PCBs, PCDD/Fs AND PBDEs IN SPIDER CRABS: COMPARISON WITH MUSSEL AND SEA BASS CONTAMINATION Conclusion  The highest contaminant levels in spider crab muscle were measured at Antifer (Seine Bay). However, even those do not raise any sanitary problems based on the fixed TDI for PCDD/Fs and DL-PCBs at 2.33 pg TEQ.kg -1 b.w. per day (JECFA, 2002), and for 7 indicator PCBs at 0.01 µg. kg -1 b.w. per day (AFSSA, 2003).  The PCB and PBDE distributions are species-dependant (influence of trophic level, feeding mode and metabolisation capacities), and are not related with the geographical situation and contamination levels.  PCDD/F patterns are also species-dependant, although differences were observed in spider crabs from Antifer and the other sampling areas. The very important PCB levels measured at Antifer and the possible traces of PCDFs in technical PCB mixtures, could increase their concentrations in the environment but also modify their distribution in the biota. Objectives PCBs, PCDD/Fs and PBDEs are very persistent and toxic pollutants for marine organisms and humans. However, very little information is available on the presence of these compounds in exploited decapod crustaceans from the French waters. This study allowed:  to obtain first data on PCB, PCDD/F and PBDE levels and distribution in the spider crab Maja brachydactyla. This crustacean species was chosen because of its important commercial interest in certain French regions like Brittany and Normandy.  to contribute to a better understanding of the factors acting on the distribution of these contaminants in crustaceans. For that purpose, spider crab contamination was compared to that of mussels, considered as good indicators of marine pollution, and that of sea basses, because fishes are known to be able to biotransform some contaminants. Sampling and analysis  Spider crabs were collected in February 2003 on five sampling areas: Antifer (Seine Bay) where RNO measured the highest PCB levels in mussels since 70’s, and the others along the Brittany and Normandy coasts which are very little contaminated by such man-made compounds.  Mussels Mytilus edulis and sea basses Dicentrarchus labrax were collected at Antifer (Seine Bay) in February  For spider crabs and sea basses, analyses were performed on muscle; for mussels, the whole soft body were analysed.  The 17 toxic 2378-substituted PCDD/Fs, 7 indicator PCBs, 12 dioxin-like PCBs and 13 PBDEs were analysed by high resolution GC-MS. N. Bodin, A. Abarnou, A-M. Le Guellec Département Biogéochimie et Ecotoxicologie, IFREMER, Centre de Brest - BP Plouzané, France Contamination comparison between organisms PBDEs PCBs PCDD/Fs  CB153 is always the main congener in all samples and represents 40-50% of  18 PCBs.  Mussels and sea basses show similar PCB patterns with predominance of CB153, CB101, CB118 and CB138. However, different levels of CB180 are observed due to the different feeding mode of these species.  For spider crabs, the main congeners are the CB118 and CB180. The slight presence of CB52, CB101 and CB138 compared to mussels argue for the biotransformation of these compounds by spider crab.  Very different dioxin patterns are observed between the three species. In mussels, PCDDs (60% of  17 PCDD/Fs) > PCDFs, oppositely to spider crabs and sea basses (PCDDs = 25% of  17 PCDD/Fs).  As well greater levels of highly toxic congeners (2378- TCDF (F1), PeCDF (F3)), as lower concentrations of OCDD (D7) in spider crabs and sea basses suggested the enzyme induction in these species compared to mussels.  BDE47 is the main compound in all samples. For mussels and spider crabs, it represents 60% of  13 PBDEs, against 80% in sea basses.  The other major congeners are the BDE28, BDE99, BDE100, BDE153, BDE154, BDE183.  The BDE99 can theoretically be metabolised in BDE47 by debromination processes. The profiles show that sea basses have greater metabolisation capacities than crustaceans, and the last ones higher than mussels for this congener. Spider crab contamination Concentrations in pg.g -1 d.w.  All contaminants present higher levels in specimen from Antifer which confirms a chronic pollution of the whole Seine Bay mainly due to contaminant inputs by the Seine River.  PCB concentrations measured at Antifer are 6 to 20 higher than those from the other sites. For PCDD/Fs and PBDEs, they exceed only by a factor 3 to 5.  Total TEQ varies from 0.7 (Granville) to 6.8 (Antifer). Moreover, the contribution of DL-PCBs to the Total TEQ is nearly 2 times higher in crustaceans than that of PCDD/Fs. The comparison of contamination of three species (mussel, spider crab and sea bass) collected in the same period and area (February at Antifer) allowed to evaluate the influence of biological factors on the distribution of PCB, PCDD/F, and PBDE. These three organisms were selected because of their different trophic level, feeding mode and metabolisation capacities. [X]/[  PCDD/Fs]*100 [X]/[CB153]*100 [X]/[BDE47]*100  PCDD/Fs:  At Antifer, PCDFs represent 75% of  17 PCDD/Fs, oppositely to other sites (PCDFs = 40-45%).  In all cases, OCDD (D7) and HpCDD (D6) are prevalent among PCDDs. For PCDFs, 2378-TCDF (F1) and PeCDF (F3) are main compounds.  PCBs and PBDEs: [X]/[CB153]*100  Similar patterns are observed whatever the site and the contamination level.  For PCBs, main compounds are CB153> CB118>CB180>CB138.  For PBDEs, major congeners are BDE47> BDE99>BDE100>BDE28. [X]/[  PCDD/Fs]*100 [X]/[BDE47]*100