Estimation of human exposure to halogenated contaminants from wild and farmed fish, shellfish and shrimp

Fish and fish products contribute substantially to the human exposure to organohalogenated contaminants. In recent years, several organohalogen contaminant surveys on wild and farmed fish consumed in The Netherlands were carried out. This resulted in a substantial amount of data on the concentrations of polychlorinated dibenzo-p-dioxins and –furans (PCDD/Fs), polychlorinated biphenyls (PCBs), hexachlorobenzene (HCB), p,p’-DDT, -DDD and -DDE, polybrominated diphenyl ethers (PBDEs), hexabromocyclododecane (HBCD) and perfluorooctane sulfonate (PFOS). These datasets are integrated and combined contaminant exposures are estimated. The objective of this study was to specify (i) the main contributing fish species to the human exposure in The Netherlands; (ii) the main contributing contaminants, and (iii) to determine the contribution of recently introduced farmed species like pangasius and tilapia. The exposure is dominated by PCBs (sum of seven indicator congeners) and PFOS. PFOS shows a distinct exposure pattern as compared to the other contaminants (e.g. because there is no contribution from salmon). From a species point of view, herring and farmed salmon are the main contributors to the contaminant exposure from fish, followed by cod, plaice and mussels. The contribution of farmed tilapia, pangasius and shrimp was very low (<1% for all species). Introduction The human exposure to organohalogenated contaminants has been the subject of several studies. Often individual contaminant groups (e.g. polychlorinated dibenzo-p-dioxins and -furans (PCDD/Fs), polychlorinated biphenyls (PCBs), and polybrominated diphenyl ethers (PBDEs)) were studied, but in some cases multiple contaminant groups were investigated in food basket studies and studies on individual food items (e.g. shellfish). Many exposure studies point towards fish and shellfish as the important sources for human exposure to contaminants (1,2). In The Netherlands, dairy is the predominant source for exposure to PBDEs and PCDD/Fs and dioxin-like PCBs (dl-PCBs) because dairy consumption is high (3,4). Fish is also an important source of exposure. However, in spite of the presence of these contaminants, fish consumption is promoted because it contains selenium and unsaturated (omega-3 and 6) fatty acids which are believed to be beneficial for human health (5,6). Contaminants in fish, shellfish and shrimp from The Netherlands 291 The fish and shellfish we consume is a very heterogeneous group. They originate from different waters (e.g. freshwater, brackish, marine), have different positions in an aquatic food chain (pelagic or beenthic prey or predator) or may be farmed. Fish feeds may contain high amounts of marine proteins and lipids, or may consist of vegetable ingredients. All these variables determine to what extent fish is contaminated with organohalogenated contaminants. In several studies, exposure assessments were carried out on single contaminants (e.g PBDEs or hexachlorobenzene (HCB) or PCDD/Fs and dl-PCBs (2,4,7,8), or a few contaminant groups (1,9). In a Swedish study the exposure from fish decreased in the following order: PCBs (349 ng/day), DDTs (256 ng/day), chlordanes (87 ng/day), HCB (36 ng/day), hexachlorocyclohexane (35 ng/day), PBDEs (23 ng/day) and total-TEQ (31 pg/day) (1). These exposure calculations were based on 13 fish samples. In the present study the dietary exposure from fish to multiple contaminant groups (i.e. PCDD/Fs, PCBs, HCB, DDTS, PBDEs, hexabromocyclododecane (HBCD) and perfluorooctane sulfonate (PFOS)) was estimated for The Netherlands. In recent Dutch surveys and monitoring studies edible wild fish species such as eel, herring, mussels, shrimp, cod, plaice, tuna, pike-perch and sole and several farmed species including salmon, eel, trout, pangasius, tilapia and shrimp were investigated for the above mentioned contaminants. The availability of these data allows an integrated exposure analysis of several contaminants based on a diverse group of fish species. Materials and methods The human exposure to contaminants is determined by combining information on contaminant concentrations in fish with information on the consumed quantities of fish. The contaminant data was taken from several studies (see Table 4.14). In most studies the same species were analysed. Therefore, we have collected data for all contaminants in cod and related species (Gadidae family), plaice, sole, wild eel and farmed eel, mussels, wild and farmed shrimp, herring, mackerel, sole, plaice, salmon, trout, pangasius and tilapia. Pike-perch and tuna data were not available for all contaminants and were therefore left out in this study. An overview of the contaminants studied is presented in Table 4.14. As many contaminant concentrations were rather low, detection and quantification limits (LOD and LOQ, respectively) could have a substantial influence on the final result. Therefore, the selection of contaminants in this study was limited to those of which considerable numbers of concentrations were above the LOD/LOQ. For the OCPs, the study was limited to HCB (86% >LOD). p,p’-DDE was present in all samples (100% >LOD) and p,p’-DDT and -DDD in the majority of the samples. The selection of the other contaminants was made in a similar way. Additional criteria were applied for PCDD/Fs, PCBs, PBDEs and PFOS (see Table 4.14). This study was limited to the edible parts (i.e. data on livers was excluded). Data on Western Scheldt fish were not considered because only very little fish from