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Environmental fate & pathways

Biodegradation in water and sediment: simulation tests

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Description of key information

Standard biodegradation studies are not applicable to petroleum UVCB substances, therefore in accordance with Annex XI Section 1.3 testing is not scientifically necessary and the endpoint has been fulfilled using QSAR calculations for relevant constituents.  PETRORISK is a well documented and peer reviewed model that is widely used across the petrochemicals industry. This substance fits within the criteria of the model and there are no reservations about the validity of the model runs. It is expected that this data is reliable with restrictions.

 

QSAR predictions of half-lives of VHGO have also been provided to support the read-across from VHGO to registration substance.

Key value for chemical safety assessment

Additional information

The predicted degradation half-lives in surface water and sediment for constituents of this substance range between 1 and 33,435 days and 5 and 133,742 days, respectively.

 

It should be borne in mind that this is the full range of predicted values, and that this may be misleading or unrepresentative of the properties of the UVCB substance as a whole. The range should therefore be treated with caution and not taken out of context.   The substance is a hydrocarbon UVCB. Standard tests for this endpoint are intended for single substances and are not appropriate for this complex substance. However, this endpoint is characterised using quantitative structure property relationships for representative hydrocarbon structures that comprise the hydrocarbon blocks used to assess the environmental risk of this substance with the PETRORISK model (see Product Library in PETRORISK report attached in IUCLID section 13).  

For purposes of PBT assessment, the substance has been assessed using a combination of QSAR predictions and confirmatory experimental testing for representative constituents using a hydrocarbon block approach. For details see report titled 'Evaluation of PBT for Petroleum Substances' in IUCLID section 13.