Dioxins in Baltic Herring and Sprat

Background, Aims and Scope. The concentration of chlorinated dibenzo-p-dioxins and dibenzofurans in many fish from the Baltic requires monitoring, since it approaches or exceeds the European Union threshold limit value of 4 pg TEQ/g wet weight of fish for human consumption. The concentrations, expressed in TEQs, are important for toxicology and regulations, but hide the concentrations of the individual congeners, which are important for other environmental sciences, source allocation, and for the detection of measurement errors. This report evaluates the results of a survey reported earlier only in the terms of the TEQ concentrations. Methods. Principal Component Analysis (PCA) was used to reduce the dimensions of the data (17 = 7 chlorinated dibenzo-pdioxin and 10 chlorinated dibenzofuran congeners) to three principal components. This facilitated the interpretation of the congener profiles. Slopes of the congener concentrations as a function of age of the fish were estimated by least squares regression. The results were compared with a large set of data for lake trout from Lake Ontario. Results and Discussion. The congener profiles of Baltic herring are less scattered than those of sprat. The profiles of herring from the central Baltic differ from those of herring from the Gulf of Riga and both appear to be affected relatively minimally by the age of the fish. The congener profiles of herring from the western Gulf of Finland are similar to those from the central Baltic, those from middle Gulf of Finland are similar to those from the Gulf of Riga. Both seem to be more affected by age of the fish than the profiles of the first two groups. The concentrations of several pentachloroand hexachloro-dibenzop-dioxins and dibenzofurans increase with the age of the fish Conclusion. PCA is a good technique for the evaluation of the congener profiles. The resulting loading and score plots provide a good graphic summary of the multidimensional data. Additional analyses are needed to confirm the observed profile patterns. A comparison with the results of a long-term monitoring from another area shows that the age of the fish is a more important factor than the year of capture. Recommendation and Outlook. The surveys should continue for a number of years and the results should be presented and evaluated both in terms of the TEQs as well as in terms of weight concentrations. Since the concentrations do not appear to change Introduction There are large regional differences in the concentrations of chlorinated dibenzo-p-dioxins (CDD) and dibenzofurans (CDF) in fish from the Baltic (Vartiainen et al. 1997, Olsson et al. 2002, Vuorinen et al. 2002). The European Union (EU) Council Regulation 2375/2001 established a threshold limit value for 4 pg TEQ/g fresh weight. Some of the fish caught in the Baltic Sea exceed the EU limits on concentrations of dioxin in food (The Baltic Marine Environment 1999–2002, 2003). The highest concentrations were found in fatty old specimens from the Bothnian Sea (The Baltic Marine Environment 2003) and the Gulf of Finland. According to Vartiainen et al. (1997) and Vuorinen et al. (2002), the highest CDD and CDF concentrations, 2.9–24 pg TEQ/g wet weight, were found in fish from the inner part of the Gulf of Finland. The concentration of CDD and CDF in Baltic herring from the northern part of the Baltic Sea increases with the age of the fish (Hallikainen and Kiviranta 2002). In 1995, the German Ministry of Consumer Protection, Food and Agriculture carried out a comprehensive survey of dioxin contamination of important food groups, including fish. Samples of fish and fish products with a market share of over 1% (184 samples) were analyzed. The highest values, 2.9 pg TEQ/g wet weight, were found in herring from the Baltic Sea. This study confirmed the EU report of June 2000 which dealt with the CDD and CDF contamination in ten European countries. The report concluded that the contamination in most seafood species is below 1 pg TEQ/g product Research Articles Dioxins in Baltic Herring and Sprat ESPR – Environ Sci & Pollut Res 11 (3) 2004 187 weight, with the exception of shrimp, eel and some Baltic fish species (Klinkhard 2001). The EU regulation may ban the human consumption of herring and salmon from the Baltic. However, Sweden and Finland were granted a transition period, during which an extensive monitoring and reporting of CDD and CDF levels is required. In the Estonian program, the TEQ concentrations of CDD and CDF in Baltic herring (Clupea harengus) and sprat (Spratus spratus) collected in the fall of 2002, and the biological characteristics of the fish have been reported by Otsa et al. (2003). In all nine Baltic herring and eight Baltic sprat samples taken from Estonian coastal waters during the fall of 2002, the CDD and CDF concentration in pg TEQ/g wet weight was below the EU threshold. Accordingly, Baltic herring and sprat from the sampled areas of Estonian coastal waters are suitable for human consumption. Of the three Baltic herring samples taken from the Central Baltic Sea the CDD and CDF concentration of only one fish, 5–6 years old and > 17 cm long, was above the EU threshold (Otsa et al. 2003). A preliminary assessment of the data in terms of CDD and CDF congener profiles was given by Roots et al. (2003). This paper evaluates the profiles of the CDD and CDF congeners by chemometrics. 1 Materials and Methods