Survey of Chemical Contaminants in Wild Caught Fish, Crustaceans and Cephalopods England and Wales 2025-26

The Food Standards Agency’s (FSA’s) 2025–2026 England and Wales survey of contaminants in wild-caught fish, crustaceans and cephalopods is a standalone ad-hoc survey and was undertaken as a small, risk-based data gathering and horizon-scanning exercise. Its primary purpose was to assess levels of regulated contaminants, including heavy metals, dioxins and PCBs, and to gather evidence on emerging contaminants such as per- or poly- fluoroalkyl substances (PFAS) and inorganic arsenic, which have maximum levels set in the European Union (EU). The survey builds on the Food Standards Agency’s evidence base for assessing risks from both established and emerging contaminants and may help to inform future policy and risk management decisions. Sampling was informed by previous survey findings and other contaminant monitoring programmes such as that in Northern Ireland (NI).

While this work was not designed as a compliance monitoring programme, the data may support food businesses in meeting regulatory requirements, including those set out in Great Britain (GB) Assimilated Regulation 1881/2006.

FSA in NI conduct an annual wild caught fishery products official control monitoring programme testing for various contaminants. Monitoring of contaminants in wild caught fishery products is undertaken to satisfy official control requirements under Regulation (EU) 2017/625. Under Windsor Framework arrangements, EU law is applicable in Northern Ireland. The sampling is risk based, reviewed annually and included in the Northern Ireland Contaminant Control Plan submitted to the EU annually.

The 2024-2025 and the 2025-26 reports provide data on the levels of PFAS and heavy metals in wild caught fish, crustaceans and molluscs sampled by FSA in NI during these time periods.

Results from Northern Ireland monitoring in 2024/25 and 2025/26.

Executive Summary

One hundred and four samples of wild caught fish, crustaceans and cephalopods were purchased from fish markets across England and Wales and analysed for the contaminants: mercury, lead, cadmium, total arsenic, inorganic arsenic and per- and polyfluoroalkyl substances (PFAS): perfluoro-n-nonanoic acid (PFNA), linear and branched perfluorohexanesulfonic acid (PFHxS), linear and branched perfluorooctanesulfonic acid (PFOS), perfluoro-n-decanoic acid (PFDA), linear perfluoro-1-butanesulfonate (PFBS), perfluoro-n-dodecanoic acid (PFDoA), perfluoro-n-heptanoic acid (PFHpA), perfluoro-n-hexanoic acid (PFHxA), perfluoro-n-pentanoic acid (PFPeA), perfluoro-n-butanoic acid (PFBA) and perfluoro-n-octanoic acid (PFOA). A sub-set of these samples (n = 20) were analysed for polyaromatic hydrocarbons (PAHs) and another sub-set (n = 20) were analysed for dioxins (2,3,7,8-TCDD, 1,2,3,7,8-PeCDD, 1,2,3,4,7,8-HxCDD, 1,2,3,6,7,8-HxCDD, 1,2,3,7,8,9-HxCDD, 1,2,3,4,6,7,8­HpCDD, OCDD, 2,3,7,8-TCDF, 1,2,3,7,8-PeCDF, 2,3,4,7,8-PeCDF, 1,2,3,4,7,8-HxCDF, 1,2,3,6,7,8­HxCDF, 1,2,3,7,8,9-HxCDF, 2,3,4,6,7,8-HxCDF, 1,2,3,4,6,7,8-HpCDF, 1,2,3,4,7,8,9-HpCDF, OCDF) and PCBs (PCB 28, PCB 52, PCB 77, PCB 81, PCB 101, PCB 105, PCB 114, PCB 118, PCB 123, PCB 126, PCB 138, PCB 153, PCB 156, PCB 157, PCB 167, PCB 169, PCB 180 and PCB 189).

Key findings include:

• Mercury was detected above the maximum level of 0.5 mg/kg in one of the bass samples at a concentration of 0.72 mg/kg

• Concentrations of all other heavy metals in the samples tested were below the GB and EU maximum levels for each species

• Concentrations of inorganic arsenic were below the European Union (EU) maximum levels for each species. There are no maximum levels set for inorganic arsenic in GB.

• Concentrations of dioxins and PCBs were below the GB and EU maximum levels for these compounds

• Concentrations of PFAS analytes (linear and branched PFOS, PFOA, PFNA and linear and branched PFHxS) were below the EU maximum levels for these compounds. Note there are currently no restrictions for these substances in fish in GB legislation

• Concentrations of PAHs were low, the GB and EU maximum levels do not apply to these products

Introduction

Fera Science Ltd (Fera) was contracted by the Food Standards Agency (FSA) to assess the occurrence levels of various contaminants in a specified number of species of wild caught fish, crustaceans and cephalopods landed in England and Wales between June 2025 and January 2026.

The surveillance work primarily functions as a knowledge gathering initiative which forms part of the FSA’s evidence-base for risk management of both emerging and pre-established contaminants in wild caught fish, crustacean and cephalopod products.

Secondary to this, the dataset may supplement the responsibilities of food businesses to comply with the provisions set out in GB Assimilated Regulation 1881/2006.

Materials and Methods

Samples

Sample purchase and collection was subcontracted to HallMark Veterinary & Compliance Services. To plan the purchase and collection of samples, a list of required products was designed by the FSA to give, as far as possible, a representative sample set. Samples were allocated to species by considering popular seafood in the UK, the quantity of that species landed in each region as well as a split between species types (pelagic vs demersal, oily vs lean, predatory fish etc.); these were taken across five regions (Southeast England, Southwest England, Northeast England, Northwest England and Wales) between July 2025 and February 2026. The species to be sampled included: bass, sardines, cuttlefish, monks & anglers, crab, hake, sole, plaice, skates & rays, gurnard, dogfish, lemon sole, haddock, mackerel, bass, whiting, shrimps & prawns, sprats, lobster and nephrops. When samples of a certain species were not available, e.g. not currently being caught in UK waters, then in consultation with the FSA these samples were replaced with alternative species/sampling locations. The planned versus actual sample numbers for each species/location are provided in Appendix A. A full list of the sample details for the samples collected is given in Appendix B. On receipt at the laboratory each sample was assigned a unique laboratory reference number, and the sample details were logged into a database.

Sample Preparation

For fin fish, samples were filleted to collect edible muscle tissue and exclude skin, bones and organs except for sardines, which had the heads, tails and fins removed. For cephalopods, only the mantle meat was retained for analysis and for crustacea, only the white meat was taken to represent the sample.

The selected tissue was homogenised in a blender. Aliquots of the blended tissue were taken for each of the analyte suites: metals (including inorganic arsenic), PFAS, PAHs, and dioxins/PCBs if required. An extra portion was retained as a spare. The aliquots requiring dioxins/PCBs analysis were also freeze-dried and further homogenised in a blender. Aliquots were stored in a freezer until required for analysis except for the freeze-dried material used for dioxins/PCB analyses which was stored at room temperature.

Metals Analysis

Samples were analysed for total arsenic, cadmium, mercury and lead by following In-house Methods; FSG 461, FSG 457, FSG 463. Aliquots of homogenised test sample were digested in a mixture of concentrated nitric acid and hydrochloric acid using a high-pressure microwave system. Quantification was by inductively coupled plasma-mass spectrometry (ICP-MS) with collision cell. Quality checks included blanks, spikes and certified reference materials.

All data were corrected for reagent blank and spike recovery. The Reporting Limit was equal to, or exceeded, 10 x standard deviation of reagent blank values adjusted for dilution and sample weight. Reference material results were all satisfactory. Results are United Kingdom Accreditation Service (UKAS) accredited (International Organization for Standardization (ISO) 17025).

Dioxin and PCB Analysis

The following analytes were determined:

Dioxins - all 17, 2,3,7,8-Cl substituted PCDDs and PCDFs.

Dioxin-like PCBs - IUPAC numbers 77, 81, 105, 114, 118, 123, 126, 156, 157, 167, 169, and 189.

Non-Dioxin-like PCBs - IUPAC numbers 28, 52, 101, 138, 153, 180.

The method used for the preparation, extraction and analysis of samples has been reported previously (Fernandes et al. 2004; 2008) and forms part of the CEN method – EN16215:2012 for PCDD/F and PCB analysis. In brief, samples were fortified with ¹³C-labelled analogues of target compounds and exhaustively extracted using mixed organic solvents. Ortho substituted PCBs were separated from non-ortho substituted PCBs and PCDD/Fs by fractionation on activated carbon. The two fractions were further purified using adsorption chromatography on alumina. Analytical measurement was carried out using gas chromatography-high resolution mass spectrometry (GC-HRMS).

The analysis is accredited (UKAS) to ISO 17025, with the inclusion of an in-house reference material and method blanks which were evaluated prior to the reporting of sample data and were used to determine the limits of detection. Further quality assurance measures included the successful participation in available international inter-comparison exercises such as European Union Reference Laboratory (EURL) and Food Analysis Proficiency Assurance Scheme (FAPAS) run proficiency test (PT) exercises on dioxins, dioxin-like PCBs, ICES-6 PCBs. Additionally, quality control evaluation for the accompanying data follows the criteria specified for chlorinated dioxins and PCBs (REUL, 2017).

Per and Poly Fluorinated Alkyl Substances (PFAS)

Aliquots of homogenised test samples were spiked with isotope standards (internal standards) and extracted using alkalised methanol. The resulting solvent extracts were solvent exchanged into potassium hydroxide and passed through WAX SPE columns. WAX columns allow for the retention of both short and longer chain PFAS analytes due to the ionic exchange and reverse phase properties. Non-specific interferences were retained on the column whilst PFAS analytes were eluted using ammonia in methanol.

Samples were concentrated and reconstituted in 50:50 methanol: water and analysed by UPLC-MS/MS and quantified against calibration standards of known concentrations of the PFAS. The methodology is accredited under flexible scope with validated competence to ISO method 17025.6.5 Inorganic Arsenic Analysis

Analysis was carried out by HPLC-ICP-MS, based on CEN FprEN 16802 – Foodstuffs – Determination of elements and their chemical species – Determination of inorganic arsenic in foodstuffs of marine and plant origin by anion-exchange HPLC-ICP-MS. Aliquots of homogenised test samples were extracted with a mixture of nitric acid and hydrogen peroxide at 90°C. The inorganic arsenic was separated from other arsenic compounds by anion exchange HPLC, coupled to ICP-MS for the detection of arsenic. Quality checks included the analysis of blanks, spikes, and CRMs. The methodology was accredited under flexible scope with validated competence to ISO method 17025.

PAH Analysis

The following analytes were determined:

Naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, benzo­[c]­fluorene, pyrene, benzo­[g,h,i]­fluoranthene, benz­[a]­anthracene, benzo­[b]­naphtho­[2,1-d]­thiophene, cyclopenta­[c,d]­pyrene, chrysene, 5-methylchrysene, benzo­[b]­fluoranthene, benzo­[j]­fluoranthene, benzo­[k]­fluoranthene, benzo­[e]­pyrene, benzo­[a]­pyrene, indeno­[1,2,3-cd]­pyrene, dibenz­[a,h]­anthracene, benzo­[g,h,i]­perylene, anthanthrene, dibenzo­[a,l]­pyrene, dibenzo­[a,e]­pyrene, dibenzo­[a,i]­pyrene, dibenzo­[a,h]­pyrene and coronene.

The method used for the preparation, extraction and analysis of samples has been reported previously (Rose et al. 2007). In brief, samples were fortified with ¹³C-labelled analogues of target compounds and subjected to saponification followed by liquid-liquid extraction. Clean-up was by DMF/cyclohexane partition followed by elution through a silica gel column. Analytical measurement was carried out using gas chromatography mass spectrometry (GC-MS).

The analysis is accredited (UKAS) to ISO 17025, with the inclusion of an in-house reference material and method blanks which were evaluated prior to the reporting of sample data and were used to determine the limits of detection. Further quality assurance measures included the successful participation in available international inter-comparison exercises such as European Union Reference Laboratory (EURL) and Food Analysis Proficiency Assurance Scheme (FAPAS) run proficiency test (PT) exercises.

Results

One hundred and four samples of wild caught fish were purchased from fish markets across England and Wales and analysed for the contaminants: mercury, lead, cadmium, total arsenic, inorganic arsenic and PFAS. A sub-set of these samples (n = 20) were analysed for PAHs, and another sub-set (n = 20) were analysed for dioxins and PCBs. Concentrations of the contaminants in the wild caught fish samples were compared to GB and EU legislation where available.

Metals Analyses

Mercury (Hg) was detected above the maximum level of 0.5 mg/kg in one of the bass samples at a concentration of 0.72 mg/kg. The GB and EU maximum levels for these elements are given in Appendix C.

A risk assessment was undertaken which indicated that the tolerable weekly intake for methylmercury at this reported level was exceeded in all age groups, except for adults. For inorganic mercury, exceedance occurs only at the 97.5th percentile for toddlers. While these exceedances are undesirable, they are considered unlikely to pose a long-term health concern, as sustained consumption of fish at these concentrations by these groups is improbable.

Dioxin and PCB Analysis

Concentrations of dioxins and PCBs were below the GB and EU maximum levels for these compounds (REUL, 2006; REUL, 2015) given in Appendix C.

PFAS Analysis

Of the EU regulated PFAS analytes (linear and branched PFOS, PFOA, PFNA and linear and branched PFHxS) no residues were detected above the EU maximum levels (EU, 2022) note there are currently no maximum levels in place for these substances in fish in GB legislation):

The EU maximum levels for these substances are given in Appendix C.

Inorganic Arsenic Analysis

There are currently no maximum levels established in GB for inorganic arsenic in fish and shellfish. The EU has established maximum levels for inorganic arsenic in a range of foods under Commission Regulation (EU) 2023/915, amended by Commission Regulation (EU) 2025/1891, with limits set for fish and other seafood to help reduce consumer exposure to this genotoxic carcinogen. There were no exceedances of the EU maximum levels.

PAH Analysis

Concentrations of analysed levels of PAHs in the fishery products analysed are provided in Appendix C. Analysis of PAH levels were taken for interest and data gathering purposes, despite there being no MLs in GB or the EU for PAHs in these commodities.

Discussion

The non-compliant mercury result in Bass whilst undesirable, is unlikely to pose a long-term health concern, as sustained consumption of fish containing mercury at that level by the non-adult population is improbable.

With the exception of the single non-compliant Bass sample landed in Wales, which exceeded the GB maximum level for mercury, all of the remaining fish, crustaceans and cephalopods sampled in this survey were compliant with GB and EU contaminants maximum levels.

Acknowledgements

Thanks to HallMark Veterinary & Compliance Services for purchasing the samples. Thanks also to all the staff at Fera who contributed to this project.

Appendix

A. Sampling Plan

B. Sample Details

C. Results Table

Metals and inorganic Arsenic results

Dioxins and PCB results

EU Regulated PFAS results

Additional PFAS results

PAH results