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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

An OECD guideline 301 D, closed bottle test, was performed on Akypoquat 131: 64.3% and 71% biodegradability was observed after 15 and 28 days, respectively and 60% degradation was achieved within the 10 day window.

The substance is therefore considered as readily biodegradable meeting the 10-d window criterion.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information

A ready biodegradability study was performed to assess the biotic degradation of the test item according tothe OECD Guideline 301 D.

BOD bottles were filled with mineral medium inoculated withinfluent + effluent sewage plantand test substance added at the following concentrations of 22.1, 7.63, 4.37 and 2.93 mg/L; 15.2, 6.24, 3.89 and 2.45 mg/L; 10.8, 5.79, 3.42 and 2.45 mg/L. Mineral nutrient solution without test substance without inoculum (2 replicates) and Mineral nutrient solution without test substance but with inoculum (2 replicates) were included.

The concentrations of dissolved oxygen in bottles from each group incubated at 20 °C in darkness were measured at the start of the test and 5, 15 and 28 days.

4 measured concentrations: the first concentration tested is unacceptable (too high); The test substance was biodegraded by 71 % after 28 days (mean of the 3 lowest tested concentrations) and 64.3 % of biodegradability after 15 days (mean of the 3 lowest tested concentrations). Therefore test substance is readily biodegradable, 10-day window criteria fulfilled.

Test substance is considered as readily biodegradable based on the biodegradation percentage of 71 % at day 28 and 10 days window criteria fulfilled.