Registration Dossier

Environmental fate & pathways

Biodegradation in water: screening tests

Currently viewing:

Administrative data

Link to relevant study record(s)

Description of key information

The test substance was assesed for ready biodegradation using a closed vessel test according to OECD Test Guideline 301 B. The test substance achieved 11.3 % biodegradation in 28 days and therefore cannot be classified as being readily ultimately biodegradable.
The test substance was also assessed for inherent biodegradability using a modified closed bottle test. The test substance exhibited little or no biodegradation under the modified test conditions.

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed

Additional information

The test substance was assessed for ready biodegradation according to OECD Test Guideline 301 B using a closed vessel test. The test substance achieved 11.3 % biodegradation in 28 days and therefore cannot be classified as being ultimately readily biodegradable.

The test substance was also assessed for inherent biodegradation. The test conditions employed in this study were based on those of the ready biodegradability test with the exception that the incubation period was extended from 28 days to 56 days. Because of this modification the test cannot be considered as an assessment of ready biodegradability but it is an indicator of inherent and ultimate biodegradability. However, it must be noted that this modified sealed vessel test is not an OECD / EEC method for the assessment of inherent biodegradability and the results are not comparable. The standard inherent tests (OECD 302 series) have a higher concentration of micro-organisms and hence offer a higher chance of detecting biodegradation than ready test conditions.

In the OECD / EEC approved test for inherent biodegradability 70 % Dissolved Organic Carbon (DOC) removal is the accepted pass level. However, for this modified sealed vessel ready test a substance was considered to classify as inherently biodegradable if the extent of biodegradation (measured as CO2 production) after 56 days was 60 % or greater. This level was selected on the basis that as a pass criterium in tests of ready biodegradability 60 % CO2 production is equivalent to 70 % Dissolved Organic Carbon removal.

The test substance exhibited little or no biodegradation under the modified ready test conditions.