Agent Orange: An herbicide and defoliant containing 2,4-D and 2,4,5-T and trace amounts of dioxin. Agent Orange was used as a defoliant in the Vietnam War. There has been concern about Agent Orange as a carcinogen and teratogen (cause cancer and birth defects).

The Institute of Medicine of the National Academies in the US has found "sufficient evidence" of an association between exposure to Agent Orange and the risk of developing chronic lymphocytic leukemia (CLL), non-Hodgkin lymphoma (NHL), Hodgkin disease, and soft tissue sarcoma.