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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

In a Closed Bottle Test conducted according to OECD TG 301 D, EU Method C.4.E and OPPTS 835.3110, the test item was determined to be readily biodegradable (5.2.1 -1).

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information

A Closed Bottle Test was conducted under GLP-conditions, according to the guidelines OECD TG 301 D, EU Method C.4.E and OPPTS 835.3110, in order to check the rate of biodegradation [%] of the test item 6-Aminocaproic acid by determination of oxygen uptake of the microorganisms during exposure (5.2.1 -1). The test was carried out over a period of 28 days with non-adapted activated sludge from a municipal sewage treatment plant. The activated sludge was pretreated by washing with isotonic saline solution, resuspension in mineral salts medium and aeration for 6 days at the test temperature. 2.0 mL/L test medium were used for inoculation (cell concentration of pre-conditioned inoculum: 104‑105 cells/L). The test item was tested in duplicates at a concentration of 10.0 mg/L, which corresponds to a ThODNH4of 6.2 mg O2/L. A procedure control with the reference substance sodium benzoate and also a toxicity control, containing the test item as well as the reference item was performed simultaneously.

In result, the test item replicates exceeded the 10 % level unequivocally and passed the level of 60 % on day 3. Futhermore, after 28 days a biodegradation of 83.9 % (based on its measured COD) was reached.In thistest the test item biodegradation curve reached its plateau about on the 5thday, from that day slight increases in biodegradability values occurred. The biodegradation of the procedure control passed the level of 60 % after 5 days and after 28 days a biodegradation of 79.6% was determined. In the toxicity control the biodegradation came to 45.2% after 28 days, thus no inhibtion of biodegradation by the test item was observed.

 

In conclusion, all validity criteria were fulfilled. The test item is regarded to be in the 10-d-window and after 28 days readily biodegradable.