Chemical Contaminants in Wild Caught Fish and Crustaceans – Northern Ireland.

This report is part of the 2022-23 wild caught fish survey for the UK and Northern Ireland. For more information on the contaminants monitoring programme for wild caught fish, crustaceans and cephalopods in England and Wales, you can see the corresponding report here.

1. Executive Summary

Sixty-two samples of wild caught fish and crustaceans were collected between April 2022 – March 2023 from the two main fish markets in Northern Ireland and on occasion fish processing establishments and analysed for the contaminants: mercury, lead and cadmium (heavy metals). A sub-set of the 62 samples (n = 15) were tested for dioxins and PCBs:

• 1,2,3,4,6,7,8-HeptaCDD

• 1,2,3,4,6,7,8-HeptaCDF

• 1,2,3,4,7,8,9-HeptaCDF

• 1,2,3,4,7,8-HexaCDD

• 1,2,3,4,7,8-HexaCDF

• 1,2,3,6,7,8-HexaCDD

• 1,2,3,6,7,8-HexaCDF

• 1,2,3,7,8,9-HexaCDD

• 1,2,3,7,8,9-HexaCDF

• 1,2,3,7,8-PentaCDD

• 1,2,3,7,8-PentaCDF

• 2,3,4,6,7,8-HexaCDF

• 2,3,4,7,8-PentaCDF

• 2,3,7,8-TetraCDD

• 2,3,7,8-TetraCDF

• OctaCDD

• OctaCDF

and PCBs (dioxin-like and non-dioxin-like PCBs included for analysis)

• PCB 28 (2,4,4′-Trichlorobiphenyl) *

• PCB 52 (2,2′,5,5′-Tetrachlorobiphenyl) *

• PCB 77 (3,3′,4,4′-Tetrachlorobiphenyl, 3,3′,4,4′-PCB)

• PCB 81 (3,4,4’,5-Tetrachlorobiphenyl)

• PCB 101 (2,2′,4,5,5′-Pentachlorobiphenyl) *

• PCB 105 (2,3,3′,4,4′-Pentachlorobiphenyl)

• PCB 114 (2,3,4,4’,5-Pentachlorobiphenyl)

• PCB 118

• PCB 123

• PCB 126

• PCB 138 (2,2′,3,4,4′,5′-Hexachlorobiphenyl) *

• PCB 153 (2,2′,4,4′,5,5′-Hexachlorobiphenyl) *

• PCB 156 (2,3,3′,4,4′,5-Hexachlorobiphenyl)

• PCB 157

• PCB 167

• PCB 169

• PCB 180 (2,2′,3,4,4′,5,5′-Heptachlorobiphenyl) *

• PCB 189

* non-dioxin-like PCBs.

Taking into account the measurement uncertainty, mercury was detected above the maximum regulatory level of 0.5 mg/kg in one of the Dublin Bay prawn samples at a concentration of:

• 0.68 mg/kg (± 0.14 mg/kg – measurement uncertainty)

Concentrations of lead and cadmium were less than the maximum EU regulatory limits for all samples tested.

Concentrations of dioxins and PCBs were below the EU regulatory limits for these compounds.

2. Introduction

2.1. Background to the study

Eurofins Food Testing Ireland Ltd (Public Analysts) was contracted by the Food Standards Agency (FSA) in Northern Ireland to assess the levels of various chemical contaminants (heavy metals, Dioxins and Polychlorinated Biphenyls (PCBs) in a number of species of wild caught fish and crustaceans landed in Northern Ireland between April 2022 and March 2023.

2.2. Aims and Objectives of the Study

The official control surveillance programme is undertaken to comply with Article 70 of Commission Implementing Regulation (EU) 2019/627 (EU, 2019) which requires a monitoring programme to be established for wild caught fishery products to control compliance with EU legislation on contaminants. Regulation (EC) No. 1881/2006, as amended (EU, 2023), sets down the maximum levels for certain contaminants in food, including fishery products.

The data has the potential to provide support to certifying officers in their attestation of the compliance of wild caught fishery products landed in Northern Ireland with contaminants legislation when signing Export Health Certificates.

The aim of the work was to determine concentrations of defined chemical contaminants in wild caught fishery products to assess whether the levels were within the limits prescribed in Regulation (EC) No. 1881/2006, as amended (EU, 2023), and were safe for placing on the market.

3. Methodology

3.1. Samples

Sixty-two samples of wild caught fish and crustaceans were collected between April 2022 – March 2023 from the two main fish markets in Northern Ireland and on occasion fish processing establishments (Annex A). Sample collection was undertaken by authorised officers from Newry, Mourne and Down District Council. To plan the purchase and collection of samples, FSA in NI shared a list of required products with authorised officers from Newry Mourne and Down District Council to give, as far as possible, a representative view of the types of products affected by chemical contaminants in NI.

The number of samples of each species collected for analyses were determined based on the quantity of that species landed in NI. The species sampled included:

• nephrops (Dublin Bay Prawn)

• horse mackerel

• mackerel

• haddock

• crab (Brown crab)

• herring

• blue whiting

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. For crustacea, only the white meat was taken to represent the sample. The selected tissue was homogenised in a blender. The aliquots for either metals or dioxins/PCBs analyses were immediately weighed out and the remaining material was stored in a freezer.

3.3. Metals analysis

Samples were analysed for cadmium, mercury and lead using an in-house (Eurofins WEJ Contaminants GmbH) method based on EN ISO 15763: Determination of trace elements - determination of cadmium, mercury and lead in foodstuffs by Inductively coupled plasma mass spectrometry (ICP-MS) after pressure digestion.

Aliquots of homogenised test sample material were digested in an acid solution using a high-pressure microwave system. The solution was diluted as required before analysis. Quantification of the four elements was by ICP-MS.

The analysis is accredited to ISO 17025, with the inclusion of certified and in-house reference materials and method blanks which were evaluated prior to the reporting of sample data and were used to determine the limits of quantification.

3.4. Dioxin and PCB analysis

Samples were prepared for analysis using a cold extraction method and analysed for dioxins and PCBs using methods by Eurofins Lab Zeeuws-Vlaanderen outlined in Commission Regulation (EU) 2017/644 (EU, 2017). The following analytes were determined:

Dioxins:

• 1,2,3,4,6,7,8-HeptaCDD

• 1,2,3,4,6,7,8-HeptaCDF

• 1,2,3,4,7,8,9-HeptaCDF

• 1,2,3,4,7,8-HexaCDD

• 1,2,3,4,7,8-HexaCDF

• 1,2,3,6,7,8-HexaCDD

• 1,2,3,6,7,8-HexaCDF

• 1,2,3,7,8,9-HexaCDD

• 1,2,3,7,8,9-HexaCDF

• 1,2,3,7,8-PentaCDD

• 1,2,3,7,8-PentaCDF

• 2,3,4,6,7,8-HexaCDF

• 2,3,4,7,8-PentaCDF

• 2,3,7,8-TetraCDD

• 2,3,7,8-TetraCDF

• OctaCDD

• OctaCDF

Dioxin-like PCBs:

• PCB 77 (3,3′,4,4′-Tetrachlorobiphenyl, 3,3′,4,4′-PCB)

• PCB 81 (3,4,4’,5-Tetrachlorobiphenyl)

• PCB 105 (2,3,3′,4,4′-Pentachlorobiphenyl)

• PCB 114 (2,3,4,4’,5-Pentachlorobiphenyl)

• PCB 118

• PCB 123

• PCB 126

• PCB 156 (2,3,3′,4,4′,5-Hexachlorobiphenyl)

• PCB 157

• PCB 167

• PCB 169

• PCB 189

Non-dioxin-like PCBs:

• PCB 28 (2,4,4′-Trichlorobiphenyl)

• PCB 52 (2,2′,5,5′-Tetrachlorobiphenyl)

• PCB 101 (2,2′,4,5,5′-Pentachlorobiphenyl)

• PCB 138 (2,2′,3,4,4′,5′-Hexachlorobiphenyl)

• PCB 153 (2,2′,4,4′,5,5′-Hexachlorobiphenyl)

• PCB 180 (2,2′,3,4,4′,5,5′-Heptachlorobiphenyl)

The value of each congener was multiplied by its World Health Organisation-Toxicity Equivalent Factor (WHO-TEFs). The product was presented as the Toxic Equivalency (TEQ).

• Lower-bound: the concept which requires using zero for the contribution of each congener <Limit of Quantification (LOQ).

• Medium-bound: the concept which requires using half of the limit of quantification calculating the contribution of each congener < LOQ.

• Upper-bound: the concept which requires using the limit of quantification for the contribution of each congener < LOQ.

The analysis is accredited to ISO 17025. Each sample is analysed with the addition of certified standards. The recovery of the standards is checked in each sample against the EU regulation (EU) 2017/644 (EU, 2017). The LOQ is dependent on the LOD, sample weight and sample matrix.

4. Results and Discussion

The concentrations of the contaminants measured in the sixty-two samples were determined by Eurofins and were compared to limits prescribed in Regulation (EC) No. 1881/2006, as amended (EU, 2023).

4.1. Metals analyses

Concentrations of mercury, cadmium and lead are given in Table 1 in Annex B.

Taking into account the measurement uncertainty, mercury was detected above the maximum regulatory level of 0.5 mg/kg in one of the Dublin Bay prawn samples at a concentration of:

• 0.68 mg/kg (± 0.14 mg/kg – measurement uncertainty)

4.2. Dioxin and PCB analysis

Concentrations of dioxins and PCBs were below the regulatory limits for these compounds and are provided in Table 2 in Annex B.

Acknowledgments

Fera Science Ltd.

• Title: Chemical contaminants in wild caught fish and crustaceans – Northern Ireland

• Customer: Food Standards Agency – Northern Ireland

• FSA NI Project Officer: Will Wiltshire

• Report Number: Report FR/002638-57

• Fera Project: Number FR/002638-57

• Compiled by: Emma Bradley

• Authorised by: Susan MacDonald

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