US chemical companies that made Agent Orange and the government and military authorities who ordered its spraying on Vietnam knew the human health toll it could take, according to official and unofficial documents detailing the history of the deadly defoliant.

A review of the documents related to the use of Agent Orange – a dioxin-laden herbicide – in Vietnam, including decades-old declassified papers from the companies that manufactured it and the government and military that used it, provides compelling evidence that those in charge also concealed evidence of the devastating effects it could have on people.