ACCUMULATION OF HALOGENATED AROMATIC-HYDROCARBONS AND ACTIVITIES OF CYTOCHROME-P450 AND GLUTATHIONE-S-TRANSFERASE IN CRABS (ERIOCHEIR JAPONICUS) FROM JAPANESE RIVERS

The hepatopancreases of freshwater crabs (Eriocheir japonicus) collect ed from three Japanese rivers (Barato, Shiribetsu, and Tone) were anal yzed for planar halogenated aromatic hydrocarbons (HAHs), including po lychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), and co planar polychlorinated biphenyls (PCBs). The hepatic glutathione S-tra nsferase (GST)dependent enzyme activities in the crab hepatopancreas w ere also measured to examine their potential as biomarkers for the con taminants. Crabs from the Tone River, which runs through industrial, a gricultural, and urban areas, have the highest concentrations of HAHs (4,100 pg/g fat weight), followed by those from the Barato River (2,43 0-2,970 pg/g fat weight), whereas crabs from the Shiribetsu River were relatively less contaminated (1,350-1,800 pg/g fat weight). Identific ation of numerous PCDD and PCDF congeners in crabs from all three rive rs provided evidence that one of the major sources of PCDDs and PCDFs was waste incineration. In addition, crabs from the Barato and Shiribe tsu Rivers were notably contaminated with 1,3,6,8- and 1,3,7,9-TeCDD c ongeners, which suggests that a possible source was chlornitrofen, whi ch has been extensively used in paddy fields as a herbicide. Calculati on of 2,3,7,8-tetrachlorinated dibenzo-p-dioxin toxic equivalents (TEQ s) showed that the causal contaminants of higher TEQs in crabs from th e Tone River (94.7 TEQ picograms per gram fat weight) were PCDDs and P CDFs, although the most important contributor to the total TEQs was co planar PCBs (49.95%). The crab hepatopancreas appeared to have abiliti es to transfer glutathione to 1-chloro-2,4-nitrobenzene (CDNB) and 3,4 -dichloronitrobenzene (DCNB). The crabs with the highest TEQ levels sh owed the highest GST activities. The current results and our previous data lead us to conclude that cytochrome P450 and GST-dependent enzyme activities (benzo[a]pyrene hydroxylation and CDNB and DCNB conjugatio n) in freshwater crab hepatopancreases are likely to be useful biomark ers for the contamination of planar aromatic hydrocarbons such as benz o[a]pyrene, PCDDs, PCDFs, and coplanar PCBs.