REPORT 2021 INTERLABORATORY COMPARISON ON POPs IN FOOD 2020: The twenty-first round of an international study Interlaboratory Comparison on POPs in Food 2020 The twenty-first round of an international study Nanna Bruun Bremnes, Line Småstuen Haug and Cathrine Thomsen 2 Published by Norwegian Institute of Public Health Division for Infection Control and Environmental Health Department of Environmental Health Section of Environmental Exposure and Epidemiology January 2021 Title: Interlaboratory Study on POPs in Food The twenty-first round of an international study Authors: Nanna Bruun Bremnes Line Småstuen Haug Cathrine Thomsen Order: The report may be downloaded as a pdf-file from the webpage: www.fhi.no/ILC Cover grafic design: Fete Typer Keywords (MeSH): Interlaboratory Comparison, POPs, Dioxins, PCBs, PBDEs, PFASs Citation: Bremnes NB, Haug LS, Thomsen C. Interlaboratory Comparison on POPs in Food 2020. Oslo: The Norwegian Institute of Public Health Interlaboratory Comparison on POPs in Food 2020 • The Norwegian Institute of Public Health 3 Contents Summary ___________________________________________________________________________ 4 Introduction _________________________________________________________________________ 7 Design and practical implementation ___________________________________________________ 10 Study design and reporting of results: PCDDs/PCDFs, mono-ortho substituded PCBs, non-ortho substituted PCBs, PBDEs and HBCDs 10 Study design and reporting of results: PFASs 11 Confidentiality 11 Collection, preparation, and distribution of samples 11 Statistical analysis 12 The final report and certificate 13 Coordination 13 Results ____________________________________________________________________________ 14 Presentation in the report 14 Summarizing comments on results 14 PCDDs/PCDFs 14 Analyte solution-2020 14 Egg yolk-2020 14 Salmon-2020 15 Fish oil -2020 15 Dioxin-like PCBs 15 Analyte solution-2020 15 Egg yolk-2020 15 Salmon-2020 15 Fish oil -2020 15 Total TEQ 16 Indicator PCBs 17 Analyte solution-2020 17 Egg yolk-2020 17 Salmon-2020 17 Fish oil -2020 17 PBDEs 17 Analyte solution-2020 17 Egg yolk-2020 17 Salmon-2020 17 Fish oil -2020 18 HBCD 18 PFASs 18 Lipid content 18 Acknowledgements __________________________________________________________________ 18 Appendix A: Participants’ affiliations and addresses Appendix B: Study announcement and instructions for participants Appendix C: WHO TEFs for human risk assessment Appendix D: Homogeneity testing Appendix E: Summary of results Consensus of congener concentrations Consensus of TEQ values Consensus statistics Laboratories’ reported TEQs Interlaboratory Comparison on POPs in Food 2020 • The Norwegian Institute of Public Health 4 Laboratories’ Z-scores Z-score plots Appendix 1: Presentation of results for Analyte solution-2020 Appendix 2: Presentation of results for Egg yolk-2020 Appendix 3: Presentation of results for Salmon-2020 Appendix 4: Presentation of results for Fish oil-2020 Appendix 5: Presentation of results for Perch-2020 Appendix 6: Presentation of results for lipid determination-2020 Summary The 21st round of the Interlaboratory Comparison on POPs in Food was conducted in 2020 by the Norwegian Institute of Public Health (NIPH). The study included the determination of the 2,3,7,8-chlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs), as well as dioxin-like non-ortho and mono-ortho chlorinated biphenyls (PCBs) in three different food items. Additionally, the participating laboratories could determine the concentrations of six indicator PCBs, polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecanes (HBCDs) in the same food samples. For the second time a fourth matrix was added, designated for the determination of the following poly- and perfluoroalkyl substances (PFASs): Perfluorooctanesulfonate (PFOS), perfluorohexanesulfonate (PFHxS), perfluorooctanoate (PFOA), perfluorononanoate (PFNA), perfluorodecanoate (PFDA) and perfluoroundecanoate (PFUnDA). The objectives of this interlaboratory comparison study were A. To offer a tool for quality assurance to the participating laboratories B. To assess the between laboratory reproducibility C. To assess the readiness of expert laboratories worldwide to determine levels of chlorinated and brominated persistent organic pollutants, as well as for PFASs, in regular foodstuffs. With respect to PCDDs/PCDFs, non-ortho PCBs, mono-ortho PCBs, indicator PCBs, PBDEs and -HBCD, the 2020-round of the study was performed on unfortified homogenates of Egg yolk, Salmon and Fish oil. An unfortified homogenate of perch was offered for the determinationα of PFASs. If desired, the laboratories could also determine the concentrations of PCDDs/PCDFs, non- ortho PCBs, mono- -HBCD in standard solutions from Cambridge Isotope Laboratories, provided by NIPH. ortho PCBs, indicator PCBs, PBDEs and α The test materials were sent to 68 laboratories worldwide in January, and results were returned from 64 of these. Due to the ongoing corona-pandemic there has been some delays this year. A draft report would normally have been published in July, but due to the extended deadline for submitting results it was not made available on our webpage www.fhi.no/ILC until early November 2020, and the deadline for commenting on the published results was set to December 15th 2020. This report presents the reported results for all seventeen 2,3,7,8-substituted PCDDs/PCDFs, the four non-ortho substituted PCBs #77, 81, 126 and 169 and the eight Interlaboratory Comparison on POPs in Food 2020 • The Norwegian Institute of Public Health 5 mono-ortho substituted PCBs #105, 114, 118, 123, 156, 157, 167, 189 in the three food items on a fresh weight and lipid weight basis. The results of eight PBDEs #28, 47, 99, 100, 153, 154, 183 and 209, six indicator PCBs #28, 52, - - -isomers are also presented. T101,he results 138, 153 of PFOS,and 180, PFHxS, and total PFOA, HBCDs PFNA, as PFDA well as and the PFUnDA α , β and in γ a sample of Perch are also included. The consensus concentration (assigned value) for each analyte in the four food samples was determined as follows: For the seventeen 2,3,7,8-substituted PCDDs/PCDFs, the four non- ortho substituted PCBs and the eight mono-ortho substituted PCBs non-detected congeners were assigned a concentration corresponding to the reported detection limits. The median of all reported concentrations for each analyte was then calculated. All values above twice the median was removed from the calculation. The consensus median and consensus mean as well as standard deviation (SD) were calculated from the remaining data, and this second median was called consensus value. For the PBDEs, the indicator PCBs and HBCDs the non-detects were removed from the data set. The median of all reported concentrations for each analyte was then calculated. All values above twice the median were removed from the calculation. The consensus median (consensus value) and consensus mean as well as standard deviation (SD) were calculated from the remaining data. When calculating the results for PFASs in the sample of Perch, we adopted the same approach as we used for the indicator PCBs and PBDEs. However, as the number of reported results were much lower for PFAS than for the other groups of analytes, outliers would contribute to a larger degree. Therefor we have chosen to remove low outliers, as well as high outliers, from the PFAS data set. Toxic equivalents (TEQs) were calculated from the consensus medians of individual congeners using the toxic equivalency factors derived by WHO 2006 (from 2012: WHO2006TEQs as opposed to WHO1998TEQs as in the reports published before 2012). Z-scores for the PCDD/PCDF TEQs were calculated for each laboratory using ±20 % of the =0.2), on both fresh weight and lipid weight basis. Further, Z-scores were calculated for the non-ortho PCB TEQ, the mono- orthoconsensus PCB TEQTEQss, asthe a totalvalue TEQ, for target the sum standard of six indicator deviation PCBs, (σ the sum of eight PBDEs, total HBCD, and the three isomers of HBCD and for each single congener in all three matrices of Egg yolk, Salmon and Fish oil =0.2) (both on a fresh weight and a lipid weight basis). The z-scores for PFASs were calculated in the same way, but on fresh weight basis only. (σ The consensus values of the standard solutions were calculated as mentioned above with the exception of the removal of all values exceeding ±50 % of the median prior to the final calculation of the consensus median and mean. The consensus values for the lipid contents were calculated by first excluding results deviating more than two SD from the mean of all values, and then re-calculating the median, mean and SD. The sample of Fish oil was the sample in this study with the highest total TEQ (4.7 pg TE/g fw, WHO2006TEFs). For this sample, Z-scores within ±1 were obtained by 91 % of the participating laboratories, and Z-scores within ±2 were achieved by 96 % of the participants (Z scores within ±1 and ±2, corresponds to a trueness of ±20 % and ±40 %, Interlaboratory Comparison on POPs in Food 2020 • The Norwegian Institute of Public Health 6 respectively). The Fish oil -sample was closely followed by the Salmon-sample, with a consensus total TEQ of 4.5 pg TE/g fw (WHO2006TEFs). For this sample 82 % of the participants achieved Z-scores within ±1, and 93 % achieved Z-scores within ±2. For the sample of Egg yolk, which on beforehand was assumed to be the sample with lowest level of contamination (total TEQ=0.29 pg TE/g, WHO2006TEFs, fresh weight), Z- scores within ±1 were obtained by 74 % of the reporting participants on fresh weight basis, and Z-scores within ±2 was achieved by 90 % of the participants. This clearly mirrors the high number of non-detects reported for the PCDD/PCDFs, and the variation in the reported limits of detection reported by the participants. The relative standard deviation (RSD) calculated for the total TEQ after removal of outliers was 7.6 and 11 % for the two samples that had the highest levels of contamination (Fish oil and Salmon, respectively). For the lower contaminated Egg yolk-sample, the corresponding RSD was 10 %.