PCBs in biota - Marine online assessment tool

Since 2012, polychlorinated biphenyl concentrations in biota are broadly similar and generally achieve the target described in the UK Marine Strategy Part One (HM Government, 2012). 83% of the assessments in the Greater North Sea and 74% of assessments in the Celtic Sea have met the associated UK targets. However, the most toxic dioxin-like compound (CB118) still exceeds target threshold levels in some areas.

Background

UK target on concentration of contaminants (polychlorinated biphenyl)

This indicator is used to assess progress against the target set out in the UK Marine Strategy Part One (HM Government, 2012), which requires that concentrations of the substances identified within relevant legislation and international obligations are below the levels at which adverse effects are likely to occur. The polychlorinated biphenyls considered are CB28, CB52, CB101, CB118, CB138, CB153 and CB180.

Key pressures and impacts

In the UK Initial Assessment (HM Government, 2012) the key pressures associated with this indicator were riverine and direct inputs of legacy polychlorinated biphenyls arising from point and diffuse sources, atmospheric deposition and acute events that have entered marine sediments and can then accumulate in fish and shellfish and top predators (biota). These are still relevant.

Measures taken to address the impacts

There is a robust UK legislative framework in place for controlling and reducing pollution from the main sources of contaminants (energy production, transport, urban and industrial uses), including appropriate consenting regimes and River Basin Management Plans described in the UK Marine Strategy Part Three (HM Government, 2015). However, many of the polychlorinated biphenyls in marine sediments entered the sea before many of the controls were put in place and, due to their persistence, are still present. Removing these sediments from the sea is not a practicable option.

Monitoring, assessment and regional co-operation

Areas that have been assessed

Status and trends assessments were conducted for the UK portion of the Greater North Sea and Celtic Seas Marine Strategy Framework Directive (European Commission, 2008a) sub-regions, and, where possible, at the smaller scale of the UK biogeographic marine regions set out in Charting Progress 2 (UKMMAS, 2010).

Monitoring and assessment methods

Risk-based monitoring and assessment of the status and trends of polychlorinated biphenyl concentrations in biota was conducted within the annual UK Clean Seas Environmental Monitoring Programme using methods and principles set out in the OSPAR Coordinated Environmental Monitoring Programme. The assessment analysed the results of individual monitoring stations and also synthesised the result to assess trends on the biogeographic regional level.

Assessment thresholds

Environmental Assessment Criteria were derived by OSPAR for the assessment of polychlorinated biphenyl concentrations in biota. Concentrations below the Environmental Assessment Criteria rarely cause any chronic effects in marine organisms.

OSPAR also has a long term ultimate objective to achieve concentrations of close to zero for man-made substances in the marine environment, and whilst not a target described in the UK Marine Strategy Part One (HM Government, 2012), the status and trend results were used to examine progress towards this objective.

Regional co-operation

The UK has been a key player in the development, monitoring and assessment of the OSPAR “polychlorinated biphenyls in biota” common indicator. The UK results have been used in the OSPAR Intermediate Assessment (OSPAR Commission, 2017).

Further information

Polychlorinated biphenyls are very stable, which means that they not biodegrade in the environment and humans and animals cannot break them down. Some polychlorinated biphenyls can vaporise and be easily redistributed by air. Polychlorinated biphenyls accumulate in marine animals, such as dab (Figure 1), with greater concentrations found higher up the food chain.

Figure1. The common dab (Limanda limanda), a key species used in contaminant monitoring (Source: Cefas).

Polychlorinated biphenyl compounds are extremely toxic to animals and humans, causing reproductive and developmental problems, damage to the immune system, interference with hormones and cause cancer. Seven specific compounds (CB28, CB52, CB101, CB118, CB138, CB153 and CB180) were recommended for monitoring by the European Union Community Bureau of Reference (European Commission, 2001). These were selected as indicators of wider polychlorinated biphenyl contamination due to their relatively high concentrations and toxic effects. The monitoring data are used to investigate trends in polychlorinated biphenyl concentrations and to compare concentrations against two sets of OSPAR assessment criteria: Background Assessment Concentrations and the Environmental Assessment Criteria. The Environmental Assessment Criteria for polychlorinated biphenyls in biota is derived from the Environmental Assessment Criteria for sediment and is called the EAC^passive. The values in sediment were set so that concentrations below the Environmental Assessment Criteria should not cause chronic effects in sensitive marine species and present no significant risk to the environment. Environmental Assessment Criteria are analogous to the Environmental Quality Standards used to assess contaminant concentrations in water (European Commission, 2008b), for example under the Water Framework Directive (European Commission, 2010). Background Assessment Concentrations are used to assess whether concentrations are near background values for naturally occurring substances and close to zero for man-made substances, the ultimate aim of the OSPAR Hazardous Substances Strategy.

Polychlorinated biphenyls (Figure 2) are industrial compounds with multiple industrial and commercial uses. It has been estimated that globally 1.3 million tonnes of polychlorinated biphenyl compounds have been produced (Breivik and others, 2007). Polychlorinated biphenyls have been used as coolants and lubricants in transformers, capacitors, and other electrical equipment. They have also been used as plasticisers and sealing agents in products such as rubber and especially in polyvinyl chloride plastics used to coat electrical wiring, adhesives, paints and inks. Although, the usage of polychlorinated biphenyls was generally banned over 30 years ago, they still exist in old electrical equipment and environmental media to which humans can be exposed. Polychlorinated biphenyls are expected to be present in electronic waste streams from which they can leach into the environment (Menad and others 1998). Human populations are exposed mainly via food, mostly from contaminated animal fats. Indoor air can also contribute to human exposure. Worldwide monitoring programs have shown that polychlorinated biphenyls are present in most samples of human milk (Pietrzak-Fiecko and others, 2005).

Figure 2. Polychlorinated biphenyls. (Source: Wikimedia Commons)

Polychlorinated biphenyls do not burn easily, are good insulators and very resistant (Bergman and others, 2012). These properties contribute greatly to polychlorinated biphenyls having become environmental contaminants which are regulated by the Stockholm Convention of Persistent Organic Pollutants adopted to European Union legislation in Regulation (EC) No 850/2004 (European Commission, 2004). The chemical inertness and heat stability properties that make polychlorinated biphenyls desirable for industry also protect them from destruction when the products in which they are used are discarded. These same properties enable residues to persist in the environment for long periods of time and to be transported worldwide when contaminated particulate matter travels through waters, precipitation, wind, and other physical forces (Jaward and others, 2004; Eckhardt and others, 2007; Gioia and others, 2008).

All polychlorinated biphenyls can induce formation of reactive oxygen species, genotoxic effects, immune suppression, an inflammatory response, and endocrine effects to various extents and through different pathways (Sepulveda and others, 2010; Lauby-Secretan and others, 2013). Of the 209 polychlorinated biphenyl congeners, the most toxic are the so-called ‘dioxin-like’ polychlorinated biphenyls: the four non-ortho (CB77, 81, 126 and 169) and eight mono-ortho (CB105, 114, 118, 123, 156, 157, 167 and 189). Only CB118 is monitored.

Due to their persistence, potential to bioaccumulate and toxicity they have been included on the OSPAR List of Chemicals for Priority Action (OSPAR Commission, 2004). OSPAR Commission (2004) presented a monitoring strategy for which contracting parties should continue to measure polychlorinated biphenyls under the OSPAR Co-ordinated Environmental Monitoring Programme on a mandatory basis in biota (fish and mussels) and sediments for temporal trends and spatial distribution, covering polychlorinated biphenyl congeners CB28, CB52, CB101, CB118, CB138, CB153 and CB180. Marine sediments, in particular those with a high organic carbon content, may accumulate hydrophobic compounds, like polychlorinated biphenyls, to considerably higher levels than those of the surrounding waters. The sampling strategy is defined by the purpose of the monitoring programme and the natural conditions of the region to be monitored. Typically sampling approaches include fixed-station sampling, stratified random sampling, or stratified fixed sampling. Muddy sediments, such as those containing a high proportion of fine material, are preferable for organic contaminant monitoring, although sieving of sediments may be an alternative (OSPAR Commission, 2002). Jepson and others (2016) found Europe's cetaceans to have levels of polychlorinated biphenyls that are among the highest found in the oceans, showing that despite the ban and decline in marine sediments and certain fish, polychlorinated biphenyls still persist at high levels in European cetaceans.

Assessment method

Assessment methodology for polychlorinated biphenyls in biota

This 2016 assessment of data from the Clean Seas Environmental Monitoring Programme describes the trends and status of contaminant concentrations in biota at monitoring stations around the UK. Assessments are made for many time series, each of a single contaminant in a single species at a single monitoring station. This section describes how the results of the individual time series are synthesised to assess status and trends at the biogeographic regional level. Specifically, it considers polychlorinated biphenyl concentrations in biota. The congeners assessed here were (with chemical abstracts service numbers provided in brackets): CB28 (CAS Nr. 7012-37-5), CB52 (CAS Nr. 35693-99-3), CB10 (CAS Nr. 37680-73-2), CB118 (CAS Nr. 31508-00-6), CB138 (CAS Nr. 35065-28-2), CB153 (CAS Nr. 35065-27-1) and CB180 (CAS Nr. 35065-29-3).

The regional assessment only considers coastal and offshore sampling stations and excludes estuarine stations. The results are, therefore, based on the monitoring data collected within the waters assessed under the Marine Strategy Framework Directive (European Commission, 2008a) and are used as part of the UK’s assessment of Contaminants.

The monitoring stations where there are suitable data are shown in Figure 3, with the purple circles showing stations where there is trend and status information for at least one polychlorinated biphenyl compound, and the blue circles showing stations where there is only status information. The areas delineated by the thinner black lines are the biogeographic regions; those delineated by the thicker black lines are the Marine Strategy Framework Directive sub-regions. The number of time series in each biogeographic region is given in Tables 1 and 2.

Figure 3. Trend and status (purple circles) and status only (blue circles) monitoring stations used to assess polychlorinated biphenyls concentrations in biota.

Table 1. Number of stations used in the UK polychlorinated biphenyls in biota trend assessment, by Marine Strategy Framework Directive sub-region.

Sub-region	Biogeographic region	CB28	CB52	CB101	CB118	CB138	CB153	CB180	Total
Greater North Sea	Northern North Sea	5	6	12	14	16	16	11	80
	Southern North Sea	1	3	8	8	8	8	6	42
	E Channel	0	2	2	2	2	2	2	12
	total	6	11	22	24	26	26	19	134
Celtic Seas	Scottish Continental Shelf	0	0	0	1	0	2	0	3
	Minches & W Scotland	2	3	4	4	4	5	2	24
	Irish Sea	15	15	26	29	26	29	18	158
	W Channel & Celtic Sea	0	0	2	2	2	2	2	10
	total	17	18	32	36	32	38	22	195

Table 2. Number of stations used in the UK polychlorinated biphenyls in biota trend assessment, by Marine Strategy Framework Directive sub-region.

Sub-region	Biogeographic region	CB28	CB52	CB101	CB118	CB138	CB153	CB180	Total
Greater North Sea	Northern North Sea	20	16	22	21	20	24	17	140
	Southern North Sea	9	8	9	9	9	9	9	62
	E Channel	2	2	2	2	2	2	2	14
	total	31	26	33	32	31	35	28	216
Celtic Seas	Scottish Continental Shelf	5	2	7	7	3	8	2	34
	Minches & W Scotland	8	7	16	19	11	18	7	86
	Irish Sea	29	30	32	34	32	32	29	218
	W Channel & Celtic Sea	2	2	2	2	2	2	2	14
	total	44	41	57	62	48	60	40	352