A field study in support of the monitoring of priority substances in German freshwater fish: derivation of fillet-to-whole fish conversion factors

Abstract

Background: Bioaccumulating contaminants in surface waters are preferably monitored in fish for assessing the related risks to and via the aquatic environment. Consequently, the European Water Framework Directive (WFD) requires a monitoring of certain priority substances such as mercury, polybrominated diphenyl ethers (PBDE), perfluorooctane sulfonic acid and its derivatives (PFOS), hexachlorobenzene (HCB), hexabromocyclododecanes (HBCDD) and polychlorinated dioxins/dioxin-like compounds (dioxins) in freshwater and coastal fish. Tissue levels have to comply with biota environmental quality standards (EQSs) given in Directive 2013/39/EU. EQSs are justified either by risks for human health (assessed on the basis of fillet) or secondary poisoning of wildlife (based on whole fish). To support the practical implementation of the WFD biota monitoring in Germany, comparative investigations of target fish species caught at six sites were performed. Results: At each site, at least three fish species listed in a national guidance document were sampled (e.g., chub, roach, bream, perch). Beside biometric data, concentrations of seven priority substances were determined in pooled fillet and carcass samples and whole fish data were calculated. The EQSs for PBDE and mercury were exceeded in nearly all fillet and whole fish samples. PFOS was above the EQS at several sites especially in perch, while HCB exceeded the EQS only at one site (Elbe River). All fillet and whole fish samples complied with the EQSs for dioxins and HBCDD. Based on wet weight concentrations of a homogeneous set of 20 composite sample pairs of 3-5 yearold fish, the following fillet-to-whole fish conversion factors were derived: mercury 0.81, PBDE 5.4, HCB 3.6, PFOS 2.7, dioxins 5.3, and HBCDD 1.8. Conclusions: Recommendations on selection of target fish species, age or tissue given by EU and national guidance documents are practical and feasible. However, further adjustments of the samplings such as the determination of site-specific length-age relationships are required from both ecological and risk assessment perspectives. The derived conversion factors allow the translation of fillet-to-whole fish concentrations (and vice versa), and thus the EQS compliance assessment for the appropriate tissue (fillet for human health, whole fish for wildlife risks) if only one tissue is investigated.

Selection and application of trophic magnification factors for priority substances to normalize freshwater fish monitoring data under the European Water Framework Directive: a case study

“…It is also doubtful whether the 5% lipid content of fish is a realistic base for normalizations of PS fillet concentrations. In a previous study [6], the lipid content of fish from six German water bodies was 1.5 ± 0.5% (mean ± standard deviation; n = 36) in fillets and 5.2 ± 1.6% (n = 36) in whole fish. The fish lipid contents were not correlated to the trophic positions (for example, predatory perch had often lowest fillet lipid contents in comparison to lower trophic level fish).…”

“…Fish monitoring data used in the present study originate from two German sites, the Moselle River and a lake-like widening of the slow-flowing Havel River (Großer Wannsee). Details of fish sampling, preparation, and analysis are described in detail by Radermacher et al [23] and Rüdel et al [6].…”

“…Stable isotope determinations of fish composite samples were performed by agroisolab GmbH, Jülich, Germany, and evaluated for fish trophic level as described in Rüdel et al [6]. Mussel samples collected in parallel to the fish samples from each site were used as baseline organisms (TL = 2).…”

Chemicals of emerging concern in marine specimens of the German Environmental Specimen Bank

“…Chemical analysis and quality assurance/quality control are outlined in the Additional file 1 and in Neugebauer et al [53] (FR), Rüdel et al [54,55] (PFAS) and Radermacher et al [56] (cVMS).…”

“…PFAS were analyzed in blue mussels and eelpout filet and liver by HPLC-MS/MS [54,55]. Samples of blue mussels and liver tissue were extracted with methyl tert.-butyl ether and analyzed by HPLC-MS/MS with atmospheric pressure ionization in the negative ion electrospray mode.…”