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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

The substance is considered to be readily degradable on the basis of the results of a well reported, GLP-compliant, guideline ready biodegradability study, without deviations, which is considered to be key, and which is further supported by a less well reported, guideline ready biodegradability study and a study reporting 84% biodegradation after 14 days.  The substance is readily biodegradable under the conditions of the tests.

Key value for chemical safety assessment

Biodegradation in water:
readily biodegradable
Type of water:
freshwater

Additional information

The key study is a Klimisch-1, GLP-compliant, guideline study without deviation and carried out according to the Manometric Respirometry test (OECD 301 F, EC C.4-D). Nominal initial test substance concentration was 102 mg/L, corresponding to 252 mg ThOD/L. The test was performed using aerobic activated sludge microorganisms . The test substance achieved a mean degradation of 61% by day 7, and 83% by the end of the study. The day-7 results clearly show that the 10-day window criterion was met. The substance is considered to be readily biodegradable under the conditions of the test. Also, a toxicity control containing both the test substance and sodium benzoate achieved >25% (64%) degradation after 14 days, showing that the test substance can be assumed not to be inhibitory to aerobic activated sludge microorganisms.

A supporting study conducted in accordance with the Modified MITI Test I (OECD 301 C, EU C.4-F) in 1975 is reported by the Japanese National Institute of Technology and Evaluation (NITE). Nominal initial test substance concentration was 100 mg/L. The test was performed using aerobic activated sludge microorganisms collected from sewage, soil and natural waters at 10 sites around Japan, at a concentration of 30 ppm. The duration of the test was only 14 days, after which the test substance had achieved a degradation of 84% measured by oxygen uptake, 97.1% measured by TOC removal, and 100% measured by GC analysis of the test substance. No data to confirm the validity of the test were specifically reported, but the tests are understood to be considered valid if the aniline reference substance achieved >40% degradation by day 7 and >60% degradation by day 14. No data was reported to indicate whether or not the 10-day window criterion was met, but the test substance was reported to be readily biodegradable.