Characteristics of Halogenated Polycyclic Aromatic Hydrocarbons in Flue Gas from Waste Incinerators

Introduction Halogenated polycyclic aromatic hydrocarbons (PAHs) are widespread environmental pollutants 1,2 . Chlorinated PAHs (ClPAHs) and brominated PAHs (BrPAHs) are structurally similar to other halogenated hydrocarbons such as polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), and biphenyls (PCBs). Although the environmental fates and effects of dioxins have been studied in detail, little is known about the those of halogenated PAHs. Cl-/BrPAHs with three to five aromatic rings have been reported to occur in various environmental matrices. However, because of the lack of purified, individual Cl-/BrPAHs analytical standards, accurate quantification was not previously possible. Recent synthesis and purification of individual halogenated PAHs in our laboratory made the congener-specific analysis of Cl-/BrPAHs possible 2,3 . In terms of the toxicity, several Cl-/BrPAH congeners elicit dioxin-like toxic potencies in an in vitro bioassay 4 . The sources of ClPAHs can be related to various reactions in which chlorine and aromatic precursors exist (e.g., automobile exhaust, chlor-alkali processes, and waste incineration). The distribution of individual ClPAHs in various solid waste incinerators 5 and in environmental samples from an electronic waste recycling facility and a chemical-industrial complex in China 6 has been reported in earlier studies. Earlier studies on the formation of halogenated hydrocarbons from combustion processes were limited to dioxins, polychlorinated naphthalenes (PCNs), and PCBs. Little attention has been paid to the quantitation of ClPAHs released from waste incineration 7 . Therefore, the occurrence, fate, and emission profiles of Cl-/BrPAHs in incinerators are not clearly understood. In this study, we determined individual concentrations of 25 ClPAHs and 10 BrPAHs in flue gas samples collected from 16 incinerators in Japan. Identification and quantification of individual Cl/BrPAHs were accomplished by the use of standards synthesized in our laboratory. The overall goal of this study was to reveal formation mechanisms of Cl-/BrPAHs and to assess environmental impact of Cl-/BrPAHs from incineration. The four types of incinerators selected for this study had various incineration capacities, and received various types of solid wastes. We also examined the correlation between Cl-/BrPAH concentrations and the corresponding parent PAH concentrations, and dioxins in flue gas samples.