Scottish Marine and Freshwater Science Volume 5 Number 15: Development of a Sampling Programme and Measurement of Contaminants in Food for Marine Strategy Framework Directive Descriptor 9

MSFD Descriptor 9 Requirements: Targets and Indicators

Details of the criteria and indicators for GES for the eleven descriptors are provided in the European Commission decision document (Commission Decision 2010/477/ EU) which Member States must use when implementing the Directive.

For Descriptor 9, the Commission Decision Document states that:

• Contaminants in fish and other seafood for human consumption do not exceed levels established by Community legislation or other relevant standards.
• In the different regions or sub-regions Member States need to monitor in edible tissues (muscle, liver, roe, flesh, soft parts as appropriate) of fish, crustaceans, molluscs and echinoderms, as well as seaweed, caught or harvested in the wild, the possible presence of substances for which maximum levels are established at European, regional or national level for products destined for human consumption.

The indicators listed for Descriptor 9 are:

• 9.1. Levels, number and frequency of contaminants:
• 9.1.1 Actual levels of contaminants that have been detected and number of contaminants which have exceeded maximum regulatory levels.
• 9.1.2 Frequency of regulatory levels being exceeded.

The UK Government and Devolved Administrations developed proposals for more detailed targets and indicators of Good Environmental Status for each of the eleven descriptors, through which we will measure progress towards achieving Good Environmental Status.

For Descriptor 9 (Levels, numbers and frequency of contaminants) the GES target and indicators proposed for contaminants in seafood by the UK is:

For contaminants where regulatory levels have been set, 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 ³.

Therefore, for monitoring compliance with GES, contaminant concentrations in fish and seafood should be compared against the regulatory levels. Descriptor 9 will cover those substances for which regulatory levels have been laid down. Commission Regulation EC/1881/2006 specifies Maximum Permitted Concentrations ( MPCs) in food (including the muscle meat of fish, bivalve molluscs and crustaceans) for lead, cadmium, mercury, dioxins ^[ii] , dioxin-like ^[iii] polychlorinated biphenyls ( DL-PCBs) and benzo[ a]pyrene ( Table 1). Regulation EC/1259/2011 provides amended limits for dioxins and DL-PCBs plus additional limits for non DL-PCBs ( ICES 6; CB28, 52, 101, 138, 153 and 180) ^[iv] ( Table 1). Furthermore, MPCs are provided for dioxins (including DL-PCBs) and non DL-PCBs in fish liver and derived products. In 2012 MPCs for polycyclic aromatic hydrocarbons ( PAHs) in fish were removed from regulation EC/1881/2006 and the MPC for bivalve molluscs was reduced. New levels are likely to be introduced for other contaminants such as three additional PAHs, polybrominated diphenyl ethers ( PBDEs), and inorganic arsenic.

Monitoring should be undertaken in accordance with the sampling and analytical performance requirements defined in Commission Regulation EC/1883/2006. Information on the sampling location will also be required so contaminant data can be traced back to a (sub) regional level.

This report reviews the contaminants in fish and shellfish monitoring activities currently undertaken in Scotland and the suitability of these activities in addressing the requirements of Descriptor 9. Contaminant data currently available for biota were compared to regulatory levels. To fill identified gaps for assessing progress towards GES for Descriptor 9, a sampling programme was designed targeting fish species important in the human diet (based on landings from each sub-region).

Table 1

Regulatory limits on the maximum permitted concentrations (wet weight) of certain environmental contaminants in edible portions of fish and shellfish (whole fish if appropriate). TEQ = Toxic Equivalent Concentration (summed concentrations of certain planar organic compounds based upon their relative toxicity ⁵).

Regulation	Compound or element	Maximum permitted concentration	Species to which the limit applies
EC/1881/2006 EC/1881/2006 EC/1881/2006 EC/1881/2006	Pb Pb Pb Pb	0.3 mg kg -1 0.5 mg kg -1 1.0 mg kg -1 1.5 mg kg -1	Fish and shellfish with the main exceptions indicated below: Crustacea (excluding crab brown meat & head / thorax of lobster) Cephalopods (without viscera) Bivalve molluscs
EC/629/2008 EC/629/2008 EC/629/2008 EC/629/2008 EC/629/2008 EC/629/2008	Cd Cd Cd Cd Cd Cd	0.05 mg kg -1 0.1 mg kg -1 0.2 mg kg -1 0.3 mg kg -1 0.5 mg kg -1 1.0 mg kg -1	Fish and shellfish with the exceptions indicated below: Bonito, common two-banded seabream, eel, grey mullet, horse mackerel or scad ( Trachurus sp.), louvar or luvar, sardine, sardinops, tuna, wedge sole. Bullet tuna Anchovy, swordfish Crustacea (excluding crab brown meat & head / thorax of lobster and similar large crustaceans) Cephalopods (without viscera), bivalve molluscs
EC/1881/2006 EC/629/2008	Hg Hg	0.5 mg kg -1 1.0 mg kg -1	Fish and shellfish with the exceptions of crab brown meat, head / thorax meat of lobster (and similar spp.) and the species indicated below: Anglerfish, Atlantic catfish, bonito, eel, emperor, orange roughy, rosy soldierfish, grenadier, halibut, kingklip, marlin, megrim, mullet, pink cusk eel, pike, plain bonito, poor cod, Portuguese dogfish, rays, redfish, sail fish, scabbard fish, seabream, pandora, shark (all species), snake mackerel or butterfish, sturgeon, swordfish, tuna.
EC/1881/2006 EC/1881/2006 EC/1881/2006	Benzo[ a]Pyrene Benzo[ a]Pyrene Benzo[ a]Pyrene	5.0 μg kg -1 5.0 μg kg -1 5.0 μg kg -1	Smoked fish and fishery products Crustacea & cephalopods, other than smoked and excluding crab brown meat, head / thorax meat of lobster (and similar spp.) Bivalve molluscs
EC/1259/2011	Dioxins & furans 1	3.5 pg g -1 TEQ	Fish muscle and fishery products, excluding eel and freshwater fish
EC/1259/2011	Dioxins, furans & DL-PCBs 1	6.5 pg g -1 TEQ	Fish muscle and fishery products, excluding eel and freshwater fish
EC/1259/2011 EC/1259/2011 EC/1259/2011	ICES 6 PCBs Dioxins & DL-PCBs ICES 6 PCBs	75 μg kg -1 20 pg g -1 TEQ 200 μg kg -1	Fish and fishery products, excluding eel and freshwater fish Fish liver and derived products, with the exception of marine oils Fish liver and derived products, with the exception of marine oils

¹Individual compounds as listed in EC Regulation EC/1881/2006.

Current Scottish Monitoring of Contaminants in Biota

The Food Standards Agency for Scotland ( FSAS), Scottish Environment Protection Agency ( SEPA) and Marine Scotland Science ( MSS) undertake contaminant monitoring in marine biota for a range of purposes. These include the UK Clean Seas Environment Monitoring Programme ( CSEMP, including MSFD Descriptor 8) and the FSAS annual surveys of contaminants in shellfish from commercial harvesting areas. Fish and shellfish contaminant monitoring programmes are described below.

Contaminants in Fish

Hazardous substances are measured in fish collected from Scottish sites for a number of studies. MSS monitor contaminants in fish at sites around Scotland for programmes such as the UK CSEMP and Clyde trend monitoring programme ( Figure 1). Contaminants included on the OSPAR Coordinated Environmental Monitoring Programme ( CEMP) ^[v] are analysed as part of the CSEMP ⁶. Of the contaminants with EC regulatory levels (lead, cadmium, mercury, benzo[ a]pyrene, dioxins, DL-PCBs and non DL-PCBs), dioxins and most DL-PCBs (only CB118 is monitored as one of ICES7 PCBs) are not monitored for the UK CSEMP. Dioxins and DL-PCBs are included on the OSPAR pre- CEMP and, therefore, analysis of these contaminant groups is not mandatory ⁶. Furthermore, concentrations of DL-PCBs will be much lower than non DL-PCBs ( ICES7 PCBs) and, therefore, the OSPAR pre- CEMP states that analysis in biota is only required if concentrations for the ICES7 PCBs are 100 times higher than the Background Assessment Concentration for these marker PCBs. Dioxin concentrations will also be much lower than concentrations of the ICES7 PCBs. To detect dioxins at such low levels the favoured technique for chemical analysis uses high-resolution mass spectrometry ( HRMS). As neither MSS nor SEPA currently have access to high resolution mass spectrometry, this analysis would have to be outsourced at high cost. However, papers have been published looking at alternative methods to predict the total TEQs (for dioxins and 'dioxin-like' CBs) in fish tissue, using total or indicator PCB concentrations. These models have previously been applied to Marine Scotland PCB data for fish and have been described in detail elsewhere ⁷. In summary, Bhavsar et al. ⁸ proposed that the total PCB (Aroclor equivalent) concentration could be used to estimate the total TEQ for dioxin and 'dioxin-like' PCBs. Lasrado et al. ⁹ looked at four models to predict TEQs using the US Environment Protection Agency fish tissue study. The authors concluded that the analysis of selected compounds or total PCBs could be used to estimate total TEQs and proposed models.

The main focus of the CSEMP has been to meet the temporal trend monitoring requirements of the OSPAR international agreement and in respect of compliance with EC Directives such as the Water Framework Directive ( WFD) ( EC/2000/60), Dangerous Substances Directive ( DSD) (76/464/ EEC) and Shellfish Waters Directive (79/923/ EEC). The OSPAR CEMP requires the determination of lead, cadmium, PCB, and brominated flame retardant concentrations in fish liver, and mercury in fish muscle tissue; these plus PAHs and a wider range of trace metals are required to be monitored in mussels. For CSEMP, MSS monitor contaminants in plaice ( Pleuronectes platessa), dab ( Limanda limanda) or flounder (Platichthys flesus) from 10 sites annually. The use of modern analytical methodologies means that data for the three specified metals (and several others) are routinely obtained for both liver and muscle of fish. CSEMP contaminant data are submitted to the UK Marine Environment Monitoring and Assessment National database ( MERMAN) and from there to international databases.

Organic contaminants ( PCBs and polybrominated diphenyl ethers, PBDEs) have been measured in fish (plaice) liver from the Firth of Clyde as part of the MSS Clyde Trend Monitoring Programme. Seven fixed sites (five test sites (Skelmorlie, Hunterston, Irvine Bay, Holy Loch and Garroch Head) and two reference sites at Colonsay and Pladda) ( Figure 1) have been monitored for organic contaminants annually. Fish liver has been analysed for PCBs since 1992 at Garroch Head and Pladda, and at all other sites since 1999. PBDEs have also been analysed in recent and historical plaice liver samples (dating back to 1997). Data from the Clyde trend monitoring programme is now also submitted to the MERMAN database.

Additional fish samples have been collected from sites on the east coast in recent years by MSS. Dab and haddock were sampled from offshore of the Firth of Forth in 2008 and flounder were collected from Alloa and Tancred Bank in the Forth estuary and from St Andrews Bay in 2008, 2010 and 2011 ( Figure 1). PCBs were measured in fish liver and metals in liver and muscle and the data submitted to MERMAN.

The above environmental monitoring programmes existed pre- MSFD and generated data that were used in the UK's Initial Assessment for the MSFD. However, they were not designed for food monitoring and in producing the Initial Assessment, the authors noted gaps in the existing monitoring programmes with respect to their suitability for both environmental (Descriptor 8) and food (Descriptor 9) monitoring for the MSFD. Changes to the Scottish Descriptor 8 monitoring programme ¹⁰ were mostly to include geographical areas not previously considered, and hence gaps with respect to monitoring for Descriptor 9 remain.

The monitoring programmes described above focussed on fish species suitable for environmental monitoring (flatfish such as flounder, plaice, and dab), but these species only form a small proportion of Scottish landings, so are not the most suitable for food monitoring. For example, there were 304,400 tonnes of fish (pelagic and demersal) landed by Scottish vessels in 2013 with a value of £292 million, and plaice accounted for <1% of the total landings into Scotland ¹¹. Furthermore, the size ranges specified for fish sampling under the CSEMP means that most fish sampled are smaller than can be legally caught by commercial fisheries and, except for metals, contaminants are measured in fish liver rather than in the edible flesh.

Bioaccumulation of contaminants in fish is dependent on factors such as fat content, age and trophic level of the fish. Lipophilic contaminants, such as PAHs and PCBs, will accumulate more in fish tissue with a higher fat content. Due to the high lipid content of the liver, organic compounds (such as PCBs) will accumulate more in the liver than the muscle; therefore, these contaminants are measured in the liver for environmental monitoring programmes such as the CSEMP and the Clyde trend monitoring programme. In addition, many contaminants (including mercury) will bio-magnify, with fish higher up the food chain having higher concentrations of contaminants than fish of low trophic level. The fish species used for environmental monitoring are of relatively low trophic level (<3.5) ¹², the size-ranges are smaller than commercially caught fish and most of the data are for liver, hence the on-going CSEMP and Descriptor 8 monitoring will produce contaminant data that will be of limited use for assessing progress towards GES under Descriptor 9.

Figure 1: Scottish CSEMP fish monitoring sites regions, sampled annually for contaminant analysis. The grey lines show the Scottish sea areas ².

In recent years there has been an increasing commercial interest in deep water fisheries. More than 130 deep water species are found in waters to the west of the UK, of which about 12 are fished commercially, including roundnose grenadier ( Coryphaenoides rupestris), black scabbard ( Aphanopus carbo) and black dogfish ( Centroscyllium fabricii). Roundnose grenadier and black scabbard are targeted for the consumer market, whilst black dogfish are mainly caught as by-catch but are also used for fishmeal. The latest official information for deep water species landed into Scotland shows that total landings of black scabbard was 1,998 tonnes in 2012, accounting for 0.6% of all landings ¹³. Halogenated persistent organic pollutants ( PCBs and PBDEs) and total lipid were measured in the liver and muscle of three species of deep water fish (black scabbard, black dogfish (liver only) and roundnose grenadier) collected from the Rockall fishing area, to the west of Scotland, between 2006 and 2011 ⁷. Both contaminant groups were detected in the muscle and liver, with concentrations higher in the liver and PCB concentrations higher than PBDEs. Trace metal concentrations were also determined in the flesh and liver of deep water fish collected in September 2006 ¹⁴. The data were not submitted to the MERMAN database.

In addition to their annual shellfish monitoring programme (below), the FSAS has undertaken periodic surveys of contaminants (including PAHs, dioxins and PCBs) in food, including fish, since 1989 ^15-17. The main purpose of these surveys is to allow the dietary intake of contaminants such as dioxins and DL-PCBs from processed fish and fish products to be estimated. Currently these data are not submitted to MERMAN.

Contaminants in Mussels

Under the UK CSEMP, SEPA monitor contaminants (trace metals, PCBs, PAHs and PBDEs) in native mussels collected from the intertidal zone from a range of sites across Scotland in January-March each year ( Figure 2). Samples are collected to assess compliance with the Environmental Quality Standards ( EQSD) daughter Directive of the WFD. In total, 56 shellfish sites around Scotland are monitored and data (metals, PCBs and PAH) submitted to the MERMAN database. MSS work with SEPA to undertake an integrated assessment of contaminants and their biological effects at approximately 6 sites per year. Many of these mussel sites are in remote areas ( e.g. Shetland and the Western Isles) and so provide 'background' data. Following the repeal of the Dangerous Substances Directive (76/464/ EEC) and the Shellfish Waters Directive (2006/113/ EC), SEPA are currently reviewing the extent and frequency of their mussel monitoring programme, but data from their on-going monitoring could be of use for assessments under Descriptor 9, if from areas that may be harvested for human consumption.

Contaminants have also been measured in mussels as part of MSS's Long Term Hazardous Substances Monitoring Programme. Farmed, rope grown mussels (Loch Etive and Loch Ewe) and wild mussels (Straad on the west coast and Shell Bay and Aberdeen Breakwater) have been collected monthly and analysed for hazardous substances with the aims of assessing the status of Scottish mussels with respect to concentrations of hazardous substances, and of investigating site and seasonal differences. Mussels from Loch Etive have been analysed for PAHs since 1999, and Loch Ewe, Straad, Aberdeen Breakwater and Shell Bay since 2005, when PCBs and PBDEs were introduced to the programme. All data were submitted to MERMAN until the monitoring programme at all sites ended in 2012.

Figure 2: Scottish shellfish monitoring sites, including MSS's Long Term Hazardous Substances Monitoring Programme ( LTHSMP) 2005-2012 sites, MSS integrated assessment sites and SEPA's Shellfish Water and Dangerous Substances Directive sites. Grey lines show the Scottish sea areas ².

FSAS Shellfish Monitoring Programme

The Shellfish Hygiene Directive (79/923/ EEC) includes the requirement to assess a range of elements of end product quality in shellfish offered for sale for human consumption. EU contaminants in foodstuffs regulations ( EC/1881/2006, as amended) require that a range of contaminants do not exceed given MPCs in foodstuffs for sale for human consumption. The FSAS is the competent authority for this work. Therefore, as part of statutory monitoring (as detailed in Regulation ( EC) 1881/2006) FSAS conducts annually monitoring of chemical contaminants in newly classified shellfish areas and/or shellfish areas which were subject to sanitary surveys. Directive monitoring only includes commercially harvested shellfish and, therefore, sampling does not include industrialised estuaries. This monitoring covers:

• Metals (chromium, manganese, cobalt, nickel, copper, zinc, arsenic, selenium, silver, cadmium, lead and mercury).
• PAHs.
• Dioxins and PCBs.
• Organochlorine pesticides.

These data are not currently submitted to the MERMAN database, but may be in future, and should be of use for Descriptor 9 assessments.

Comparison of data to Regulatory Levels

European regulatory levels ( EC/1881/2006 and EC/1259/2011) are available for PAHs (benzo[ a]pyrene), trace metals (Cd, Hg and Pb), dioxins, DL-PCBs and non DL-PCBs ( ICES6 PCBs) in fish muscle, crustecea and bivalve molluscs and also for dioxins (including DL-PCBs) and non DL-PCBs in fish liver and derived products ( Table 1). Dioxins and DL-PCBs (except for CB118 which is one of the ICES7 PCBs) are not currently monitored in Scotland for CSEMP purposes. However, there are now limits available for the ICES6 PCBs ( CB28, 52, 101, 138, 153 and 180) in fish muscle and liver ( EC/1259/2011; 75 μg kg ^-1 wet weight for fish muscle and 200 μg kg ^-1 wet weight for fish liver) which are routinely analysed as part of environmental monitoring programmes such as CSEMP. Additionally, maximum levels are likely to be set for three more PAHs and for inorganic arsenic (As) in the near future.

Recent (2007-2013) data was extracted from the MERMAN database for PAHs and metals in mussels, for metals in fish muscle and PCBs in mussels and fish liver sampled from Scottish sea areas. FSAS supplied MSS with data for dioxins, PCBs (including DL-PCBs), trace metals and PAHs in shellfish collected as part of their annual monitoring programme. All data (individual results) were compared to regulatory levels.

Fish

For fish muscle only trace metals data are available in the MERMAN database for Scottish sites. The muscle tissue from plaice, dab or flounder have been collected at Scottish sites ( CSEMP and Clyde trend monitoring) in eight Scottish sea areas (Solway Firth and North Channel, Clyde, Minches and Malin Sea, East Shetland, Fladen, East Scotland Coast, Moray Firth and Forth). To date there are 364 fish muscle samples with data for trace metals in MERMAN from the last seven years (2007-2013). Of these none exceeded the maximum level for Hg (0.5 mg kg ^-1 wet weight). Two samples exceeded the maximum level for Pb (0.3 mg kg ^-1 wet weight), one in the Moray Firth and one in the Fladen, and three for Cd (0.05 mg kg ^-1 wet weight), two in the East Scotland sea area (both from Montrose Bank in 2009) and one in the Solway Firth and North Channel (2007). PCBs data for fish liver (dab, plaice and flounder) are also held in MERMAN; non DL-PCB data are available for 434 fish liver samples (2007-2013). Forty-five samples exceeded the maximum level for the ICES6 PCBs in fish liver (200 µg kg ^-1 wet weight), all from the Clyde. Although dioxins and most DL-PCBs are not monitored in fish, concentrations will be much lower than for non DL-PCB concentrations. Dioxin toxic equivalent ( TEQ) concentrations were estimated using published models ^8,9 for the 434 samples (2007-2013) with PCB data in MERMAN. Nine samples (Lasrado model ⁹) or twenty-six samples (Bhavsar model ⁸), all from the Clyde (Loch Long, Holy Loch and Garroch Head), exceeded the total TEQ for liver of 20 pg g ^-1 wet weight. These samples also were above the MPC for the non DL-PCBs in fish liver.

PCBs were measured in deep water fish muscle as part of MSS deep sea research projects (2006-2012). Dioxin toxic equivalent ( TEQ) concentrations, estimated from the PCB concentrations in fish muscle using published models ^8,9, were below the EU MPC ⁷. Furthermore, none of the fish muscle samples gave concentrations greater than 75 μg kg ^-1 wet weight for the sum of the ICES6 PCBs. Therefore, there is no risk to human health from consumption of these deep water fish. However, almost half of the 2009, 2011 and 2012 roundnose grenadier (21 out of 43) and black dogfish (10 out of 20) liver samples gave concentrations for the sum of the ICES6 PCBs above 200 μg kg ^-1 wet weight. Sixteen of these samples also gave an estimated dioxin TEQs above the MPC of 20 pg g ^-1 wet weight. The liver of both species have a very high lipid content (means of 51.8% - 74.7%) so are likely to accumulate higher concentrations of hydrophobic contaminants compared to species with a lower lipid content. The MPC is on a wet weight basis and, therefore, the high lipid content is not accounted for. Although food safety levels were exceeded it is unlikely that the liver of these species will be for the consumer market. Trace metal concentrations were also measured in fish collected in September 2006 ¹⁴. The concentrations of Hg and Pb were below the MPC, but Cd concentrations exceeded the MPC in 66% of round nose grenadier from the Rockall sea area. However, deep water fish represent less than 1% of total Scottish landings ( e.g. black scabbard accounts for 0.6% of total Scottish landings ¹³).

The FSA have also published contaminant data in fish from their food surveys. The most recent survey, in 2006, investigated dioxins and PCBs in 165 samples of processed fish and fish products purchased in the UK ¹⁵. The samples analysed covered a wide range of fish and shellfish related products from supermarkets, independent retailers and specialist retailers. Fish analysed included cod, haddock, herring and mackerel. The concentrations of dioxins and DL-PCBs were below relevant EU regulatory limits in all of the samples. Total TEQ concentrations were in the range 0.01 - 3.17 pg g ^-1 wet weight, below the MPC of 6.5 pg g ^-1 wet weight for the total TEQ (dioxins plus DL-PCBs). Concentrations were generally higher in crab and in oily fish such as anchovies, herring, mackerel and salmon. In 2006 a survey of farmed and wild fish and shellfish was undertaken ¹⁶. Samples were taken from retail outlets throughout the UK so there was no information on where samples were collected. Forty-seven composite samples, including mackerel, herring, wild and farmed salmon and farmed trout, were measured for PCBs and dioxins. Dioxins and PCBs were at low concentrations in nearly all of the samples. Total TEQ concentrations were in the range 0.02-28 pg g ^-1 wet weight, with the highest concentration in a sample of mackerel. One mackerel and one herring sample exceeded the MPC of 8 pg g ^-1 TEQ wet weight ^[vi] for the sum of dioxins and DL-PCBs.

In 2009 the FSAS undertook a survey of Scottish deep water fish, freshwater fish and non-commercial mussel beds for a range of contaminants including PCBs ¹⁷. Thirty-two marine fish (muscle only) were analysed for PCBs, DL-PCBs, dioxins, PBDEs, PFCs, phthalates, brominated dioxins, chlorinated naphthalenes and trace metals. The contribution to the TEQ was higher for the DL-PCBs compared to the dioxins. Concentrations were lower in shellfish compared to fish and concentrations in marine fish were lower than freshwater fish. However, in all cases the total TEQs (dioxin and DL-PCBs) were lower than the MPC, with the highest concentration in a sample of roach (3.5 pg g ^-1 TEQ wet weight). Therefore, the concentrations were not of concern with respect to human health. For trace metals, nearly all fish samples were below the MPCs, with the mercury MPC exceeded in a couple of cases for ling and blue ling.

As it is possible to estimate the TEQ concentrations from the PCB concentrations using published models, and concentrations are likely be below the MPC in most Scottish sea areas, no additional monitoring of dioxins in fish is proposed for MSFD Descriptor 9.

Shellfish

PAH data for mussels collected at Scottish sites over the last seven years (2007 to 2013, inclusive) were extracted from the MERMAN database. Five hundred and twenty-seven mussel samples, collected from nine Scottish regions (Clyde, Minches and Malin Sea, Hebrides, North Scotland Coast, West Shetland, East Shetland, East Scotland Coast, Moray Firth and Forth) have been analysed for PAHs. Samples were collected as part of MSS's long term monitoring hazardous substances programme and by SEPA for the Dangerous Substances Directive and the Shellfish Waters Directive. Samples were mainly wild mussels, apart from MSS Loch Etive and Loch Ewe samples which are rope grown. Of the 527 mussel samples in MERMAN, 327 samples had data for benzo[ a]pyrene of which 10 had concentrations greater than the MPC of 5 µg kg ^-1 wet weight. Eight of these were from sites in the Clyde region, one in the Forth and one in the Minches and Malin Sea (Tobermory).

PCB data for 422 mussel samples collected between 2007 and 2013 from nine regions (Clyde, Minches and Malin Sea, Hebrides, North Scotland Coast, West Shetland, East Shetland, East Scotland Coast, Moray Firth and Forth) were obtained from MERMAN. This extraction included both SEPA and MSS data. Only one sample, from the Tay estuary, exceeded the MPC of 75 µg kg ^-1 wet weight for the ICES6 PCBs in fish and fishery products.

Three-hundred and twenty-seven mussel samples, collected from nine Scottish regions (Clyde, Minches and Malin Sea, Hebrides, North Scotland Coast, West Shetland, East Shetland, East Scotland Coast, Moray Firth and Forth), have been analysed for trace metals over the last seven years (2007-2013) and data submitted to MERMAN. Data for Cd and Pb are available for all sites and for Hg for all but five sites. Most of these samples were collected and analysed by SEPA for the Dangerous Substances Directive and the Shellfish Waters Directive. Concentrations of Cd and Hg in all mussel samples were below the MPC of 1.0 mg kg ^-1 wet weight and 0.5 mg kg ^-1 wet weight, respectively. For Pb, seven samples exceeded the MPC of 1.5 mg kg ^-1 wet weight, three from the Clyde, two from the Forth, and two from Minches and Malin Sea.

Contaminants data ( PAHs, PCBs, dioxins, trace metals) for the FSAS annual shellfish monitoring programme (2006-2011, inclusive) was provided to MSS. In total 139 shellfish samples (mussels, oysters, clams, razorfish, scallops and cockles) were analysed for PAHs. Benzo[ a]pyrene was measured in all samples and all were below the regulatory level of 5 µg kg ^-1 wet weight for bivalve molluscs. Shellfish samples were also analysed for dioxins and PCBs (non DL-PCBs and DL-PCBs). In all cases the total TEQs (dioxin and DL-PCBs) and ICES6 PCB concentrations were lower than the EU regulatory limits of 6.5 pg g ^-1 TEQ wet weight and 75 µg kg ^-1 wet weight, respectively.

Between 2006 and 2011, 109 shellfish samples (mussels, oysters, clams, razorfish, scallops and cockles) were analysed for trace metals. All concentrations of Hg and Pb were below the regulatory level for bivalve molluscs. One sample exceeded the regulatory levels for Cd in bivalve molluscs, a scallop sample from Argyll and Bute in 2006.