Interlaboratory Comparison on POPs in Food 2018. The nineteenth round of an international study

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Interlaboratory Comparison on POPs in Food 2020. The twenty-first round of an international study

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 α-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 determination of PFASs. If desired, the laboratories could also determine the concentrations of PCDDs/PCDFs, nonortho PCBs, mono-ortho PCBs, indicator PCBs, PBDEs and α-HBCD in standard solutions from Cambridge Isotope Laboratories, provided by NIPH. 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 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, 101, 138, 153 and 180, and total HBCDs as well as the α-, β- and γ-isomers are also presented. The results of PFOS, PFHxS, PFOA, PFNA, PFDA and PFUnDA in 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 nonortho 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 consensus TEQs as a value for target standard deviation (σ=0.2), on both fresh weight and lipid weight basis. Further, Z-scores were calculated for the non-ortho PCB TEQ, the monoortho PCB TEQs, the total TEQ, the sum of six indicator PCBs, 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 (σ=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. 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 %, 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), Zscores 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 %. Considering the levels of contamination in the three food samples in this study, it may be concluded that the abilities and performance of laboratories worldwide in determining dioxin-like compounds is generally good. For the food samples, 44-51 laboratories reported results for the six indicator PCBs. The total consensus concentrations on fresh weight basis for six indicator PCBs were 1505 pg/g (17 %) in Egg yolk, 24189 pg/g (16 %) in Salmon and 27557 pg/g (12 %) in Fish oil, with total RSDs given in parentheses. 27-30 laboratories reported concentrations for all seven of the tetra- to hepta-PBDEs and 20 laboratories reported concentrations for PBDE-209. The consensus concentrations of the sum of the PBDEs with PBDE-209 excluded, were on fresh weight basis 52 (16 %), 1245 (11 %) and 2128 (21 %) pg/g in Egg yolk, Salmon and Fish oil, respectively, with total RSDs given in parentheses. The consensus concentrations for PBDE-209 were 202 (n=20, RSD=55 %), 27 (n=20, RSD=71 %) and 75 (n=20, RSD=109 %) pg/g fresh weight in Egg yolk, Salmon and Fish oil, respectively. The consensus concentrations calculated for HBCDs are indicative, as only a few laboratories reported results (n=4-5). 1 4-18 laboratories reported results for the different PFASs in the sample of Perch. The sample was known to be contaminated with PFOS (consensus concentration 13526 pg/g fw). 67 % of the participants obtained a Z-score ±2 for PFOS, and 50 % obtained Z-scores ≤1. For PFDA (consensus concentration 496 pg/g fw), 60 % of the participants obtained zscores ≤1, and for PFUnDA (consensus concentration was 30o pg/g fw) 57 % obtained zscores ≤1. The consensus values for PFHxS, PFOA and PFNA are indicative due to few reported results (many non-detects).publishedVersio

Multiple pathways of human exposure to poly- and perfluoroalkyl substances (PFASs): From external exposure to human blood

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Low levels of per- and polyfluoroalkyl substances (PFAS) detected in drinking water in Norway, but elevated concentrations found near known sources

Per- and polyfluoroalkyl substances (PFAS) are ubiquitous contaminants which are also found in drinking water. Concentration levels in drinking water vary widely and range from a very low contribution to total daily exposure for humans to being the major source of uptake of PFAS. PFAS concentrations in Norwegian drinking water has been rarely reported. We investigated concentrations of 31 PFAS in 164 water samples, representing both source water (i.e., before drinking water treatment) and finished drinking water. Samples were taken from 18 different water bodies across Norway. The 17 waterworks involved supply drinking water to 41 % of the Norwegian population. Only four of the waterworks utilised treatment involving activated carbon which was able to significantly reduce PFAS from the source water. Samples of source water from waterworks not employing activated carbon in treatment were therefore considered to represent drinking water with regards to PFAS (142 samples). All samples from one of the water bodies exceeded the environmental quality standard (EQS) for perfluorooctane sulfonic acid (PFOS) according to the water framework directive (0.65 ng/L). No concentrations exceeded the sum of (20) PFAS (100 ng/L) specified in the EU directive 2020/2184 for drinking water. Several EU countries have issued lower guidelines for the sum of the four PFAS that the European Food Safety Authority (EFSA) has established as the tolerable weekly intake (TWI) for PFOS, perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), and perfluorohexane sulfonic acid (PFHxS). Denmark and Sweden have guidelines specifying 2 and 4 ng/L for the sum of these PFAS. Only one of the 142 drinking water samples exceeded the Danish TWI and contained a sum of 6.6 ng/L PFAS. A population exposure model, for individuals drinking water from the investigated sources, showed that only 0.5 % of the population was receiving PFAS concentrations above the Danish limit of 2 ng/L.publishedVersio

A cost-minimisation analysis of performing point-of-care ultrasonography on patients with vaginal bleeding in early pregnancy in general practice:a decision analytical model

BACKGROUND: Spotting and light vaginal bleeding are common and usually harmless symptoms in early pregnancy. Still, vaginal bleeding may be the first sign of an abortion and often causes distress to pregnant women and leads to an expectation of an ultrasonography examination of the uterus. As point-of-care ultrasonography (POCUS) is increasingly being integrated into general practice, these patients may be clinically evaluated and managed by general practitioners (GPs). This can potentially reduce referrals of patients from the primary to the secondary healthcare sector resulting in societal cost-savings. The primary purpose of this study was to investigate whether the accessibility of POCUS in general practice for patients with vaginal bleeding in early pregnancy is cost-saving compared to usual practice where GPs do not have access to POCUS. A secondary purpose of this study was to estimate a remuneration for GPs performing POCUS on these patients in general practice. METHODS: A cost-minimisation analysis was based on a decision tree model reflecting the two alternatives: general practice with and without GPs having access to POCUS. The robustness of the model results was investigated using probabilistic sensitivity analysis and the following deterministic sensitivity analyses: one-way analyses for the model input parameters and a scenario analysis with a change from a societal to a healthcare sector perspective. An expected remuneration reflecting the add-on cost of Danish GPs performing POCUS was estimated based on the related costs: cost of an ultrasonography scanner, GP’s time consumption, ultrasonography training, and utensils per scanning. RESULTS: The difference in average cost between the two alternatives from a societal perspective was estimated to be €110, in favour of general practice with GPs using POCUS. The deterministic sensitivity analyses demonstrated robustness of the results to plausible changes in the input parameters. The expected remuneration for performing POCUS in this specific setting was estimated to be €32 per examination. CONCLUSION: Having GPs perform POCUS on patients with vaginal bleeding in early pregnancy is cost-saving compared to usual practice. The results should be taken with caution as this study was based on early modelling with uncertainties associated with the input parameters in the model. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12913-022-07463-y

Early-life exposome and lung function in children in Europe: an analysis of data from the longitudinal, population-based HELIX cohort

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