Polybrominated diphenyl ethers (PBDE) are a class of brominated aromatic compounds with a basic structure consisting of two phenyl rings linked by an ether bond. There are 209 possible compounds, referred to PBDE congeners, which differ in the number and position of the bromine atoms in the two phenyl rings (Figure 1). PBDEs form the same number of congeners and the substitution patterns are identical to the PCB congeners. Hence, the PBDEs share the same congener numbering system as proposed for PCBs.
Figure 1. Basic structure of PBDEs (Brn = 0-5; Brm =1-5).
PBDEs constitute an important and widely used group of additive flame retardants generally used in concentration between 5 % and 30 % by weight in many different materials, e.g. plastics, textiles, electronic casings and circuitry. As they are mixed into polymers and not chemically bound to the plastic or textiles, they might separate or leach from the products into the environment.
The three commercial technical mixtures of PBDEs are: PentaBDE, OctaBDE and DecaBDE. They are composed of a mixture of congeners and named according to their average bromine content.
Based on the composition of the technical PBDE mixtures, occurrence in the environment and in food, the Panel on Contaminants in the Food Chain (CONTAM) of EFSA considered the following eight PBDE congeners to be of primary interest: BDE-28, -47, -99, -100, -153, -154, -183 and -209, which are relevant for dietary PBDE exposure (Figure 2).
Figure 2. Structure of the eight PBDE congeners under consideration by the CONTAM panel.