The status of the Baltic Sea marine environment in terms of contamination by hazardous substances is assessed using several core indicators. Each indicator focuses on one important aspect of the complex issue. In addition to providing an indicator-based evaluation of the status of the Baltic Sea in terms of concentrations of hexabromocyclododecane (HBCDD) in the marine environment, this indicator along with the other hazardous substances core indicators is used to develop an overall integrated assessment of contamination status.
The core indicator on HBCDD concentrations addresses the Baltic Sea Action Plan's (BSAP) hazardous substances segment's ecological objectives 'Concentrations of hazardous substances close to natural levels' and 'All fish safe to eat'.
The core indicator is relevant to the following specific BSAP commitment:
Agree by 2009, if relevant assessments show the need, to initiate adequate measures such as the introduction of use restrictions and substitutions in the most important sectors identified by the Contracting Parties and taking as a starting point the HELCOM list of substances or substance groups of specific concern to the Baltic Sea (in which HBCDD is included).
The core indicator also addresses the following qualitative descriptors of the MSFD for determining good environmental status (European Commission 2008b):
Descriptor 8: 'Concentrations of contaminants are at levels not giving rise to pollution effects' and
Descriptor 9: 'Contaminants in fish and other seafood for human consumption do not exceed levels established by Community legislation or other relevant standards'.
and the following criteria of the Commission Decision (European Commission 2010):
Criterion 8.1 (concentration of contaminants)
Criterion 9.1 (levels, number and frequency of contaminants).
HBCDD is a substance (group) on the revised Water Framework Directive (WFD) Priority Substance list. It has also been identified as a Substance of Very High Concern (SVHC), meeting the criteria of a PBT (persistent, bioaccumulative and toxic) substance pursuant to Article 57(d) in the REACH (Registration, Evaluation, Authorisation and Restriction of Chemicals) regulation.
HBCDD is included in Annex XIV of the REACH regulation based on its hazardous properties, the volumes used and the likelihood of exposure to humans or the environment (European Commission 2011). This means that HBCDD cannot be used or placed on the market without first being approved by the European Chemicals Agency, ECHA. According to the harmonized classification and labelling (ATP03) approved by the European Union, this substance is suspected of damaging fertility or the unborn child and may cause harm to breast-fed children.
In December 2009, HBCDD was considered by the Executive Body (EB) of the UNECE (United Nations Economic Commission for Europe) Convention on Long-Range Transboundary Air Pollution (LRTAP) to meet the criteria for POPs, set out in EB decision 1998/2. Since 26th of November 2014, HBCDD is listed in Annex A of the Stockholm Convention, meaning that parties must take measures to eliminate the production and use of the chemical.
The commercially available brominated flame retardant hexabromocyclododecane (HBCDD or HBCD) is lipophilic, has a high affinity to particulate matter and low water solubility. The technical product consists of three stereoisomers, 70–95 % γ-HBCDD and 3–30% of α- and β-HBCDD, proportions depending on the manufacturer and the production method used. However, HBCDD is known to undergo thermal rearrangement, i.e. a shift in the relative amount of each stereoisomer can be seen if HBCDD, or a material containing HBCDD, is heated above 140°C. This has for instance been shown by Peled et al. (1995) and Heeb et al. (2010). The result of the transformation is that a relative increase of α-HBCDD and a relative decrease of γ-HBCDD could be observed. The transformation rate is dependent on time and temperature. HBCDD in this core indicator refers to the sum of the three diastereoisomers unless otherwise stated.
HBCDD is persistent in air and is subject to long-range transport. It is found to be widespread also in remote regions, and found in e.g. air and biological samples in the Arctic region (de Wit et al. 2006, EFSA 2011). The low volatility of HBCDD has been predicted to result in significant sorption to atmospheric particulates, with the potential for subsequent removal by wet and dry deposition. The transport potential of HBCDD was considered to be dependent on the long-range transport behaviour of the atmospheric particles to which it sorbs.
HBCDD has a strong potential to bioaccumulate and biomagnify. Available studies demonstrate that HBCDD is well absorbed from the rodent gastro-intestinal tract. Of the three diastereoisomers constituting HBCDD, the α-form is much more bioaccumulative than the other forms. HBCDD is very toxic to aquatic organisms. In mammals, studies have shown reproductive, developmental and behavioural effects with some of the effects being trans-generational and detectable even in unexposed offspring (Eriksson et al. 2006; Viberg et al. 2006, 2007). Beside these effects, data from laboratory studies with Japanese quail and American kestrels indicate that HBCDD at environmentally relevant doses could cause eggshell thinning, reduced egg production, reduced egg quality and reduced fitness of hatchlings (Fernie et al. 2009). Recent advances in the knowledge of HBCDD-induced toxicity includes a better understanding of the potential of HBCDD to interfere with the hypothalamic-pituitary-thyroid (HPT) axis, its potential ability to disrupt normal development, to affect the central nervous system, and to induce reproductive and developmental effects.
HBCDD has been found in human blood, plasma and adipose tissue. The main sources of exposure to humans presently known is through contaminated food and dust. For breast feeding children, mothers' milk is the main exposure route, but HBCDD exposure also occurs at early developmental stages as it is transferred across the placenta to the foetus. Swedish human breast milk data from 1980 to 2004 show that HBCDD levels have increased since HBCDD was commercially introduced as a brominated flame retardant in the 1980s (Fängström et al. 2008). Though information on the human toxicity of HBCDD is to a great extent lacking, and tissue concentrations found in humans are seemingly low. Embryos and infants are vulnerable groups that could be at risk, particularly to the observed neuroendocrine and developmental toxicity of HBCDD.
Because of the properties of HBCDD as a persistent, bioaccumulating, and toxic compound and in combination of the globally extensive use, HBCDD is considered a relevant substance to monitor in the entire Baltic Sea area. Monitoring species are available, and the substance is expected to be found in the whole area.
Use of synthetic compounds to increase fire resistance of materials.
Substances, energy and litter- Input of other substances (e.g. synthetic substances, non-synthetic substances, radionuclides) - diffuse sources, poit sources, atmospheric deposition, acute-events.
The HBCDD is mainly used in expanded polystyrene (EPS) and extruded polystyrene (XPS) in the construction industry (as thermal insulation), as well as coating of textiles to improve their fire resistance (Marvin et al. 2011; ECB 2008; EFSA 2011). Furthermore, HBCDD is present in a number of different consumer products, mainly packaging material but also polystyrene food containers and foam boards (Rani et al. 2014). The use of HBCDD globally is extensive and the use in EU (not counting imported articles and products containing HBCDD) was estimated to be around 12,000 tonnes in 2006 (Relevance figure 1).
Since HBCDD is used as an additive flame retardant (i.e. not chemically bound to the material) the release of HBCDD occurs by leaching from the material to which it was added (http://chm.pops.int; EFSA 2011). There are a number of studies which identify HBCDD in different media, e.g. in air (EFSA 2011), moss – atmospheric deposition (Schlabach et al. 2002) and soil (Covaci et al. 2009). Furthermore, HBCDD has been shown to be taken up by plants (Li et al. 2011). Covaci et al. (2006) concludes that α-HBCDD is the most commonly occurring diastereoisomer in wildlife.
Estimated emissions within the EU from HBCDD production and handling, associated with micronizing (fine grade grinding) of HBCDD is about 3 kg per year. The estimated release of particles during usage of EPS and XPS has been estimated to 100 g per tonne EPS and 5 g per tonne XPS. This amounts to an estimated release of approximately 560 kg HBCDD per year (of which 530 kg and 30 kg are from the use of EPS and XPS, respectively, assuming a use of 3% HBCDD in both EPS and XPS). This can be compared to a total estimated release of around 3000 kg per year in the EU, including all known sources (ECHA, 2009).
Relevance figure 1. The use of HBCDD in the EU during the years 2006–2007 expressed in tonnes per year. EPS = Expanded polystyrene, XPS = Extruded polystyrene and HIPS = High impact polystyrene, minor sources are not shown as bars. Adapted from ECHA 2009.
The estimated degradation and persistence of HBCDD differs somewhat depending on type of test and experimental setup, but some studies have identified debrominated transformation products, and a shorter half-life has been seen in anaerobic compared to aerobic conditions (EFSA 2011). In vitro experiments have shown that mammalian hepatic microsomes can debrominate HBCDD and that γ-HBCDD is metabolized faster than α-HBCDD (MacInnis et al. 2010).