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PBT assessment

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PBT assessment: overall result

PBT status:
the substance is PBT / vPvB
Justification:

At least o-terphenyl fulfils both vP and vB criteria. As o-terphenyl occurs in significant concentrations in the UVCB substance (> 0.1 %), the UVCB “terphenyl, hydrogenated” is considered to fulfil vPvB criteria.

The UVCB substance was assessed by evaluating the different relevant constituents present in the substance. Detailed information in provided in Section 8 of the CSR. 

The group level is used to group the constituents into groups of “similar” constituents (see Table 1 of CSR for an overview of the different groups, what they contain and their concentration range). In total 10 groups were identified:

Group T: the group containing the terphenyl constituents,

Group HT1: the group containing terphenyl structures of which one ring is hydrogenated,

Group HT2: the group containing terphenyl structures of which two rings are hydrogenated,

Group HT3: the group containing terphenyl structures of which three rings are hydrogenated,

Group Q: the group containing the quaterphenyl constituents,

Group HQ1: the group containing quaterphenyl structures of which one ring is hydrogenated,

Group HQ2: the group containing quaterphenyl structures of which two rings are hydrogenated,

Group HQ3: the group containing quaterphenyl structures of which three rings are hydrogenated,

Group P: the group containing the pentaphenyl constituents,

Group ‘other’ (1 & 2): other non-defined structures/constituents.

Justification of vPvB classification for o-terphenyl:

For ortho-terphenyl and meta-terphenyl, the potential for primary and ultimate degradation is demonstrated in studies on ortho-terphenyl. According to the approach of the study authors the half-life for disappearance of parent substance is below the threshold for freshwater and the original calculations based on study results revealed very short dissipation half-lifes- demonstrating that the mixture as tested does not persist in soil. Based on recent evaluation results of the eMSCA, the modelling approach chosen by the study authors was not appropriate to describe the degradation of the compound in soil. According to the outcome of remodelling of the study results by the eMSCA terphenyl fulfils the vP criterion in soil based on the degradation study by Monsanto Company (1989) and remodelling by eMSCA. The different isomers of terphenyl, quaterphenyl, and polyphenyl were not differentiated in this study. Nevertheless the reliability of this soil dissipation test is limited due to the fact that information on the composition of the tested mixture is missing. In general eMSCA considers that degradation of a hydrocarbon in a mixture study (such as Monsanto Company (1989)) may be overestimated compared to testing of each constituent separately (due to co-metabolism). However, in the present case the possible overestimation is acceptable as the half-life for terphenyl fulfills the vP criterion.