The International Agency for Research on Cancer (IARC) is an intergovernmental agency established in 1965, which forms part of the World Health Organization of the United Nations. Since 1971 it has published a series of Monographs on the Evaluation of Carcinogenic Risks to Humans that have been highly influential in the classification of possible carcinogens. 

Group 1: The agent (mixture) is Definitely carcinogenic to humans. Group 2A: The agent (mixture) is Probably carcinogenic to humans. Group 2B: The agent (mixture) is Possibly carcinogenic to humans. Group 3: The agent (mixture or exposure circumstance) is Not classifiable as to its carcinogenicity to humans.

Group 4: The agent (mixture) is Probably Not carcinogenic to humans. 

LIST OF GROUP 1 CARCINOGENS  (The agent is carcinogenic to humans)

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1. HIV-Human Immunodeficiency Virus Type 1 

2. Human T-cell Lymphotropic Virus Type 1 (HTLV-I)

3. HPV-Human Papillomavirus 16,18,31,33,35,39,45,51,52,56,58,59,66

4. Hepatitis B Virus (chronic infection with)

5. Hepatitis C Virus (chronic infection with)

6. Human Herpesvirus 8 

7. Epstein-Barr Virus


1. Helicobacter Pylori (infection with)


1. Clonorchis Sinensis (infection with)

2. Opisthorchis Viverrini (infection with)

3. Schistosoma Haematobium (infection with)


1. 2-Naphthylamine

2. Acetaldehyde assoc.. with consumption of alcoholic beverages

3. 4-Aminobiphenyl

4. Aflatoxins

5. Aristolochic Acids/Plants Containing Them

6. Arsenic/Inorganic Arsenic Compounds

7. Asbestos

8. Azathioprine

9. Benzene

10. Benzidine/ Dyes Metabolized to

11. Benzo Pyrene

12. Beryllium/Beryllium Compounds

13. Chlornapazine (N,N-Bis(2-chloroethyl)-2-naphthylamine)

14. Bis(chloromethyl)ether

15. Chloromethyl Methyl Ether

16. 1,3-Butadiene

17. 01,4-Butanediol Dimethanesulfonate (Busulphan, Myleran)

18. Cadmium/Cadmium Compounds

19. Chlorambucil

20. Methyl-CCNU (1-(2-Chloroethyl)-3-(4-methylcyclohexyl)-1-nitrosourea; Semustine)

21. Chromium(VI) Compounds

22. Ciclosporin

23. Cyclophosphamide

24. 1,2-Dichloropropane

25. Diethylstilbestrol

26. Estrogen Therapy, Postmenopausal

27. Estrogen-Progestogen Oral Contraceptives (combined)

28. Ethanol in Alcoholic Beverages

29. Erionite

30. Ethylene Oxide

31. Etoposide (alone & in comb. w/) Cisplatin and Bleomycin

32. Fluoro-Edenite Fibrous Amphibole

33. Formaldehyde

34. Gallium Arsenide

35. Lindane

36. Melphalan

37. Methoxsalen (8-Methoxypsoralen) plus Ultraviolet A Radiation

38. 4,4'-Methylenebis(2-chloroaniline) (MOCA)

39. MOPP, Chemotherapy including Alkylating Agents

40. Mustard Gas (Sulfur Mustard)

41. 2-Naphthylamine

42. Neutron Radiation

43. Nickel Compounds

44. 4-(N-Nitroso methylamino)-1-(3-pyridyl)-1-butanone (NNK)

45. N-Nitrosonornicotine (NNN)

46. 2,3,4,7,8-Pentachloro dibenzofuran

47. 3,4,5,3’,4’-Pentachlorobiphenyl(PCB-126)

48. Tamoxifen

49. 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD)

50. Thiotepa (1,1',1"-Phosphinothioylidynetrisaziridine)

51. Thorium-232 and its decay products, administered intravenously as a colloidal dispersion of thorium-232 dioxide

52. Treosulfan

53. Trichloroethylene

54. o-Toluidine

55. Vinyl Chloride


1. Phosphorus-32, as Phosphate

2. Plutonium

3. Radioiodine's, short-lived Isotopes, including Iodine-131, from Atomic Reactor Accidents and Nuclear Weapons Detonation (exposure during childhood)

4. Radionuclides, A & B Particle-Emitting Internally Deposited

5. Radium-224, Radium-226, Radium-228 and its decay products

6. Radon-222 and its decay products

7. Silica Dust, Crystalline (inhaled in the form of quartz or cristobalite from occupational sources)

8. Talc Containing Asbestiform Fibers


1. Outdoor Air Pollution

2. Particulate Matter in Outdoor Air Pollution


1. Ionizing Radiation (all types)

2. Ultraviolet Radiation including Solar Radiation

3. X-Radiation and Gamma Radiation


1. Aflatoxins (naturally occurring mixtures of)

2. Alcoholic Beverages

3. Areca Nut

4. Betel Quid with Tobacco

5. Betel Quid without Tobacco

6. Coal-Tar Pitches

7. Coal-Tars

8. Coal, Indoor Emissions (from household combustion of)

9. Engine Exhaust, Diesel

10. Estrogen-Progestogen Menopausal Therapy, (combined)

11. Estrogen-Progestogen Oral Contraceptives (combined)

12. Fission Products, including Strontium-90

13. Leather Dust

14. Mineral Oils, Untreated and Mildly Treated

15. Paints Containing Benzene

16. Phenacetin, Analgesic Mixtures Containing

17. Plants Containing Aristolochic Acid

18. Polychlorinated Biphenyls, Dioxin-Like

19. Processed Meats, consumption of

20. Salted Fish (Chinese-style)

21. Shale-Oils

22. Soot (chimney sweeps)

23. Wood Dust


1. Acheson Process (Occupational Exposure associated with)

2. Acid Mists, strong inorganic

3. Aluminum Production

4. Auramine Production

5. Boot/Shoe Manufacture and Repair (see leather Dust and benzene)

6. Chimney Sweeping (see Soot)

7. Coal Gasification

8. Coal Tar Distillation

9. Coke (fuel) Production

10. Furniture and Cabinet Making (see wood dust)

11. Hematite mining (underground) with exposure to radon

12. Iron and Steel Founding (occupational exposure to)

I3. Isopropanol Manufacture (strong-acid process)

14. Glass Making

15. Magenta Dyes, manufacture of

16. Painting (see benzene)

17. Paving and Roofing with coal tar pitch

18. Rubber Manufacturing Industry

19. Sandblasting (see silica dust)

20. Smokeless Tobacco

21. Tobacco Smoke, second hand

22. Tobacco Smoking

23. Ultraviolet-Emitting Tanning Devices