Profiles of Polychlorinated Dibenzo-p-dioxins and Dibenzofurans in Fish Livers and Gills from Dongting Lake, China

Dongting Lake is located in the northeastern part of Hunan Province in the People’s Republic of China. The lake covers about 2,740 km 2 , making it the second-largest freshwater lake in China. The lake is an important source of freshwater fish. However, it is also an endemic region of schistosomiasis. Oncomelania hupensis gredler is the only lodging host of schistosome and plays a vital role in schistosomiasis spread. To kill Oncomelania hupensis gredler large amounts of sodium pentachlorophenate (NaPCP), which was found containing polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) impurities, had been sprayed for over 30 years (Bao et al., 1995). PCDD/Fs are chemically stable, persistent hydrophobic organic chemicals and are thought to be biomagnified via the food chain. Those isomers with chlorinated substitutions in the 2, 3, 7, and 8 positions are thought to pose a risk to human health due to their toxicity, carcinogenic potency, and potential effects on animal reproductive and immunological systems. Although the spraying of Na-PCP has been prohibited in the region since 1996, recent studies have indicated that the sediments, soils, and breast milk around Dongting Lake area are contaminated by PCDD/Fs (Zheng et al., 1997; Gao et al., 2005; Zheng et al., 2003). Fish are usually used as bioindicators for the environmental medium and food webs, and can reflect the PCDD/ Fs contaminant status. Moreover, humans are consumers of fish, and exposure assessments now routinely consider fish ingestion as a potential route of human exposure to chemicals in the environment. Consequently, monitoring programs establish limits for the maximum content of these toxicants in a variety of foods. An important regulation is that the European Community (EC) has set a limit of 4 pg/g wet weight of toxic equivalents (WHOPCDD/F-TEQ) for the muscle meat of fish and fishery products (EC, 2001). As do most organic contaminants, PCDD/Fs accumulate in certain organs with the highest proportions found in the fish liver (Wu et al., 2001). This paper describes the levels and bioaccumulation profiles of PCDD/Fs in different fish species livers and gills from Dongting Lake region.