Shin-ichi Sakai

Kyoto University, Environment Preservation Center
(Yoshida-honmachi, Sakyo-ku, Kyoto 606-8501, Japan)

Abstract

The physico-chemical characteristics, toxicity and environmental behavior of polybrominated dioxins (PBDDs/DFs) were surveyed in this study and the presence of dioxins contained in flame retardants and their behavior during the processes of incineration and melting were discussed. Identified was the polybrominated diphenylether (PBDEs) research trend and the related problems to be solved. Most experimental results in the past have shown that, in general, polybrominated dioxins (PBDDs/DFs) are likely to decompose earlier than polychlorinated dioxins (PCDDs/DFs) . On the other hand, they have taken a careful view that PBDDs/DFs should be handled equally with PCDDs/DFs in toxicity. PBDDs/DFs levels in resins containing PBDEs are generally high, often at the level of ppm and more. If resins and wastes containing PBDDs/DFs are incinerated properly, the destruction rate can be expected to be 90%. However, PBDDs/DFs may be formed as byproducts during the processes of incineration and flue gas treatment. Incineration residues sometimes contain brominated dioxins at the level of ppm. Therefore, a melting treatment is thought to be effective for residues and flame retarded plastics. Taking into account the fact that PBDEs increase in mother's milk, identification of human exposure pathways and the investigation of their control points are present urgent issues.

Key words: polybrominated dioxins, PBDDs/DFs, polybrominated diphenylether, flame retardants, plastics, incineration and melting