Page "Herbicide" Paragraph 73

* 2, 4, 5-Trichlorophenoxyacetic acid ( 2, 4, 5-T ) was a widely used broadleaf herbicide until being phased out starting in the late 1970s.

While 2, 4, 5-T itself is of only moderate toxicity, the manufacturing process for 2, 4, 5-T contaminates this chemical with trace amounts of 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin ( TCDD ).

TCDD is extremely toxic to humans.

With proper temperature control during production of 2, 4, 5-T, TCDD levels can be held to about. 005 ppm.

Before the TCDD risk was well understood, early production facilities lacked proper temperature controls.

Individual batches tested later were found to have as much as 60 ppm of TCDD.