The name comes from the pink stripe painted on the barrels to identify the contents.
Agent Pink was only used during the early "testing" stages of the spraying program before 1964.
Agent Pink's only active ingredient was 2,4,5-trichlorophenoxyacetic acid (2,4,5-T), one of the common phenoxy herbicides of the era.
Even prior to Operation Ranch Hand (1962–1971) it was known[1][2][3][4][5][6] that a dioxin, 2,3,7,8-tetrachlorodibenzo-para-dioxin (TCDD), is produced as a byproduct of the manufacture of 2,4,5-T, and was present in any of the herbicides that used it, but to greater proportion in the earlier Agents, such as Pink.
[7] A 2003 Nature paper by Stellman et al., which re-apprised the average TCDD content of Agent Orange from the 3 ppm that USAF had reported to a level of 13 ppm, also estimated that Agent Pink may have had 65.5 ppm of TCDD on average.