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.
