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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

The available screening testing data relevant to the FLL Substances provide a weight of evidence for ready biodegradability. In this case, the appropriate conclusion (from page 23 of Chapter R.11 of ECHA guidance) is as follows: 
• Evidence of ready biodegradation - If the substance is readily biodegradable, or if the criteria for ready biodegradability are fulfilled with exception of the 10-day window, there is no reason to perform further biodegradation tests for the PBT/vPvB assessment. The conclusion is that the substance is not fulfilling the criteria for Persistence (P)
However, given that ready biodegradability was not observed for one of the tests, there is uncertainty in this conclusion and, therefore, the results of QSAR modelling were also considered as additional evidence.
The BIOWIN predictions indicate that the fish oil derivative would not satisfy the QSAR criteria for classification as P. However, there is some uncertainty in this conclusion given that the BIOWIN 6 probability was <0.5 for the fish oil derivative (meaning that the second criterion is partially fulfilled).
START Biodegradability is Class I (easily biodegradable chemical) for the molecule. The START Biodegradability QSAR is a rule-based system based on structural alerts for persistence or easy biodegradability from Environment Canada's Categorization Program (Environment Canada, 2003).
These results support the conclusion of not P that is reached by the BIOWIN modelling described above.

Key value for chemical safety assessment

Additional information

Refer to Chapter 8 "PBT assessment" of the CSR