Monitoring programme for pharmaceuticals, illegal substances, contaminants and microbiology in aquatic products imported to Norway from third countries

As a member of the European Economic Area (EEA), Norway is obliged to monitor the conformity of food and feed products imported to the EEA area. Included in this activity is analytical examinations of seafood with respect to microorganisms or the presence of undesirable substances. The Norwegian Food Safety Authority (NFSA) is the competent authority regarding veterinary border control in Norway. On behalf of NFSA, IMR carried out the analytical examination of the seafood samples in this monitoring programme and elaborated this report.

1.1 - Microbial parameters

A selection of microbiological parameters was used to evaluate the safety and quality of seafood products and whether proper hygienic measures were applied during production or transport. To examine for possible faecal contamination, analyses for commonly applied indicator organisms were conducted, including assays for coliforms, thermotolerant coliform bacteria, bacteria in the Enterobacteriaceae family, Escherichia coli and enterococci. In addition, examination for coagulase positive staphylococci and sulphite reducing clostridia were conducted on a selection of samples, either heat treated or under vacuum. Furthermore, a selection of samples was examined for specific pathogens relevant for food safety, including norovirus, hepatitis A virus, Vibrio spp., bacteria in the genus Salmonella and  Listeria monocytogenes . Vibrios are naturally occurring in marine and estuarine environments, with some species being potential human pathogens. There are currently no regulations on vibrios in food, however their presence in seafood is monitored as they are expected to become an increasing problem with increasing seawater temperatures. Salmonella are faecal bacteria commonly found in the gastrointestinal tract of warm-blooded animals and may contaminate a range of food and feed items. Salmonella is one of the leading causes of food borne infections in the world and can cause serious disease in humans depending on serotype involved and the susceptibility of the infected person. L. monocytogenes ( Lm ) can be found among animals and humans , as well as in the environment. Lm can establish in food processing facilities due to their biofilm-forming abilities and natural resistance to commonly used decontaminants, from which they can contaminate food processed in those facilities. Lm can cause serious infections, particularly in young children, the elderly and people with a compromised immune system. It is an increasing food-safety issue that is mainly relevant for lightly preserved foods with an extended shelf-life and that are not intended for heat-treatment prior to consumption, as exemplified by cold-smoked non frozen fish products. The EU microbiological criteria for  Salmonella and  Lm ¹ , implemented by Norway has through the EEA agreement, formed a basis for the evaluation.

1.2 - Parasitic nematodes

Fillets of fish were analysed for the presence of anisakid nematodes using the UV-press method (ISO 23036-1:2021) ² . European regulations states that fisheries products that are obviously contaminated with parasites must not be placed on the marked for human consumption ³ .

1.3 - Unauthorised and prohibited substances

Farmed seafood products were analysed for several unauthorised and prohibited veterinary medicinal products. Chloramphenicol is an antibiotic agent that exhibit activity against a broad spectrum of microorganisms. Due to a rare but serious dose-independent adverse effect (aplastic anaemia), this agent is not authorized in the treatment of food-producing animals, including fish. Nitrofurans were previously widely used in veterinary medicine as an antimicrobial agent. They were banned by the European Union (EU) in 1995 due to concerns about the carcinogenicity of possible residues in the edible tissue ⁴ . Samples were also analysed for the dyes; malachite green, crystal violet and brilliant green; metronidazole and s teroids .

1.4 - Authorised veterinary drugs

Farmed seafood samples were analysed for residues of veterinary drugs that are authorised for use in food producing animals and checked for compliance according to the Maximum Residue Limits (MRLs) as listed in EU 2010/37 ¹¹ . The samples were analysed for residues of antibiotic agents, drugs used against intestinal parasites and anti sea lice agents.

1.5 - Histamine

The survey also included the biogenic amine histamine, following Commission Regulation (EU) No 1019/2013 ⁵ of 23 October 2013 amending Annex I to Regulation (EC) No 2073/2005 ¹ as regards histamine in fishery products .

1.6 - Undesirable trace elements

Undesirable trace elements relevant for seafood safety occur naturally in the environment, with large variations. The analysed levels are influenced by different factors including the geological presence, anthropogenic sources and environmental conditions. These compounds may accumulate in food chains and thus find their way into seafood. Farmed seafood can be affected via contaminated feed. The elements cadmium (Cd), mercury (Hg), and lead (Pb) were measured and the compliance of the values with the EU maximum levels (ML) (as listed in EU 2023/915) ⁶ was evaluated. Arsenic (As), was also included, although there is currently no maximum level in seafood.

1.7 - Persistent organic pollutants - POPs’ ( dioxin, PCB, PBDE, PFAS )

Persistent organic pollutants (POP’s) form a diverse group of substances with a range of chemical and toxicological characteristics. POPs are persistent in the environment and accumulate in food chains. Some classes of POPs are considered a human health dietary risk. The compliance of selected samples with established maximum levels for food stuffs ⁶ was evaluated for these contaminants: sum of dioxins (polychlorinated dibenzo-para-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs)), sum of dioxins and dioxins like PCBs (dl-PCBs), and the EU selected “non-dioxin like-PCBs”. In addition, flame-retardant compounds in the polybrominated diphenyl ethers family (PBDEs) were measured. However, maximum levels in food have not been established for the BDEs. The EU recommends a monitoring of the BDE compounds in food ⁷ . Seafood is considered a potential contributor to BDE-99 exposure, which is the BDE compound considered most relevant to food-safety ⁸ . In 2023, maximum levels were established for perfluorinated compounds. The levels were set for perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA): perfluorononanoic acid (PFNA), and perfluorohexane sulfonic acid (PFHxS), individually and for their sum⁵. For the sum, lower bound concentration is calculated on the assumption that all the values below the limit of quantification are zero⁶ .

Sampling was carried out by NFSA at the Norwegian Border Inspection Posts (BIPs) while analytical examinations and the writing of this report was carried out by IMR. The sampling targeted hazards associated with different imported products, and took into account import volumes, compositional nature of the products, results from previous monitoring, geographical origin of samples, and information available in the RASFF (Rapid Alert System for Food and Feed).

Fresh samples were shipped without delay to IMR whereas frozen samples were stored frozen in the BIPs until shipment in the frozen state to IMR for analysis. Upon arrival, samples were registered at the IMR sample reception unit, each sample was photographed, and relevant information registered in a Laboratory Information Management System (LIMS). Microbiological assays were done prior to all other sample handling procedures to prevent contamination. The samples were subsequently prepared for analyses and split in sub-samples (aliquots) for the different assays and analytical methods.

In general, the edible part was selected for analyses according to a manual specified for each type of sample. For undesirable chemical compounds where a legal maximum level is established, the tissue specified in the regulation was selected. The analytical methods and procedures used were quality assured and accredited according to the ISO 17025:2005 standard ⁹ , unless otherwise specified.

The evaluations of the analytical data in the report were based on the EU maximum levels and recommendations ^1,5,6 . The maximum levels provide a legal framework for trade. For undesirables with no established maximum level, interpretation of the analytical values was based on scientific expert opinions when available.

A total of 96 samples from the NFSA at Norwegian BIPs, were examined by a selection of methods for microorganisms, and undesirable chemical species as shown in Table 1.

3.1 - Microbial parameters

Ninety-six samples were analysed for the presence of potential human pathogenic bacteria and spoilage bacteria. All samples were compliant with the regulations.

Of the 96 samples, 75 were examined for the presence of coliform bacteria. Eleven samples had levels above or at the detection limit (10 colony forming units, cfu/g), where the highest value found was 4300 cfu/g in a sample of “popcorn shrimps” (category “other”/“processed seafood”). The remaining samples with values above the detection limit contained 10-40 cfu/g, and consisted of frozen fish fillets or shrimp imported from Viet Nam, China, The Philippines or India. Further, 93 samples were analysed for the presence of thermotolerant coliform bacteria, where nine samples had levels above the method detection limit (10 cfu/g). Of these, the highest measured value was 3100 cfu/g in the aforementioned sample of “popcorn shrimp”, whereas values between 10-70 cfu/g were measured in other processed seafood products, fish fillets and fresh oysters imported from Viet Nam, Canada, China or the Philippines.

For enterococci, ten of 61 samples examined contained values at or above the detection limit of 100 cfu/g. The highest values detected were 1100, 2100 and 3100 cfu/g in three separate samples of frozen whiteleg shrimp or giant tiger prawns imported from Viet Nam or India, and 11 400 cfu/g in the previously mentioned sample of “popcorn shrimp”, imported from Viet Nam (Table 2). The remaining six positive samples contained between 100 to 700 cfu/g, and consisted of frozen whiteleg shrimp or processed seafood imported from Viet Nam (Table 2).

High numbers of intestinal bacteria such as faecal coliforms and enterococci indicates faecal contamination of the product, either from the environment or during production, and may convey gastrointestinal diseases to the consumer. However, sufficient h eat-treatment will kill such bacteria if present. In any case, good kitchen hygiene should be practised when handling these products to avoid cross-contaminating surfaces and other food-items.

Five samples, where four consisted of fresh or frozen oysters imported from Canada or Korea, and one consisted of “seafood cocktail” (Category Processed seafood), were examined for the presence of Escherichia coli , and the numbers were below detection limit in all samples.

Ninety-three sample were analysed for the presence of Salmonella and found negative. Listeria monocytogenes was detected qualitatively in four of the 50 samples analysed, and the subsequent quantitative analysis found the number to below the detection limit of 10 cfu/g (Table 2). The positive samples consisted of two trout fillets imported from Peru, one sample of Pangasius fillets imported from Viet Nam, and one sample of Humboldt squid fins imported from Chile (Table 2). As these products were not intended to be consumed without further heat treatment, the products were compliant with EU regulations.

Thirteen samples were analysed for the presence of coagulase positive staphylococci. None of these samples had levels above the detection limit (100 cfu/g). Twenty samples were analysed for the presence of sulphite reducing clostridia. Two samples were of fish oil imported from Peru both had 100 cfu/g (Table 2). The detection limit of the method is 100 cfu/g.

Twenty samples were analysed for the presence of potentially human pathogenic Vibrio spp., where four samples were found positive. One sample of Eastern oysters imported from Canada contained Vibrio alginolyticus , one sample of frozen whiteleg shrimp imported from Viet Nam contained V. parahaemolyticus , another sample of frozen whiteleg shrimp also from Viet Nam contained V. cholera , and finally, one sample of Giant tiger prawns from India contained V. parahaemolyticus and V. cholerae (Table 2) . Vibrio- strains isolated from these samples were identified using both MALDI-TOF MS and biochemical tests (API 20E). The V. cholerae isolated from whiteleg shrimp was analysed for the presence of genes associated with toxin production by the Norwegian Institute of Public Health, and was found to not be toxin-producing. Non-toxin producing V. cholerae does not cause cholera, however, they may still cause milder gastrointestinal symptoms, including diarrhoea. V. parahaemolyticus may also cause gastrointestinal infections depending on the presence of toxin genes. V. algionolyticus on the other hand, is usually associated with waterborne wound- or ear-infections, and not with foodborne gastrointestinal infections. Heat-treatment will kill vibrios if present in the products, but good kitchen hygiene should be practised when handling these products to avoid cross-contaminating surfaces and other food-items.

One sample of Pacific oysters from Korea was examined for the presence of Norovirus type I and II, as well as Hepatitis A by RT-PCR in accordance with ISO 15216-1:2017 (Horizontal method for determination of hepatitis A virus and norovirus in food using real-time RT-PCR -Part 1: Method for quantification) , and was found negative for all three parameters . The sample was analysed by the Norwegian University of Life Sciences (NMBU), who is the Norwegian NRL for Norovirus and Hepatitis A in food and water.

3.2 - Parasitic nematodes

Fillets of frozen fish from two samples were analysed for the presence of anisakid nematodes. A sample consisting of three bullet mackerel imported from Viet Nam contained no parasites, whereas one sample of shortfin scad contained two parasites in the muscle tissue.

3.3 - Unauthorised and prohibited substances

Residues of malachite green and leuco malachite green were detected at a total concentration of 1.4 μg/kg in a sample of milkfish ( Chanos chanos ) from the Philippines. Leuco malachite green was also detected, 0.17 μg/kg, in a sample of barramundi ( Lates calcarifer ) from Vietnam. Residues of other dyes, crystal violet and brilliant green, was not detected in the samples. Residues of metronidazole was detected, 0.96 μg/kg, in a sample of whiteleg shrimp ( Penaeus vannamei Boone ) from Vietnam. No residues of nitrofurans or steroids were found in the samples.

3.4 - Authorised veterinary drugs

No residue of antibiotic agents was detected in the six samples analysed for antibiotic agents. One sample was analysed for drugs used against internal and external parasites; no residues were detected. C ypermethrin and deltametrin has been used as both anti sea lice agent and as a pesticide (Bernhard 2023) ¹² . For 2024, cypermethrin and deltametrin were below the LOQ for the sample analysed.

3.5 - Histamine

Histamine is a biogenic amine produced by bacterial degradation of the amino acid histidine, if scombroid fish species are exposed to improper storage or transport conditions. A total of eight relevant samples were selected for analysis, and all measured values were below the maximum permitted levels.

3.6 - Undesirable trace elements

A total of 26 samples were analysed for undesirable trace elements. None of the samples exceeded the maximum levels established for mercury, cadmium or lead.

3.7 - Persistent organic pollutants – POPs’ ( dioxin, PCB, PBDE, PFAS )

Analyses of dioxin, dl-PCB, PCB6 and PBDE were performed in 12 samples, none of the results were above the established maximum levels for dioxin, dioxin and dl-PCB, PCB6. Analyses of PFAS were performed in 12 samples, also for this group of compounds, none of the results were above the established maximum levels.

A total of 96 samples collected by the official staff at the Norwegian Border Inspection Posts of the Norwegian Food Safety Authority were examined for selected chemical and microbiological undesirables in 2024 .

Selected microbiological analyses were performed on 96 samples. Four samples contained L. monocytogenes , but as the samples were not from ready-to-eat products, they were considered compliant according to current regulations.

Four samples harboured potentially human pathogenic Vibrio spp. However, there are currently no regulations or limits regarding the presence of these bacteria in food items.

None of the other samples examined were identified with undesirable or unacceptable microorganisms according to EU regulations, though some contained high values of intestinal microorganisms. Most vibrios are marine bacteria that are naturally occurring in the environment, including in animals such as bivalves and crustaceans. Fecal coliforms and enterococci, however, are intestinal bacteria found in humans or animals, and may indicate poor hygienic conditions either during farming of animals (aquaculture) or during processing of the products (aquaculture and wild caught).

Undesirable trace elements were measures in twenty-six samples of seafood. Further, twelve samples were measured for dioxin, dl-PCB, PCB6, PBDE, and PFAS were measured in twelve samples of seafood. None of the samples had levels exceeding the respective maximum levels.

Substances prohibited for use in animals intended for food were analysed in nineteen samples. Residues of malachite green and leuco malachite green were detected in milkfish ( Chanos chanos ) from the Philippines. Leuco malachite green was also detected in barramundi ( Lates calcarifer ) from Vietnam. Residues of metronidazole was detected in whiteleg shrimp ( Penaeus vannamei Boone) from Vietnam.

The chemical spoilage indicator histamine was examined in eight relevant samples, and all values were below the maximum permitted level.

(1) The European Commission. COMMISSION REGULATION (EC) No 2073/2005 of 15 November 2005 on Microbiological Criteria for Foodstuffs ; 2005. https://doi.org/10.1109/MACE.2010.5536537.

(2) ISO 23036-1:2021 - Microbiology of the food chain — Methods for the detection of Anisakidae L3 larvae in fish and fishery products — Part 1: UV-press method . https://www.iso.org/standard/74372.html (accessed 2024-05-01).

(3) Eurpoean Union. REGULATION (EC) No 853/2004 OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL of 29 April 2004 down Specific Hygiene Rules for Food of Animal Origin . https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX%3A02004R0853-20241109 (accessed 2025-05-19).

(4) Scientific Opinion on Nitrofurans and Their Metabolites in Food ; Wiley-Blackwell Publishing Ltd, 2015; Vol. 13. https://doi.org/10.2903/J.EFSA.2015.4140.

(5) The European Commisssion. COMMISSION  REGULATION  (EU)  No  1019/2013 of  23  October  2013 Amending  Annex  I  to  Regulation  (EC)  No  2073/2005  as  Regards  Histamine  in  Fishery  Products ; 2013.

(6) European Parliament and the Council of the European Union. Commission Regulation (EC) No 1881/2006 of 19 December 2006 Setting Maximum Levels for Certain Contaminants in Foodstuffs. Official Journal of the European Union 2006, Versão Con (364), 5–24.

(7) COMMISSION RECOMMENDATION of 3 March 2014 on the Monitoring of Traces of Brominated Flame Retardants in Food (Text with EEA Relevance). https://doi.org/10.2903/j.efsa.2010.1789.

(8) EFSA Panel on Contaminants in the Food Chain (CONTAM). Scientific Opinion on Polybrominated Diphenyl Ethers (PBDEs) in Food ; Wiley-Blackwell Publishing Ltd, 2011; Vol. 9. https://doi.org/10.2903/J.EFSA.2011.2156.

(9) ISO/IEC 17025:2005 - General requirements for the competence of testing and calibration laboratories . https://www.iso.org/standard/39883.html (accessed 2023-05-16).