Agent Purple

Agent Purple is the code name for a powerful herbicide and defoliant used by the U.S. military in their 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 and Orange were also used to clear brush in Canada.

Agent Purple was chemically similar to the better-known Agent Orange, both of them were consisting of a mixture of the herbicides 2,4-D and 2,4,5-T and in both cases the 2,4-D and 2,4,5-T constituted equal shares of the Agent. The difference was in the form of 2,4,5-T. While all the 2,4,5-T in Agent Orange was n-butyl ester 2,4,5-T in Agent Purple the 2,4,5-T was itself mixture of its two salt forms: 60% n-butyl ester 2,4,5-T, and 40% isobutyl ester 2,4,5-T.

The Agent Purple had then the following composition: 50% n-butyl ester 2,4-D, 30% n-butyl ester 2,4,5-T, and 20% isobutyl ester 2,4,5-T.

It was later discovered that during the manufacture of 2,4,5-T that Agents Orange and Purple were contaminated with varying levels of tetrachlorodibenzodioxin (TCDD), a dioxin that is a toxic and persistent substance. 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 1965 as well as in earlier tests conducted by the US military outside of Vietnam. About 500,000 gallons were sprayed in Vietnam total. (~1.9 million liters). When the need to clear brush around CFB Gagetown in Canada arose, quantities of Agent Purple and Agent Orange were also sprayed there in a testing program during 1966 and 1967.