Agent Purple is the code name for a powerful herbicide and defoliant used by the U.S. military in its Herbicidal Warfare program during the Vietnam War. The name comes from the purple stripe painted on the barrels to identify the contents. It was one of the so-called "rainbow herbicides" that included the more infamous Agent Orange.

Agent Purple is chemically similar to the better known Agent Orange, consisting of a mixture of the herbicides 2,4-D and 2,4,5-T. It was later discovered that Agents Orange and Purple had been contaminated with varying levels of tetrachlorodibenzodioxin (TCDD), a dioxin that is a toxic and persistent substance, as a side-effect of the manufacturing process of 2,4,5-T. Agent Purple is reputed to have three times the dioxin levels of Agent Orange, 45 parts per million as opposed to 13 parts per million in Agent Orange.

Agent Purple was used only in the earliest stages of the spraying program, between 1962 and 1964. Only small amounts were sprayed in total.

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