Carcinogene

Carcinogen, or carcinogene in French, is any substance, agent, or radiation capable of producing cancer by initiating tumor formation, promoting growth of abnormal cells, or facilitating other steps of carcinogenesis. Carcinogenicity depends on dose, exposure duration, and individual factors such as genetics and age.

One formal way to categorize carcinogens is through the International Agency for Research on Cancer (IARC) Monographs, which assign groups: Group 1 (carcinogenic to humans), Group 2A (probably carcinogenic to humans), Group 2B (possibly carcinogenic), Group 3 (not classifiable), Group 4 (probably not carcinogenic). Widely recognized carcinogens include tobacco smoke, asbestos, ultraviolet (UV) radiation, benzene, formaldehyde, and processed meat (Group 1).

Mechanisms of carcinogenesis include DNA damage via mutations and DNA adducts, chromosomal aberrations, and epigenetic changes; chronic inflammation, hormonal and metabolic effects can also promote tumor development. Carcinogenic risk is influenced by dose, timing of exposure, and individual susceptibility.

Exposure occurs through inhalation, ingestion, dermal contact, or radiation. Carcinogenicity is typically evaluated with animal studies and in vitro assays; the Ames test for mutagenicity is a common screening tool; long-term rodent bioassays assess tumor formation. Regulation relies on hazard identification (classification) and risk management, with agencies setting exposure limits, labeling requirements, and prohibiting certain substances. IARC classifies hazards; other systems assess actual risk in populations.

Public health efforts focus on reducing exposure, monitoring occupational and environmental sources, and communicating risk to the public. Researchers continue to study mechanisms of carcinogenesis and to identify both existing and emerging carcinogens, including chemicals, radiation, and certain biological agents.