Tendances des teneurs en polybromodiphényléthers (PBDE) dans le poisson, les mollusques et crustacés

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 products that have been produced are pentaBDE, octaBDE and decaBDE, containing mixtures of different PBDEs relating to the number of bromines attached to the compound. 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 et al., 2003). Leakage of PBDEs occurs during production, use, or disposal of such products, and PBDEs are mainly transferred to the ocean via rivers and through diffuse distribution in the atmosphere (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 great disadvantage in the environment where they persist for very long periods. Increased concentrations of these compounds have been measured in environmental samples since the 1970s (de Wit, 2002). PBDEs are toxic, persist 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 as neurotoxic, immunotoxic and to affect thyroid hormone receptors in sensitive human populations (de Wit, 2002). Effects on behaviour and learning (Eriksson et al., 2006a,b) and hormonal function (Legler, 2008) have been reported in mammals, while reduced reproductive success has been documented in birds (Fernie et al., 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. Therefore, only low concentrations of decaBDE are found in fish, in contrast to lower-brominated BDEs, which are more commonly found in marine organisms. PBDEs can potentially photodegrade in the environment (Nyberg et al., 2013).

The use of substance groups pentaBDE and octaBDE has been banned in the European Union since 2004 (Commission regulation (EC) No 552/2009). At present the use of decaBDE is only restricted in electrical and electronic products (European Court of Justice, 2008). However, decaBDE is no longer produced within EU (UNEP, 2014). Although there is no production within the European Union, existing stocks of PBDE-containing products may still act as a diffuse source.

In 2009, tetraBDE, pentaBDE, hexaBDE and heptaBDE were listed under the Stockholm Convention (2009). As a result, Parties to the Convention must take action to eliminate the production and use of these compounds.

The Committee for Socio-economic Analysis (SEAC) adopted the proposal from the European Chemicals Agency (ECHA) to restrict the use of decaBDE as a flame-retardant in plastics and textiles. SEAC confirmed its draft Opinion of June 2015, that the proposed restriction is the most appropriate European Union-wide measure in terms of its socio-economic cost benefit ratio. Having considered the 14 comments received during the public consultation on the draft Opinion, SEAC supported additional derogations for military aircraft, road vehicles, spare parts for machinery, and agricultural and forestry vehicles.

The European Foods Safety Authority recommended these eight substances 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).

PBDE concentrations in biota are calculated but not assessed because there are no OSPAR Background Assessment Concentrations (BACs) or Environmental Assessment Criteria (EACs) developed with which to assess status. There is an Environmental Quality Standard (EQS) derived within European Union to protect marine and freshwater ecosystems as well as humans from adverse effects of chemicals in the aquatic environments. However, the EQS is set for fish at trophic level four and the normalisation process required for OSPAR contaminant data to trophic level four has not yet been agreed.

For the QSR2010, data analysed for the period 2000–2005 show widespread contamination of the marine environment with PBDEs in all components of marine ecosystems. Regular monitoring of PBDEs in the biota commenced at an OSPAR scale under the Coordinated Environmental Monitoring Programme (CEMP) in 2008.

Assessment Area Results

Concentrations of six polybrominated diphenyl ether (PBDE) congeners (BDE-28, BDE-47, BDE-99, BDE-100, BDE-153, BDE-154) are measured in biota samples (fish, mussels and oysters). The number of time series used in each assessment area is shown in Table a. None of the areas in Arctic Waters were considered to have enough monitoring sites to give sufficient information for an assessment. Monitoring sites defined as polluted and assessment areas with too few monitoring sites were excluded from the assessment. The data were used to investigate temporal trends in PBDE concentrations and to compare concentrations and patterns between assessment areas.

No status assessment was made for the PBDEs in biota.

Figure ashows the estimated mean PBDE concentration for each assessment area, showing concentrations for the most recent year of available data (usually 2015). Mean PBDE concentrations are all <1 µg/kg wet weight. The assessment areas showing the highest concentrations were the English Channel, Northern North Sea, Southern North Sea and the Irish Sea. The lowest concentrations were found in the Iberian Sea. However, the species monitored differ between assessment areas and this may be reflected in the overall mean for a given area. Samples from the Iberian Sea, the assessment area with the lowest mean PBDE concentration, are taken only from mussels, which is likely to explain the low mean concentrations of PBDEs since mussels across the assessment areas show lower PBDE concentrations than fish on a wet weight basis. The pattern is similar between assessment areas with BDE-47, a tetra-brominated congener (one of the two main components in the penta-commercial mixture) dominating.

Temporal trends in PBDE concentrations were assessed in areas where there were more than five years of data. The results indicate downward trends in the majority of assessment areas (Figure 3). Downward trends are seen in the Southern North Sea, Northern North Sea, English Channel, Irish and Scottish West Coast, Irish Sea, and Iberian Sea. The PBDE congener BDE-99 (the other main congener in the penta-commercial mixture) consistently shows the largest annual decrease in all assessment areas.

Individual Time Series Results per Monitoring Site

A summary of individual time series results at monitoring sites across the OSPAR Maritime Area for PBDEs in biota is presented here http://dome.ices.dk/osparmime2016/regional_assessment_biota_organo-bromines.html. In summary, in 11 out of 339 monitoring sites, mean concentrations of PBDE in biota increased over the assessment period (1996–2015). It should be noted that not all individual time series results are included in the area assessments (see number of time series used in each assessment area in Table a), in accordance with the criteria set out in the Assessment Methods.

Confidence Assessment