Classification of Carcinogenic Substances by IARC

The International Agency for Research on Cancer (IARC) is a recognized body that conducts research on carcinogenic substances globally and is a part of the World Health Organization (WHO). IARC classifies and publishes carcinogenic substances into different groups.

 

The following are descriptions and examples of carcinogenic substances classified by each group. This information is provided based on content available from the official IARC website:

Group 1: Carcinogenic to humans

• Source: IARC Monographs on the Identification of Carcinogenic Hazards to Humans
• This group includes substances that have been conclusively proven to be carcinogenic to humans. These substances have been shown to have harmful effects on human health through scientific research or clinical trials.
• Examples: Asbestos, arsenic, tobacco, alcohol

Group 2A: Probably carcinogenic to humans

• Source: IARC Monographs on the Identification of Carcinogenic Hazards to Humans
• This group includes substances that are probably carcinogenic to humans based on evidence from human or animal studies. There is sufficient evidence that supports their carcinogenicity, although absolute carcinogenicity has not been fully established.
• Examples: Saffron, formaldehyde, acetaldehyde

Group 2B: Possibly carcinogenic to humans

• Source: IARC Monographs on the Identification of Carcinogenic Hazards to Humans
• This group includes substances that have shown evidence of carcinogenicity in humans or animals, but there are still uncertainties. More research is needed to clarify their carcinogenic potential.
• Examples: Bisphenol A, styrene, nitromethane

Group 3: Not classifiable as to its carcinogenicity to humans

Source: IARC Monographs on the Identification of Carcinogenic Hazards to Humans

This group includes substances currently not classifiable as to their carcinogenicity to humans. This means that there is no sufficient evidence of carcinogenicity in humans.

Examples: Coffee, salt, fluoxetine

 

Group 4: Probably not carcinogenic to humans

• Source: IARC Monographs on the Identification of Carcinogenic Hazards to Humans
• This group includes substances for which there is a lack of sufficient data to evaluate their carcinogenic potential. Additional research is needed. IARC's investigations and research provide assessments of recognized carcinogenic substances worldwide, and this information serves as critical guidelines for health authorities and policymakers. In addition to this, IARC publishes various reports and studies on carcinogenic substances.