List of IARC Group 1 carcinogens

# Overview
Substances, mixtures and exposure circumstances in this list have been classified by the IARC as Group 1: The agent (mixture) is carcinogenic to humans. The exposure circumstance entails exposures that are carcinogenic to humans.
This category is used when there is sufficient evidence of carcinogenicity in humans. Exceptionally, an agent (mixture) may be placed in this category when evidence of carcinogenicity in humans is less than sufficient but there is sufficient evidence of carcinogenicity in experimental animals and strong evidence in exposed humans that the agent (mixture) acts through a relevant mechanism of carcinogenicity.

# Agents and groups of agents
- Aflatoxins (naturally occurring mixtures of)
- 4-Aminobiphenyl
- Arsenic and arsenic compounds1
- Asbestos
- Azathioprine
- Benzene
- Benzidine
- Beryllium and beryllium compounds2
- Chlornapazine (N,N-Bis(2-chloroethyl)-2-naphthylamine)
- Bis(chloromethyl)ether
- Chloromethyl methyl ether
- 1,4-Butanediol dimethanesulfonate (Busulphan; Myleran)
- Cadmium and cadmium compounds2
- Chlorambucil
- Methyl-CCNU (1-(2-Chloroethyl)-3-(4-methylcyclohexyl)-1-nitrosourea; Semustine)
- Chromium(VI) compounds2
- Ciclosporin
- Cyclophosphamide
- Diethylstilboestrol
- Dioxin
- Epstein-Barr virus
- Erionite
- Ethylene oxide
- Etoposide in combination with cisplatin and bleomycin
- Formaldehyde
- Gamma radiation
- Gallium arsenide
- 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
- Methoxsalen (8-Methoxypsoralen) plus ultraviolet A radiation
- MOPP and other combined chemotherapy including alkylating agents
- Mustard gas (Sulfur mustard)
- 2-Naphthylamine
- Neutron radiation
- Nickel compounds2
- Oestrogen therapy, postmenopausal
- Oestrogens, nonsteroidal1
- Oestrogens, steroidal1
- Opisthorchis viverrini (infection with)
- Combined (estrogen-containing) forms of hormonal contraception3
- 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, -particle-emitting, internally deposited4
- Radionuclides, -particle-emitting, internally deposited4
- 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 fibres
- Tamoxifen5
- 2,3,7,8-Tetrachlorodibenzo-para-dioxin
- Thiotepa (1,1',1"-Phosphinothioylidynetrisaziridine)
- Thorium-232 and its decay products, administered intravenously as a colloidal dispersion of thorium-232 dioxide
- Treosulfan
- Vinyl chloride
- X-Radiation

# Mixtures
- Alcoholic beverages
- Analgesic mixtures containing phenacetin
- Areca nut
- Betel quid with tobacco
- Betel quid without tobacco
- Coal-tar pitches
- Coal-tars
- Mineral oils, untreated and mildly treated
- Salted fish (Chinese-style)
- Shale-oils
- Soots
- Tobacco products, smokeless
- Wood dust

# Exposure circumstances
- Aluminium production
- Arsenic in drinking water
- Auramine, manufacture of
- Boot and shoe manufacture and repair
- Coal gasification
- Coke (fuel) production
- Furniture and cabinet making
- Haematite mining (underground) with exposure to radon
- Secondhand smoke
- 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)
- Tobacco smoking

# Notes
- This evaluation applies to the group of compounds as a whole and not necessarily to all individual compounds within the group.
- Evaluated as a group.
- There is also conclusive evidence that these agents have a protective effect against cancers of the ovary and endometrium.
- Specific radionuclides for which there is sufficient evidence for carcinogenicity to humans are also listed individually as Group 1 agents.
- There is also conclusive evidence that this agent (tamoxifen) reduces the risk of contralateral breast cancer.