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PBT assessment

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PBT assessment: overall result

PBT status:
further information relevant for the PBT assessment is necessary

Rosin ester substances are UVCB substances made up of constituents with different properties, which will behave differently when released to the environment. The PBT assessment of rosin ester substances therefore considers the PBT potential of each of the constituents, rather than the substance as a whole.

Rosin ester substances consist of esters of rosin, and non-esterified resin acids. The rosin esters can be mono-, di-, tri- or tetra-esters depending on the alcohol and the production process. Methanol can form mono-esters, ethylene glycol, diethylene glycol and triethylene glycol can form mono- and di-esters, glycerol can form mono-, di- and tri-esters and pentaerythritol can form mono-, di-, tri- and tetra-esters. In each case, the esterification reaction results in a UVCB containing esters with varying numbers of ester bonds, formed by the reaction of the various resin acids with the alcohol. In addition, non-esterified resin acids will also remain as constituents in the UVCB.

As the substances contain too many constituents to assess each one individually, representative structures have been assessed in order to screen the potential for persistence and bioaccumulation of different fractions within the UVCBs. Based on the results of the QSAR screening assessment, di, tri and tetra esters are not considered to be bioaccumulative and are therefore not PBT / vPvB. Free resin acids within the UVCBs are not considered to be persistent or bioaccumulative based on measured data, and are therefore not PBT / vPvB. Some mono-ester constituents exceed the screening criterion for bioaccumulation based on QSAR predictions, and biodegradation predictions are borderline for persistence. As the QSAR results show some uncertainty, directready biodegradation testing of the mono-ester fraction is currently ongoing to clarify the persistence assessment for these constituents. This testing was requested in Final Decision letters received from ECHA on 9 February 2017 for the category members resin acids and rosin acids, hydrogenated, esters with glycerol and resin acids and rosin acids, hydrogenated, esters with pentaerythritol.

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