Abstract
Hexabromobenzene (HBB) is a commonly used flame retardant. It is mainly used indoors, and its estimated annual production was about 900 tons in Japan in 1976.
Hexane solutions of HBB were exposed to sunlight, fluorescent lamps and high pressure mercury lamps, and the residual as well as photodegradation products were determined by GC and GC-MS. The HBB half lives under sunlight, fluorescent lamps and high pressure mercury lamps were 150, 6400 and 3.2min, respectively. Penta-, tetra-, tri- and di-bromobenzene were found as photodegradation products. The same stepwise debromination process occurred under these three irradiation sources but at different rates. In the case of sunlight, the degradation rate of HBB depended on the diurnal light intensity. Hexachlorobenzene (HCB) showed a half life that was about three times longer than HBB under a high pressure mercury lamp, which indicates the higher photodegradability of HBB. The photodegradation processes and the environmental fate of HBB and its impact on biota are also discussed.
