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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

The test substance was not readily biodegradable under the conditions of this test (< 10% CO2/ThCO2). The required pass level for ready biodegradability within a ten days window was not reached. 

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed

Additional information

Biodegradation in water: screening tests

Key study

The carbon dioxide evolution test (former Sturm test) is a static method to evaluate the ultimate aerobic biodegradability of a test substance in water. The test was conducted according to guideline under GLP conditions. The test substance, a defined inorganic medium and inoculum (municipal activated sludge from wastewater treatment plant) were incubated and aerated at up to 28 days. The biologically produced carbon dioxide is trapped and measured. The biodegradation degree is expressed as produced carbon dioxide in relation to the calculated theoretical carbon dioxide value (ThCO2) using the initial concentration of total organic carbon of the test substance (TOC). In addition, the dissolved organic carbon (DOC) content was determined to be < 10%.

The degree of biodegradation was < 10% CO2/ThCO2 after an exposure period of 28 days. The test substance was not readily biodegradable under the conditions of this test. The required pass level for ready biodegradability within a ten days window was not reached.

 

Supporting study

The bioelimination of the test substance (12% act. ingr.) was determined in a Zahn-Wellens/EMPA test according to OECD 302B. The test substance was tested at a nominal concentration of 1 mg/L. Two tests were running parallel. The test was terminated after 3 hours, because only the bioelimination by adsorption should be determined.The adsorption of the test substance after 3 hours was 80%.

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