On the combustion and photolytic degradation products of some brominated flame retardants

Abstract: Many modern products, especially electronic goods, are protected by brominated flame retardants (BFR). Some of the most common flame retardants are polybrominated diphenylethers (PBDE), tetrabromobisphenol-A (TBBP-A) and hexabromocyclododecane (HBCD). These compounds have been found in environmental samples and shown to have physiological effects on experimental animals. This thesis considers end-of-life aspects of brominated flame retardants. When spread in the environment, these compounds may be degraded into other forms. For example, if sludge contaminated with PBDE is used as an agricultural fertilizer, the PBDE could be degraded by sunlight to species of PBDE with lower degree of bromination and, to some extent, also form polybrominated dibenzofurans (PBDF). In addition, PBDF and polybrominated dibenzo-p-dioxins (PBDD) are formed during combustion of brominated flame retardants. When waste products with brominated flame retardants are co-combusted with household waste or other chlorinated fuel, polybrominated- chlorinated dibenzo-p-dioxins (PBCDD) and polybrominated- chlorinated dibenzofurans (PBCDF)will be formed. The bromin/chlorine composition of dioxins and furans is dependent on the bromine/chlorine ratio in the fuel, but the types of brominated flame retardants that are being combusted is less important. In the studies reported here, bromine levels higher than "normal" for household waste has been used. The results show that there is a pronounced increase in total dioxin levels in fluegas when when bromine is present, implying that waste containing brominated flame retardants should only be incinerated at combustion plants with effecient air pollution control devices.