In October 2022, the World Health Organization (WHO) convened an expert panel in Lisbon, Portugal in which the 2005 WHO TEFs for chlorinated dioxin-like compounds were reevaluated.
Background
Since the early 1990's, WHO has organized expert consultations with the objective to harmonize the TEFs for dioxins and dioxin-like compounds on the international level, thereby giving recommendations to national regulatory authorities. TEF expresses the toxicity of dioxins, dibenzofurans and dioxin-like PCBs relative to the most toxic form of dioxin, 2,3,7,8-TCDD. The latest WHO TEFs for dioxin and dioxin-like compounds were established by WHO through a similar expert consultation in 2005.
Since the previous 2005 consultation, a large amount of congener-specific data has been published on estimates of relative potency (REPs) and potential TEF selections. These relative potency data from individual studies have been added to an updated REP database, and these data have been used in a Bayesian meta-regression approach to determine whether or not changes in TEFs would be warranted. The methods applied for this TEF re-evaluation directly follow recommendations made by the 2005 WHO expert consultation.
