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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

The biodegradation of cloquintocet-mexyl in water was determined in a ready biodegradation test according to the principles of the EU C4-C (CO2 Evolution Test) method.  Although significant degradation of the test material was observed, the degree of degradation was not sufficient to conclude cloquintocet-mexyl as 'readily biodegradable'.

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed

Additional information

The key study (Baumann, 1993) investigated the biodegradation of cloquintocet-mexyl in water according to the EU C4 -C (CO2 Evolution Test) method. This study was GLP compliant and is considered to be reliable without restrictions.

A solution of the inoculated (activated sludge collected from a sewage treatment plant) mineral medium was spiked with 23.9 mg technical grade cloquintocet-mexyl as sole source of organic carbon and incubated at 22°C in the dark. Degradation was followed by determining the carbon dioxide produced which was trapped in sodium hydroxide solution. The amount of carbon dioxide produced from the test substance was expressed as percentage of the theoretical carbon dioxide. The mineralisation of cloquintocet-mexyl under the test conditions was 38 % in 29 days. Based on this result, cloquintocet-mexyl is classified as ‘not ready biodegradable’.