Liver Of Cod Research Articles

Assessment of the quality of canned cod liver

The task of this work is to analyze the quality indicators of canned food called Cod liver in Murmansk style. To achieve this goal, methods of organoleptic and physicochemical analysis were applied. In the course of the study we studied the change in the quality of canned food made from the liver of raw Atlantic cod (Gadus morhua, Linnaeus, 1758), which was caught in the fall-winter period. For this purpose, the actual content of fats, proteins, carbohydrates, vitamins A and B2, the acid number and the calculation of the product energy value were determined.

Identification of species falsification of cod liver by polymerase chain reaction

With the increase in consumer demand for fish products, the number of enterprises offering their products on the market has increased, which has led to a decrease in the quality of these goods. Cod liver is an expensive raw material for the production of canned food. In order to reduce production costs, manufacturers replace cod liver with salmon milk, in particular pink salmon, which is a species falsification. Modern methods of fish and fish products research are used to detect falsification in laboratory practice. The advantage of this method is that it is the most specific and sensitive for identifying the species of the raw material composition of the product and the finished product, since the DNA molecule does not lose its ability to perform an informative function under the influence of physical or chemical parameters, which characterizes it as the most stable structure of any animal organism. The research was carried out in the conditions of the Department of Molecular Research of the North-Western branch of the FGBI VNIIZH. The research material was 12 samples of canned fish sterilized from the liver of Atlantic cod. At the first stage, sample preparation was carried out by homogenizing samples into mortars, then 8 samples of each sample were taken, DNA extraction was carried out using a set of "GMO-Sorb-B". At the next stage, using the "Rotor-Gene 6000" amplifier, a polymerase chain reaction was set up, using kits for detecting the DNA of cod, haddock, pollock and DNA of salmon fish and differentiating species: pink salmon, chum salmon and sockeye salmon. As a result of the conducted studies, it was established that the liver of cod declared in the composition was not detected in one sample, since the content of cod fish was not detected in all samples from this sample, but the presence of pink salmon DNA was established. The results obtained indicate the specific falsification of canned cod liver.

Environmentally realistic concentrations of chlorinated, brominated, and fluorinated persistent organic pollutants induce the unfolded protein response as a shared stress pathway in the liver of Atlantic cod (Gadus morhua).

In the North Sea and North Atlantic coastal areas, fish experience relatively high background levels of persistent organic pollutants. This study aimed to compare the mode of action of environmentally relevant concentrations of mixtures of halogenated compounds in Atlantic cod. Juvenile male cod with mean weight of 840 g were exposed by gavage to dietary mixtures of chlorinated (PCBs, DDT analogs, chlordane, lindane, and toxaphene), brominated (PBDEs), and fluorinated (PFOS) compounds for 4 weeks. One group received a combined mixture of all three compound groups. The results showed that the accumulated levels of chemicals in cod liver after 4weeks of exposure reflected concentrations found in wild fish in this region. Pathway analysis revealed that the treatment effects by each of the three groups of chemicals (chlorinated, brominated, and fluorinated) converged on activation of the unfolded protein response (UPR). Upstream regulator analysis predicted that almost all the key transcription factors (XBP1, ERN1, ATF4, EIF2AK3, and NFE2L2) regulating the UPR were significantly activated. No additive effect was observed in cod co-treated with all three compound groups. In conclusion, the genome-wide transcriptomic study suggests that the UPR pathway is a sensitive common target of halogenated organic environmental pollutants in fish.

Terrestrial fatty acids from feed oil in feed for farmed salmonids are transferred to the liver, gonads, and muscle of wild Atlantic cod (Gadus morhua)

Abstract Wild fish attracted to salmon farms feed on waste feed that presently contain high levels of fatty acids of terrestrial origin. This study examines whether mature Atlantic cod (Gadus morhua) caught at spawning grounds has eaten salmon waste feed. Cod were caught at four spawning grounds around Smøla (Norway), an area with multiple salmon farms, during the spawning season in 2018 (n = 327) and 2019 (n = 488). The fatty acid (FA) profile of their livers, gonads (ovary and testis), and muscles (2019) were determined. Multivariate k-mean cluster analysis of liver FA profiles revealed three main clusters, which could be allocated to trophic niches using known fatty acid trophic markers (FATMs). Of the sampled cod in 2018 and 2019, 13 % and 20 % respectively had high liver concentrations of terrestrial FATMs (18:1n-9, 18:2n-6, and 18:3n-3), indicating waste feed feeding. The remaining cod could be assigned to either the pelagic or benthic food chain. The cod identified as feeding on waste feed had large, fatty livers. The terrestrial FAs were also transferred to the muscle and gonad lipids. It is postulated that the latter may result in gametes with sub-optimal lipid composition, potentially impacting fitness, which warrants further investigation.

Comparative histopathology of livers from Baltic cod infected with the parasitic nematode Contracaecum osculatum

Infection levels with the parasitic nematode Contracaecum osculatum in Eastern Baltic cod have increased in the last decades. Eastern Baltic cod is transport host for this parasite that has a high affinity for the liver of the fish. The liver is a highly vital organ and damage to the liver tissue can result in reduced functionality of the organ. Previous studies have revealed that cod with high infections loads reveal impaired physiological performance, reduced nutritional condition and show signs of having a liver disease. Yet, little is known about the pathological changes and inflammatory reactions of the cod liver related to the infections. In this study, we performed histological examinations on 30 Baltic cod livers caught in the eastern part of the Baltic Sea (length; 38 ± 0.9cm, weight; 454 ± 34.8gram) and three Sound cod livers (length; 63 ± 2.9cm, weight; 3396 ± 300.2gram) to categorize the degree of inflammation and its relation to pathological changes in infected cod livers. We further investigated how C.osculatum infection levels varied with intensity of inflammation and co-infections. We found that high infection loads with C.osculatum caused severe inflammation in the liver tissue of cod and reduced fat content of the hepatocytes. Conspicuous amounts of glycogen were found in the muscle and intestinal epithelial cells of the nematodes and parasitic co-infections occurred more frequently in the most heavily infected livers.

Parasite load of Atlantic cod Gadus morhua in the Baltic Sea assessed by the liver category method, and associations with infection density and critical condition

AbstractDuring the 2010s, Atlantic cod Gadus morhua L. in the eastern Baltic Sea experienced increasing infection loads of the parasitic nematode Contracaecum osculatum (Rudolphi) in their livers. Starting in 2021, a mandatory part of the routine sampling protocol on Baltic monitoring surveys is to assign a liver category to individual cod livers, based on the number of nematodes visible on the liver surface, to follow spatiotemporal changes in nematode infection loads. The validity of the liver category method has never been evaluated. Based on data from 642 cod livers, the method was verified and found to be a good predictor of the total number of nematodes. Moreover, the probability of cod being in a critical condition increased with the parasite load. In addition to their direct applicability to Baltic cod, the present findings may inspire others working with disease in fish stocks to include parasite monitoring.

Development and Application of Novel Chemiluminescence Immunoassays for Highly Sensitive Detection of Anisakis simplex Proteins in Thermally Processed Seafood.

The third-stage larvae (L3) of Anisakis simplex are the most important source of hidden allergens in seafood products. However, there exist no commercial methods for detecting Anisakis proteins in food. Furthermore, only a few methods have been validated for the detection of A. simplex in thermally processed food. The aims of our study are (i) the development and validation of high-sensitivity chemiluminescent (CL) immunoassays for the detection of A. simplex proteins in processed seafood, (ii) and A. simplex antigen detection in common seafood products from Polish markets. We developed and validated CL sandwich ELISA (S-ELISA) and CL competitive ELISA (C-ELISA) methods for A. simplex proteins detection in food, with respective detection limits of 0.5 and 5 ng/mL. The usefulness of the assays for detecting A. simplex proteins in highly processed food was evaluated by examination of autoclaved canned fish spiked with A. simplex larvae (1–8 larvae/200 g). Commercial real-time PCR was unable to detect A. simplex in autoclaved samples at all levels of enrichment with Anisakis larvae. CL-S-ELISA was used to test various types of seafood products from Polish markets. Among all tested products (n = 259), 28% were positive. A. simplex antigens were found mostly (n = 39) in smoked fish products: mackerel, herring, cod, and hake. Other positive samples were found in marinated herrings, canned cod livers, canned mackerels, and surimi sticks. In tuna, Atlantic argentine, anchovy, sardine, sprat, and squid products, A. simplex antigens were not detected. This study provides novel effective tools for the detection of A. simplex proteins in processed food and highlights the potential allergic hazards for Anisakis-sensitized Polish consumers of seafood.

Proteomics and lipidomics analyses reveal modulation of lipid metabolism by perfluoroalkyl substances in liver of Atlantic cod (Gadus morhua)

The aim of the present study was to investigate effects of defined mixtures of polycyclic aromatic hydrocarbons (PAHs) and perfluoroalkyl substances (PFASs), at low, environmentally relevant (1× = L), or high (20× = H) doses, on biological responses in Atlantic cod (Gadus morhua). To this end, farmed juvenile cod were exposed at day 0 and day 7 via intraperitoneal (i.p.) injections, in a two-week in vivo experiment. In total, there were 10 groups of fish (n = 21-22): two control groups, four separate exposure groups of PAH and PFAS mixtures (L, H), and four groups combining PAH and PFAS mixtures (L/L, H/L, L/H, H/H). Body burden analyses confirmed a dose-dependent accumulation of PFASs in cod liver and PAH metabolites in bile. The hepatosomatic index (HSI) was significantly reduced for three of the combined PAH/PFAS exposure groups (L-PAH/H-PFAS, H-PAH/L-PFAS, H-PAH/H-PFAS). Analysis of the hepatic proteome identified that pathways related to lipid degradation were significantly affected by PFAS exposure, including upregulation of enzymes in fatty acid degradation pathways, such as fatty acid β-oxidation. The increased abundances of enzymes in lipid catabolic pathways paralleled with decreasing levels of triacylglycerols (TGs) in the H-PFAS exposure group, suggest that PFAS increase lipid catabolism in Atlantic cod. Markers of oxidative stress, including catalase and glutathione S-transferase activities were also induced by PFAS exposure. Only minor and non-significant differences between exposure groups and control were found for cyp1a and acox1 gene expressions, vitellogenin concentrations in plasma, Cyp1a protein synthesis and DNA fragmentation. In summary, our combined proteomics and lipidomics analyses indicate that PFAS may disrupt lipid homeostasis in Atlantic cod.

Anisakid nematode larvae in the liver of Atlantic cod Gadus morhua L. from West Greenland.

Anisakid nematode larvae occur frequently in the liver of Atlantic cod, but merely few infection data from cod in waters around Greenland exist. The present study reports the occurrence of third-stage anisakid larvae in the livers of 200 Atlantic cod caught on fishing grounds along the West coast of Greenland (fjord systems of Maniitsoq) in May, June, August and September 2017. Classical and molecular helminthological techniques were used to identify the nematodes. A total of 200 cod livers were examined, and 194 were infected with third-stage nematode larvae (overall prevalence of infection 97%) with a mean intensity of 10.3 (range between 1 and 44 parasites per fish). Prevalences recorded were 96% for Anisakis simplex (s.l.), 55% for Pseudoterranova decipiens (s.l.) and 8% for Contracaecum osculatum (s.l.). Sequencing the mtDNA cox2 from 8 out of 23 these latter larvae conferred these to C. osculatum sp. B. A clear seasonal variation was observed, with a rise in A. simplex (s.l.) and P. decipiens (s.l.) occurrence in June and August and a decline in September. The study may serve as a baseline for future investigations using the three anisakids as biological indicators in Greenland waters.

Evaluations of the Peroxidative Susceptibilities of Cod Liver Oils by a 1H NMR Analysis Strategy: Peroxidative Resistivity of a Natural Collagenous and Biogenic Amine-Rich Fermented Product.

High-resolution 1H nuclear magnetic resonance (NMR) analysis was employed to molecularly screen the lipid, lipid oxidation product (LOP), and antioxidant compositions of four natural (unrefined) cod liver oil (CLO) products. Products 1–3 were non-fermented CLOs, whilst Product 4 was isolated from pre-fermented cod livers. Supporting analytical data that were acquired included biogenic amine, flavanone, tannin, phenolic antioxidant, α-tocopherol, and oxygen radical absorbance capacity (ORAC) determinations by recommended HPLC, LC/MS/MS, or spectrophotometric methods. SDS-PAGE, HPLC, and 1H NMR analyses investigated and determined collagenous antioxidants and their molecular mass ranges. 1H NMR analysis of aldehydic LOPs was employed to explore the susceptibilities/resistivities of each CLO product to peroxidation that is induced by thermal stressing episodes (TSEs) at 180°C, or following prolonged (42 day) storage episodes at 4 and 23 °C. Product 4 displayed extremely high ORAC values, which were much greater than those of Products 1–3, and that were predominantly ascribable to significant levels of peroxidation-blocking and/or aldehyde-consuming collagenous polypeptides/peptides and ammoniacal agents therein. Significantly lower levels of toxic aldehydes were generated in the pre-fermented Product 4 during exposure to TSEs, or the above long-term storage episodes. These results confirmed the enhanced peroxidative resistivity of a fermented, antioxidant-fortified natural CLO product over those of non-fermented unrefined products. Product 4: Green Pasture Blue Ice™ Fermented Cod Liver Oil.

Indicators of Osmotic and Ion Regulation in the Fish of the White Sea

The osmotic concentration; the concentrations of sodium and potassium; the content of total, free, attached water fractions in plasma; and the content of interstitial and cerebrospinal fluid, in the brain, muscles, liver, and erythrocytes typical for the fish in the native environment were determined for cod Gadus morhua. Under stress, a protective reaction is implemented, it prevents tissue dehydration by increasing the osmotic concentration in the interstitial fluid in the European flounder Platichthys flesus, spotted wolffish Anarhichas minor, lumpsucker Cyclopterus lumpus, and short-horn sculpin Myoxocephalus scorpius. The osmotic concentration preconditioned by inorganic ions in the muscles, liver, and erythrocytes of cod is significantly lower compared to the internal environment. The lack of ions in the tissues is compensated by the accumulation of organic osmolytes. Similar patterns are observed in euryhaline species when acclimated to the marine environment and in freshwater fish in the zone of critical salinity. Values of the osmotic concentration and sodium and potassium content in the blood plasma and tissues of the White Sea fish refer to the corresponding regulation ranges obtained for euryhaline and freshwater fish in the salinity range compatible with life activity.

Dioxin-like polybrominated biphenyls (PBBs) and ortho-substituted PBBs in edible cod (Gadus morhua) liver oils and canned cod livers

This study investigates the occurrence of polybrominated biphenyls (PBBs), a legacy flame retardant, in fishery products such as medicinal grade cod liver oils and canned liver products, sourced from the North Atlantic during 1972–2017. It also assesses the dietary and supplementary (the oils were commonly administered as dietary supplements to children and youth) intake of PBBs from these products. Summed ortho-PBB concentrations ranged from 770 to 1400 pg g−1 fat in the oils and from 99 to 240 pg g−1 whole weight in canned livers, with PBB-49, 52, 101 and 153 accounting for most of these levels. Among the more toxic non-ortho-PBBs, PBB-126 and PBB-169 were not detected, but PBB-77 concentrations ranged from 0.6 to 5.78 pg g−1 fat in the oils and 0.06–0.126 pg g−1 whole weight in canned livers. During 1972–1993, PBB contamination levels were similar for cod liver oils from the Baltic Sea and other North Atlantic regions, but over the timescale of the study, Baltic Sea products appear to show a decline in PBB concentrations. As PBB-77 was the only dioxin-like PBB detected in the samples, the corresponding supplementary (oils, 1972–2001) and dietary (cod liver from 2017) intakes were very low, at < 0.001 pg TEQ kg−1 bm d−1 (or < 0.01 pg TEQ kg−1 bm d−1 upper bound) for the sum of all the measured dioxin-like PBBs –four to six orders of magnitude lower than that arising from other dioxin-like contaminants that were shown to occur in these products, from earlier studies.

Compositional profiles, persistency and toxicity of polychlorinated naphthalene (PCN) congeners in edible cod liver products from 1972 to 2017

Edible cod liver products including cod liver oil and canned cod liver, sampled over the last five decades from the North Atlantic region, including the Baltic Sea were analysed for a set of persistent and toxicologically significant polychlorinated naphthalene (PCN) congeners with some of the highest relative potencies (dioxin-like toxicity) among PCNs. The targeted congeners showed a near-universality of occurrence in all samples apart from the most recent sample of cod liver oil which was assumed to be highly purified, as cod livers from the same period and location showed appreciable amounts of PCNs. The majority of dominant congeners in legacy technical PCN mixtures were absent or occurred in low concentrations, raising the possibility that congeners arising from combustion related sources may be acquiring a greater significance following the decline and elimination of PCN production. The apparent appreciation in the relative amounts of PCN#70 in the last three to four decades may provide support for this view. The PCN contribution to dioxin-like toxic equivalence (TEQ) that was estimated for these samples (range 1.2–15.9 pg TEQ g−1) was significant in comparison to the EU regulated value of 1.75 pg TEQ g−1 for dioxins in fish oils. Most of the TEQ was associated with PCNs 66/67, 64/68, 69 and 73. Although metabolic processes are likely to influence this distribution, the profile is a little different to that observed in the tissues of higher order animals where PCNs #66/67 and #73 may contribute approximately 90% to the summed TEQ.

Local immune depression in Baltic cod (Gadus morhua) liver infected with Contracaecum osculatum.

Third-stage larvae of the anisakid nematode Contracaecum osculatum infecting cod (Gadus morhua) liver elicit a host immune response involving both innate and adaptive factors, but the reactions differ between liver and spleen. Inflammatory reactions occur in both liver and spleen, but a series of immune effector genes are downregulated in liver infected with nematodes whereas these genes in spleen from the same fish are upregulated. A series of novel primer and probe sets targeting cod immune responses were developed and applied in a real-time quantitative polymerase chain reaction set-up to measure the expression of immune-relevant genes in liver and spleen of infected and uninfected cod. In infected liver, 12 of 23 genes were regulated. Genes encoding cytokines associated with inflammatory reactions (IL-1β, IL-6, IL-8) were significantly upregulated, whereas genes encoding effector molecules, assisting the elimination of pathogens, C-reactive protein (CRP)-PII, hepcidin, lysozyme G1, lysozyme G2, C3 and IgDm, were significantly downregulated. The number of downregulated genes increased with the parasite burden. In spleen, 14 of 23 immune genes showed significant regulation and nine of these were upregulated, including genes encoding CRPI, CRPII, C3, hepcidin and transferrin. The general gene expression level was higher in spleen compared to liver, and although inflammation was induced in nematode-infected liver, the effector molecule genes were depressed, which suggests a worm-induced immune suppression locally in the liver.

The occurrence and distribution of nonylphenols and nonylphenol ethoxylates in different species of fish.

The aim of this study was to analyze the accumulation of nonylphenols (NPs) and nonylphenol ethoxylates (NPEOs) in the muscles, liver, and bile of flounder (Platichthys flesus), cod (Gadus morhua), and eels (Anguilla anguilla). The flounder and cod were caught in the Gulf of Gdańsk (the Baltic Sea), while the eels were sampled in the Vistula and Szczecin lagoons (the Baltic Sea) and in the inland waters of the Masurian Lake District. NP concentrations in muscles were low in all the samples analyzed and ranged from 14.2 to 28.2 μg-1 kg ww. In contrast, a wide range of NP concentrations were observed in livers, which seemed to depend on both the species and the feeding status of the fishes. NP levels in flounder and eel livers were from three to twenty times higher than those in the muscles, but they were below the limit of quantitation (LOQ) in all the cod liver samples. The mean concentration of NPs in the liver of flounder caught in the Gulf of Gdańsk was 222 μg kg-1 ww, while in that of the eel ranged from 57 μg kg-1 ww in fish caught in the Masurian Lake District to 519 μg kg-1 ww in eels caught in the Vistula Lagoon. NPs were detected in bile in only a few eel samples, which indicated that bile analysis has limited applications for estimating NP contamination in marine fish. The NPEOs in all the samples analyzed were below the LOQ.

Perfluoroalkyl substances (PFAS) in beaked redfish (Sebastes mentella) and cod (Gadus morhua) from arctic fishing grounds of Svalbard

ABSTRACTThe present study gives an overview about the concentration of PFAS in liver, fillet and belly flap of beaked redfish (Sebastes mentella) and cod (Gadus morhua) caught in pristine arctic fishing grounds of Svalbard. Out of 17 analysed substances, only six perfluoroalkyl acids (PFAAs) could be detected in the fish. The most frequently quantified substances were PFOS and perfluoroundecanoic acid (PFUnA) in liver (100%) and fillet (at least 40% and 70%, respectively) of beaked redfish and cod, and in belly flap of beaked redfish (100%). Compared to cod, beaked redfish showed significant higher PFAA concentrations with highest levels in liver. Multiple comparisons of group differences for PFAA concentrations among fish species and matrices were independent of the evaluation method, but not for the PFAA-pattern analysis. The risk assessment of PFOS indicated that beaked redfish and cod caught in the Barents Sea can be a relevant exposure source for consumers.

Distribution of polybrominated diphenyl ethers (PBDEs) in Newfoundland seafood and associations with human serum thyroid hormone concentrations

OPS 20: Chemicals, biomarkers, omics, Room 110, Floor 1, August 27, 2019, 4:30 PM - 5:30 PM The marine ecosystem around the island portion of the province of Newfoundland and Labrador is contaminated with PBDEs from the St Lawrence River and the Labrador Current. Newfoundland has a long history of fishing and of consuming local seafood, therefore exposure to PBDEs through local seafood consumption could present a widespread health issue for the province. The aim of this study was to explore local seafood consumption as a possible PBDE exposure source in Newfoundland. Cod and turbot livers from Newfoundland were tested for PBDEs by gas chromatography mass spectrometry (GC-MS). Eighty residents from two communities on the north and south coasts of the island were surveyed for local seafood consumption, and tested for serum PBDE concentrations (GC-MS). ∑PBDE (28, 47, 99, 156, and 209) levels were higher in cod (38.7 ng/g) than in turbot (10.4 ng/g). ∑PBDEs from fish livers from the north (37.36 ng/g) and south (34.27 ng/g) coast of Newfoundland were not significantly different. Newfoundland residents consumed local cod more than any other species, and older participants ate more cod than younger participants (p=0.000). Participant serum concentrations of PBDEs were 0.03 mmol/g (PBDE-28), 1.04 mmol/g (PBDE-47), 0.03 mmol/g (PBDE-99), 0.40 mmol/g (PBDE-100), 2.99 mmol/g (PBDE-153) and 4.78 mmol/g (∑PBDEs). Concentrations of PBDE-153 (p=0.018) and ∑PBDEs (28, 33, 47, 99, 100, and 153; p=0.010) were positively associated with local cod consumption. Residents of the island Newfoundland show evidence pf PBDE exposure, with possible local seafood consumption as a source. Associations between seafood consumption and PBDE levels were found, but associations were congener-specific. Further studies are needed using larger population in other parts of the province, and exploring other possible sources of exposure.

Transcriptomic analysis of Baltic cod (Gadus morhua) liver infected with Contracaecum osculatum third stage larvae indicates parasitic effects on growth and immune response

High infection levels due to third-stage larvae of the anisakid nematode Contracaecum osculatum have been documented in cod from the eastern part of the Baltic sea during the latest decades. The nematode larvae mainly infect the liver of Baltic cod and prevalence of infection has reached 100% with a mean intensity up to 80 parasites per host in certain areas and size classes. Low condition factors of the cod have been observed concomitant with the rise in parasite abundance suggesting a parasitic effect on growth parameters. To investigate any association between parasite infection and physiological status of the host we performed a comparative transcriptomic analysis of liver obtained from C. osculatum infected and non-infected cod. A total of 47,025 predicted gene models showed expression in cod liver and sequences corresponding to 2084 (4.43%) unigenes were differentially expressed in infected liver when compared to non-infected liver. Of the differentially expressed unigenes (DEGs) 1240 unigenes were up-regulated while 844 unigenes were down-regulated. The Gene Ontology (GO) enrichment analysis showed that 1304 DEGs were represented in cellular process and single-organism process, cell and cell part, binding and catalytic activity. As determined by the Kyoto Encyclopedia of Gene and Genomes (KEGG) Pathways analysis, 454 DEGs were involved in 138 pathways. Ninety-seven genes were related to metabolic pathways including carbohydrate, lipid, and amino acid metabolism. Thirteen regulated genes were playing a role in immune response such as Toll-like receptor signaling, NOD-like receptor signaling, RIG-I-like receptor signalling and thirty-six genes were associated with growth processes. This indicates that the nematode infection in Baltic cod may affect on molecular mechanisms involving metabolism, immune function and growth.

PBDEs in cod (Gadus morhua) liver products (1972–2017): Occurrence and human exposure

PBDEs occur in a range of commonly consumed foods but there is very little current information on occurrence in dietary supplements such as cod liver oil or cod livers used as food. This study retrospectively investigated a number of these products, sourced from the Baltic Sea and North Atlantic, historically dating from 1972 to 2017. For the sum of 17 measured PBDEs (ΣPBDE), the concentrations ranged from 9.9 to 415 ng g−1 for the oils and from 10.5 to 13 ng g−1 for canned liver products. Concentrations in the oils were highest during the period from 1993 to 2001. For all samples, BDE-47 was the dominant congener with a maximum detected concentration of 308 ng g−1 in a Baltic cod liver oil from 1993. Human exposure to PBDEs from recommended doses were estimated for adults, teenagers and children. Depending on the age group, BDE-47 intakes ranged from 1.3 to 211.5 ng kg−1 bm day−1 (Baltic Sea), 2.9–12.7 ng kg−1 bm day−1 (Atlantic, Norway) and 1.1–4.8 ng kg−1 bm day−1 (Atlantic, Iceland). Intakes for the other dominant congeners, BDE-49, BDE-99 and BDE-100, were relatively low. The intake estimates of ΣPBDE were highest for Baltic cod liver oils ranging from 2.2 to 284.8 ng kg−1 bm day−1 for adults, 2.8–178 ng kg−1 bm day−1 for teenagers and 2.0–127.8 ng kg−1 bm day−1 for a child. Estimated weekly intake of ΣPBDE from canned cod liver was highest for adults, ranging from 17.6 to 25.1 ng kg−1 bm.

A retrospective investigation into the occurrence and human exposure to polychlorinated naphthalenes (PCNs), dibenzo-p-dioxins and furans (PCDD/Fs) and PCBs through cod liver products (1972–2017)

A retrospective analysis of a number of historical medicinal grade cod liver oil samples produced in Northern Europe revealed relatively high contamination levels of PCNs, PCDD/Fs and PCBs. The total toxic equivalence (TEQ) associated with PCDD/Fs, dl-PCBs and PCNs was in the range 95–427 pg g-1 for Baltic cod liver oils and from 70 to 148 pg g-1 for oils sourced from the North Atlantic. The corresponding range for canned cod liver products (Baltic Sea) sampled in 2017 ranged from 52 to 104 pg g-1 fat (33–34 pg g-1 ww). The contribution from PCBs to the overall TEQ toxicity was around 3–6-fold higher than from PCDD/Fs and ranged from 24 to 318 pg TEQ g-1ww. The estimated summed TEQ intakes of PCDD/Fs, dl-PCBs and dl-PCNs resulting from the consumption of the daily recommended doses was highest for the Baltic cod liver oils ranging from 16 to 293 pg kg-1 body mass (bm) day-1 for an adult, 20–183 pg kg-1 bm day-1 for a teenager and 15–131 pg kg-1 bm day-1 for a child. The contribution to daily adult TEQ intake from PCNs alone, although relatively small is estimated to contribute up to 5-fold above the recent EFSA proposed TWI of 2 pg kg-1 bm. The results indicate that although currently produced fish oils may undergo rigorous purification procedures and show low contaminant levels, cod livers sourced from the Baltic and consumed locally, continue to contribute substantially to the dietary intake of these contaminants.