Contaminants in seafood

The extent to which Good Environmental Status has been achieved

Good Environmental Status (GES) has been achieved for Descriptor 9 for shellfish. Our assessment for contaminants in seafood (D9) only considered shellfish data as finfish data were not available. Therefore, no GES assessment for finfish could be carried out.  

Recent surveys (2016 – 2020) of contaminant concentrations in shellfish, from fishing grounds, show that all samples observed for metals (cadmium, lead and mercury), Polycyclic aromatic hydrocarbons (PAHs), and dioxins and dioxin-like polychlorinated biphenyls (PCBs) were compliant with regulations.

Progress since previous assessments

This assessment confirms the results of previous assessments for contaminants in shellfish (2012 and 2019), which indicated that contaminant levels in seafood on the UK market do not exceed maximum levels set out in the legislations mentioned in the following management section. However, it must be considered that no fish samples were included in this most recent assessment, and that in 2019 some fish samples were above set assessment criteria set for human health. 

How progress has been assessed

Assessment overview

To determine whether GES has been achieved for D9, one indicator (Contaminants in Seafood) assessment was completed. This assessment looked at three chemical groups that measured the concentrations of heavy metals, polycyclic aromatic hydrocarbons (PAHs), and dioxins and dioxin-like polychlorinated biphenyls (PCBs) in shellfish from across the Greater North Sea and Celtic Seas.  

The concentrations of these contaminants were then assessed against the relevant human health assessment criteria as set in the Annex of Retained Regulation (European Commission) No 1881/2006. To achieve GES, concentrations of heavy metals, PAHs and PCBs in shellfish tested must be below the human health criteria limits set in such regulation.   

296 shellfish samples were analysed in total from across 99 sample locations in commercial shellfishery areas. Most sample locations were in Scottish and Northern Irish waters.     

The table below sets out the criteria, it’s associated target and the relevant indicator elements that were used to assess progress toward meeting GES for contaminant concentrations in seafood.  For each indicator element we set out whether it has been met, not met or partially met, across both UK sub regions. 

Table 1. Summary overview of the status for Contaminant Concentrations in Seafood (D9)  

Criteria 1 

Contaminant concentrations in seafood 

2019 Target 

For contaminants where regulatory levels have been set, and a risk assessment has indicated that concentrations in some commonly eaten seafood may be of concern to the public if they exceed current precautionary advice to restrict consumption of certain higher risk species, there should be a high rate of compliance based on relevant surveys and including samples originating from commercial fishing grounds in the Greater North Sea and the Celtic Seas. 

Indicator* 

Contaminant concentrations in seafood 

Indicator element 

Heavy metals (Cadmium, Lead, Mercury). 

Greater North Sea 

met for shellfish  

Celtic Seas 

met for shellfish 

Indicator element 

Polycyclic aromatic hydrocarbons (PAHs) 

Greater North Sea 

met for shellfish 

Celtic Seas 

met for shellfish 

Indicator element 

Dioxins and dioxin-like Polychlorinated biphenyls (PCBs) 

Greater North Sea 

met for shellfish 

Celtic Seas 

met for shellfish 

*This indicator is formed of three sub-elements that are assessed against the relevant criteria in the European Commission Reg 1881/2006. 

All results show that, for the shellfish tested, there was a high level of compliance with regulatory thresholds set in legislation. 

Heavy metals 

Of the shellfish samples for metals, 97 samples for lead, 125 samples for cadmium and 59 samples tested for mercury, there were no non-compliant samples. 

Polycyclic aromatic hydrocarbons (PAHs) 

Of the 14 total shellfish samples tested, there were no non-compliant samples for either benzo(a)pyrene or the sum of four PAHs (benzo(a)anthracene, chrysene, benzo(b)fluoranthene and benzo(a)pyrene). 

Dioxins and dioxin-like PCBs 

Only one shellfish sample was tested for dioxins and dioxin-like PCBs and this was compliant. 

Table 2. Summary results of the shellfish sampled between 2016 and 2020 for compliance with the relevant human health standard (see details in the contaminant concentrations in seafood indicator assessment). 

Contaminant 

Number samples 

Mean 

95th Percentile 

Maximum 

Limit 

Units 

Metals 

 

 

 

 

 

 

Lead 

97 

0.13 

0.39 

1.18 

1.5 

mg/kg 

Cadmium 

125 

0.1 

0.22 

0.74 

1 

mg/kg 

Mercury 

59 

0.01 

0.03 

0.04 

0.5 

mg/kg 

PAHs 

 

Benzo(a)anthracene 

14 

1.28 

- 

3.98 

* 

μg/kg 

Chrysene 

14 

1.36 

- 

4.04 

* 

μg/kg 

Benzo(b)fluoranthene 

14 

2.59 

- 

8.04 

* 

μg/kg 

Benzo(a)pyrene 

14 

0.99 

- 

3.44 

5 

μg/kg 

Sum of PAH4* 

14 

6.2 

- 

19.5 

30 

μg/kg 

Dioxins and dioxin-like PCBs 

 

 

 

 

 

 

Sum of dioxins 

1 

0.5 

- 

- 

3.5 

pg/g 

Sum of dioxins and dioxin-like PCBs 

1 

0.81 

- 

- 

6.5 

pg/g 

Sum of ICES 6 

1 

3.64 

- 

- 

75 

ng/g 

*no individually set maximum levels – included in PAH4 

  

  

  

  

  

  

Detailed assessments

Achievement of targets and indicators used to assess progress in 2024

Drivers, activities and pressures affecting the state of the marine environment

The main drivers in the UK that influence human activities are related to meeting societal needs for energy, food, and materials. Associated pressures from such activities which lead to contamination from hazardous substances include:  

  • Power production using non-renewable resources, not only in Western Europe but also from the long-range transportation of atmospheric emissions, particularly from coal burning, long-range transport by ships and air (mainly mercury), and legacy contamination in sediments and historic landfills. 

  • Chemicals for domestic use, and waste products from other sectors and industrial production, such as pharmaceuticals and personal care products.  

  • Local drivers with local influence such as industry outputs and wastewater from major cities. There are also hotspots of historic pollution, buried in sediments and released during storm events, dredging operations and ship movement. These latter sources can have a major influence on shipping lanes and harbour management.  

  • Land use and agriculture can have a more widespread impact, either via diffuse run-off or more direct diffusion from aquaculture. 

Impact of pressure on ecosystem services

The impact of current and past pressures from human activities within the UK collectively contribute to the presence of hazardous substances in sediments and biota. Such impacts can lead to measurable biological effects in seafood such as hormonal and behavioural changes; reduced species fitness; reduced breeding success; and mortality. Specific ecosystem services affected include decline or potential extinction of marine populations; harvesting for commercial or leisure purposes; water and sediment quality regulation; nursery population and habitat maintenance; coastal protection and global climate regulation. Impacts on these ecosystem services can affect human activities such as recreation, tourism, fisheries and aquaculture, and inflict economic losses on individuals, enterprises and communities. 

Impacts of climate change on pressures and state

The UK Marine Strategy assessment did not factor in the impact of climate change on assessment outcomes. In general, however, temperature increases result in higher chemical reaction rates and could lead to higher biological uptake. A temperature increase of around 2˚C would increase reaction rates by about 20%. Increased temperature alone has been shown to affect the volatilisation of pesticides and of Persistent Organic Pollutants (POPs), increasing airborne transport risks. Temperature rise also means more rain, which leads to floods and higher run-offs of metals and POPs. For mercury, it has been suggested that the increasing temperatures, with related increasing hypoxia, fires and reduced ocean circulation, will increase methylmercury production in sediments, leading to higher releases from anoxic sediments to the overlying water columns. Increased storm frequencies could also lead to more coastal erosion (including of coastal landfills) and disturbance of sediments which are more likely to release legacy contaminants.  

Climate change could outweigh the current measures in place to reduce the inputs of contaminants, especially the historic contaminants which are stored in sediments. Assessments could also become more difficult with the current sampling resolutions (number of datapoints and frequency) to assess trends and status as the data may become more variable due to the effects of climate change.   

Management actions taken

The actions we are taking to achieve GES for contaminants in seafood are set out in the UK Marine Strategy Part 3 2025: Programme of Measures. Many national and international regulations have been put in place to prevent contamination: 

Given that all contaminants measured in the shellfish samples are within set existing regulations fr contaminant concentration in food, the management actions appear to be having a proactive impact. However, we do not know if fish may be affected by contaminants to a level that they effect human health when consumed. This is because whilst fish were not analysed this time due to a lack of suitable data being available for the assessment period, some sources of contaminants still exist, and their extent is having an environmental impact. Careful consideration needs to be given to emerging contaminants and how these should be managed. 

Human activities and their associated pressures could see new or improved measures applied e.g., in waste disposal. However, coastal development could continue to disturb contaminants in seabed sediment (e.g., through dredging of sediments from shipping lanes and harbours). 

Next steps

Evidence challenges

There are no consistent evidence programmes for Contaminants in Seafood (D9). Assessments are based on best available data from a set of shellfish samples, which may change between reporting cycles.  

Our headline challenges are: 

  • To improve the certainty and reliability of assessments by increasing the sampling of shellfish from across the UK, especially in southern and eastern waters.  

  • To consider how to fill evidence gaps for finfish.  

Operational objectives

To continue to ensure we meet GES for Contaminant in seafood we need to investigate options for finfish sampling. We could consider ways to enable finfish samples to be collected from across commercial fishing grounds around the UK and assess these against the human health regulatory assessment criteria in 1881/2006 for instance. Although there is obligatory monitoring of contaminants in finfish required under Commission Implementing Regulation (EU) 2019/627, the monitoring undertaken is not suitable for the purposes of this assessment. There is no equivalent monitoring in OSPAR.  

Technical Detail: Good Environmental Status for the next cycle

Overarching target 

Concentrations of contaminants in fish and other seafood caught or harvested for human consumption in UK seas do not exceed the relevant maximum levels listed in EU Regulation 1881/2006 (as amended) or other relevant standards and are not increasing’. 

Criteria 

2024-2030 GES  targets 

Comment 

Indicators 

Contaminant concentrations in seafood  

For contaminants where regulatory levels have been set, there should be a high rate of compliance with conventions based on relevant surveys and including samples originating from commercial fishing grounds in the Greater North Sea and the Celtic Seas. 

The part of the 2019 Target that focussed on human health has been removed as is does not sensibly fit within UKMS assessment purposes but rather is covered by food safety legislation and processes. 

 

 

One indicator composed of several elements. 

Indicator: Contaminant Concentrations in Seafood. 

 

Elements: 

Concentrations of heavy metals. Concentrations of PAHs. 

Concentrations of Dioxins and dioxin-like PCBs 

 

References

HM Government. (2012) ‘Marine Strategy Part One: UK Initial Assessment and Good Environmental Status’ (accessed 17th October 2023) at https://www.gov.uk/government/publications/marine-strategy-part-one-uk-initial-assessment-and-good-environmental-status. 

HM Government (2015) ‘Marine Strategy Part Three: UK Programme of Measures’ (accessed 17th October 2023) at https://www.gov.uk/government/publications/marine-strategy-part-three-uk-programme-of-measures . 

Retained Regulation (EC) No 1881/2006 of 19 December 2006 setting maximum levels for certain contaminants in foodstuffs (Text with EEA relevance), available at: https://www.legislation.gov.uk/eur/2006/1881 (accessed 17th  October 2023) 

 

Retained Regulation (EC) No 178/2002 of the European Parliament and of the Council of 28 January 2002 laying down the general principles and requirements of food law, establishing the European Food Safety Authority and laying down procedures in matters of food safety, available at: https://www.legislation.gov.uk/eur/2002/178/ (accessed 17th October 2023) 

 

Retained Regulation (EU) 2017/644 of 5 April 2017 laying down methods of sampling and analysis for the control of levels of dioxins, dioxin-like PCBs and non-dioxin-like PCBs in certain foodstuffs and repealing Regulation (EU) No 589/2014 (Text with EEA relevance), available at: https://www.legislation.gov.uk/eur/2017/644/ (accessed 17th October 2023) 

Retained Regulation (EU) 2016/582 of 15 April 2016 amending Regulation (EC) No 333/2007 as regards the analysis of inorganic arsenic, lead and polycyclic aromatic hydrocarbons and certain performance criteria for analysis (Text with EEA relevance), available at: https://www.legislation.gov.uk/eur/2016/582 (accessed 17th October 2023) 

Contributors

E. E. Manuel Nicolaus1 and Izaak Fryer-Kanssen2  

1Centre for Environment, Fisheries and Aquaculture 

2Food Standards Agency