough

  • Acetaldehyde (from consuming alcoholic beverages)
  • Acid mists, strong inorganic
  • Aflatoxins
  • Alcoholic beverages
  • Aluminum production
  • 4-Aminobiphenyl
  • Areca nut
  • Aristolochic acid (and plants containing it)
  • Arsenic and inorganic arsenic compounds
  • Asbestos (all forms) and mineral substances (such as talc or vermiculite) that contain asbestos
  • Auramine production
  • Azathioprine
  • Benzene
  • Benzidine and dyes metabolized to benzidine
  • Benzo[a]pyrene
  • Beryllium and beryllium compounds
  • Betel quid, with or without tobacco
  • Bis(chloromethyl)ether and chloromethyl methyl ether (technical-grade)
  • Busulfan
  • 1,3-Butadiene
  • Cadmium and cadmium compounds
  • Chlorambucil
  • Chlornaphazine
  • Chromium (VI) compounds
  • Clonorchis sinensis (infection with)
  • Coal, indoor emissions from household combustion
  • Coal gasification
  • Coal-tar distillation
  • Coal-tar pitch
  • Coke production
  • Cyclophosphamide
  • Cyclosporine
  • Diethylstilbestrol
  • Epstein-Barr virus (infection with)
  • Erionite
  • Estrogen postmenopausal therapy
  • Estrogen-progestogen postmenopausal therapy (combined)
  • Estrogen-progestogen oral contraceptives (combined) (Note: There is also convincing evidence in humans that these agents confer a protective effect against cancer in the endometrium and ovary)
  • Ethanol in alcoholic beverages
  • Ethylene oxide
  • Etoposide
  • Etoposide in combination with cisplatin and bleomycin
  • Fission products, including strontium-90
  • Formaldehyde
  • Haematite mining (underground)
  • Helicobacter pylori (infection with)
  • Hepatitis B virus (chronic infection with)
  • Hepatitis C virus (chronic infection with)
  • Human immunodeficiency virus type 1 (HIV-1) (infection with)
  • Human papilloma virus (HPV) types 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59 (infection with) (Note: The HPV types that have been classified as carcinogenic to humans can differ by an order of magnitude in risk for cervical cancer)
  • Human T-cell lymphotropic virus type I (HTLV-1) (infection with)
  • Ionizing radiation (all types)
  • Iron and steel founding (workplace exposure)
  • Isopropyl alcohol manufacture using strong acids
  • Kaposi sarcoma herpesvirus (KSHV)/human herpesvirus 8 (HHV-8) (infection with)
  • Leather dust
  • Magenta production
  • Melphalan
  • Methoxsalen (8-methoxypsoralen) plus ultraviolet A radiation
  • 4,4′-Methylenebis(chloroaniline) (MOCA)
  • Mineral oils, untreated or mildly treated
  • MOPP and other combined chemotherapy including alkylating agents
  • 2-Naphthylamine
  • Neutron radiation
  • Nickel compounds
  • N’-Nitrosonornicotine (NNN) and 4-(N-Nitrosomethylamino)-1-(3-pyridyl)-1-butanone (NNK)
  • Opisthorchis viverrini (liver fluke; infection with)
  • Painter (workplace exposure as a)
  • 3,4,5,3′,4′-Pentachlorobiphenyl (PCB-126)
  • 2,3,4,7,8-Pentachlorodibenzofuran
  • Phenacetin (and mixtures containing it)
  • Phosphorus-32, as phosphate
  • Plutonium
  • Radioiodines, including iodine-131
  • 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
  • Rubber manufacturing industry
  • Salted fish (Chinese-style)
  • Schistosoma haematobium (flatworm; infection with)
  • Semustine (methyl-CCNU)
  • Shale oils
  • Silica dust, crystalline, in the form of quartz or cristobalite
  • Solar radiation
  • Soot (as found in workplace exposure of chimney sweeps)
  • Sulfur mustard
  • Tamoxifen (Note: There is also conclusive evidence that tamoxifen reduces the risk of contralateral breast cancer in breast cancer patients)
  • 2,3,7,8-Tetrachlorodibenzo-para-dioxin
  • Thiotepa
  • Thorium-232 and its decay products
  • Tobacco, smokeless
  • Tobacco smoke, secondhand
  • Tobacco smoking
  • ortho-Toluidine
  • Treosulfan
  • Ultraviolet (UV) radiation, including UVA, UVB, and UVC rays
  • Ultraviolet-emitting tanning devices
  • Vinyl chloride
  • Wood dust
  • X- and Gamma-radiation

Group 2A: Probably Carcinogenic To Humans

These substances most likely cause cancer and should be avoided as much as possible. Some of these substances are listed as probable causes of cancer because of inability to conclusively test their effects on humans.

  • Acrylamide

    Shiftwork that involves disrupting the circadian rhythm (natural sleep patterns) probably causes cancer, according to IARC. Photo by: opnurse

  • Adriamycin (doxorubicin)
  • Androgenic (anabolic) steroids
  • Art glass, glass containers, and press ware (manufacture of)
  • Azacitidine
  • Biomass fuel (primarily wood), emissions from household combustion
  • Bischloroethyl nitrosourea (BCNU)
  • Captafol
  • Carbon electrode manufacture
  • Chloramphenicol
  • alpha-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
  • Cobalt metal with tungsten carbide
  • Creosotes
  • Cyclopenta[cd]pyrene
  • Dibenz[a,h]anthracene
  • Dibenzo[a,l]pyrene
  • Diethyl sulfate
  • Dimethylcarbamoyl chloride
  • 1,2-Dimethylhydrazine
  • Dimethyl sulfate
  • Engine exhaust, diesel
  • Epichlorohydrin
  • Ethyl carbamate (urethane)
  • Ethylene dibromide
  • N-Ethyl-N-nitrosourea
  • Frying, emissions from high-temperature
  • Glycidol
  • Hairdresser or barber (workplace exposure as)
  • Human papillomavirus (HPV) type 68 (infection with)
  • Indium phosphide
  • IQ (2-Amino-3-methylimidazo[4,5-f]quinoline)
  • Lead compounds, inorganic
  • Mate, hot
  • 5-Methoxypsoralen
  • Methyl methanesulfonate
  • N-Methyl-N´-nitro-N-nitrosoguanidine (MNNG)
  • N-Methyl-N-nitrosourea
  • Nitrate or nitrite (ingested) under conditions that result in endogenous nitrosation
  • Nitrogen mustard
  • N-Nitrosodiethylamine
  • N-Nitrosodimethylamine
  • 2-Nitrotoluene
  • Non-arsenical insecticides (workplace exposures in spraying and application of)
  • Petroleum refining (workplace exposures in)
  • Polychlorinated biphenyls (PCBs)
  • Procarbazine hydrochloride
  • Shiftwork that involves circadian disruption
  • Styrene-7,8-oxide
  • Teniposide
  • Tetrachloroethylene (perchloroethylene)
  • Trichloroethylene
  • 1,2,3-Trichloropropane
  • Tris(2,3-dibromopropyl) phosphate
  • Vinyl bromide (Note: For practical purposes, vinyl bromide should be considered to act similarly to the human carcinogen vinyl chloride.)
  • Vinyl fluoride (Note: For practical purposes, vinyl fluoride should be considered to act similarly to the human carcinogen vinyl chloride.)

Group 3: Possibly Carcinogenic to Humans

These substances have not been conclusively proven to cause cancer in humans, but there is sufficient doubt as to their safety. While some organizations choose to ignore this group because of their inconclusive status, we recommend a “better safe than sorry,” attitude. Avoid and reduce exposure as much as possible.

  • The radio frequency of wireless phones is listed as “possibly carcinogenic” by IARC. Photo by: Andrew Magill.

    A-a-C (2-Amino-9H-pyrido[2,3-b]indole)

  • Acetaldehyde
  • Acetamide
  • Acrylonitrile
  • Adapalene
  • AF-2 (2-(2-Furyl)-3-(5-nitro-2-furyl)acrylamide)
  • Aflatoxin M1
  • para-Aminoazobenzene
  • ortho-Aminoazotoluene
  • 2-Amino-5-(5-nitro-2-furyl)-1,3,4-thiadiazole
  • Amsacrine
  • ortho-Anisidine
  • Antimony trioxide
  • Aramite
  • Auramine (technical-grade)
  • Azaserine
  • Aziridine
  • Benz[j]aceanthrylene
  • Benz[a]anthracene
  • Benzo[b]fluoranthene
  • Benzo[j]fluoranthene
  • Benzo[k]fluoranthene
  • Benzo[c]phenanthrene
  • Benzofuran
  • Benzyl violet 4B
  • 2,2-Bis(bromomethyl)propane-1,3-diol
  • Bleomycin
  • Bracken fern
  • Bromodichloromethane
  • Butylated hydroxyanisole
  • b-Butyrolactone
  • Caffeic acid
  • Carbon black
  • Carbon tetrachloride
  • Catechol
  • Chlordane
  • Chlordecone (Kepone)
  • Chlorendic acid
  • para-Chloroaniline
  • 3-Chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone
  • Chloroform
  • 1-Chloro-2-methylpropene
  • Chlorophenoxy herbicides
  • 4-Chloro-ortho-phenylenediamine
  • Chloroprene
  • Chlorothalonil
  • Chrysene
  • CI Acid Red 114
  • CI Basic Red 9
  • CI Direct Blue 15
  • Citrus Red No. 2
  • Cobalt and cobalt compounds 1
  • Cobalt sulfate and other soluble cobalt(II) salts
  • para-Cresidine
  • Cycasin
  • Dacarbazine
  • Dantron (Chrysazin, 1,8-Dihydroxyanthraquinone)
  • Daunomycin
  • DDT (p,p’-DDT)
  • N,N’-Diacetylbenzidine
  • 2,4-Diaminoanisole
  • 4,4′-Diaminodiphenyl ether
  • 2,4-Diaminotoluene
  • Dibenz[a,h]acridine
  • Dibenz[a,j]acridine
  • 7H-Dibenzo[c,g]carbazole
  • Dibenzo[a,e]pyrene
  • Dibenzo[a,h]pyrene
  • Dibenzo[a,i]pyrene
  • 1,2-Dibromo-3-chloropropane
  • 2,3-Dibromopropan-1-ol
  • Dichloroacetic acid
  • para-Dichlorobenzene
  • 3,3′-Dichlorobenzidine
  • 3,3′-Dichloro-4,4′-diaminodiphenyl ether
  • 1,2-Dichloroethane
  • Dichloromethane (methylene chloride)
  • 1,3-Dichloropropene (technical grade)
  • Dichlorvos
  • 1,2-Diethylhydrazine
  • Diglycidyl resorcinol ether
  • Dihydrosafrole
  • Diisopropyl sulfate
  • 3,3′-Dimethoxybenzidine (o-Dianisidine)
  • para-Dimethylaminoazobenzene
  • trans-2-[(Dimethylamino)methylimino]-5-[2-(5-nitro-2-furyl)-vinyl]-1,3,4-oxadiazole
  • 2,6-Xylidine (2,6-Dimethylaniline)
  • 3,3′-Dimethylbenzidine (o-Tolidine)
  • 1,1-Dimethylhydrazine
  • 3,7-Dinitrofluoranthene
  • 3,9-Dinitrofluoranthene
  • 1,6-Dinitropyrene
  • 1,8-Dinitropyrene
  • 2,4-Dinitrotoluene
  • 2,6-Dinitrotoluene
  • 1,4-Dioxane
  • Disperse Blue 1
  • 1,2-Epoxybutane
  • Ethyl acrylate
  • Ethylbenzene
  • Ethylene dichloride
  • Ethyl methanesulfonate
  • Foreign bodies, implanted in tissues
  • Polymeric, prepared as thin smooth films (with the exception of poly(glycolic acid))
  • Metallic, prepared as thin smooth films
  • Metallic cobalt, metallic nickel and an alloy powder containing 66-67% nickel, 13-16% chromium and 7% iron 2-(2-Formylhydrazino)-4-(5-nitro-2-furyl)thiazole
  • Fumonisin B1
  • Furan
  • Glu-P-1 (2-Amino-6-methyldipyrido[1,2-a:3′,2′-d]imidazole)
  • Glu-P-2 (2-Aminodipyrido[1,2-a:3′,2′-d]imidazole)
  • Glycidaldehyde
  • Griseofulvin
  • HC Blue No. 1
  • Heptachlor
  • Hexachlorobenzene
  • Hexachloroethane
  • Hexachlorocyclohexanes
  • Hexamethylphosphoramide (HMPA)
  • Human immunodeficiency virus type 2 (infection with)
  • Human papillomaviruses: some types other than 16, 18, 31 and 33
  • Hydrazine
  • 1-Hydroxyanthraquinone
  • Indeno[1,2,3-cd]pyrene
  • Iron-dextran complex
  • Isoprene
  • Lasiocarpine
  • Lead
  • Magnetic fields (extremely low frequency)
  • MeA-a-C (2-Amino-3-methyl-9H-pyrido[2,3-b]indole)
  • Medroxyprogesterone acetate
  • MeIQ (2-Amino-3,4-dimethylimidazo[4,5-f]quinoline)
  • MeIQx (2-Amino-3,8-dimethylimidazo[4,5-f]quinoxaline)
  • Merphalan
  • 2-Methylaziridine (Propyleneimine)
  • Methylazoxymethanol acetate
  • 5-Methylchrysene
  • 4,4′-Methylene bis(2-methylaniline)
  • 4,4′-Methylenedianiline
  • Methylmercury compounds 1
  • 2-Methyl-1-nitroanthraquinone (uncertain purity)
  • N-Methyl-N-nitrosourethane
  • Methylthiouracil
  • Metronidazole
  • Michler’s base (4,4′-methylene-bis(N,N-dimethyl)benzenamine)
  • Michler’s ketone (4,4′-bis(dimethylamino)benzophenone)
  • Microcystin-LR
  • Mirex
  • Mitomycin C
  • Mitoxantrone
  • Monocrotaline
  • 5-(Morpholinomethyl)-3-[(5-nitrofurfurylidene)amino]-2-oxazolidinone
  • Nafenopin
  • Naphthalene
  • Nickel, metallic and alloys
  • Niridazole
  • Nitrilotriacetic acid and its salts 1
  • 5-Nitroacenaphthene
  • 2-Nitroanisole
  • Nitrobenzene
  • 6-Nitrochrysene
  • Nitrofen (technical-grade)
  • 2-Nitrofluorene
  • 1-[(5-Nitrofurfurylidene)amino]-2-imidazolidinone
  • N-[4-(5-Nitro-2-furyl)-2-thiazolyl]acetamide
  • Nitrogen mustard N-oxide
  • Nitromethane
  • 2-Nitropropane
  • 1-Nitropyrene
  • 4-Nitropyrene
  • N-Nitrosodi-n-butylamine
  • N-Nitrosodiethanolamine
  • N-Nitrosodi-n-propylamine
  • 3-(N-Nitrosomethylamino)propionitrile
  • N-Nitrosomethylethylamine
  • N-Nitrosomethylvinylamine
  • N-Nitrosomorpholine
  • N-Nitrosopiperidine
  • N-Nitrosopyrrolidine
  • N-Nitrososarcosine
  • Ochratoxin A
  • Oestrogen-progestogen therapy, postmenopausal
  • Oil Orange SS
  • Oxazepam
  • Palygorskite (attapulgite) (long fibres, >5 µm)
  • Panfuran S (containing dihydroxymethylfuratrizine)
  • Phenazopyridine hydrochloride
  • Phenobarbital
  • Phenolphthalein
  • Phenoxybenzamine hydrochloride
  • Phenyl glycidyl ether
  • Phenytoin
  • PhIP (2-amino-1-methyl-6-phenylimidazo(4,5-b)pyridine)
  • Polychlorophenols and their sodium salts (mixed exposures)
  • Ponceau MX
  • Ponceau 3R
  • Potassium bromate
  • Progestins
  • Progestogen-only contraceptives
  • 1,3-Propane sultone
  • β-Propiolactone
  • Propylene oxide
  • Propylthiouracil
  • Radiofrequency electromagnetic fields, such as, but not limited to, those associated with wireless phones
  • Refractory ceramic fibres
  • Riddelliine
  • Safrole
  • Schistosoma japonicum (infection with)
  • Sodium ortho-phenylphenate
  • Special-purpose fibres such as E-glass and ‘475’ glass fibres
  • Sterigmatocystin
  • Streptozotocin
  • Styrene
  • Sulfallate
  • Tetrafluoroethylene
  • Tetranitromethane
  • Thioacetamide
  • 4,4′-Thiodianiline
  • Thiouracil
  • Titanium dioxide
  • Toluene diisocyanates
  • Trichlormethine (Trimustine hydrochloride)
  • Trp-P-1 (3-Amino-1,4-dimethyl-5H-pyrido[4,3-b]indole)
  • Trp-P-2 (3-Amino-1-methyl-5H-pyrido[4,3-b]indole)
  • Trypan blue
  • Uracil mustard
  • Vanadium pentoxide
  • Vinyl acetate
  • 4-Vinylcyclohexene
  • 4-Vinylcyclohexene diepoxide
  • Zalcitabine
  • Zidovudine (AZT)
  • Bitumens, extracts of steam-refined and air-refined
  • Carrageenan, degraded
  • Chlorinated paraffins of average carbon chain length C12 and average degree of chlorination approximately 60%
  • Coffee (urinary bladder)
  • Diesel fuel, marine
  • Engine exhaust, gasoline
  • Fuel oils, residual (heavy)
  • Gasoline
  • Magenta dyes (CI Basic Red and fuschins)
  • Pickled vegetables (traditional in Asia)
  • Polybrominated biphenyls [Firemaster BP-6, 59536-65-1]
  • Toxaphene (Polychlorinated camphenes)
  • Toxins derived from Fusarium moniliforme
  • Welding fumes
  • Carpentry and joinery
  • Cobalt metal without tungsten carbide
  • Dry cleaning (occupational exposure as)
  • Firefighting (occupational exposure as)
  • Printing processes (occupational exposure as)
  • Talc-based body powders (perinal use of)
  • Textile manufacturing industry (work in)