IARC Group 2A carcinogens

IARC Group 2A Carcinogens are substances, mixtures, and exposure circumstances that have been evaluated by the International Agency for Research on Cancer (IARC) and found to be probably carcinogenic to humans. This classification is the second highest in terms of the strength of evidence for carcinogenicity assessed by IARC, which is part of the World Health Organization (WHO). The IARC classifies carcinogens into several groups based on the evidence available: Group 1 (carcinogenic to humans), Group 2A (probably carcinogenic to humans), Group 2B (possibly carcinogenic to humans), Group 3 (not classifiable as to its carcinogenicity to humans), and Group 4 (probably not carcinogenic to humans).

Classification Criteria

The classification into Group 2A is based on limited evidence of carcinogenicity in humans and sufficient evidence of carcinogenicity in experimental animals. Limited evidence in humans means that a positive association has been observed between exposure to the agent and cancer but that other explanations for the observations (technically termed as "chance, bias, or confounding") could not be ruled out with reasonable confidence. Sufficient evidence in experimental animals means that there is a causal relationship between the agent and an increased incidence of cancer in more than one species, strain, or sex of animals, or in multiple experiments, preferably with different routes of administration or using different doses.

Examples of IARC Group 2A Carcinogens

Some well-known examples of substances and exposures classified as Group 2A carcinogens include:

• Diesel engine exhaust
• Red meat (consumption of)
• Hot beverages (drinking at very hot temperatures)
• Glyphosate (widely used herbicide)
• Indoor emissions from household combustion of coal

Implications for Public Health

The classification of an agent as a Group 2A carcinogen implies that there is credible evidence suggesting it could cause cancer in humans, but the evidence is not yet conclusive. Public health policies may be influenced by such classifications, leading to recommendations to limit exposure to these agents. For example, guidelines may be developed to reduce occupational exposure to diesel engine exhaust or to advise against the consumption of red meat and very hot beverages at temperatures that could increase the risk of cancer.

Regulatory and Research Implications

Regulatory agencies around the world may use IARC classifications to set exposure limits and to guide research priorities. The classification of an agent as probably carcinogenic to humans highlights the need for further research to clarify the relationship between exposure to the agent and cancer risk. It also underscores the importance of developing and implementing strategies to minimize exposure to these agents, especially in occupational settings and through dietary recommendations.

Controversies and Criticisms

The IARC's classifications, including those for Group 2A carcinogens, have sometimes been the subject of controversy and criticism. Critics argue that the classification process can lead to public confusion, especially when substances commonly consumed or used by the public, such as red meat or glyphosate, are classified as probably carcinogenic. The IARC maintains that its classifications are based on a thorough review of the available scientific evidence and are intended to inform, not to prescribe specific regulatory actions.

See Also

• Carcinogen
• International Agency for Research on Cancer
• World Health Organization
• Epidemiology of cancer
• Occupational safety and health