A comparison of the properties of the major commercial PBDPO/PBDE product to those of major PBB and PCB products.

Decabromodiphenyl oxide (DBDPO), a highly effective polybrominated diphenyl oxide (PBDPO) flame retardant (FR) used primarily in electrical and electronic equipment, is the second highest volume brominated flame retardant (BFR) and accounts for 82% of the PBDPO usage globally. The apparent similarities in chemical structure between the DBDPO, polychlorinated and polybrominated biphenyl (PCB, PBB) molecules have led to the presumption that these substances also share similar toxicological and environmental properties. However, DBDPO's physical/chemical properties, applications, environmental release, and toxicology differ substantially from the former PCB/PBB products. DBDPO is a heavier and larger molecule than components of the predominant PCB/PBB products used in the past, and the commercial DBDPO product has a lower water solubility and vapor pressure than the former PCB and PBB products. DBDPO's detection in the environment is generally in sediments near known point sources, and its primary use in thermoplastics limits its environmental release from end products. PBB environmental release has been primarily associated with one accident occurring in the US in 1973. The PCBs, used in applications with a high potential for environmental release, were detected in diverse locations around the world as early as in the 1970s. Current releases of PCB are considered related to an environmental cycling process of congeners previously released into the environment; however, DBDPO's physical/chemical properties do not indicate a similar potential. Extensive testing of the DBDPO commercial product has demonstrated that it is toxicologically and pharmacokinetically different from the predominant PCB and PBB products used in the past. Thus, although the chemical structures of DBDPO, PBB, and PCB appear similar, the properties of DBDPO are distinctly different.