Heating of BDE-209 and BDE-47 in plant oil in presence of o,p′-DDT or iron(III) chloride can produce monochloro–polybromo diphenyl ethers

Heating processes of food can alter the concentrations and composition of organohalogen compounds. In this study the fate of two polybrominated diphenyl ether (PBDE) congeners, decabromodiphenyl ether (BDE-209) and 2,2′,4,4′-tetrabromodiphenyl ether (BDE-47) was analyzed when heated in plant oil with and without additional compounds. When the PBDEs were heated in pure plant oil, no transformation was observed. Heating of decabromodiphenyl ether (BDE-209) together with ortho,para′-dichlorodiphenyltrichloroethane (o,p′-DDT) or iron(III) chloride in plant oil resulted in the formation of monochloro–nonabromodiphenyl ethers (Br₉Cl-DEs). Almost 10% of the initial amount of BDE-209 was transferred into Br₉Cl-DEs. Heating BDE-47 in the presence of iron(III) chloride produced two monochlorinated transformation products which were tentatively identified as 2,2′,4-tribromo-4′-chlorodiphenyl ether (4′-Cl-BDE-17) and 2,4,4′-tribromo-2′-chlorodiphenyl ether (2′-Cl-BDE-28). However, the reactivity was smaller and no Br → Cl exchange was observed with o,p′-DDT. The conditions used in our experiments (200 °C; heating 30 min–3 h) indicate that such reactivity may also occur during cooking of fish, meat and other food samples.