IARC (International Agency for Research on Cancer)
At a glance: The WHO agency classifying how strongly evidence links agents to cancer.
The IARC Monographs classify agents by certainty of carcinogenicity: Group 1, carcinogenic to humans; Group 2A, probably carcinogenic; Group 2B, possibly carcinogenic; and Group 3, not classifiable. 45 This classification reflects the level of certainty that a substance can cause cancer, not the level of risk associated with exposure. 46 In other words, IARC provides a hazard classification rather than a risk classification. Mutagen explains a related type of agent that can permanently alter genetic material.