Monitoring program for pharmaceuticals, illegal substances, and contaminants in farmed fish

Official control systems provide the regulatory framework necessary to enforce European Union (EU) legislation and standards related to food safety and animal health. These systems ensure that food business operators comply with established legal requirements, thereby mitigating fraudulent practices and preserving the integrity of food products. Furthermore, official controls are designed to maintain consistent standards of safety and quality across the entire agri-food chain. Through systematic inspection, monitoring, and verification activities, competent authorities are able to identify, assess, and manage risks associated with food production, processing, and distribution. Consequently, these controls enhance consumer protection and strengthen confidence in food products placed on the market within the EU and European Economic Area (EEA).

As a member of the EEA, Norway aligns its regulatory control framework with EU standards, thereby facilitating harmonised practices and regulatory cooperation within the internal market. Official controls in Norway are conducted in accordance with Regulation (EU) 2017/625¹ on official controls, which has been incorporated into national law through the EEA Agreement and implemented via the Norwegian Food Act (Matloven) and associated regulations. The Norwegian Food Safety Authority (NFSA; Mattilsynet) is responsible for carrying out these controls and ensuring compliance with legislation governing food and feed safety, as well as animal health and welfare.

Based on their relevance to aquaculture production, residues and substance groups were included into the Norwegian national control plan for pharmacologically active substances in farmed fish, in accordance with Annexes I and II of Commission Delegated Regulation (EU) 2022/1644.² Similarly, contaminant groups were included in the control plan in line with Commission Delegated Regulation (EU) 2022/931.³ In addition to contaminants that are regulated with legal maximum limits in fish, the occurrence of several emerging contaminants in farmed fish was investigated in 2025. These compounds were identified as emerging chemical risks in food and feed by the European Food Safety Authority (EFSA), the Norwegian Scientific Committee for Food and the Environment (VKM), and the Institute of Marine Research (IMR) and were selected for monitoring based on their relevance to aquaculture production. All samples reported here were collected by the NFSA as part of the official monitoring program and subsequently analysed by the IMR.

1.1 - Prohibited or unauthorised pharmacologically active substances in food-producing animals (Group A substances)

Fish samples intended for testing for unauthorised compounds were collected without prior notification to producers. Official inspectors from the NFSA collected samples across all stages of aquaculture production to obtain a representative overview of farmed fish during the production cycle. Substances monitored under Group A include prohibited growth promoters, such as steroids, stilbenes, and β-agonists, as well as unauthorised pharmacologically active feed additives, including resorcylic acid lactones, and other unauthorised veterinary medicinal products. Among these, compounds considered particularly relevant for aquaculture include chloramphenicol, nitrofurans, metronidazole, and certain dyes.

Analytical methods applied for the detection of Group A substances must comply with the minimum method performance requirements (MMPRs) established by the European Union⁴, and European reference laboratories (EU-RLs)⁵, ensuring harmonised and reliable control of prohibited substances. As no maximum residue levels (MRLs) are defined for Group A compounds, the detection of any residue is considered non-compliant and represents a potential risk to human health.

1.2 - Pharmacologically active substances authorised for use in food-producing animals (Group B substances)

Current EU legislation (Commission Regulation (EU) 37/2010)⁶ provisions the assignment of limits for all legally applied pharmacologically active substances in products intended for human consumption, where required, in order to protect public health. A maximum residue limit (MRL) is defined as the highest legally permitted concentration of residues of a veterinary medicinal product in food and is established on a substance-specific and commodity-specific basis. For fish, the MRLs are set for muscle and skin in natural proportions. Residue levels below the established MRL are considered safe and are not expected to pose a risk to consumer health. In 2025, samples analysed for authorised veterinary medicinal products were collected at processing facilities and are therefore representative of fish intended for placement on the market for human consumption.

1.3 - Regulated contaminants in food

Samples analysed for contaminants were collected at fish processing facilities and are representative of fish ready for human consumption. In the EU, maximum levels (ML) for specific contaminants in food are established under Commission Regulation (EU) 2023/915⁶ to ensure consumer protection. For fish, MLs are defined for selected groups of halogenated persistent organic pollutants, including dioxins, dioxins and dioxin-like polychlorinated biphenyls (PCBs), PCB-6 (the sum of 6 non-dioxin-like PCBs), and per- and polyfluoroalkyl substances (PFAS). Maximum levels (MLs) in fish fillet have been established for the heavy metals mercury, cadmium, and lead, and since 2025 also for inorganic arsenic. These compounds are therefore included in the official control plan for contaminants as part of the 2025 monitoring plan.

1.4 - Other, non-regulated contaminants

A broad range of contaminants was additionally included in the 2025 monitoring programme, despite not having established MLs. These substances were selected based on their classification as emerging contaminants, or their relevance to aquaculture production. The data presented herein provide insights into their occurrence in farmed fish fillet. This includes the quantification of several non-regulated chemical elements, as well as the characterization of organic arsenic and mercury species. A range of brominated flame retardants (BFRs) were measured, including both “legacy” compounds such as polybrominated diphenyl esters (PBDEs), and novel halogenated flame retardants. In addition, an extensive screening of chlorinated and organophosphorus pesticides was performed in 2025, alongside targeted analyses of processing-related contaminants originating from feed production, residues from cage treatment agents, and various environmental pollutants.

2.1 - Sampling

Samples were collected at fish farms and slaughterhouses across all aquaculture-producing regions in Norway by official inspectors from the NFSA. The sampling strategy followed a randomised design with respect to both season and geographic distribution. In 2025, a total of 1913 fillet samples of Atlantic salmon (Salmo salar), rainbow trout (Oncorhynchus mykiss), brown trout (Salmo trutta), Atlantic halibut (Hippoglossus hippoglossus), and Atlantic cod (Gadus morhua) were analysed.

All samples were transported to the IMR in a frozen state prior to analysis. Determination of substances with anabolic effects and other unauthorised compounds were performed on individual fish samples. In contrast, analyses of authorised pharmacologically active substances and contaminants were conducted on pooled samples, each comprising fillet material from three fish originating from the same cage or farm.

2.2 - Pre-treatment

Sample identities were anonymised prior to analysis at the IMR, and a back-up sample was retained for all collected material. For the analysis of Group B substances and regulated contaminants, pooled samples were prepared by homogenizing muscle tissue from three fish originating from the same cage or farm. Fillet samples were obtained from the Norwegian Quality Cut (NQC) of the fish.^7,8 For Group A substances, sampling also included small fish at early life stages collected on farms, and in these cases, the whole fish were used, excluding the head, tail and gut.

The maximum residue limits (MRL) for veterinary medicinal products are established for muscle and skin in natural proportions.⁹ Therefore, according to the analytical protocol, any detection of drug residues in the muscle was followed by a re-analysis of the back-up sample, consisting of muscle and skin in natural proportions, in duplicate.

2.3 - Analytical methods

Laboratory procedures and the majority of the analytical methods were accredited in accordance with standard ISO 17025. A summary of the applied analytical methods including their limit of quantification (LOQ) and/or limit of detection (LOD) is provided in Table A 1. The LOQ is the lowest concentration at which a substance can be reliably quantified, whereas the LOD represents the lowest concentration at which the method is able to detect the substance. For all analytical methods, each batch of analyses included a procedural blank, and a quality control sample with a known composition and concentration of the target analyte. Method performance is regularly verified through participation in interlaboratory proficiency testing schemes and through the analysis of certified reference materials, where available.

3.1 - Prohibited or unauthorised pharmacologically active substances in food-producing animals (Group A)

In 2025, a total of 941 individual fillet samples (Table 1) were tested for residues of illegal substances, including stilbenes (187 samples), steroids (102 samples), resorcylic acid lactones (zeranol & beta-zearalanol; 187 samples), beta agonists (92 samples), and unauthorised veterinary drugs including chloramphenicol (94 samples), nitrofurans (92 samples), metronidazole (102 samples), dapsone (88 samples) and dyes (189 samples). The samples were mainly taken from Atlantic salmon, but also samples from rainbow trout, Atlantic cod, and Atlantic halibut were analysed.

The individual substances included in the monitoring of these substance groups, analytical methods, and reference limits are listed in Table A 1. The evaluation criterion for samples for official controls of illegal substances is presence.

Chemical analysis of dyes detected and confirmed presence of leucocrystal violet in three individual samples of farmed fish collected in 2025 from different locations. Leucocrystal violet is the reduced metabolite of crystal violet, a synthetic dye previously used in veterinary medicine, including aquaculture, as an antifungal and antiparasitic agent. A follow-up investigation conducted by the NFSA concluded that the presence of this substance in three individual samples did not indicate illegal use but was most likely attributable to sample contamination. However, despite a thorough review of all sampling and analytical procedures, the source of the contamination could not be identified.

No residues of any other unauthorised compounds were detected in any of the samples.

^* A list of summed individual substances and their limits of detection and reference limits is provided in Table A 1.

3.2 - Pharmacologically active substances authorised for use in food-producing animals (Group B)

Samples analysed for veterinary drugs were collected at processing facilities and are therefore representative of fish ready for human consumption. The maximum residue limits (MRL) for veterinary drugs are established for muscle and skin in natural proportions.⁹ Therefore, according to the analytical protocol, any detection of residues in muscle samples would be followed by a re-analysis of the backup sample, consisting of muscle and skin in natural proportions, performed in duplicate.

3.2.1 - Group B1a, Antimicrobial substances

In 2025, 249 pooled fillet samples each comprising fillet of three fish per sample, taken at processing sites (Group B-samples), were tested for residues of antibacterial substances using chemical analysis methods (Table 2). The majority of samples were obtained from Atlantic salmon. However, additional samples from rainbow trout, brown trout, Atlantic cod and Atlantic halibut were analysed. No antibacterial agent residues were detected above LOQ in any of the samples analysed. In addition, 88 individual fish samples collected at the farm (Group A-samples) were analysed for sulfonamides and ormethoprim and trimethoprim (Table 2). None of the analysed substances were detected at concentrations above LOQ.

^* Analysed in 88 individual fillet samples taken at the farm. ^† Sum of 22 individual sulfonamides. See Table A 1 for list. ^‡ No MRL established.

3.2.2 - Group B1b, Insecticides, fungicides, anthelmintics and other antiparasitic agents

Residues of anti-sea-lice agents (Table 3) and agents for treatment of endoparasites (Table 4) were monitored in a total of 614 pooled fillet samples. Data for all measured anthelmintics are reported in this section, although some do not have assigned MRL values.

Cypermethrin and deltamethrin were monitored in 109 samples in 2025 (Table 3). Cypermethrin was detected in one sample of rainbow trout at a concentration of 1.3 µg/kg and below the MRL for cypermethrin in fish (Salmonidae), which is established at 50 µg/kg.^9,10 Deltamethrin was detected in 14 samples in 2025. The maximum value of deltamethrin measured was 5.2 µg/kg in Atlantic halibut, which is below the MRL of 10 µg/kg^9,11 established for deltamethrin residues from use as veterinary drugs in fin fish. The median values of the deltamethrin detections in Atlantic salmon were 1.2 µg/kg (10 samples) and 1.8 µg/kg in Atlantic halibut (3 samples), respectively. In rainbow trout, deltamethrin was detected in one sample at a concentration of 1.2 µg/kg.

Cypermethrin and deltamethrin are synthetic pyrethroid substances that have been authorised for use as pharmaceutical delousing agents applied as bath treatments in aquaculture farm cages. Cypermethrin is no longer used as a veterinary medicinal product in aquaculture production, whereas deltamethrin retains marketing authorisation but has been used only to a very limited extent in recent years. Both substances are also widely used as insecticides in large-scale agricultural production. Residues of cypermethrin and deltamethrin detected in fish may therefore originate from non-pharmaceutical sources, including environmental exposure or transfer from plant-based feed ingredients. For deltamethrin, a contribution from veterinary medicinal use cannot be excluded. However, the low reported usage suggests that such use is unlikely to be a major source of the residues observed.

Results are provided in Section 3.4.3.2 for other pyrethroid compounds that are not regulated, neither as pharmaceuticals nor as pesticides. These include bifenthrin, cyfluthrin, fenvalerate, lambda-cyhalothrin, and permethrin. No samples had levels above LOQ.

No residues of other anti-sea lice agents or antiparasitic agents were detected in any of the samples in 2025.

^* No MRL established. ^** MRL established for Salmonidae only (muscle and skin in natural proportions).

^* MRL established for fin fish (muscle and skin in natural proportions). ^** No MRL established for fin fish.

3.2.3 - Group B1c, Sedatives

No residues of isoeugenol were found in any of the 114 samples analysed (Table 5).

3.3 - Regulated contaminants in fish fillet

3.3.1 - Dioxins, dl-PCBs and PCB-6

Levels of dioxin (PCDD+PCDF), dioxin-like PCBs (dl-PCBs) and non-dioxin-like PCBs (PCB-6) in farmed fish were measured in a total of 111 pooled fillet samples. The sums of dioxins, dioxins + dl-PCBs and PCB-6 are calculated as upper bound.⁶ Accordingly, the numerical LOQ values were used for calculating the sums for congeners with levels below LOQ. PCB-6 is the sum of the following 6 non-dioxin-like PCB congeners: 28, 52, 101, 138, 153, and 180.

The levels of dioxins and dl-PCBs are reported as ng toxic equivalents 2005 (TEQ05)/kg and represent the sum of 17 different PCDD/F and 12 dl-PCBs where each congener was multiplied by a Toxic Equivalency Factor (TEF). TEF values are determined by the World Health Organization (WHO), and the toxicity of each congener is expressed relative to the most toxic form of dioxin, which has a TEF value of 1.^6,12 TEF values have recently been reevaluated and updated.¹³ However, the new values have not yet been incorporated into the legal framework, and the 2005 TEF is currently still applied for the calculation of the TEQ.

Dioxin levels measured in different species of farmed fish in 2025 (Table 6) were similar to the levels found in the previous years. For salmon, the median of the sum of dioxins was 0.14 ng TEQ/kg w.w. The maximum values were found in Atlantic salmon (0.24 ng TEQ/kg w.w.) and in Atlantic halibut (0.29 ng TEQ/kg w.w), and were below the EU maximum level (ML) of 3.5 ng TEQ/kg w.w.⁶

The median of the sum of all 29 PCDD/F and dl-PCBs was 0.29 ng TEQ/kg w.w. for salmon, which is nearly the same as in 2024 (0.31 ng TEQ/kg w.w.). The highest result for sum dioxin and dl-PCBs was 0.87 ng TEQ/kg w.w., measured in Atlantic halibut. All measured values were below the EU maximum level of 6.5 ng TEQ/kg w.w..⁶ The median of PCB-6 for salmon was 2.5 μg/kg w.w. The highest level of PCB-6 in any sample was measured in Atlantic salmon, at 6.2 μg/kg w.w.. For PCB-6, a maximum level is set at 75 μg/kg w.w. in the EU.⁶

3.3.2 - Perfluorinated compounds

Per- and polyfluoroalkyl substances (PFAS) constitute a large and diverse group of synthetic chemicals characterised by a wide range of physicochemical properties and extensive industrial and commercial use for more than 50 years. PFAS are increasingly detected as environmental contaminants, and certain compounds have been associated with adverse health effects. Since 2023, MLs have been established for fish fillet for four individual PFAS (PFOS, PFOA, PFNA, PFHxS) as well as for their sum (PFAS-4).⁶ 

^†Measured in 201 samples in total; n(Atlantic salmon)= 174, n(Rainbow trout)= 11, n(Atlantic cod)= 10, n(Brown trout)= 2; n(Atlantic halibut)= 4. ^‡No ML assigned. ^§LB = lower bound ^¶The Maximum Levels established for four individual PFAS compounds, and their sum is depending on both the fish species and the intended use; the given values denote MLs for fillet not intended to be used for the production of food for infants and children, and for fillet that is intended to be used in the production of food for infants and children in brackets.⁶

In 2025, a total of 335 fillet samples were analysed for PFAS. The results on PFAS measurements are presented in Table 7, while the full names of the analysed PFAS compounds are provided in Table A 1 and Table A 2, Appendix. Most PFAS compounds were not detected at concentrations above their respective LOQs in any of the samples. None of the samples exceeded the MLs established by EU.⁶ PFPeA and PFOS were detected above the LOQ in one Atlantic salmon sample, with a PFOS concentration of 0.15 µg/kg w.w., which is below the established MLs of 7 and 2 µg/kg w.w. for PFOS in fish fillet. The lower ML of 2 µg PFOS/kg w.w. was established for fish fillet that is intended to be used in the production of food for infants and children. PFOS was not detected in any of the Atlantic halibut, Atlantic cod, brown trout or rainbow trout samples.

3.3.3 - Heavy metals

Three heavy metals are regulated as contaminants in fin fish under Commission Regulation (EU) 2023/915, including mercury, cadmium, and lead.⁶ In September 2025, regulation (EU) 2023/915 was amended through Commission Regulation (EU) 2025/1891 to include MLs for inorganic arsenic (iAs; sum of As^(III) and As^(V)) for fish and other seafood.¹⁴ Inorganic arsenic is classified as carcinogenic and toxic to humans. The newly established ML for fish muscle was specified at 0.5 mg iAs/kg for flatfishes (Pleuronectiformes species), such as Atlantic halibut, but also for haddock (Melanogrammus aeglefinus), herring (Clupea species), ray (Rajidae species) and shark (all species). For all other fish species, the ML was established at 0.1 mg iAs/kg w.w..

In 2025, monitoring of the levels of the regulated heavy metals included 297 samples of Atlantic salmon, 17 samples of rainbow trout, five samples of brown trout, 21 samples of Atlantic cod, and seven samples of Atlantic halibut (Table 8). Of the samples analysed for heavy metals and chemical elements, inorganic arsenic was determined in 30 samples in addition to the total arsenic content, which is shown in Table 9.

No fish fillet sample had total mercury levels above the MLs⁶, which is 0.3 mg/kg for Atlantic salmon, rainbow trout, and Atlantic cod, 0.5 mg/kg for brown trout, and 1 mg/kg for Atlantic halibut. The highest concentrations of total mercury were 0.099 mg/kg w.w. in samples of Atlantic cod and 0.062 mg/kg w.w. in halibut. Except for the higher maximum level found in cod the median and maximum levels were similar to results from 2024. Mercury can be present in multiple chemical forms; see Section 3.4.2.2 for mercury speciation analysis.

In the 2025 analyses, no measurements of Cd were above LOQ in any of the species. In 2024, only one sample was found to be higher than LOQ and in 2023, four of 377 total samples had cadmium levels above LOQ (maximum in 2023 was 0.002 mg/kg w.w.).

Lead was found in one sample of Rainbow trout, at 0.008 mg/kg w.w. This level is below the EU ML, which is set at 0.30 mg/kg w.w. in muscle meat of fish.⁶ All remaining samples of Atlantic salmon and the other species had lead concentrations below the LOQ. The number of detections and levels of lead are similar to the 2024 monitoring.

None of the samples contained inorganic arsenic above the LOQ (1.4 – 3.2 µg iAs/kg fillet w.w.).

^*Maximum levels for mercury are dependent on fish species, and are 0.3 mg/kg for Atlantic salmon, rainbow trout, and Atlantic cod; 0.5 mg/kg for brown trout; and 1 mg/kg w.w. for Atlantic halibut. ^**Maximum levels for cadmium are dependent on the fish species, and it is 0.05 mg/kg w.w. for all included species. ^***Maximum levels for inorganic arsenic are dependent on the fish species and are 0.5 mg/kg for Atlantic halibut and 0.1 mg/kg w.w. for all other fish species included in the monitoring.

3.3.4 - Feed additives

Butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) are synthetic antioxidants authorised for use as feed and feed ingredients additives in conventional animal feed in the EU/EEA¹⁵ where their inclusion in high-fat aquaculture feed helps maintain nutritional integrity by preventing rancidity. However, in organic aquaculture production the use of feed additives is restricted, and the use of BHA and BHT as feed additives is not authorised.^16,17 In 2025, six samples of Atlantic salmon fillet from organic farming were included for monitoring of residues of BHA and BHT. The method LOQs were 0.2 mg/kg w.w. for each BHA and BHT, and no residues of BHA or BHT were found above LOQ in any of the measured samples.

3.4 - Other, non-regulated contaminants

National authorities are required to carry out official controls not only on contaminants that are subject to EU maximum levels, but also on other substances that may pose a risk to public health. As specified in Regulation (EU) 2017/625¹, along with Delegated Regulation (EU) 2022/931³ and Implementing Regulation (EU) 2022/1646¹⁸, the selection of such substances should take into account factors including occurrence data, toxicological relevance, consumer exposure, and the availability of suitable analytical methods. This risk-based approach ensures that national control plans remain targeted, proportionate, and capable of addressing both established and emerging food safety concerns.

In the case of fish and fishery products, this enables the inclusion of non-regulated contaminants in national monitoring programs, where their relevance is supported by a risk-based assessment.

3.4.1 - Chemical elements

Beyond the three regulated heavy metals and the regulated arsenic species reported in Section 3.3.3, several non-regulated chemical elements were also analysed in 2025, including both essential and non-essential elements (Table 9). In total, 347 farmed fish samples were analysed. There are currently no EU limits established for any of these elements for fish fillet. These elements are important to monitor as they can be toxic in higher concentrations, but they may also modulate toxicity of other elements. A well-known example is the protective effect of selenium towards mercury toxicity. Arsenic (as total arsenic) was present in every sample analysed. The levels found are lower than what is found in wild caught cod and halibut. See section 3.4.2.1 for results of organic arsenic analysis. For many of these elements, continued monitoring is establishing background levels, which will help to detect incidences of pollution or feed contamination. This will be the case for elements such as chromium, nickel, cobalt, vanadium, and silver.

Copper is found at low levels around 0.4 mg /kg w.w. in the salmonids and even lower in cod and halibut. Since copper still has some use in anti-fouling, these data are important to keep track of. Zinc, manganese and iron are more interesting for their role as nutrients but as for most of the trace elements, they can pose problems at high levels. The values from 2025 are in the expected low range for these elements.

3.4.2 - Metal species

Chemical elements are often present in more than one chemical form, or so-called species. Arsenic and mercury can be present in organic molecules. In the context of chemical monitoring of farmed fish, it is relevant to distinguish between different arsenic and mercury species, because they vary greatly in terms of their rates of transfer, toxicity and potential health risks. Different metal species can have unique toxicity and rates of feed-to-fillet transfer in farmed fish, and also different bioavailability in humans.

3.4.2.1 - Arsenic speciation

In addition to the proportion of inorganic arsenic (section 3.3.3), occurrence of several organic arsenic species was investigated in 30 samples in 2025 (Table 10). Fish and seafood (especially crustacea) often contain relatively high levels of total arsenic compared to terrestrial food products, but the major form of As in seafood is typically present as organic arsenic compounds. Arsenobetaine, the dominant organic arsenic form, is considered non-toxic to humans. Arsenobetaine is not found in terrestrial food products. There are no established MLs for total arsenic in fish, nor its organic chemical forms. Arsenobetaine was present in all analysed samples, with measured levels showing that the majority of arsenic was present as arsenobetaine. As for total arsenic the maximum value of 2.4 mg/kg w.w. was found in a sample of Atlantic halibut. The median and maximum levels of arsenobetaine in Atlantic salmon were 0.30 mg/kg w.w. and 1.4 mg/kg w.w., respectively. In addition, although to a minor degree, dimethylarsinate was present in nearly all samples of Atlantic salmon (median: 0.005 mg/kg w.w., maximum: 0.008 mg/kg w.w.) and rainbow trout (median: 0.005 mg/kg w.w., maximum: 0.006 mg/kg w.w.). Arsenocholine, tetramethyl arsonium ion and trimethylarsine oxide were not found above LOQs in any of the 30 analysed samples (Table 10).

3.4.2.2 - Mercury speciation

Total and methyl mercury were evaluated in 32 samples in 2025 (Table 11). While total mercury analysis gives an overall estimate of mercury contamination, it does not distinguish between its chemical forms, which differ significantly in potential toxicity to consumers and feed-to-fish muscle transfer. In fish muscle, methyl mercury typically accounts for more than 90% of the total mercury, and it is the form that is readily absorbed by the human body and known for its neurotoxic effects, particularly harmful to developing nervous systems in foetuses and young children. As opposed to arsenic, the inorganic form of mercury is considered to be less toxic than the organic mercury forms. As expected, the analyses showed that majority of mercury was present in its organic methylated form in the four fish species sampled. While there is currently no specific ML established for methyl mercury in fish, none of the samples exceeded the ML for total mercury in fish (see also Table 8).

3.4.3 - Pesticides

3.4.3.1 - Organochlorine and organophosphorus pesticides

A suite of organochlorine and organophosphorus pesticides was determined in 109 pooled fillet samples (Table 12).

Among the organochlorine pesticides, the following were found in at least one sample: α-hexachlorocyclohexane, β-hexachlorocyclohexane, γ-hexachlorocyclohexane (Lindane), hexachlorobenzene, cis-nonachlor, trans-nonachlor, and mirex. The organochlorine pesticides are mostly banned for use in the EU. They are present in the environment as persistent, legacy contaminants. There is currently no MRL established for any of these compounds in fish fillet, yet as opposed to various terrestrial food products.

The analysis included three organophosphorus pesticide residues (chlorpyrifos, chlorpyrifos-methyl and pirimiphos-methyl). Of several organophosphorus pesticides that are used on crop used as feed ingredients in aquafeeds, these three pesticides are known to be most dominantly present in salmon feed.¹⁹ No residues of chlorpyrifos or chlorpyrifos-methyl were detected in any of the samples. There is currently no MRL established for chlorpyrifos or chlorpyrifos-methyl in fish fillet, however the use of these pesticides have recently been banned in the EU.²⁰ Pirimiphos-methyl was detected in 35 of 88 samples of Atlantic salmon, with a maximum concentration of 1.4 µg pirimiphos-methyl/kg fillet w.w. Three samples of Atlantic halibut contained residues of pirimiphos-methyl, with a maximum concentration of 1.6 µg/kg. In brown trout it was detected in one sample with a maximum concentration of 0.2 µg pirimiphos-methyl/kg fillet w.w.. No residues of pirimiphos-methyl were detected in samples of rainbow trout or Atlantic cod. There is currently no MRL established for pirimiphos-methyl in fish fillet, yet. However, MRLs are established for this pesticide in various terrestrial animal food products.

For other organochlorine pesticides, the amount present is calculated as a sum including metabolites or transformation products.²¹ The results for these groups of pesticides are presented in Table 13. To calculate the sum of the components, conversion factors (Table A 3, Appendix) are used to adjust for different molecular weights. The sums in Table 13 were calculated according to the upper bound (UB) formula.²¹

For DDT and chlordane, levels were calculated for both all measured metabolites, as well as the sums of metabolites according to the legal residue definitions established through Regulation (EC) No 149/2008.²² When using UB calculations, the numerical value of LOQ is used as a concentration value for each non-quantified analyte. UB thus represents a “worst case scenario.” As an example, all measurements of endosulfan are below LOQ, however, a sum is generated based on the LOQ-values. The results for individual organochlorine pesticides that are not summed are presented in Table 12. There are currently no MRLs established in fish fillet for any of the listed pesticides, as opposed to several terrestrial food products.²⁰

^*DDT (sum of p,p´-DDT, o,p´-DDT, p,p´-DDD, o,p´-DDD, p,p´-DDE and o,p´-DDE) expressed as DDT. ^†Legal residue definition according to Reg. (EC) No 149/2008²²: DDT (sum of p,p´-DDT, o,p´-DDT, p-p´-DDE and p,p´-TDE (DDD), expressed as DDT). ^‡ Chlordane (sum of cis - and trans -isomers and oxychlordane expressed as chlordane). ^§ Legal residue definition according to Reg. (EC) No 149/2008²²: Chlordane (sum of cis- and trans-chlordane).

3.4.3.2 - Pyrethroid pesticides

None of the following pyrethroid substances were detected in any of the samples: bifenthrin, cyfluthrin, fenvalerate, lambda-cyhalothrin, and permethrin. A total of 109 samples were included in the monitoring in 2025, that included samples of 88 Atlantic salmon, 8 rainbow trout, 2 brown trout, 7 Atlantic cod, and 4 Atlantic halibut. The LOQs ranged between 0.49 and 2.0 µg/kg w.w.

Cypermethrin and deltamethrin are pyrethroid pesticides that also have pharmacological uses and have regulated MRLs. Results for these compounds are provided in section 3.2.2.

3.4.3.3 - Wide scope pesticide screen

In 2025, 17 pooled samples of Atlantic salmon, one pooled sample of rainbow trout and one pooled sample of cod were analysed on a wide scope screen that included 542 pesticides with LOQs ranging from 0.005-0.2 mg/kg w.w. None were above detection limit in any samples. The complete list of pesticide analytes and their LOQs are given in List A 1.

3.4.4 - Persistent organic pollutants

3.4.4.1 - Brominated flame retardants

Brominated flame retardants (BFRs) are a group of synthetic chemicals used in a wide range of consumer products to reduce their flammability. Due to their persistence, bioaccumulation and potential toxicity, the production and use of several BFRs including polybrominated diphenyl ethers (PBDEs) have been prohibited or restricted through the Stockholm Convention on Persistent Organic Pollutants. However, these persistent chemicals are widely present and can bioaccumulate through the food web, including marine fish used as feed ingredients. In 2025, levels of several PBDEs (Table 14) were monitored in 111 samples of farmed fish. In addition, due to growing concerns about health risks, levels of several halogenated flame retardants and related compounds were measured in 14 samples (Table 15). The measured substances include a diverse group of halogenated organic contaminants, primarily brominated and chlorinated flame retardants, such as dechlorane compounds (e.g. Dechlorane Plus and related adducts), alternative brominated flame retardants (e.g. BTBPE, DBDPE, and brominated benzoates and phthalates), and brominated phenolic or anisole derivatives. These compounds represent a mixture of substances listed in Annex I of the Stockholm Convention as POPs, substances under increasing regulatory scrutiny, and emerging contaminants derived from both primary industrial use and environmental transformation processes. Their presence in fish fillet reflects a combination of legacy contamination, ongoing emissions from materials and products, and natural or microbial transformation pathways. However, there are currently no EU maximum levels for any BFR substances in food products.

3.4.4.2 - Short + medium chain chlorinated paraffins (SCCP/MCCP)

Short- and medium-chain chlorinated paraffins (SCCPs and MCCPs) are industrial chemicals and contaminants of emerging concern regarding food safety, due to their persistence, their potential for bioaccumulation and possible toxic effects. SCCPs and MCCPs are complex mixtures used mainly as flame retardants, plasticisers, and lubricant additives. Classified as persistent organic pollutants, SCCPs are listed under Annex A of the Stockholm Convention on POPs, mandating their global phase-out with time-limited exemptions for specific applications. MCCPs have been identified as a Substance of Very High Concern (SVHC) under REACH since 2021 and were recently added to Annex A of the Stockholm Convention with the aim of global elimination.²³ The EU is in the process of implementing a near-ban under the POPs regulation, with time-limited exemptions for certain uses.²⁴ Their presence in food is being monitored and assessed due to potential health impacts. There are limited data on levels in food, especially in fish, highlighting the need for collection of occurrence data. Therefore, measurement of SCCPs and MCCPs was included in the monitoring in farmed fish in 19 samples of Atlantic salmon, two samples rainbow trout and one sample of each brown trout and Atlantic cod (Table 16). SCCPs were not detected in rainbow trout, brown trout or Atlantic cod samples, but were present in 15 of the 19 samples of salmon, with the highest measured concentration at 16.6 mg SCCPs/kg ww. MCCPs were detected in most of the salmon samples, but also samples of rainbow trout and brown trout. The maximum concentration of the sum of MCCPs (UB calculated) were 39.7 mg MCCPs/kg ww in salmon, 24.6 mg MCCPs/kg ww in rainbow trout and 15.7 mg MCCPs/kg ww in brown trout, respectively.

3.4.5 - Processing contaminants from feed

Monochloropropanediol (MCPD) and glycidyl esters are process contaminants that can be introduced into farmed fish through the use of refined vegetable oils in aquafeed. These compounds may be transferred to fish fillets, particularly in lipid-rich tissue, raising concerns for food safety. Monitoring their occurrence in fish is important to assess potential dietary exposure, support regulatory risk assessments, and ensure the safety and quality of farmed fish products. In 2025, total MCPD, including 2-monochloropropane-1,3-diol (2-MCPD), 3-monochloropropane-1,2-diol (3-MCPD) and 3-MCPD esters, as well as glycidyl esters were measured in 18 farmed fish samples (Table 17). Total MCPD was found below measurement LOQs in all included samples. Glycidyl esters were detected in 12 samples of Atlantic salmon, and one rainbow trout fillet with a maximum value of 86 µg glycidyl esters/kg fillet and 33 µg glycidyl esters/kg fillet, respectively.

* Glycidyl esters and total 3‑MCPD were not determined in one salmon sample each due to technical issues. **For one sample of Atlantic salmon the LOQ was raised to 25 µ g/kg w.w., because of matrix interferences. ***For one sample of Atlantic salmon the LOQ was raised to 100 µ g/kg w.w., because of matrix interferences.

3.4.6 - Antifouling treatment for sea cages

Tralopyril is an active compound authorised for use in anti-fouling treatments for sea cages. A total of 48 samples (38 Atlantic salmon samples, four rainbow trout samples, three Atlantic cod samples and three Atlantic halibut samples) were screened for residues of tralopyril using LC-MS/MS (Table 18). All Atlantic halibut samples contained tralopyril, with a maximum concentration of 0.36 µg/kg w.w. Tralopyril was detected in three of four rainbow trout muscle samples, with a maximum concentration of 1.1 µg/kg w.w., and in four of 38 Atlantic salmon muscle samples, with a maximum concentration of 0.09 µg/kg. There was no tralopyril detected above LOQ (0.06 µg tralopyril/kg w.w.) in any of the Atlantic cod samples.

3.4.7 - Aromatic hydrocarbons

3.4.7.1 - Monocyclic aromatic hydrocarbons

Monocyclic aromatic hydrocarbons (MAHs) are environmental pollutants introduced into aquatic environments from for example industrial discharges, shipping activities, oil pollution or atmospheric deposition. Because some MAHs are classified as toxic and potentially carcinogenic (e.g. benzene), but occurrence data in fish fillet are scarce, measurement of benzene, ethylbenzene, styrene, toluene and xylene were included into the monitoring program of farmed fish in 2025 (Table 19). Most monocyclic aromatic hydrocarbons were below LOQ. Only toluene was detected in one sample of Atlantic salmon with a concentration close to the LOQ (0.01 mg toluene/kg ww).

Residues of leucocrystal violet were found in three samples of Atlantic salmon taken at three different locations. A follow-up investigation of the samples and production sites conducted by the NFSA concluded that the presence of leucocrystal violet resulted from contamination of the samples rather than illegal use of crystal violet during production. However, the source of contamination could not be identified.

No residues of other illegal substances were detected in any of the farmed fish samples analysed in 2025.

Residues of the authorised pharmacologically active substances cypermethrin and deltamethrin were detected. However, the concentrations of all measured residues were below the respective MRLs for the compounds. Both substances are authorised for use as anti-sea lice treatment but are also broadly used as plant protection agents. No residues of other authorised veterinary pharmaceuticals, such as antibiotics, endoparasitic agents or sedatives were found in any of the samples.

There were no exceedances of EU maximum levels for contaminants that have established MLs for fish fillet (sum dioxins, sum dioxins and dl-PCBs, PCB-6, mercury, lead, cadmium, inorganic arsenic and PFAS).

In 2025, the monitoring of several contaminants of emerging concern for food safety of farmed fish fillets continued. The presence of multiple environmental contaminants classified as POPs under the Stockholm Convention, as well as processing contaminants present in feed and substances used for aquaculture net coating underlines the relevance of a risk-based monitoring approach, as several compounds fall within categories of regulatory concern and warrant prioritisation in future monitoring activities. Current data are insufficient to fully define normal or background levels and associated variability, highlighting the need for expanded and systematic data collection. Improved datasets will be essential for refining exposure assessments, reducing uncertainty, supporting robust future risk assessments, and ensuring that contaminant levels remain within acceptable limits for human consumption.

1. Regulation (EU) 2017/625 of the European Parliament and of the Council of 15 March 2017 on official controls and other official activities performed to ensure the application of food and feed law, rules on animal health and welfare, plant health and plant protection products, amending Regulations (EC) No 999/2001, (EC) No 396/2005, (EC) No 1069/2009, (EC) No 1107/2009, (EU) No 1151/2012, (EU) No 652/2014, (EU) 2016/429 and (EU) 2016/2031 of the European Parliament and of the Council, Council Regulations (EC) No 1/2005 and (EC) No 1099/2009 and Council Directives 98/58/EC, 1999/74/EC, 2007/43/EC, 2008/119/EC and 2008/120/EC, and repealing Regulations (EC) No 854/2004 and (EC) No 882/2004 of the European Parliament and of the Council, Council Directives 89/608/EEC, 89/662/EEC, 90/425/EEC, 91/496/EEC, 96/23/EC, 96/93/EC and 97/78/EC and Council Decision 92/438/EEC (Official Controls Regulation) (Text with EEA relevance). ( https://eur-lex.europa.eu/eli/reg/2017/625/oj/eng , 2017).

2. Commission Delegated Regulation (EU) 2022/1644 of 7 July 2022 supplementing Regulation (EU) 2017/625 of the European Parliament and of the Council with specific requirements for the performance of official controls on the use of pharmacologically active substances authorised as veterinary medicinal products or as feed additives and of prohibited or unauthorised pharmacologically active substances and residues thereof (Text with EEA relevance). (C/2022/4400, 2022).

3. Commission Delegated Regulation (EU) 2022/931 of 23 March 2022 supplementing Regulation (EU) 2017/625 of the European Parliament and of the Council by laying down rules for the performance of official controls as regards contaminants in food (Text with EEA relevance). ( https://eur-lex.europa.eu/eli/reg_del/2022/931/oj/eng , 2022).

4. Commission Implementing Regulation (EU) 2021/808 of 22 March 2021 on the performance of analytical methods for residues of pharmacologically active substances used in food-producing animals and on the interpretation of results as well as on the methods to be used for sampling and repealing Decisions 2002/657/EC and 98/179/EC (Text with EEA relevance). p. 84–109 (OJ L 180, 21/05/2021, 2021).

5. European Reference Laboratories (EURL). EURL Guidance on Minimum Method Performance Requirements (MMPRs) for specific pharmacologically active substances in specific animal matrices. (2022).

6. Commission Regulation (EU) 2023/915 of 25 April 2023 on maximum levels for certain contaminants in food and repealing Regulation (EC) No 1881/2006 (Text with EEA relevance). p. 103–157 (OJ L 119, 05/05/2023, , 2023).

7. Nøstbakken, O.J., Moxness Reksten, A., Hannisdal, R., Dahl, L. & Duinker, A. Sampling of Atlantic salmon using the Norwegian Quality cut (NQC) vs. Whole fillet; differences in contaminant and nutrient contents. Food Chem 418, 136056 (2023).

8. NS-9401 (1994). Atlantic salmon - Reference sampling for quality measurements. Norges standardiseringsforbund. Oslo. (1994).

9. Commission Regulation (EU) No 37/2010 of 22 December 2009 on pharmacologically active substances and their classification regarding maximum residue limits in foodstuffs of animal origin (Text with EEA relevance). p. 1–72 (OJ L 15, 20.1.2010, 2009).

10. EFSA. Review of the existing maximum residue levels for cypermethrins according to Article 12 of Regulation (EC) No 396/2005. EFSA Journal 21, e07800 (2023).

11. EFSA. Review of the existing maximum residue levels for deltamethrin according to Article 12 of Regulation (EC) No 396/2005. EFSA Journal 13, 4309 (2015).

12. Van den Berg, M. et al. The 2005 World Health Organization reevaluation of human and Mammalian toxic equivalency factors for dioxins and dioxin-like compounds. Toxicological sciences: an official journal of the Society of Toxicology 93, 223-241 (2006).

13. DeVito, M. et al. The 2022 World Health Organization reevaluation of human and mammalian toxic equivalency factors for polychlorinated dioxins, dibenzofurans and biphenyls. Regulatory Toxicology and Pharmacology 146, 105525 (2024).

14. Commission Regulation (EU) 2025/1891 of 17 September 2025 amending Regulation (EU) 2023/915 as regards maximum levels of inorganic arsenic in fish and other seafood. ( https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=OJ:L_202501891 , 2025).

15. Commission Implementing Regulation (EU) 2020/1399 of 5 October 2020 concerning the authorisation of butylated hydroxyanisole as a feed additive for all animal species except cats (Text with EEA relevance) ( https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:32020R1399&from=EN , 2020).

16. Regulation (EU) 2018/848 of the European Parliament and of the Council of 30 May 2018 on organic production and labelling of organic products and repealing Council Regulation (EC) No 834/2007. ( https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:32018R0848 , 2018).

17. Commission Implementing Regulation (EU) 2021/1165 of 15 July 2021 authorising certain products and substances for use in organic production and establishing their lists (Text with EEA relevance). ( https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX%3A02021R1165-20260101 , 2021).

18. Commission Implementing Regulation (EU) 2022/1646 of 23 September 2022 on uniform practical arrangements for the performance of official controls as regards the use of pharmacologically active substances authorised as veterinary medicinal products or as feed additives and of prohibited or unauthorised pharmacologically active substances and residues thereof, on specific content of multi-annual national control plans and specific arrangements for their preparation (Text with EEA relevance). ( https://eur-lex.europa.eu/eli/reg_impl/2022/1646/oj/eng , 2022).

19. Donald, C.E. et al. Pesticide residues in aquaculture salmon filet and feed: Quantitative and qualitative screening profiles of legacy and current-use pesticides using GC-EI-MS/MS and LC-ESI-IMS-QToF. Journal of Chromatography B 1269, 124864 (2026).

20. EU Pesticides Database - European Commission. https://ec.europa.eu/food/plant/pesticides/eu-pesticides-database/start/screen/mrls

21. SANTE, E.D. Analytical Quality Control and Method Validation Procedures for Pesticide Residues Analysis in Food and Feed. SANTE 11312/2021 V2. (2024).

22. Commission Regulation (EC) No 149/2008 of 29 January 2008 amending Regulation (EC) No 396/2005 of the European Parliament and of the Council by establishing Annexes II, III and IV setting maximum residue levels for products covered by Annex I thereto (Text with EEA relevance). ( https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX%3A02008R0149-20080901 , 2008).

23. Stockholm Convention on Persistent Organic Pollutants (POPs): The new POPs under the Stockholm Convention. ( https://chm.pops.int/TheConvention/ThePOPs/TheNewPOPs/tabid/2511/Default.aspx , 2026).

24. Persistent organic pollutants – medium-chain chlorinated paraffins. (European Commission, https://ec.europa.eu/info/law/better-regulation/have-your-say/initiatives/14835-Persistent-organic-pollutants-medium-chain-chlorinated-paraffins_en , 2026).

25. Commission Regulation (EU) No 310/2011 of 28 March 2011 amending Annexes II and III to Regulation (EC) No 396/2005 of the European Parliament and of the Council as regards maximum residue levels for aldicarb, bromopropylate, chlorfenvinphos, endosulfan, EPTC, ethion, fenthion, fomesafen, methabenzthiazuron, methidathion, simazine, tetradifon and triforine in or on certain products (Text with EEA relevance). ( https://eur-lex.europa.eu/legal-content/EN/TXT/HTML/?uri=CELEX:32011R0310 , 2011).

26. Commission Regulation (EC) No 839/2008 of 31 July 2008 amending Regulation (EC) No 396/2005 of the European Parliament and of the Council as regards Annexes II, III and IV on maximum residue levels of pesticides in or on certain products (Text with EEA relevance). ( https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX%3A02008R0839-20080831 , 2008).

27. Commission Regulation (EU) 2015/868 of 26 May 2015 amending Annexes II, III and V to Regulation (EC) No 396/2005 of the European Parliament and of the Council as regards maximum residue levels for 2,4,5-T, barban, binapacryl, bromophos-ethyl, camphechlor (toxaphene), chlorbufam, chloroxuron, chlozolinate, DNOC, di-allate, dinoseb, dinoterb, dioxathion, ethylene oxide, fentin acetate, fentin hydroxide, flucycloxuron, flucythrinate, formothion, mecarbam, methacrifos, monolinuron, phenothrin, propham, pyrazophos, quinalphos, resmethrin, tecnazene and vinclozolin in or on certain products (Text with EEA relevance). ( https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX%3A02015R0868-20150610 , 2015).