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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

The ready biodegradability of the test substance was examined in a test (BASF SE, 21G0474/083472, 2008) according to the OECD 301 A (Ready Biodegradability: DOC Die Away Test, 2008) under GLP conditions. The removal of dissolved organic carbon (DOC) after an exposure period of 28 days was determined to be < 10 % (mean value of two tests assays). Therefore the test substance was found to be not readily-biodegradable under the test conditions and the 10 days windows criteria was consequently not fulfilled. 

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed

Additional information

The ready biodegradability of the test substance was examined in a test (BASF SE, 21G0474/083472, 2008) according to the OECD 301 A (Ready Biodegradability: DOC Die Away Test, 2008) under GLP conditions. The biodegradation of the test substance was followed by exposure to the activated sludge of a domestic waste water treatment plant from Mannheim (Germany). An appropriate aliquot of the activated sludge suspension was pre-aerated for about 24 hours before exposure. The concentration of the sludge was adjusted to 6 g/L dry weight. The concentration of the test substance was 31 mg/L (corresponding to 20 mg/L DOC). The DOC Die Away test was performed in 2 L conical flaks filled up to a volume of 1000 mL. For preparation of the test assays, first the required volume of demineralized water and the solutions of mineral medium were dosed to the test vessels. The blank control assays (BC) was prepared with only mineral medium. The test substance assays (TS) was prepared with the test substance with concentration of 20 mg/L DOC; the reference substance assay (RS) was prepared with aniline with a concentration of 20 mg/L DOC. The assay for inhibition control (IH) was prepared with the test substance and the reference substance in the same concentration in relation to its dissolved organic carbon contents. The test of physical chemical elimination (PC) was prepared with test substance in the concentration of 20 mg/L DOC. For avoidance of bacterial grow the assay was inhibited by adding of 10 mg/L mercury chloride. The test assay of adsorption control (AC) was prepared in the same way. The pH-values of all test assays were measured and adjusted to 7.4 ± 0.2. Aliquots of the prepared inoculum suspension were added to all test vessels (exceptional PC- assay); to adjust a concentration of activated sludge of 30 mg/L dry weight. The test assays were mixed carefully before sampling for DOC-measurement at the begin of exposure. The sampling in the AC test assay was performed before adding of the inoculum. The reference substance (aniline) was biodegraded 92 % (DOC) after 14 days, the biodegradation degree in the inhibition control after 14 days was determined to be 47 % (DOC), the physico-chemical (abiotic) elimination of the test substance (% DOC) after 28 days was determined to be < 10 % and the degree of the elimination of the test substance by adsorption (% DOC) was determined to be < 10 % after 7 days. The validity criteria were fulfilled. The removal of dissolved organic carbon (DOC) after an exposure period of 28 days was determined to be < 10 % (mean value of two tests assays). Therefore the test substance was found to be not readily-biodegradable under the test conditions and the 10 days windows criteria was consequently not fulfilled.