Hazardous substances enter the marine environment from natural sources (e.g. polycyclic aromatic hydrocarbons (PAHs) from oil seeps, volcanoes and forest fires) and as a result of human activities, and reach the sea via direct discharges, through rivers and estuaries or via the atmosphere. The potential hazard associated with the different substances depends on their individual properties and behaviour following release. As explained in the introduction, we have identified concentration thresholds above which these substances could be toxic both to marine organisms and to human consumers of seafood. The Clean Seas Environmental Monitoring Programme (see previous page) directly monitors a limited number of hazardous chemicals, selected on the basis of a risk assessment and subject to there being agreed methodological guidelines, quality assurance procedures and assessment criteria available. For other contaminants, such as tributyltin (TBT), we can assess impacts by studying the biological effects they cause.

Data are still sparse at the regional scale; we may have too few sampling sites to characterise a region with high confidence. However, a major development since Charting Progress has been a redesign of the hazardous substances monitoring programme to make it more effective at detecting changes over time. For the first few years, the old and new programmes have run side to by side to provide continuity.

Inputs of hazardous substances

The downward trend in inputs of contaminants over time reported in Charting Progress for rivers, sewage works and industrial discharges has continued for mercury, cadmium and lindane to both the Celtic Sea and the North Sea, but for polychlorinated biphenyls (PCBs) concentrations have stabilised.

Between 1990 and 2007, anthropogenic emissions of cadmium to the atmosphere decreased by 84%, of copper by 57%, of lead by 96%, of zinc by 55% and of mercury by 80%. Figure 4.1 shows deposition of cadmium to sea areas surrounding the UK in 2006.

While industrial change has caused some of these decreases, improved abatement at the remaining sources has also contributed.

Produced water from offshore oil and gas platforms contains natural toxic aromatic hydrocarbons which are a component of oil as well as treatment chemicals. Discharges of oil in produced water fell by about 25% during the period 2002 to 2006, largely due to reductions in the volume of water discharged. The oil content of the discharged water remained constant at about 20 ppm until 2006, but reduced to about 15 ppm in 2007 thanks to improved produced water management. This brought the overall reduction in the amount of oil discharged from 2002-2008 to close to 50% (see Figure 4.2). This is a good example of effective regulation, in which the UK exceeded the reduction required by OSPAR.

Emissions of PAHs to the atmosphere have decreased by 84% since 1990. In 2007, the largest source of PAHs was road transport combustion, followed by domestic combustion (Figure 4.3). Twelve years earlier, the major source was the aluminium smelting industry, which contributed around 50%. Since then, thanks to improved practices, this industry is now responsible for only 1% of total PAH emissions.

Seawater

The evidence from seawater measurements is very encouraging. Inputs and concentrations of the most commonly monitored contaminants in seawater have fallen since Charting Progress as a result of earlier controls placed upon their use and are generally below UK EQS limits (for more information on UK EQSs, see http://www.environment­agency.gov.uk/research/planning/40295.aspx).

In addition, we found virtually no toxicological hazard from metals in water samples analysed for the EU Directives on Dangerous Substances (mainly in estuarine waters) and Shellfish Waters (mainly in coastal waters); nearly 99% of metal concentrations were below the UK EQS values in 2007, although 6% of copper concentrations exceeded the EQS (e.g. see Figure 4.4). Biological water quality (assessed using the percentage of oyster embryos that develop successfully in the water samples) is good or very good everywhere, except in the Tees estuary close to industrial discharges.

However, because concentrations of many contaminants in water are both low and very variable, the UK marine monitoring programme under CSEMP focuses on measuring contaminant levels in biota and sediments, where accumulation means that concentrations are generally higher and less variable. This increases the power of the monitoring programme to observe changes in concentrations over time.

Sediments

Analysis of contaminants in sediments reveals more clearly where there are problems, particularly in estuaries that have been heavily industrialised over time. While metal concentrations in sediments are generally lower in Scotland and the western Irish Sea, they are higher in England and Wales, with a number of industrialised estuaries, such as the Tees, Tyne, Thames, Severn and Mersey (in the case of mercury), showing levels that are high enough to have potential toxicological effects (Figure 4.5). Similarly, sediment PAH concentrations were high in the Tees, Tyne, Wear, and Milford Haven estuaries, and hence potentially toxic to sediment-dwelling organisms (Figure 4.5). The capacity of the sediment to support biota is generally good at all locations studied, except in parts of the Tees, Wear and Thames estuaries where the presence of adverse biological effects may be linked to the high PAH concentrations.

There has been no significant overall trend in the concentrations of metals in sediments since Charting Progress, although both upward and downward trends can be seen at specific locations for all eight metals (cadmium, mercury, lead, arsenic, chromium, copper, nickel, zinc) determined. However, if metal inputs from rivers, sewage discharges and industry continue to decline, we would expect future assessments to find decreasing concentrations in the sediments where anthropogenic inputs have exceeded natural sources.

Concentrations of PCBs, were also determined in surface sediments. They are present in the environment as a result of widespread historical use of these products, mainly in electrical transformers. In particular, we found that concentrations of the most toxic congener included in the analyses are above the EAC in most areas (CB118: Figure 4.6). This is significant because CB118 can affect neurological, immunological and reproductive processes in marine biota and humans. Generally speaking, we found the lowest concentrations of CBs at Scottish offshore sites, and the highest around south-eastern England (CB153: Figure 4.6). The few temporal trends we saw were mostly downward, although in many instances there was no apparent trend. Although the ban on new uses of PCBs was put in place in 1981, these compounds are very persistent in the environment and significant falls in environmental concentrations may take decades.

Figure 4.5 Normalised mercury and PAH concentrations in sediment.

Figure 4.6 Normalised CB118 and CB153 concentrations in sediment.

Blue and green symbols indicate concentrations below the BAC or EAC respectively; red symbols indicate concentrations above the EAC. Key to symbols

Biota

In fish and shellfish, we found the highest concentrations of contaminants in industrialised estuaries. Mercury levels in fish flesh are high in the Mersey and Thames estuaries, and lead concentrations in fish liver are similarly high in many estuaries including the Forth, Tyne, Tees, Wear, Severn, Mersey and Bann as well as in a few other coastal areas. Cadmium, mercury and lead concentrations were slightly elevated in mussels from some industrialized estuaries: Dee, Humber and Thames for cadmium; Thames and Mersey for mercury; Tyne, Tees and Forth for lead. Silver concentrations were higher in mussels from the Severn and Thames estuaries than elsewhere. Historically, the major inputs of silver were due to its widespread use in photography, which should be declining with the growth in use of digital cameras. However, the increasing use of silver nanoparticles as an antimicrobial agent may result in increased inputs. Although these metal concentrations are higher than background values, none pose a risk to human health because, in general, the shellfish tested were not from commercially harvested beds.

Figure 4.7 Normalised CB118 and CB153 concentrations in fish liver.

Green symbols indicate concentrations below the EACpassive; red symbols indicate concentrations above the EACpassive. There were no concentrations below the BAC. EACs for CBs in sediment are expressed for sediment of 2.5% organic carbon. It is possible to calculate lipid-normalised concentrations of CBs in fish liver in equilibrium with sediment containing CB concentrations equal to the EACs in sediment. These so-called EACpassive values are used as the green/red boundary for CBs in biota. Key to symbols

Although concentrations of CB138, CB153 and CB180 in fish liver are below the respective EACs, those of the more toxic CB118 are above the EAC and thus potentially toxic to the fish (see Figure 4.7). Fish liver is not eaten in the UK, and fish liver oil for use as a dietary supplement is cleaned-up during processing to reduce CB levels. We found the lowest concentrations in Scotland (Region 6) and highest in eastern England (Region 2). We found high levels of ethoxyresorufin-O-deethylase (EROD) enzyme activity in fish liver, which reflects exposure to contaminants such as dioxins, furans, planar CBs and PAHs, at sites in the North Sea and Liverpool Bay and at two historic sewage disposal sites close to the Scottish east coast.

PAHs are potentially dangerous to fish (and humans) as, when metabolised, some PAH compounds can form potentially carcinogenic compounds that can bind to DNA. We found little change in the levels of these DNA adducts in the fish from some industrialised estuaries since Charting Progress, when high concentrations were reported, suggesting that marine organisms are still at risk due to PAH contamination at these locations. PAH concentrations in mussels are illustrated in Figure 4.8.

With their introduction into the formal monitoring programmes, more data are now available for the polybrominated diphenyl ethers (PBDEs), than was the case for Charting Progress (see Figure 4.9). However, we do not have enough information to identify trends over time other than in harbour porpoises, nor have assessment criteria yet been developed within OSPAR. We found the highest concentrations in fish in industrialised estuaries, including the Clyde, Tees and Humber, and the lowest off the Scottish coast, in the Western Channel and off eastern England. In harbour porpoises from UK waters, a rapidly rising trend in blubber concentrations of the brominated flame retardant hexabromocyclododecane (HBCD) after 2001, has been reversed since 2003. This is probably because of the closure of two UK plants, one manufacturing HBCD and the other using HBCD in the manufacture of expanded polystyrene.

Concentrations of CBs in harbour porpoise blubber are reacting more slowly to controls on the use of PCBs, although these have been in place since the 1980s, and levels are declining only slowly. Concentrations of BDEs in harbour porpoise blubber have also been declining over the period 1998 to 2008, following EU risk assessment and regulation. The tissues in deep-sea fish collected from the Rockall Trough to the west of the UK contained both CBs and BDEs, but not HBCD or tetrabromobisphenol-A (TBBP-A).

Fish liver pathologies, including cancers, are higher and potentially increasing at certain Irish Sea sites, higher but static at some North Sea sites, and low and static (approaching or at background levels) at Inner North Sea and English Channel sites. The causes of the higher levels are unknown, but cancers do not result solely from exposure to hazardous substances.

Another indicator of poor health in marine biota is imposex – the imposition of male characteristics on female organisms caused by exposure to tributyltin (TBT; Figure 4.10) or hybrid male/female conditions caused by a wider range of chemicals. The extent of imposex in marine snails as a result of exposure to TBT has declined since 1998, showing that the bans on the use of TBT in antifouling paints for ships have been very effective, with evidence of recovering populations and wider improvements in the range of bottom-dwelling organisms in previously impacted areas.

Charting Progress reported evidence of endocrine disruption resulting from exposure to oestrogenic chemicals in flounder from a number of UK estuaries (Tyne, Tees, Mersey, Clyde and Forth). It assessed endocrine disruption, in this case feminisation, using vitellogenin (VTG). This is a protein normally only found in the blood of female fish. Thus, finding it in male fish indicates exposure to oestrogenic chemicals. There has been no further work since then, so we cannot say what the current status is, or assess trends since Charting Progress. Although the concentrations of VTG in males of offshore species of fish, cod and dab, are generally close to background levels, in cod from the North Sea and around Shetland, we found a marked increase in the amount of VTG at a body mass of 5 kg. This is about the size at which cod switch their diet from eating benthic invertebrates to eating other fish, both benthic and pelagic. We saw similar results in dab from UK offshore waters, suggesting that the affected fish are gradually accumulating persistent oestrogenic compounds through their diet. One report also showed the presence of egg cells in the testes of male peppery furrow shells, a filter-feeding bivalve sampled in a number of estuaries in south-west England during 2004 to 2005, including the Avon estuary previously considered to be a reference site due to the low population level and lack of industry. These findings suggest continuing impacts from oestrogenic compounds, although we cannot assess their scale. Similar studies in cod and bivalves were not reported in Charting Progress.

Our assessment shows that reductions in emissions, discharges and losses are having an impact, since we find downward trends for certain contaminants in specific contexts such as the BDEs in harbour porpoise blubber. However, it is also clear that, for some legacy chemicals, concentrations in sediments are reducing only very slowly and contaminated sediments will act as a source of persistent organic pollutants for years to come. However, even their concentrations are generally below those likely to cause effects except for historically contaminated estuaries and very coastal locations.

During 2009, there were initial assessments of the status of the UK seas under the EU Water Framework Directive (WFD). Extensive data collection within monitoring implemented for the EU Dangerous Substances and Shellfish Waters Directives, etc, informs these WFD chemical status assessments. All Scottish transitional and coastal waterbodies achieved good status for contaminants. In England and Wales, 69% of transitional waters and 91% of coastal waters assessed were at good chemical status. Less than good chemical status was, in the majority of cases, related to TBT contamination. There were few breaches of the contaminant standards at sites in Northern Ireland, with the exception of ammonia. Programmes of measures will be developed where necessary.

The WFD monitoring uses EQS limit values for water developed by the EU which are in many cases lower than those used in this assessment, with the aim of achieving improved environmental protection. For a list see Common Position (EC) No 3/2008, at http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:C:2008:071:0001...

Within the EU Marine Strategy Framework Directive, monitoring will be undertaken with a view to assessing Good Environmental Status against 11 attributes, including whether concentrations of contaminants are at levels not giving rise to pollution effects; and whether concentrations of contaminants in seafood are below the regulatory limits set to protect human consumers.

Future work

We need to understand more about the effects of mixtures of chemicals. Classical toxicology has provided a huge amount of information on the hazards of individual compounds but, in their environment, animals are exposed to more than one compound at a time. For endocrine disruptors, the effects of different chemicals might just be additive, but they could also cancel each other out or exacerbate each other’s effects. We also need more data to determine the significance of pharmaceuticals in the marine environment.

OSPAR and ICES are currently developing guidelines for monitoring and assessing integrated chemical and biological effects, initially for use within OSPAR. These will also be adopted within the CSEMP, where appropriate, and so integrated data will be available for the next in this series of UK status reports.