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PBT assessment

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PBT assessment: overall result

PBT status:
the substance is not PBT / vPvB

An evaluation of the inherent properties of the test substance is performed against the ANNEX XIII criteria. If insufficient data were available, the screening criteria as laid down in ECHA Guidance on information requirements and chemical safety assessment Chapter R.11: PBT Assessment (2014) were applied. The persistency assessment is based on the screening criteria in Annex XIII of the REACH Regulation.


The biodegradation potential of the test substance has been assessed in a OECD 301B / EC Method C.4-C and in an enhance test. The results of the regular test reveal that the test substance does not degrade (ca. 21% observed under the conditions of the test). In the enhanced test, the substance shows 15% degradation after 28 days, and 18% degradation after 42 days, suggesting that some constituents of this UVCB substance can be (partially) degraded. As the degradation percentage is not <10%, the substance cannot be easily compared with the screening criteria. As the screening criteria for not P and not vP and the screening criteria for P are currently not fulfilled, the substance will be regarded as potentially P. Results of a QSAR exercise using BIOWIN v4.10, provided further information on the ready biodegradation of 8 constituents which lacked data on biodegradation. Only 2 of these constituents were predicted to be readily biodegradable. Taking into all the information, it can be concluded that based on the criteria mentioned above the substance is persistent in the environment. The substance is concluded to be P/vP.


The bioaccumulation assessment is based on the screening criteria in Annex XIII of the REACH Regulation. A measured Log Kow of < 0.565 at 20°C have been determined in a study equivalent to the EU A.8 guideline. Since the measured log Kow is below the criterium of log Kow < 4.5 no further assessment on bioaccumulation is needed. This is further supported by results of a QSAR exercise that aimed to generate BCF data for 8 constituents for which data on bioaccumulation and/or hydrophobicity was lacking. This exercise further confirmed very low potential for bioaccumulation. Based on all the available information, the test substance is concluded to be not B/vB.


The toxicity assessment is based on the screening criteria in Annex XIII of the REACH Regulation. As the test substance does not fulfil any of the screening criteria, it is considered to be not Toxic.


In addition, the EAWAG-BBD PPS tool was used to predict biotransformation products likely or very likely to be formed through aerobic microbial degradation. The 42 transformation products that were identified, were assessed for potential PBT/vPvB properties using appropriate QSAR models. The biodegradability, log Kow and ecotoxicity of the modelled (end) products were predicted using the relevant models available in the EPI Suite software. The vast majority of the degradation (end) products were predicted to be biodegradable and therefore considered to be not potentially P/vP. The log Kow values for all of the predicted metabolites were estimated to be less than 4.5 (all were below zero) and therefore none of those metabolites is expected to have a high potential for bioaccumulation. Their aquatic toxicity was also very low. Based on the available data it can be concluded that neither of the potential degradation (end) products are likely to be PBT/vPvB. As none of the metabolites is a potential PBT/vPvB substance, this further supports the conclusion that the substance should not be considered as a PBT/vPvB substance.


In conclusion, taking into account that the substance is P/vP,  not B/vB and not T, the substance should not be considered as a PBT/vPvB substance.