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PBT assessment

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PBT assessment: overall result

Reference
Name:
Decabromodiphenyl ethane
Type of composition:
legal entity composition of the substance
State / form:
solid: particulate/powder
Reference substance:
Decabromodiphenyl ethane
PBT status:
the substance is not PBT / vPvB
Justification:

Persistence:

EBP was demonstrated to be stable and not biodegrade in several test systems, STP simulation systems, aerobic and anaerobic sediment and soil studies according to standard OECD test guidelines (OECD 308 and 307), but with prolonged exposure durations of 6 months. In the sediment it was verified that microorganisms capable of degrading organo-halogen compounds were present. A recent study in aerobic soils with 6 plant species also showed no fromation of metabolites during the 61d exposure period. A study carried out to mimick recycling in HIPS manufacture containing EBP and EBP and Sb2O3 under realistic worst case conditions and temperatures also revealed that the substance remained stable and only a minor increase of the Br9 -isomers occurred after 6 recycling cycles. Several studies in polymers and under incineration conditions have demonstrated that no polybrominated dioxin or-furans are formed during those processes.

Thus it can be concluded that the substance itsself is very peristent and does not form degradation products that could have a higher bioaccumulation or toxicity potential under environmental conditions or under reasonable worst case use conditions.

Bioaccumulation:

Two recent guideline studies according to OECD 305 and GLP with dietary exposure were performed following the substance evaluation decision. These studies demonstrated the  extremely low potential for bioaccumulation of EBP compared to known reference substances. It could also be confirmed in those studies that the substance is hardly absorbed from the gastro-intestinal tract and the low tissue levels are depurated quickly. EBP was also used as a benchmark chemical that is poorly absorbed in fish by Xiao et al. 2013. With reagrd to a possible bioaccumulation potential in terrestrial organisms, several studies have shown that a trophic magnification is unlikely and the rat toxicokinetic study also suggests very little absorption and uptake in mammalian tissues after a single oral exposure.

To investigate the uptake after repeated exposure a testing proposal for toxikokinetics in rats after repeated exposure has also been made in the last update of this dossier together with a proposal for an extended one generation study, should considerable uptake occur.

T:

The substance is not toxic to aquatic organisms up to the solubility limit. A recent 21 -d Daphnia reproduction study revealed no effect when tested at the solubility limit in the test medium. In soil and sediment organisms very high NOAECs were observed.

L. varigaetus and chironmus, NOEC=5000 mg/kg sediment dw. Mammalian toxicity studies after single and prolonged exposure did not reveal adverse effects up to the limit dose of 1000 mg/kg bw.

Likely routes of exposure:

EBP is very poorly absorbed by all routes of exposure. It has negligible solubility in water and binds to particulates which will settle out of solution. Thus, water exposures are not expected to be significant. It's very low vapor pressure indicates it will not partition to the gas phase; binding to air particulates which settle out is likely. Significant exposure via inhalation is not expected. If present in sewage influent, EBP is likely to bind to particulates in the sludge. Sludge applied to agricultural soil may be a route for a transport to that matrix, where EBP will be immobile.