This report is part of the 2022-23 wild caught fish, crustaceans and cephalopods survey for Great Britain and Northern Ireland. For more information on Chemical contaminants in wild caught fish and crustaceans in Northern Ireland you can see the corresponding report here.
1. Executive Summary
One hundred and fifty two 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 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), perfluoro-n-octanoic acid (PFOA). A sub-set of these samples (n = 76) were analysed for inorganic arsenic and another sub-set (n = 51) 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, 1,2,3,4,6,7,8-HpCDD, 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, 1,2,3,6,7,8-HxCDF, 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, PCB 189).
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Cadmium was detected above the maximum level of 0.1 mg/kg in one of the mackerel samples at a concentration of 0.16 mg/kg.
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Mercury was detected above the maximum level of 0.5 mg/kg in four of the sea bass samples at concentrations of 0.74, 0.69, 0.66 and 0.87 mg/kg.
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Concentrations of dioxins and PCBs were below the GB and European Union (EU) limits for these compounds.
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Of the regulated PFAS analytes (linear and branched PFOS, PFOA, PFNA and linear and branched PFHxS) the following were detected above the EU limits (Comission Reguation 2022/2388) note there are currently no restrictions for these substances in fish in GB legislation):
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Three cod samples (1.0, 1.5 and 1.0 µg/kg) exceeded the EU limit (0.5 µg/kg) for PFNA
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Two cod samples (0.52 and 0.47 µg/kg) exceeded the EU limit (0.2 µg/kg) for PFHxS
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Two crab samples (1.8 and 1.1 µg/kg) exceeded the EU limit (0.7 µg/kg) for PFOA
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One of the cod samples (2.6 µg/kg) exceeded the restriction for the sum of PFOS, PFOA, PFNA and PFHxS when the measurement uncertainty was taken into account (2.0 µg/kg for fish). There are currently no restrictions in the concentrations of inorganic arsenic in fish and shellfish.
2. Introduction
2.1. Background to the study
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 May 2022 and January 2023. 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 legislation (Assimilated Regulation 181/2006).
The data has the potential to provide support to certifying officers in their attestation of the compliance of wild caught fishery products landed in England and Wales with contaminants legislation when signing Export Health Certificates for export to the European Union.
2.2. Aims and Objectives of the Study
To determine concentrations of defined chemical contaminants in wild caught fishery products providing occurrence data to the FSA to support exposure calculations for the UK population and associated risk assessment(s) as well as providing data to support exports.
3. Methodology
3.1. 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 Food Standards Agency to give, as far as possible, a representative sample set. Samples were allocated to species by considering 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 four regions (South East England, South West England, North East England and Wales). The species to be sampled included: sardines, cuttlefish, monks & anglers, crab, hake, sole, plaice, skates & rays, gurnard, dogfish, lemon sole, sprats, mackerel, bass, herring, cod, haddock, lobsters and squid. 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 Annex A. A full list of the sample details for the samples collected is given in Annex B. On receipt at the laboratory, each sample was assigned a unique laboratory reference number and the sample details were logged into a database.
3.2. 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, 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.
3.3. 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 UKAS accredited (ISO 17025).
3.4. 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 (Assimilated Regulation 2017/644).
3.5. PFAS analysis
Samples were analysed for the following:
Aliquots of homogenised test samples were spiked with isotope standards (internal standards) and extracted using 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 HPLC-MS/MS and quantified against calibration standards of known concentrations of the PFAS. The methodology is accredited (flexible scope) to ISO 17025.
3.6. 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.
4. Results and Discussion
One hundred and fifty two 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 and PFAS. A sub-set of these samples (n = 76) were analysed for inorganic arsenic and another sub-set (n = 51) were analysed for dioxins and PCBs. Concentrations of the contaminants in the wild caught fish samples were compared to GB legislation where available.
4.1. Metals analyses
Cadmium was detected at a concentration of 0.16 mg/kg (0.13 mg/kg minus measurement uncertainty) in one of the mackerel samples. The maximum level for cadmium in mackerel is 0.1 mg/kg (Assimilated Regulation 1881/2006).
Mercury was detected above the maximum level of 0.5 mg/kg in four of the sea bass samples at concentrations of:
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0.74 mg/kg (0.60 mg/kg minus the measurement uncertainty of 19%)
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0.69 mg/kg (0.56 mg/kg minus the measurement uncertainty of 19%)
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0.66 mg/kg (0.53 mg/kg minus the measurement uncertainty of 19%)
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0.87 mg/kg (0.70 mg/kg minus the measurement uncertainty of 19%)
The GB limits for these elements are given in Table 1 in Annex C.
4.2. Dioxin and PCB analysis
Concentrations of dioxins and PCBs were below the GB and EU limits for these compounds (Assimilated Regulation 1881/2006) given in Table 2 in Annex C.
4.3. PFAS analysis
Of the EU regulated PFAS analytes (linear and branched PFOS, PFOA, PFNA and linear and branched PFHxS) the following were detected above the EU limits (Comission Reguation 2022/2388) note there are currently no maximum limits in place for these substances in fish in GB legislation):
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Three cod samples exceeded the EU limit (0.5 µg/kg) for PFNA when taking into account the measurement of uncertainty
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1.0 µg/kg (0.76 minus the measurement uncertainty of 24%)
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1.5 µg/kg (1.1 minus the measurement uncertainty of 24%)
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1.0 µg/kg (0.76 minus the measurement uncertainty of 24%) Two cod samples exceeded the EU limit (0.2 µg/kg) for total PFHxS when taking into account the measurement of uncertainty
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0.52 µg/kg (0.36 minus the measurement uncertainty of 30%)
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0.47 µg/kg (0.33 minus the measurement uncertainty of 30%)
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Two crab samples exceeded the EU limit (0.7 µg/kg) for PFOA when taking into account the measurement of uncertainty
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1.8 µg/kg (1.5 minus the measurement uncertainty of 18%)
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1.1 µg/kg (0.90 minus the measurement uncertainty of 18%)
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One of the cod samples exceeded the restriction for the sum of PFOS, PFOA, PFNA and PFHxS (2.0 µg/kg for fish). when taking into account the measurement of uncertainty 2.6 µg/kg (2.2 minus the measurement uncertainty of 15%)
The EU limits for these substances are given in Table 3 in Annex C.
4.4. iAs analysis
There are currently no maximum levels established in GB for inorganic arsenic in fish and shellfish. Within the EU the European Commission was considering maximum levels for inorganic arsenic (EU, 2021) as described within Table 4 in Annex C. However, these levels have not been adopted in the EU pending consideration of additional data on the occurrence of inorganic arsenic in fish and fishery products. In all cases the concentrations of inorganic arsenic measured in the wild caught fish samples were below the levels considered by the EU when taking into account the measurement of uncertainty (±26%) and given within in Table 4 of Annex C.
5. Acknowledgements
Thanks to HallMark Veterinary & Compliance Services for purchasing the samples. The FSA would like to thank the following staff at Fera who contributed to this project: Anthony Oxley, Ben Watkin, Danny Chan, Frankie Smith, Malcolm Baxter, Melanie Holland, Mike Walls, Mollie Nero, Sara Stead, Sean Panton, Victoria Bailey-Horne.
