Fish samples

from 1999 were analysed for dioxins and dioxin-like PCBs (dl-PCB) by the Norwegian Institute for Air Research (NILU) using GC/MS. This analysis was accredited according to EN-45001, a European standard preceding the ISO/IEC 17025. The rest of the analyses were performed in-house. E7080 manufacturer From 2002 until 2010, dioxins and dl-PCBs were analysed using GC/MS as described by Berntssen et al. (2005). For quality control, an in-house control sample was run with each sample series whilst the CRM WMF-01 from Wellington Laboratories (Ontario, Canada) is run for periodical validation of the method. Each sample was analysed for: polychlorinated dibenzo-p-dioxins (PCDD) which includes 2,3,7,8-TCDD, 1,2,3,7,8-PeCDD, 1,2,3,4,7,8-HxCDD, 1,2,3,6,7,8-HxCDD, 1,2,3,7,8,9-HxCDD, 1,2,3,4,6,7,8-HpCDD and OCDD, polychlorinated dibenzofurans (PCDF) which includes 2,3,7,8-TCDF,

1,2,3,7,8-PeCDF, 2,3,4,7,8-PeCDF, 1,2,3,4,7,8-HxCDF, 1,2,3,6,7,8-HxCDF, 1,2,3,7,8,9-HxCDF, 2,3,4,6,7,8-HxCDF, 1,2,3,4,6,7,8-HpCDF, 1,2,3,4,7,8,9-HpCDF and OCDF. In this paper, the term “dioxin” will include all dioxins and furans mentioned above, unless otherwise specified. The non-ortho polychlorinated biphenyls (noPCB) analysed were PCB 77, 81, 126, and 169, and the mono-ortho polychlorinated biphenyls (moPCB) PCB 105, 114, 118, 123, 156, 157, 167 and 189. For dioxins and dl-PCBs,

the mass fraction of each congener PF-01367338 was converted to toxicity equivalents (TEQ), ng TE kg− 1 wet weight (Van den Berg et al., 2006). When the sum of dioxins and dl-PCBs are calculated, mass fractions that are lower than the limit of quantification (LOQ) are set equal to the LOQ (upperbound LOQ) to avoid underestimation of the risk. For analyses before 2004, mono-ortho PCBs were not included in the sum of dioxins and dl-PCBs. In order to compare data, the average stipulated contribution of the sum of mono-ortho PCBs (4.9%) throughout the years 2004–2011 is calculated and added to the sum dioxins and dl-PCBs for the years 1999–2002. PCB6 represents six congeners of non-dioxin like PCBs 4-Aminobutyrate aminotransferase (NDL-PCBs), which are used as indicators for the entire group of NDL-PCBs, because they represent about 50% of total NDL-PCBs in food (EFSA, 2005). From 2010 PCB6 (PCB 28, 52, 101, 138, 153, and 180) was included in the dioxin and dl-PCB-method at NIFES, which led to small changes in sample preparation without any changes in the analytical principle. The method was accredited according to NS-EN ISO/IEC 17025 in 2002. PCB6 were prior to inclusion with dioxins and dl-PCBs, analysed using GC/MS as described by Berntssen et al. (2011a). In-house control sample was used in each sample run for quality control, and the CRM SRM-1974b from the National Institute of Standards and Technology (Gaithersburg, USA) was analysed at least once a year.