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Classification & Labelling & PBT assessment

PBT assessment

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PBT assessment: overall result

PBT status:
the substance is not PBT / vPvB
Justification:

Evaluating the PBT/vPvB potential of multi-constituent substances is known to be difficult as persistence and bioaccumulation testing methods are not applicable (or at least difficult to apply) for these substances. Therefore, an evaluation based on experimental results and QSAR for each constituent and impurity was performed.

Reaction mass of 2,2'-oxybisbutane (DSBE), DIPE, SBA and 2-methylpropan-2-ol (TBA) was not ready biodegradable according to testing. However, volatile ethers and olefins present in this substance are known to be subject to degradation in the atmosphere, atmospheric oxidation half-lives of 1 – 4 hours according to QSAR estimations. It can therefore be concluded that reaction mass of 2,2'-oxybisbutane (DSBE), DIPE, SBA and 2-methylpropan-2-ol (TBA) probably do not fulfil the criteria for P and vP in the environment with the exception of TBA, which may possibly fulfil the criteria. 

 According to the short-term ecotoxicity testing, reaction mass of 2,2'-oxybisbutane (DSBE), DIPE, SBA and 2-methylpropan-2-ol (TBA) does not fulfil the T screening criteria presented in the TGD IR & CSR, 2008, Chapter R.11.1, even under the assumption that the toxicity is only due to one of the constituents or one of the four representative impurities. QSAR calculation confirmed that impurities do not meet the screening criteria for T. Furthermore, the T criterion is not fulfilled based on currently available human toxicity data.

The evaluation of the bioaccumulation potential was principally based on Log Kow values of the identified main constituents. All the Log Kow values found in the literature or calculated by QSAR were < 3, or < 4.5 for DSBE (highest Log Kow = 3.8). Based on this Log Kow value, a BCF of 230 was calculated for DSBE, which is far below the B and vB criteria according to Annex XIII. Log Kow up to 4.17 were calculated by QSAR for C8 olefins present as impurities, but these substances are expected to have BCF < 1000 and biotransformation half-lives of 1.5 – 3.0 days only. All constituents and impurities present in the substance are thus considered not to meet the criteria for a classification as B or vB.

 In conclusion, reaction mass of 2,2'-oxybisbutane (DSBE), DIPE, SBA and 2-methylpropan-2-ol (TBA) does not contain substances fulfilling the criteria for T, B and vB, and is therefore not classified as PBT or vPvB. Evidences that representative impurities do not fulfil the PBT/vPvB criteria are also shown.