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Environmental fate & pathways

Biodegradation in water: screening tests

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Reference
Endpoint:
biodegradation in water: ready biodegradability
Type of information:
other: Expert assessment
Adequacy of study:
key study
Study period:
February 20, 2018
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: An assessment was performed based on QSAR modelling and available experimental data for a suitable analogue.
Qualifier:
no guideline followed
Principles of method if other than guideline:
An assessment was performed based on QSAR modelling and available experimental data for a suitable analogue.
GLP compliance:
no
Oxygen conditions:
aerobic
Inoculum or test system:
other: An assessment was performed based on QSAR modelling and available experimental data for a suitable analogue.
Key result
Parameter:
other: Ready biodegradability
Remarks on result:
other: Readily biodegradable according to QSAR prediction and read-across from a structural analogue
Validity criteria fulfilled:
not applicable
Remarks:
Expert assessment
Interpretation of results:
readily biodegradable
Conclusions:
According to QSAR modelling of trans-hex-2-en-1-ol in BioWin v4.10 and available experiment data for a suitable structural analogue, it has been concluded by expert assessment that the registered substance is readily biodegradable under aerobic conditions.
Executive summary:

To determine ready biodegradability potential of trans-hex-2-en-1-ol, an assessment was carried out with Quantitative Structure–Activity Relationship (QSAR) modelling in the Biodegradation Probability Program for Windows (BioWin) v4.10. The model is built in the Estimation Program Interface (EPI) Suite™ and it calculates the probability of a particular substance biodegrading based on the known properties of its individual fragments. Appropriate documents were referred to in order to aid modelling and evaluation, including OECD (2009): 'Guidance Document for Using the OECD (Q)SAR Application Toolbox to Develop Chemical Categories According to the OECD Guidance on Grouping of Chemicals', OECD (2014): 'Guidance on Grouping of Chemicals', and ECHA (2017): 'Guidance on Information Requirements and Chemical Safety Assessment. Chapter R.7b: Endpoint Specific Guidance - Version 4.0'. Experimental data from two studies was analysed to permit read across from a suitable structural analogue and support the QSAR prediction. The analogue substance was regarded as being suitable for read across to trans-hex-2-en-1-ol due to a shared C6 aliphatic chain and it is anticipated, therefore, that the analogue should exhibit similar environmental fate and behaviour.

The results of the QSAR prediction satisfied all cut-off criteria between ready and non-ready biodegradability provided by ECHA (2017), as well as meeting the criteria specified for ready biodegradability outlined in the BioWin v4.10 model. The time required for complete molecule mineralisation was estimated to require a time period of days to weeks. The ready biodegradability prediction for trans-hex-2-en-1-ol was supported by experimental data for the structural analogue, which similarly demonstrated a predisposition to readily biodegrade under aerobic test systems.

Trans-hex-2-en-1-ol can subsequently be regarded as readily biodegradable under aerobic conditions.

Description of key information

Trans-hex-2-en-1-ol was concluded to be readily biodegradable by expert assessment of a Quantitative Structure–Activity Relationship (QSAR) model prediction from BioWin v4.10 and available experiment data for a suitable structural analogue, which permitted read across and supported the endpoint conclusion.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information

A Klimisch score of 2 (reliable with restrictions) was assigned to the endpoint value for ready biodegradability given that it was deduced by expert assessment of a weight of evidence. Recommended OECD (2009; 2014) and ECHA (2017) guidance was referred to in order to adequately perform QSAR prediction and the experimental studies evaluated to support read across from the structural analogue had satisfied all study validity criteria and were regarded as reliable (Klimisch score = 2). The endpoint conclusion can subsequently be considered a key value for use in chemical safety assessment.