What are dioxin TEFs and TEQs?
There are 17 forms of dioxins considered to be toxic, but not all are equally toxic. The most toxic dioxin is called 2,3,7,8-TCDD, and other similar dioxins have been assigned toxicity values relative to it. These relative toxicity values are called toxicity equivalency factors (TEFs). 2,3,7,8-TCDD is assigned a TEF of 1, and the others are assigned values less than 1. Total concentrations of dioxins in the environment are reached by factoring in the TEF of each form of dioxin before adding them together. The resulting concentration is referred to as TEQ (toxic equivalent).
