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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

Aerobic biodegradation: readily biodegradable (OECD guideline 301A, GLP)
Anaerobic biodegradation: no biodegradation observed under experimental condictions; potentially toxic to bacteria at the concentration required by the guideline (OECD guideline 311, GLP)

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable

Additional information

Aerobic biodegradation

The ready biodegradability of DOPA-Glycinate (99.4% a.i.) was tested in the DOC die-away test (OECD 301A, EC C.4-A). The performance of the study was compliant to the stated guidelines.

Deviating from the guideline, test substance concentration was restricted to only 5.17 mg/L DOC due to its microbicidal properties. The employed concentration was below toxic levels, as also confirmed by the toxicity control.

The test substance was degraded by 94% (DOC removal) at the end of the test. The pass level of 70% was reached after 7 days, thus being within the 10-d window.

The test substance is not known to exhibit properties having impact on the results. The validity criteria were fulfilled. The test results indicate that the substance is readily biodegradable.

 

Anaerobic biodegradation

The biodegradation of DOPA-Glycinate at a concentration of 100 mg Corg/L was investigated according to OECD guideline 311 over a 60-day period in anaerobic aqueous medium. As inoculum microorganisms from a digester of a sewage treatment plant mainly fed with municipal wastewater were used. The rate of degradation was monitored by measuring the increase in headspace pressure in the vessels resulting from the production of carbon dioxide and methane. The amount of inorganic and methane carbon resulting from the biodegradation of the test item was calculated from the net gas production and net IC formation in the liquid phase in excess over blank control values. The extent of biodegradation was calculated from total IC and methane-C produced as a percentage of the calculated amount of carbon added as test compound.

The anaerobic biodegradation of DOPA-Glycinate was found to be 0 % after 60 days. Therefore, the test substance must be considered as not readily biodegradable under the chosen test conditions. The degradation in the toxicity control (–38 to –34 %) was lower than the degradation in the functional control (94 %). Due to the same concentration of reference item in both experimental approaches, degradation under 50 % in the toxicity control indicates an inhibiting effect of the test item on the degradation of the reference item. This signified an antibacterial effect of DOPA-Glycinate under test conditions.

Due to the results the test item can be identified as non-biodegradable under anaerobic conditions and potentially toxic to bacteria at the concentration required by the guideline.

The test item was employed at a concentration that is potentially toxic to micro-organisms. The test item concentration is, however, within the range demanded by the test guideline. Thus, the study is considered to be valid with restrictions only.