Carcinogen

**Semantic type:** Classification

**Definition:** Any chemical, biological or physical agents that increase the risk of neoplasms in humans or animals. Carcinogens include natural or synthesized compounds, certain viruses, and various sources of radiation. A carcinogen may directly alter the genetic material of cells (genotoxic), thereby initiating or promoting the process of malignant transformation; it also may induce cancers by mechanisms that do not involve a direct alteration of cellular genetic material (non-genotoxic). (NCI04)

**Synonyms:** - Cancer Causing Agents - carcinogen