Chemical Contaminants in Wild Caught Fish, Crustaceans and Molluscs – Northern Ireland 2025/26

Lay Summary

Chemical contaminants can enter aquatic environments from natural and human sources and may accumulate in fish, crustaceans and molluscs. Monitoring programmes are undertaken to assess the presence of these substances in seafood intended for human consumption and to provide data on contaminant levels in the food supply.

This report presents the findings of a survey of wild caught fish, crustaceans and molluscs landed in Northern Ireland between March 2025 and March 2026. Samples from a range of commercially harvested species were analysed for selected heavy metals and per- and polyfluoroalkyl substances (PFAS).

The study contributes to ongoing surveillance of chemical contaminants in seafood and provides information on contaminant concentrations in species landed in Northern Ireland. The data generated support the assessment of compliance with food safety requirements and contribute to the evidence base used to monitor contaminant trends over time.

Details of the monitoring programme, analytical methods and study findings are presented in the main body of this report.

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- and polyfluoroalkyl substances (PFAS) and inorganic arsenic, which have maximum levels set in the European Union. 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.

You can find the results from the England and Wales survey here.

Executive Summary

Eighty-two (82) samples of wild caught fish, crustaceans and molluscs were collected between March 2025 and March 2026 by authorised sampling officers in Northern Ireland. The samples were collected from the main landing areas and fish processing establishments. Forty-six (46) samples were analysed for the contaminants mercury, lead and cadmium (heavy metals). Thirty-six (36) samples were tested for per- and polyfluoroalkyl substances (PFAS).

Commission Regulation (EU) 2023/915 of 25 April 2023 on maximum levels for certain contaminants in food sets the regulatory limits for these contaminants in the matrices tested.

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

Concentrations of PFAS were below the EU regulatory limits for these compounds for all samples tested.

Introduction

Background to the study

The public analyst business unit of Eurofins Food Testing Ireland Limited was engaged by the Food Standards Agency (FSA) in Northern Ireland to assess the levels of various heavy metals and per- and polyfluoroalkyl substances (PFAS) chemical contaminants in a number of species of wild caught fish, crustaceans and molluscs landed in Northern Ireland between March 2025 and March 2026.

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. This is an ongoing annual programme.

Regulation (EC) No. 2023/915 (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 purpose of the work was to determine concentrations of defined chemical contaminants in wild caught fishery products and to assess whether the levels were within the prescribed limits (EU, 2023), and therefore that the products were safe for placing on the market in these respects.

Materials and Methods

Samples

Eighty-two (82) samples of wild caught fish, crustaceans and molluscs were collected between March 2025 and March 2026 by authorised sampling officers in Northern Ireland. Forty-six (46) samples were analysed for the contaminants mercury, lead and cadmium (heavy metals). Thirty-six (36) samples were tested for per- and polyfluoroalkyl substances (PFAS).

The type and number of samples of each species collected for analyses were determined based on the quantity of that species landed in Northern Ireland and any previous exceedances.

The species sampled were:

• Bream
• Brown crab
• Dublin Bay Prawns
• Eel
• Herring
• King Scallops
• Mackerel
• Mussels
• Oysters

On receipt at the laboratory (Eurofins Food Testing Ireland Limited, Dublin, Ireland) each sample was assigned a unique laboratory reference number, and the sample details were logged into a database.

Sample Preparation

For fish (including bream, eel, herring and mackerel), the maximum levels of heavy metals and PFAS apply to the muscle meat of the fish unless the fish are intended to be eaten whole, in which case the maximum levels apply to the whole fish.

For crustaceans other than crabs (including Dublin Bay prawns), the maximum levels of heavy metals and PFAS apply to muscle meat from the appendages and the abdomen, which means that the cephalothorax of crustaceans is excluded.

In case of crabs (infraorder Brachyura), the maximum levels of heavy metals and PFAS apply to the muscle meat from appendages only. (For the crab samples analysed for PFAS it was noted that an omission in laboratory records meant that it could not be confirmed whether both the appendages and abdomen or only the appendages were taken).

For king scallops (Pecten maximus), a bivalve mollusc, the maximum levels of heavy metals and PFAS apply to the adductor muscle and gonad only.

For other bivalve molluscs (including mussels and oysters), the maximum levels of heavy metals and PFAS apply to the edible parts.

The relevant tissue for each sample was homogenised in a blender. The aliquots for each analysis were immediately weighed out, and the remaining material was stored in a freezer.

Metal Analysis

The samples tested for heavy metals (cadmium, mercury and lead) were analysed by Eurofins WEJ Contaminants GmbH in Hamburg, Germany, in line with the requirements of Commission Regulation (EC) No 333/2007 (EU, 2007).

The testing was done using an in-house 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 method is accredited to ISO 17025 by DAkkS, the German Accreditation Service, and the laboratory is a designated Official Laboratory by the German State of Hamburg.

Per- and polyfluoroalkyl substances analysis

The samples tested for PFAS were analysed at Eurofins GfA Lab Service GmbH in Hamburg, Germany, in line with the requirements of Commission Implementing Regulation (EU) 2022/1428 (EU, 2022a).

The testing was done using an in-house method, reference GLS OC 400 2025-12, using LC-MS/MS. The method is accredited to ISO 17025 by DAkkS, the German Accreditation Service, and the laboratory is a designated Official Laboratory by the German State of Hamburg.

The following analytes were determined:

Results

The concentrations of the contaminants measured in all eighty-two samples were determined and compared to limits prescribed in Commission Regulation (EU) 2023/915 (EU, 2023).

Certificates of Analysis made under the provisions of the Food Safety (Sampling and Qualifications) Regulations (NI) 2013 were issued to the appropriate sampling officers and the Food Standards Agency. Results were also uploaded electronically to the UKFSS food database operated by the Food Standards Agency.

Metal analysis

Concentrations of mercury, cadmium and lead were below the regulatory limits for these compounds. Details are provided in Table 1 in Appendix B.

Per- and polyfluoroalkyl substances analysis

Limits for certain PFAS are prescribed in Commission Regulation (EU) 2023/915 (EU, 2023):

• Perfluorooctane sulfonic acid (PFOS)
• Perfluorooctanoic acid (PFOA)
• Perfluorononanoic acid (PFNA)
• Perfluorhexanesulfonic acid (PFHxS)
• Sum of PFOS, PFOA, PFNA and PFHxS

Concentrations of these PFAS were below the regulatory limits for these compounds. Details are provided in Table 2 in Appendix B.

Discussion

This official control surveillance programme examined the presence of selected heavy metals and per- and polyfluoroalkyl substances (PFAS) in fish, crustacean and mollusc samples and assessed their compliance with the requirements of Commission Regulation (EU) 2023/915.

The results indicate that all eighty-two samples analysed complied with the applicable maximum levels for mercury, cadmium, lead and regulated PFAS established under Commission Regulation (EU) 2023/915.

Metals

Mercury, cadmium and lead were not detected at concentrations exceeding the maximum levels prescribed in Commission Regulation (EU) 2023/915.

Per- and polyfluoroalkyl Substances (PFAS)

The concentrations of PFOS, PFOA, PFNA and PFHxS, as well as the sum of these compounds, were below the relevant regulatory limits in all samples analysed.

In addition, Commission Recommendation (EU) 2022/1431 on the monitoring of perfluoroalkyl substances in food requests EU Member States to test for the presence of compounds which are similar to PFOS, PFOA, PFNA and PFHxS, in order to support a dietary exposure assessment and assess the need to regulate these substances in specific commodities (EU, 2022b).

The concentrations of these additional PFAS are detailed in Table 3 in Appendix B.

There was one brown crab sample which exceeded the maximum level for PFOA, although not for total PFAS. For the crab samples analysed for PFAS it was noted that an omission in laboratory records meant that it could not be confirmed whether both the appendages and abdomen or only the appendages were taken for testing. On this basis it was not appropriate to assess these results against the maximum limits prescribed in Commission Regulation (EU) 2023/915 (EU, 2023) which apply to the muscle meat from appendages only. The laboratory has implemented corrective and preventive actions to prevent recurrence and to ensure that samples are analysed in accordance with the requirements of the relevant regulation.

Acknowledgements

Eurofins Food Testing Ireland Limited.
Mid Ulster District Council
Newry, Mourne & Down District Council