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Biodegradation in water: screening tests

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Description of key information

Degree of biodegradability of the test substance (trade name: Clearlink 1000) was determined by measuring 3 different parameters: 'BOD', 'DOC' and 'primary degradation based on the analysis of the test substance concentration' over a period of 28 days. This study was conducted in compliance with GLP and in accordance with OECD Guideline 301 C (Modified MITI Test). On  the basis of results of the study, the test substance was not found to be readily biodegradable. The percentage of biodegradability on the basis of BOD, DOC and test material analysis was measured to be 2, 0 and 0 respectively. 

Key value for chemical safety assessment

Biodegradation in water:
under test conditions no biodegradation observed

Additional information

Ready biodegradability of Clearlink 1000 in water was measured by conducting a study in accordance with GLP and OECD Guideline 301 C (Modified MITI Test). This study was considered as reliable with no restrictions and hence used as a key value for hazard assessment and classification and labeling of the substance.

Another test was also performed to assess the ready biodegradability of the test substance by exposing it to municipal activated sludge microorganisms for 29 days under controlled environmental conditions. A method for quantitative analysis (LC-MS) was used to directly measure the substance in the test cultures over time, following a simple extraction procedure. Since this study is not performed according to any standardized water screening test, it was used as a supporting study for chemical safety assessment.

Under the conditions of the key study, the test substance was not found to be readily biodegradable. The percentage of biodegradability on the basis of BOD, DOC and test material analysis was measured to be 2, 0 and 0 respectively.

Under the conditions of the supporting study, the test substance did not demonstrate biodegradability under the test conditions over 29 days incubation with aerobic municipal activated sludge. Sodium dodecyl sulfate (SDS) was used as the positive control. SDS was rapidly biodegraded in similarly prepared cultures, and also in test cultures when co-incubated with Clearlink 1000. Based on the results, the test substance was not observed to be toxic to the microorganisms as it did not inhibit removal of the reference substance from the cultures. In this study, it was determined that the test substance is recalcitrant to biodegradation over 29 days of incubation, and would not be expected to appreciably biodegrade in an aerobic biological waste water treatment processes. Based on the results of this study, it is unlikely that microbial adaptation toward Clearlink 1000 biodegradation would occur in those processes after prolonged exposures. Clearlink 1000 did not appear to be detrimental to the microbiological metabolic activity of the activated sludge based on the ability of the microbes to sufficiently biodegrade SDS in the presence of this substance.

Based on the results of both the studies, the test substance can be concluded as non-readily biodegradable.