Dioxin contaminating Vietnam is a carcinogen.

Ian Timberlake wrote an article for the Agence France Presse news service about the continued contamination of Vietnam by Agent Orange, which was used by the US military as a defoliant to aid in jungle warfare during the Vietnam War. The most toxic chemical in Agent Orange is the contaminant dioxin. Timberlake correctly points out that the people, animals, plants, dirt, water and air of many areas of Vietnam are contaminated with dioxin.

Unfortunately, he misinforms about the health effects of dioxin when he states that it is “potentially cancer-causing.” The International Agency for Research on Cancer (IARC) and the US military agree: dioxin causes cancer.

IARC is the world’s leading authority on cancer classifications. IARC uses five categories to define a chemical's ability to cause cancer in people. These categories include: the agent positively causes cancer, probably causes cancer, possibly causes cancer and probably does not represent a cancer risk.

Based on the IARC classification, dioxin – which is short for 2,3,7,8-Tetrachlorodibenzo-para-dioxin – is not potentially cancer causing. Instead, dioxin is carcinogenic to humans.

Reporters and others should use IARC to decide how to report the carcinogenicity of a chemical.