• Latest Version, 2024 Assessment

Status and Trends of Polybrominated diphenylethers (PBDEs) in Biota and Sediment

Biota sites have good geographical coverage, sediment sites are more limited. PBDEs in sediment and biota have been stable (49% of assessed stations) or declining (51%). Concentrations are below thresholds (Federal Environmental Quality Guidelines, FEQGs) for all assessment areas and congeners, except BDE209 in Irish Sea sediment, and should not cause adverse effects to marine wildlife. 

Background

Polybrominated diphenylethers (PBDEs) are a group of congeners, mainly used as flame retardants in a variety of materials including plastics, textiles, electronic products, building materials, furnishings, and vehicles (Figure 1). 

PBDEs may enter the environment through emissions from manufacturing processes, evaporation from products that contain PBDEs, recycling wastes and leachate from waste disposal sites (Figure 2). They are widespread and have been detected in air, sediments, surface waters, and fish and other marine animals. 

Figure 1: PBDEs are a group of compounds mainly used as flame retardants in a variety of materials, including furnishings 

Figure 2: Land-based waste dumping site with potential leakage of PBDEs from products containing these flame-retardants 

PBDEs are toxic, they take a long time to degrade and have the potential to accumulate in fish or shellfish (taken up either directly from the surrounding water or indirectly via food). As a result, some PBDEs were banned or restricted within the European Union starting in 2004. Further, production of some groups of PBDEs was banned in 2009 by 180 countries that are signatories to the Stockholm Convention. 

The spatial distribution of PBDEs in the marine environment is variable. They do not dissolve in water but bind strongly to soil and sediment. As a result, PBDEs in sediment are not very mobile. Some PBDE congeners tend to accumulate in fish and shellfish more than others. PBDE are known to affect the nervous, immune and endocrine systems of birds and mammals. 

Due to their persistence in the marine environment, their potential to bioaccumulate and their toxicity, monitoring of PBDEs in fish, shellfish and sediment, are required for the UK Marine Strategy. This indicator is used to assess progress against the target set out in the UK Marine Strategy Part One (which requires that concentrations of substances identified within relevant legislation and international obligations are below levels at which adverse effects are likely to occur).

Further information

Polybrominated diphenyl ethers (PBDEs) are a group of 209 different congeners. Their main use is as flame retardants in different types of material including plastics, textiles, and electronic products. The three major commercial PBDE mixtures that have been produced are pentaBDE, octaBDE and decaBDE. Globally, decaBDE is the most widely used. 

PBDEs are flame-retardants of the additive type, which means that they are physically combined with the material being treated rather than chemically combined (as in reactive flame retardants) and are more likely to diffuse out of the products (European Commission, 2001, 2003; Hutzinger and Thoma, 1987 cited in Alaee and others., 2003). Leakage of PBDE occurs during production, use, or disposal of products, and PBDEs are mainly transferred to the ocean via rivers and atmospheric transport (OSPAR, 2009). The presence of PBDEs in air samples from Arctic Canada, for example, provides evidence of their long-range transport (de Wit, 2002). 

The advantage of these compounds for industry is their high resistance to acids, bases, heat, light, and reducing and oxidising compounds. However, this becomes a disadvantage in the environment where they persist for a very long time. Increased concentrations of these compounds have been measured in environmental samples since the 1970s (de Wit, 2002). PBDEs are toxic, are persistent in the environment and can bioaccumulate. As a result, the PBDE substances included in the commercial pentaBDE- and octaBDE-mixtures were banned in the European Union in 2004, and since 2009 have been listed under the Stockholm Convention (2009), meaning that a majority of countries worldwide have agreed to phase out these compounds. 

PBDE has been reported to be neurotoxic and immunotoxic, and to affect thyroid hormone receptors in sensitive human populations (de Wit, 2002). Effects on behaviour learning (Eriksson and others, 2006a, b) and hormonal function (Legler, 2008) have been reported in mammals, while reduced reproductive success has been documented in birds (Fernie and others, 2009). 

Smaller PBDE molecules are more toxic and bioaccumulate more readily than larger molecules. Debromination of highly brominated BDEs (such as decaBDE) to these smaller forms is a possibility and justifies monitoring based on a broad set of congeners. All PBDEs are hydrophobic or ultra-hydrophobic substances that do not dissolve in water and bind strongly to soil or sediment (PBDEs are more mobile in the atmosphere because they attach to airborne particulates; dust, soot, smoke, and liquid droplets). As a result, PBDEs in sediment are not very mobile and unlikely to volatilise from the water phase. The higher the degree of bromination, the lower the water solubility. PBDEs can be photodegraded in the environment (de Wit 2004; Pan and others, 2016). 

The use of substance groups pentaBDE and octaBDE mixtures has been banned in the European Union since 2004 (Commission regulation (EC) No 552/2009). TetraBDE, pentaBDE, hexaBDE and heptaBDE were listed under the Stockholm Convention in 2009 and decaBDE in 2017 (Stockholm Convention, 2009; 2022; EU,2019). As a result, Parties to the Stockholm Convention must act to eliminate the production and use of these compounds. Although there is no production within the European Union, existing stocks of PBDE-containing products may still act as a diffuse source. 

The European Foods Safety Authority recommended eight substances (congeners) of certain interest to monitor: triBDE-28, tetraBDE-47, pentaBDE-99, pentaBDE-100, hexaBDE-153, hexaBDE-154, heptaBDE-183 and decaBDE-209 (EFSA, 2006). These were selected on the basis of analytical feasibility for their measurement, production volumes (as registered in 2006), their occurrence in food and feed, their persistence in the environment and their toxicity. For environmental monitoring within the European Union, environmental quality standards have been derived for these congeners excluding BDE-183 and BDE-209 (European Commission, 2011). 

Assessment method

Assessment criteria 

Two assessment criteria are used to assess PBDE concentrations in sediment and biota: Background Assessment Concentrations (BACs) and Federal Environmental Quality Guidelines (FEQGs). 

BACs were developed by OSPAR and for synthetic substances used for testing whether concentrations are close to zero - the ultimate aim of the OSPAR Hazardous Substances Strategy 2010-2020. BACs are statistical tools that for synthetic substances are defined in relation to low concentrations, which enable statistical testing of whether observed concentrations could be considered to be near zero. BACs are calculated according to the method set out in OSPAR (2020a; 2021). 

FEQGs are used to assess the status of both sediment and biota (fish and shellfish). Concentrations below the FEQGs should not cause any chronic effects on marine organisms. They were developed under the Canadian Environmental Protection Act from 1999, are available for individual PBDE congeners in sediment and biota and were derived from ecotoxicological testing (Environment Canada, 2013).  FEQGs are described in detail in the OSPAR (2020b) background document for sediment and biota. 

An alternative to the use of the FEQGs for biota is the Water Framework Directive (WFD) Environmental Quality Standards (EQS). The EQS are based on the human health QS (which was the lower of the calculated QSs). Due to the method used to assign the fish EQS value for PBDE (0.0085 μg kg-1 wet weight), it is very low compared to typically reported environmental concentrations in biota (even in remote environments, e.g., the Arctic). Most PBDE data for biota therefore exceed the EQS value (OSPAR 2020b). The EQS for PBDE is also low compared to the analytical capabilities of several monitoring laboratories. The QS for secondary poisoning is more similar to the FEQG (for BDE47; 44 μg kg-1 wet weight). However, while the FEQGs are available for individual congeners the EQS are based on a sum of six PBDE congeners some of which are missing from some of OSPAR’s Coordinated Environmental Monitoring Programme (CEMP) data series and the QS provides a less stringent assessment of the more toxic homologues (OSPAR 2020b). The FEQGs were therefore chosen as the principal assessment criteria, with EQS used as a supporting assessment criteria. 

For CEMP the organic contaminant concentrations in sediment are normalised to 2.5% organic carbon (the FEQGs were multiplied by a factor 2.5 as they were for sediment with 1% TOC).  

For fish, the FEQG is adjusted to a lipid weight basis (assuming the whole fish used in the toxicity trials have a 5% lipid content) by multiplying the FEQG (on a wet weight basis) by 20 (Table a, OSPAR 2020b). Fish concentrations are then usually assessed on a lipid weight basis. However, if the typical lipid content for the species / tissue is < 3% (https://dome.ices.dk/OHAT/trDocuments/2022/help_ac_basis_conversion.html), fish concentrations are assessed on a wet weight basis, with the FEQGs adjusted to a wet weight basis using the conversion factors found at https://dome.ices.dk/OHAT/trDocuments/2022/help_ac_basis_conversion.html. Shellfish concentrations are assessed on a dry weight basis (since too few samples have supporting lipid weight measurements) with the FEQGs adjusted to a dry weight basis using the conversion factors found at https://dome.ices.dk/OHAT/trDocuments/2022/help_ac_basis_conversion.html 

Table A: Background Assessment Concentrations (BACs), Federal Environmental Quality Guidelines (FEQGs) and EU EQS for polybrominated diphenyl ethers (PBDEs) in sediment and biota (fish and shellfish) 

	BAC	BAC	FEQG	FEQG	EU EQS
	Fish and shellfish   (μg/kg lw)	Sediment    (μg/kg dw)	Fish and shellfish   (μg/kg lw)	Sediment    (μg/kg dw)	Fish   (µg/kg ww)
Determinant
BDE28	0.065	0.05	2400	110
BDE47	0.065	0.05	880	97.5
BDE66	0.065	0.05		97.5
BDE85	0.065	0.05		1
BDE99	0.065	0.05	20	1
BDE100	0.065	0.05	20	1
BDE126	0.065	0.05
BDE153	0.065	0.05	80	1 100
BDE154	0.065	0.05	80	1 100
BDE183	0.065	0.05		14 000
BDE209	0.065	0.05		47.5
Sum BDE 28, 47,99, 100, 153 and 154					0.0085

Table A notes: dw – dry weight; lw – lipid weight. notes: for sediment BACs are normalised to 2.5% organic carbon. For biota BACs and FEQGs are converted to other bases (ww – wet weight, dw) using species-specific conversion factors (https://dome.ices.dk/OHAT/trDocuments/2022/help_ac_basis_conversion.html ). 

Sediment, fish, and shellfish status 

Similar analyses explored status at the assessment area scale. Two summary measures were considered: the log ratio of the fitted concentration in the last monitoring year to the FEQG; and the log ratio of the fitted concentration in the last monitoring year to the BAC. Impacted monitoring sites were also included in these analyses. 

Finally, concentration profiles across congeners at the assessment area scale were explored using the fitted log concentration in the last monitoring year. 

The number of time series used in each Marine Strategy sub-region and UK biogeographic region assessed is shown in Table B. 

Table B: Number of monitoring sites within each Marine Strategy sub-region and UK biogeographic region used in the assessment of temporal trends and status 

		Sediment	Sediment	Fish and shellfish	Fish and shellfish
Marine Strategy sub-Region	UK region	Trends	Status	Trends	Status
Greater North Sea	Northern North Sea	7	14	9	15
Greater North Sea	Southern North Sea	3	10	9	9
Greater North Sea	East Channel	2	4	2	3
Celtic Sea	Scottish Continental Shelf	0	0	0	0
Celtic Sea	Minches and Western Scotland	3	5	2	3
Celtic Sea	Irish sea	8	17	15	17
Celtic Sea	West Channel and Celtic Sea	2	2	3	3

Sediment and biota (fish and shellfish) temporal trends 

For each PBDE congener and monitoring site with observations (see specifics below), contaminant temporal trends and status were assessed using the methods described in the contaminants’ online assessment tool (http://dome.ices.dk/ohat/?assessmentperiod=2023). The results from the site-specific analyses were then synthesised to create a regional assessment based on mean concentration and trends within the 7 UK sub-regions.  

The temporal trend assessments included data from those monitoring sites that were representative of general conditions and excluded data from those monitoring sites impacted by a point source of PBDE.  Only stations with at least one year with data in the period 2016-2021 and at least five years of data along the whole time series are included in the regional assessment. The analysis was further restricted to assessment areas where there were at least three monitoring sites with trend information and where those monitoring sites had a reasonable geographic spread. For the temporal trend analysis of biota a few bird eggs and mammals time series from northerly regions were used as supplement to the fish and shellfish data. These are limited to the trend analysis and not used for the status as the thresholds for status analysis are specific to fish (Environment Canada, 2013). For sediment, the PBDE concentrations are normalised to account for changes in the bulk physical composition of the sediment, such as particle size distribution or organic carbon content, for all areas included in the sediment assessment. 

The temporal trend for each PBDE congener at each monitoring site was summarised by the estimated annual change in log concentration, with its associated standard error. The annual change in log concentration was then modelled by a linear mixed model with a fixed effect: 

• OSPAR contaminants assessment areas 

and random effects: 

• congener + congener: OSPAR contaminants assessment area + monitoring site + congener: monitoring site [biota only] + residual variation. 

The choice of fixed and random effects was motivated by the assumption that the PBDE congeners would have broadly similar trends, since they have similar sources. Thus, the fixed effect measures the common trend in PBDE congener in each contaminant’s assessment area and the random effects measure variation in trends: 

• between congeners common across OSPAR contaminants assessment areas (congener). 

• between congeners within OSPAR contaminants assessment areas (congener: contaminants assessment area). 

•  between congeners but common across tissues and species within monitoring sites (congener: monitoring site); and 

• residual variation. 

The residual variation is made up of two terms: the variation associated with the estimate of the trend from the individual time series, which is assumed known (and given by the square of the standard error); and a term which accounts for any additional residual variation not explained by the other fixed and random effects. 

Evidence of trends in PBDE concentrations at the assessment area scale was then assessed by plotting the estimated fixed effects with pointwise 95% confidence intervals. Differences between congeners were explored by plotting the predicted trend for each congener and for each congener / assessment area combination with pointwise 95% confidence intervals. 

Differences in methodology used for the MS 2018 compared with the UK MS 2024 

This assessment includes the assessment of PBDEs in sediment and biota. These were assessed separately for the 2018 MS assessment. In the UK MS 2024 FEQGs are used to assess the status of both sediment and biota (Table A). No assessment criteria were used in the MS 2018. 

Results

Polybrominated Diphenyl Ether (PBDE) concentrations were measured in sediment and biota from monitoring sites throughout much of the UK biogeographic regions (excluding estuarine sites) (Figure 3 and Figure 4). Biota is mostly fish with some shellfish. For biota there is reasonable coverage with status and trends available for four of the seven UK biogeographic regions. Across stations, observations for PBDE in biota spanned the period 2003-2021 and for PBDE in sediment the period 2006-2021. 

Figure 3: Monitoring sites used to assess PBDE concentrations in sediment in each Marine Strategy region (dark lines) and biogeographic subregion (light lines). The filled circles indicate sites where there are sufficient data to assess both status and trends; the open circles indicate sites where only status can be assessed. There are additional sites that are not shown because they were not sampled often enough. 

Figure 4: Monitoring sites used to assess PBDE concentrations in fish and shellfish in each Marine Strategy region (dark lines) and biogeographic subregion (light lines). The filled circles indicate sites where there are sufficient data to assess both status and trends; the open circles indicate sites where only status can be assessed. There are additional sites that are not shown because they were not sampled often enough. 

PBDE concentrations in sediments and fish and shellfish were compared to the OSPAR Background Assessment Concentrations (BAC) and the Federal Environmental Quality Guidelines (FEQG). Concentrations below the FEQG means that there should be no chronic effects on marine organisms. FEQGs are given for individual congeners and only a few congeners are missing FEQG assessment criteria. PBDE concentrations in fish and sediment were also compared with the Water Framework Directive (WFD) Environmental Quality Standard (EQS) which is based on human health risk (hh). 

Status Assessment 

To make an overview assessment of the status of PBDEs, the mean concentration relative to the FEQG or BAC across all PBDE congeners was used. Mean PBDE concentrations in sediment and biota (fish and shellfish) are statistically significantly below the FEQGs in all contaminants’ assessment areas (Figure 5 and Figure 6). Therefore, adverse biological effects in marine species are unlikely. Concentrations in sediments are lowest in Minches and Western Scotland and in biota in Western Channel and Celtic Sea. No assessment area had background concentrations (i.e., significantly below BAC) for either sediment (BAC: 0.05 μg/kg dw) or biota (BAC: 0.065 g/kg lw). 

Figure 5: The mean PBDE concentration (averaged over PBDEs) (coloured circles) in sediment in each biogeographic region relative to the Federal Environmental Quality Guideline (FEQG). A value of 1 occurs when the mean concentration equals the FEQG. The horizontal line indicates the upper one-sided 95% confidence limit on the mean. The mean concentration is significantly below the FEQG (p < 0.05) if its upper confidence limit is less than 1. The dark blue circle indicates that the mean concentration is significantly below the FEQG (p < 0.05) but is not also significantly below the Background Assessment Concentration. 

Figure 6: The mean PBDE concentration (averaged over PBDEs) (coloured circles) in fish and shellfish in each biogeographic region relative to the Federal Environmental Quality Guideline (FEQG). A value of 1 occurs when the mean concentration equals the FEQG. The horizontal line indicates the upper one-sided 95% confidence limit on the mean. The mean concentration is significantly below the FEQG (p < 0.05) if its upper confidence limit is less than 1. The dark blue circle indicates that the mean concentration is significantly below the FEQG (p < 0.05) but is not also significantly below the Background Assessment Concentration.

However, a completely different picture is presented when fish and shellfish concentrations are compared with the Quality Standard human health (QShh) (see Figure 7). Most series are an order of magnitude above the QShh which suggests that there is a risk associated with consumption of fish and shellfish, but this is not supported by international food regulations, which have not deemed it necessary to set food safety guidelines. 

Figure 7: The mean PBDE concentration (averaged over PBDEs) (coloured circles) in fish and shellfish in each biogeographic region relative to the Environmental Quality Standard (EQS). A value of 1 occurs when the mean concentration equals the EQS. The horizontal line indicates the upper one-sided 95% confidence limit on the mean. The mean concentration is significantly below the EQS (p < 0.05) if its upper confidence limit is less than 1. The red circle indicates that the mean concentration is not significantly below the EQS (p > 0.05). 

Trend assessment 

Temporal trends of PBDE concentrations in sediments and biota were assessed in areas where there were at least five years of data. This resulted in the assessment of three areas for sediment and ten for biota (Figure 8 and Figure 9). No increasing trends were detected. Decreasing trends were observed in sediment from the Irish Sea and in all assessed biota time series (Northern North Sea, Southern North Sea, the Irish Sea and the Western Channel and Celtic Sea). In sediment in the other areas assessed no statistically significant trends were observed for the averaged PBDE data. The average yearly decline is up to 12% (the Irish Sea) and the general decline for most assessment areas suggest that PBDE concentrations are decreasing across the UK especially in biota. 

When compared to the Marine Strategy 2018 biota assessment, a change in average rate of decline is seen for the Irish Sea, Northern North Sea and Southern North Sea. In the Marine Strategy 2018 assessment these areas showed significant decreasing trends of -13.9%, -12.3 and -16.3% yearly change in concentration, respectively, whilst in the current analysis the decrease has slowed to -12.4%, -6.8% and -7.9% per year, respectively, though confidence limits overlap for the two assessments. This could indicate that, as concentrations are getting lower in these areas, it gets harder to see the trends or that the concentrations are stabilising (input closer to output). For sediments, in the Marine Strategy 2018 assessment, no region had a significant downward trend as confidence limits overlapped with zero, whereas the Irish Sea has a significant average decrease of 5.6% per year in the latest assessment.  

Figure 8: The percentage annual change (circle, triangle) in the mean PBDE concentration (averaged over PBDEs) in sediment in each biogeographic region. The horizontal line is the associated 95% confidence interval. There is a significant change in mean concentration (p < 0.05) if the confidence interval does not cut the vertical line at 0. Circle: no significant change in mean concentration (p > 0.05). Downward triangle: significant decrease in mean concentration (p < 0.05). 

Figure 9: The percentage annual change (triangles) in the mean PBDE concentration (averaged over PBDEs) in fish and shellfish in each biogeographic region. The horizontal line is the associated 95% confidence interval. There is a significant change in mean concentration (p < 0.05) if the confidence interval does not cut the vertical line at 0. The downward triangle indicates that the mean concentration is significantly decreasing (p < 0.05). 

Further information

Mean sediment PBDE concentration for the various congeners (normalised to organic carbon) relative to the BAC for each assessment area are shown in Figure A. Mean congener sediment concentrations are above BAC except for BDE28 in the Irish Sea and BDE85 and BDE28 in the Northern North Sea, Southern North Sea and Irish Sea. For fish and shellfish (Figure B), the mean concentration of all congeners were above BAC in all assessment areas. 

Figure A: The mean concentration of individual PBDEs (coloured circles) in sediment in each biogeographic region relative to the Background Assessment Concentration (BAC). A value of 1 occurs when the mean concentration equals the BAC. The horizontal line indicates the upper one-sided 95% confidence limit on the mean. The mean concentration is significantly below the BAC (p < 0.05) if its upper confidence limit is less than 1. Light blue: the mean concentration is significantly below the BAC (p < 0.05). Dark blue: the mean concentration is significantly below the Federal Environmental Quality Guideline (FEQG) (p < 0.05) but not the BAC. Red: the mean concentration is not significantly below the FEQG (p > 0.05). 

Figure B: The mean concentration of individual PBDEs (coloured circles) in fish and shellfish in each biogeographic region relative to the Background Assessment Concentration (BAC). A value of 1 occurs when the mean concentration equals the BAC. The horizontal line indicates the upper one-sided 95% confidence limit on the mean. The mean concentration is significantly below the BAC (p < 0.05) if its upper confidence limit is less than 1. Dark blue: the mean concentration is significantly below the Federal Environmental Quality Guideline (FEQG) (p < 0.05) but not the BAC. Amber: the mean concentration is not significantly below the BAC (p > 0.05) and no FEQG is available. 

All mean congener PBDE concentrations in sediment were significantly below the FEQG in all the assessment areas except BDE209 in the Irish Sea. While the other sediment assessment areas do not have BDE209 above the FEQGs they are still a factor 10-100 above the concentrations found for the other congeners (Figure A). This could be a result of the relative lower FEQG for PBDE209 than other congeners (Table A). Alternatively, higher historic exposure and/or a longer lifetime in the sediments for BDE209 due to high particle affinity and low biodegradability (Söderstrom and others., 2004) could also impact the result. All mean congener PBDE concentrations in biota were significantly below the FEGQ in all assessment areas. Overall, no adverse biological effects are expected based on the status assessment except in the Irish Sea sediment due to BDE209. 

Temporal trends in PBDE concentrations in sediment and biota were assessed in areas where there were at least five years of data. The percentage yearly change for PBDE in each assessment area is shown in Figure c and Figure d. In most regions trends were stable or downwards. For sediments all PBDE congeners show a downward trend in the Irish Sea.  

Figure C: The percentage annual change (circle, triangle) in the mean concentration of individual PBDEs in sediment in each biogeographic region. The horizontal line is the associated 95% confidence interval. There is a significant change in mean concentration (p < 0.05) if the confidence interval does not cut the vertical line at 0. Circle: no significant change in mean concentration (p > 0.05). Downward triangle: significant decrease in mean concentration (p < 0.05). 

Figure D: The percentage annual change (circle, triangle) in the mean concentration of individual PBDEs in fish and shellfish in each biogeographic region. The horizontal line is the associated 95% confidence interval. There is a significant change in mean concentration (p < 0.05) if the confidence interval does not cut the vertical line at 0. Circle: no significant change in mean concentration (p > 0.05). Downward triangle: significant decrease in mean concentration (p < 0.05). 

For fish and shellfish all PBDE congeners show a downward trend in all areas that could be assessed, except for BDE28 in Northern North Sea and BDE154 in the Western Channel and Celtic Sea.  

A summary of individual time series results per monitoring site (across the OSPAR Maritime Area) for PBDE concentrations in sediment and biota is presented here (https://dome.ices.dk/OHAT/?assessmentperiod=2023). In summary, at 17 out of 430 sediment monitoring series (individual congeners) across the OSPAR Maritime Area, mean concentrations of PBDE in sediment are above the FEQG. In no site out of 87 sediment monitoring series (individual congeners) have concentrations increased over the assessment period, while 22 sites showed a downward trend. 

For fish and shellfish of 338 series (individual congeners), only 5 were above the FEQG and none out of 183 mean concentrations have increased over the assessment period, while 117 showed downward trends.  It should be noted that not all individual time series results are included in the assessments (see number of time series used in each assessment area in Table b), due to the criteria set out in the assessment methods. 

Confidence Assessment 

There is high confidence in the quality of the data used for this assessment. The data have been collected over many years using established sampling methodologies. There is sufficient temporal and spatial coverage in most regions, though the Eastern Channel and Scottish Continental shelf regions could not be assessed. The synthesis of monitoring site data for the assessment area scale are based on established and internationally recognised protocols for monitoring and assessment per monitoring site, therefore there is also high confidence in the methodology.

Conclusions

PBDE concentrations are stable or declining across the UK area. While the concentrations are still above the BAC, they are, in general below the FEQG. PBDE concentrations should therefore not cause adverse effects to marine organisms. Concentrations are well above the WFD QShh, but this is considered to be overly precautionary and does not mean there is a risk from consumption of seafood. 

Further information

PBDE concentrations in both sediment and biota have in general been stable (49% of assessed stations) or declining (51% of assessed stations) across the UK area for the past 20 years.   

Within the areas assessed, there is no reason to suspect general chronic effects on marine organisms as concentrations are in general below the FEQG. As the time series analysis further indicates stable to declining trends for all areas (averaged PBDEs) there is no reason to suspect that this will change over the coming years. However, no assessment areas had concentrations below the BAC (close to zero) and the environment is therefore still impacted by these man-made substances, although this impact is declining. 

Knowledge gaps

There is a lack of monitoring data for shellfish, as many sites were in estuarine waters and therefore not included in the assessment or haven’t reached the number of data points required to be assessed yet. In some sub-regions (Eastern Channel and Scottish Continental Shelf) there are insufficient monitoring sites with a good geographic spread for a status and trends assessment.  

Due to their bioaccumulation potential, there is a need to make PBDE concentrations measured in different biota (shellfish and fish) comparable. 

The EU-EQS requires further investigation (or revision) before being used as the primary assessment criteria in UK MS assessment. 

Further information

PBDE bioaccumulate, some congeners more than others (Environment Canada, 2013). A strategy is needed to make data from different monitoring species, such as shellfish and different trophic level fish, comparable. 

The method used to assign the biota Environmental Quality Standard (EQS) that is derived within European Union to protect marine and freshwater ecosystems, as well as humans, from adverse effects of chemicals in the aquatic environments, has resulted in a value for PBDE that is very low compared to typically reported environmental concentrations in biota (even for pristine areas). It therefore requires further investigation before it can be used in the OSPAR Maritime Area. Further, it is recommended to create congener specific values as the toxicity varies greatly between congeners as shown by the work on the FEQGs done by Environment Canada (2013; Table A). 

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Legler, J. (2008) New insights into the endocrine disrupting effects of brominated flame retardants. Chemosphere, 73, 216-222. 

OSPAR (2009) Background Document on Certain Brominated Flame Retardants –Polybrominated Diphenylethers, Polybrominated Biphenyls, Hexabromo Cyclododecane, Update 2009 

OSPAR (2017). Intermediate Assessment 2017. Available at: https://oap.ospar.org/en/ospar-assessments/intermediate-assessment-2017/ 

OSPAR (2020a). Background document on background assessment concentrations for Polybrominated Diphenyl Ethers (PBDE) in sediment, OSPAR Commission publication 761/2020. https://www.ospar.org/documents?v=42738 

OSPAR (2020b). Background document for Canadian Federal environmental Quality Guidelines (FEQGs) for Polybrominated Diphenyl Ethers (PBDEs) in sediment and biota, OSPAR Commission publication 760/2020. https://www.ospar.org/documents?v=42746 

OSPAR (2021). Background document on Background Assessment Concentrations (BAC) for Polybromintaed Diphenyl Ethers (PBDE) in fish and shellfish, OSPAR Commission publication number 796/2021. https://www.ospar.org/documents?v=46274 

Pan, Y., D.C.W. Tsang, Y. Wang, Y. Li, X. Yang (2016). The photodegradation of polybrominated diphenyl ethers (PBDEs) in various environmental matrices: Kinetics and mechanisms. Chemical Engineering Journal 297, 74-96 

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Authors

Jon Barber¹ 

Centre for Environment, Fisheries and Aquaculture Science 

Assessment Metadata

Please contact marinestrategy@defra.gov.uk for metadata information

Assessment metadata

Assessment Type
	UK Marine Strategy
	Contaminants
	Status and Trends of Polybrominated diphenylethers (PBDEs) in Biota and Sediment
Point of contact email	marinestrategy@defra.gov.uk
Metadata date	Wednesday, January 1, 2025
Title
Resource abstract
Linkage
Conditions applying to access and use
Assessment Lineage
Dataset metadata
Dataset DOI	The Scottish Government, Marine Directorate. 2025.https://doi.org/10.7489/12541-1

The Metadata are “data about the content, quality, condition, and other characteristics of data” (FGDC Content Standard for Digital Geospatial Metadata Workbook, Ver 2.0, May 1, 2000).

Metadata definitions

Assessment Lineage - description of data sets and method used to obtain the results of the assessment

Dataset – The datasets included in the assessment should be accessible, and reflect the exact copies or versions of the data used in the assessment. This means that if extracts from existing data were modified, filtered, or otherwise altered, then the modified data should be separately accessible, and described by metadata (acknowledging the originators of the raw data).

Dataset metadata – information on the data sources and characteristics of data sets used in the assessment (MEDIN and INSPIRE compliance).

Digital Object Identifier (DOI) – a persistent identifier to provide a link to a dataset (or other resource) on digital networks. Please note that persistent identifiers can be created/minted, even if a dataset is not directly available online.

Indicator assessment metadata – data and information about the content, quality, condition, and other characteristics of an indicator assessment.

MEDIN discovery metadata - a list of standardized information that accompanies a marine dataset and allows other people to find out what the dataset contains, where it was collected and how they can get hold of it.